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linux/drivers/misc/ntsync.c

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ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Rename NTSYNC_IOC_SEM_POST to NTSYNC_IOC_SEM_RELEASE. Use the more common "release" terminology, which is also the term used by NT, instead of "post" (which is used by POSIX). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:43 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Rename NTSYNC_IOC_SEM_POST to NTSYNC_IOC_SEM_RELEASE. Use the more common "release" terminology, which is also the term used by NT, instead of "post" (which is used by POSIX). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:43 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_MUTEX_UNLOCK. This corresponds to the NT syscall NtReleaseMutant(). This syscall decrements the mutex's recursion count by one, and returns the previous value. If the mutex is not owned by the current task, the function instead fails and returns -EPERM. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-7-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:47 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_PULSE. This corresponds to the NT syscall NtPulseEvent(). This wakes up any waiters as if the event had been set, but does not set the event, instead resetting it if it had been signalled. Thus, for a manual-reset event, all waiters are woken, whereas for an auto-reset event, at most one waiter is woken. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-12-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:52 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_SET. This corresponds to the NT syscall NtSetEvent(). This sets the event to the signaled state, and returns its previous state. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-10-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:50 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_PULSE. This corresponds to the NT syscall NtPulseEvent(). This wakes up any waiters as if the event had been set, but does not set the event, instead resetting it if it had been signalled. Thus, for a manual-reset event, all waiters are woken, whereas for an auto-reset event, at most one waiter is woken. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-12-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:52 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_SET. This corresponds to the NT syscall NtSetEvent(). This sets the event to the signaled state, and returns its previous state. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-10-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:50 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_RESET. This corresponds to the NT syscall NtResetEvent(). This sets the event to the unsignaled state, and returns its previous state. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-11-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:51 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_READ. This corresponds to the NT syscall NtQuerySemaphore(). This returns the current count and maximum count of the semaphore. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-13-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:53 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_READ. This corresponds to the NT syscall NtQueryMutant(). This returns the recursion count, owner, and abandoned state of the mutex. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-14-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:54 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_READ. This corresponds to the NT syscall NtQueryEvent(). This returns the signaled state of the event and whether it is manual-reset. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-15-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:55 -06:00
ntsync: fix a file reference leak in drivers/misc/ntsync.c struct ntsync_obj contains a reference to struct file and that reference contributes to refcount - ntsync_alloc_obj() grabs it. Normally the object is destroyed (and reference to obj->file dropped) in ntsync_obj_release(). However, in case of ntsync_obj_get_fd() failure the object is destroyed directly by its creator. That case should also drop obj->file; plain kfree(obj) is not enough there - it ends up leaking struct file * reference. Take that logics into a helper (ntsync_free_obj()) and use it in both codepaths that destroy ntsync_obj instances. Fixes: b46271ec40a05 "ntsync: Introduce NTSYNC_IOC_CREATE_SEM" Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250115025002.GA1977892@ZenIV Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-15 02:50:02 +00:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: fix a file reference leak in drivers/misc/ntsync.c struct ntsync_obj contains a reference to struct file and that reference contributes to refcount - ntsync_alloc_obj() grabs it. Normally the object is destroyed (and reference to obj->file dropped) in ntsync_obj_release(). However, in case of ntsync_obj_get_fd() failure the object is destroyed directly by its creator. That case should also drop obj->file; plain kfree(obj) is not enough there - it ends up leaking struct file * reference. Take that logics into a helper (ntsync_free_obj()) and use it in both codepaths that destroy ntsync_obj instances. Fixes: b46271ec40a05 "ntsync: Introduce NTSYNC_IOC_CREATE_SEM" Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250115025002.GA1977892@ZenIV Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-15 02:50:02 +00:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: fix a file reference leak in drivers/misc/ntsync.c struct ntsync_obj contains a reference to struct file and that reference contributes to refcount - ntsync_alloc_obj() grabs it. Normally the object is destroyed (and reference to obj->file dropped) in ntsync_obj_release(). However, in case of ntsync_obj_get_fd() failure the object is destroyed directly by its creator. That case should also drop obj->file; plain kfree(obj) is not enough there - it ends up leaking struct file * reference. Take that logics into a helper (ntsync_free_obj()) and use it in both codepaths that destroy ntsync_obj instances. Fixes: b46271ec40a05 "ntsync: Introduce NTSYNC_IOC_CREATE_SEM" Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250115025002.GA1977892@ZenIV Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-15 02:50:02 +00:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Rename NTSYNC_IOC_SEM_POST to NTSYNC_IOC_SEM_RELEASE. Use the more common "release" terminology, which is also the term used by NT, instead of "post" (which is used by POSIX). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:43 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_READ. This corresponds to the NT syscall NtQuerySemaphore(). This returns the current count and maximum count of the semaphore. