We're generally not proponents of rewrites (nasty uncomfortable things
that make you late for dinner!). So why rewrite Binder?
Binder has been evolving over the past 15+ years to meet the evolving
needs of Android. Its responsibilities, expectations, and complexity
have grown considerably during that time. While we expect Binder to
continue to evolve along with Android, there are a number of factors
that currently constrain our ability to develop/maintain it. Briefly
those are:
1. Complexity: Binder is at the intersection of everything in Android and
fulfills many responsibilities beyond IPC. It has become many things
to many people, and due to its many features and their interactions
with each other, its complexity is quite high. In just 6kLOC it must
deliver transactions to the right threads. It must correctly parse
and translate the contents of transactions, which can contain several
objects of different types (e.g., pointers, fds) that can interact
with each other. It controls the size of thread pools in userspace,
and ensures that transactions are assigned to threads in ways that
avoid deadlocks where the threadpool has run out of threads. It must
track refcounts of objects that are shared by several processes by
forwarding refcount changes between the processes correctly. It must
handle numerous error scenarios and it combines/nests 13 different
locks, 7 reference counters, and atomic variables. Finally, It must
do all of this as fast and efficiently as possible. Minor performance
regressions can cause a noticeably degraded user experience.
2. Things to improve: Thousand-line functions [1], error-prone error
handling [2], and confusing structure can occur as a code base grows
organically. After more than a decade of development, this codebase
could use an overhaul.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/android/binder.c?h=v6.5#n2896
[2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/android/binder.c?h=v6.5#n3658
3. Security critical: Binder is a critical part of Android's sandboxing
strategy. Even Android's most de-privileged sandboxes (e.g. the
Chrome renderer, or SW Codec) have direct access to Binder. More than
just about any other component, it's important that Binder provide
robust security, and itself be robust against security
vulnerabilities.
It's #1 (high complexity) that has made continuing to evolve Binder and
resolving #2 (tech debt) exceptionally difficult without causing #3
(security issues). For Binder to continue to meet Android's needs, we
need better ways to manage (and reduce!) complexity without increasing
the risk.
The biggest change is obviously the choice of programming language. We
decided to use Rust because it directly addresses a number of the
challenges within Binder that we have faced during the last years. It
prevents mistakes with ref counting, locking, bounds checking, and also
does a lot to reduce the complexity of error handling. Additionally,
we've been able to use the more expressive type system to encode the
ownership semantics of the various structs and pointers, which takes the
complexity of managing object lifetimes out of the hands of the
programmer, reducing the risk of use-after-frees and similar problems.
Rust has many different pointer types that it uses to encode ownership
semantics into the type system, and this is probably one of the most
important aspects of how it helps in Binder. The Binder driver has a lot
of different objects that have complex ownership semantics; some
pointers own a refcount, some pointers have exclusive ownership, and
some pointers just reference the object and it is kept alive in some
other manner. With Rust, we can use a different pointer type for each
kind of pointer, which enables the compiler to enforce that the
ownership semantics are implemented correctly.
Another useful feature is Rust's error handling. Rust allows for more
simplified error handling with features such as destructors, and you get
compilation failures if errors are not properly handled. This means that
even though Rust requires you to spend more lines of code than C on
things such as writing down invariants that are left implicit in C, the
Rust driver is still slightly smaller than C binder: Rust is 5.5kLOC and
C is 5.8kLOC. (These numbers are excluding blank lines, comments,
binderfs, and any debugging facilities in C that are not yet implemented
in the Rust driver. The numbers include abstractions in rust/kernel/
that are unlikely to be used by other drivers than Binder.)
Although this rewrite completely rethinks how the code is structured and
how assumptions are enforced, we do not fundamentally change *how* the
driver does the things it does. A lot of careful thought has gone into
the existing design. The rewrite is aimed rather at improving code
health, structure, readability, robustness, security, maintainability
and extensibility. We also include more inline documentation, and
improve how assumptions in the code are enforced. Furthermore, all
unsafe code is annotated with a SAFETY comment that explains why it is
correct.
We have left the binderfs filesystem component in C. Rewriting it in
Rust would be a large amount of work and requires a lot of bindings to
the file system interfaces. Binderfs has not historically had the same
challenges with security and complexity, so rewriting binderfs seems to
have lower value than the rest of Binder.
Correctness and feature parity
------------------------------
Rust binder passes all tests that validate the correctness of Binder in
the Android Open Source Project. We can boot a device, and run a variety
of apps and functionality without issues. We have performed this both on
the Cuttlefish Android emulator device, and on a Pixel 6 Pro.
As for feature parity, Rust binder currently implements all features
that C binder supports, with the exception of some debugging facilities.
The missing debugging facilities will be added before we submit the Rust
implementation upstream.
Tracepoints
-----------
I did not include all of the tracepoints as I felt that the mechansim
for making C access fields of Rust structs should be discussed on list
separately. I also did not include the support for building Rust Binder
as a module since that requires exporting a bunch of additional symbols
on the C side.
Original RFC Link with old benchmark numbers:
https://lore.kernel.org/r/20231101-rust-binder-v1-0-08ba9197f637@google.com
Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Matt Gilbride <mattgilbride@google.com>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250919-rust-binder-v2-1-a384b09f28dd@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The AMD IOMMU host page table implementation supports dynamic page table levels
(up to 6 levels), starting with a 3-level configuration that expands based on
IOVA address. The kernel maintains a root pointer and current page table level
to enable proper page table walks in alloc_pte()/fetch_pte() operations.
The IOMMU IOVA allocator initially starts with 32-bit address and onces its
exhuasted it switches to 64-bit address (max address is determined based
on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU
driver increases page table level.
But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads