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-13-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:53 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_UNLOCK. This corresponds to the NT syscall NtReleaseMutant(). This syscall decrements the mutex's recursion count by one, and returns the previous value. If the mutex is not owned by the current task, the function instead fails and returns -EPERM. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-7-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:47 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_READ. This corresponds to the NT syscall NtQueryMutant(). This returns the recursion count, owner, and abandoned state of the mutex. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-14-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:54 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_SET. This corresponds to the NT syscall NtSetEvent(). This sets the event to the signaled state, and returns its previous state. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-10-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:50 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_PULSE. This corresponds to the NT syscall NtPulseEvent(). This wakes up any waiters as if the event had been set, but does not set the event, instead resetting it if it had been signalled. Thus, for a manual-reset event, all waiters are woken, whereas for an auto-reset event, at most one waiter is woken. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-12-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:52 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_RESET. This corresponds to the NT syscall NtResetEvent(). This sets the event to the unsignaled state, and returns its previous state. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-11-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:51 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_PULSE. This corresponds to the NT syscall NtPulseEvent(). This wakes up any waiters as if the event had been set, but does not set the event, instead resetting it if it had been signalled. Thus, for a manual-reset event, all waiters are woken, whereas for an auto-reset event, at most one waiter is woken. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-12-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:52 -06:00
ntsync: Introduce NTSYNC_IOC_EVENT_READ. This corresponds to the NT syscall NtQueryEvent(). This returns the signaled state of the event and whether it is manual-reset. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-15-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:55 -06:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_SEM_POST. This corresponds to the NT syscall NtReleaseSemaphore(). This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:54 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Return the fd from NTSYNC_IOC_CREATE_SEM. Simplify the user API a bit by returning the fd as return value from the ioctl instead of through the argument pointer. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:42 -06:00
ntsync: fix a file reference leak in drivers/misc/ntsync.c struct ntsync_obj contains a reference to struct file and that reference contributes to refcount - ntsync_alloc_obj() grabs it. Normally the object is destroyed (and reference to obj->file dropped) in ntsync_obj_release(). However, in case of ntsync_obj_get_fd() failure the object is destroyed directly by its creator. That case should also drop obj->file; plain kfree(obj) is not enough there - it ends up leaking struct file * reference. Take that logics into a helper (ntsync_free_obj()) and use it in both codepaths that destroy ntsync_obj instances. Fixes: b46271ec40a05 "ntsync: Introduce NTSYNC_IOC_CREATE_SEM" Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250115025002.GA1977892@ZenIV Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-15 02:50:02 +00:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Return the fd from NTSYNC_IOC_CREATE_SEM. Simplify the user API a bit by returning the fd as return value from the ioctl instead of through the argument pointer. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:42 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Fix reference leaks in the remaining create ioctls. When ntsync_obj_get_fd() fails, we free the ntsync object but forget to drop the "file" member. This was fixed for semaphores in 0e7d523b5f7a23b1dc6ceceb04e31a60e9e3321d, but that commit did not fix the similar leak for events and mutexes, since they were part of patches not yet in the mainline kernel. Fix those cases. Fixes: 5bc2479a3585b "ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX." Fixes: 4c7404b9c2b57 "ntsync: Introduce NTSYNC_IOC_CREATE_EVENT." Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250116190717.8923-1-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-16 13:07:17 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Fix reference leaks in the remaining create ioctls. When ntsync_obj_get_fd() fails, we free the ntsync object but forget to drop the "file" member. This was fixed for semaphores in 0e7d523b5f7a23b1dc6ceceb04e31a60e9e3321d, but that commit did not fix the similar leak for events and mutexes, since they were part of patches not yet in the mainline kernel. Fix those cases. Fixes: 5bc2479a3585b "ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX." Fixes: 4c7404b9c2b57 "ntsync: Introduce NTSYNC_IOC_CREATE_EVENT." Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250116190717.8923-1-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-01-16 13:07:17 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Check wait count based on byte size. GCC versions below 13 incorrectly detect the copy size as being static and too small to fit in the "fds" array. Work around this by explicitly calculating the size and returning EINVAL based on that, instead of based on the object count. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202502072019.LYoCR9bF-lkp@intel.com/ Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> -- Suggested-by as per Arnd's request, but the only thing I changed was preserving array_size() [as noted by Geert in the linked thread]. I tested and found no regressions. v2: Add missing sign-off Link: https://lore.kernel.org/r/20250220192334.549167-1-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-20 13:23:34 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Check wait count based on byte size. GCC versions below 13 incorrectly detect the copy size as being static and too small to fit in the "fds" array. Work around this by explicitly calculating the size and returning EINVAL based on that, instead of based on the object count. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202502072019.LYoCR9bF-lkp@intel.com/ Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> -- Suggested-by as per Arnd's request, but the only thing I changed was preserving array_size() [as noted by Geert in the linked thread]. I tested and found no regressions. v2: Add missing sign-off Link: https://lore.kernel.org/r/20250220192334.549167-1-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-20 13:23:34 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Check wait count based on byte size. GCC versions below 13 incorrectly detect the copy size as being static and too small to fit in the "fds" array. Work around this by explicitly calculating the size and returning EINVAL based on that, instead of based on the object count. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202502072019.LYoCR9bF-lkp@intel.com/ Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> -- Suggested-by as per Arnd's request, but the only thing I changed was preserving array_size() [as noted by Geert in the linked thread]. I tested and found no regressions. v2: Add missing sign-off Link: https://lore.kernel.org/r/20250220192334.549167-1-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-20 13:23:34 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce alertable waits. NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects. Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20241213193511.457338-16-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:56 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL. This does not correspond to any NT syscall. Rather, when a thread dies, it should be called by the NT emulator for each mutex, with the TID of the dying thread. NT mutexes are robust (in the pthread sense). When an NT thread dies, any mutexes it owned are immediately released. Acquisition of those mutexes by other threads will return a special value indicating that the mutex was abandoned, like EOWNERDEAD returned from pthread_mutex_lock(), and EOWNERDEAD is indeed used here for that purpose. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-8-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:48 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT. This correspond to the NT syscall NtCreateEvent(). An NT event holds a single bit of state denoting whether it is signaled or unsignaled. There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions. Whether the event is manual-reset, and its initial state, are specified at creation time. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:49 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX. This corresponds to the NT syscall NtCreateMutant(). An NT mutex is recursive, with a 32-bit recursion counter. When acquired via NtWaitForMultipleObjects(), the recursion counter is incremented by one. The OS records the thread which acquired it. The OS records the thread which acquired it. However, in order to keep this driver self-contained, the owning thread ID is managed by user-space, and passed as a parameter to all relevant ioctls. The initial owner and recursion count, if any, are specified when the mutex is created. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-6-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:46 -06:00
ntsync: Introduce NTSYNC_IOC_CREATE_SEM. This corresponds to the NT syscall NtCreateSemaphore(). Semaphores are one of three types of object to be implemented in this driver, the others being mutexes and events. An NT semaphore contains a 32-bit counter, and is signaled and can be acquired when the counter is nonzero. The counter has a maximum value which is specified at creation time. The initial value of the semaphore is also specified at creation time. There are no restrictions on the maximum and initial value. Each object is exposed as an file, to which any number of fds may be opened. When all fds are closed, the object is deleted. Objects hold a pointer to the ntsync_device that created them. The device's reference count is driven by struct file. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-3-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:53 -05:00
ntsync: Introduce NTSYNC_IOC_WAIT_ALL. This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation. Because acquisition of multiple objects is atomic, some complex locking is required. We cannot simply spin-lock multiple objects simultaneously, as that may disable preëmption for a problematically long time. Instead, modifying any object which may be involved in a wait-all operation takes a device-wide sleeping mutex, "wait_all_lock", instead of the normal object spinlock. Because wait-for-all is a rare operation, in order to optimize wait-for-any, this lock is only taken when necessary. "all_hint" is used to mark objects which are involved in a wait-for-all operation, and if an object is not, only its spinlock is taken. The locking scheme used here was written by Peter Zijlstra. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-5-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:45 -06:00
ntsync: Introduce NTSYNC_IOC_WAIT_ANY. This corresponds to part of the functionality of the NT syscall NtWaitForMultipleObjects(). Specifically, it implements the behaviour where the third argument (wait_any) is TRUE, and it does not handle alertable waits. Those features have been split out into separate patches to ease review. This patch therefore implements the wait/wake infrastructure which comprises the core of ntsync's functionality. NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike poll(), it "consumes" objects when they are signaled. For semaphores, this means decreasing one from the internal counter. At most one object can be consumed by this function. This wait/wake model is fundamentally different from that used anywhere else in the kernel, and for that reason ntsync does not use any existing infrastructure, such as futexes, kernel mutexes or semaphores, or wait_event(). Up to 64 objects can be waited on at once. As soon as one is signaled, the object with the lowest index is consumed, and that index is returned via the "index" field. A timeout is supported. The timeout is passed as a u64 nanosecond value, which represents absolute time measured against either the MONOTONIC or REALTIME clock (controlled by the flags argument). If U64_MAX is passed, the ioctl waits indefinitely. This ioctl validates that all objects belong to the relevant device. This is not necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch. Some padding fields are added for alignment and for fields which will be added in future patches (split out to ease review). Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20241213193511.457338-4-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-12-13 13:34:44 -06:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00
ntsync: Set the permissions to be 0666 This allows ntsync to be usuable by non-root processes out of the box Signed-off-by: Mike Lothian <mike@fireburn.co.uk> Reviewed-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20250214122759.2629-2-mike@fireburn.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-02-14 12:28:00 +00:00
ntsync: Introduce the ntsync driver and character device. ntsync uses a misc device as the simplest and least intrusive uAPI interface. Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine. Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com> Link: https://lore.kernel.org/r/20240329000621.148791-2-zfigura@codeweavers.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-03-28 19:05:52 -05:00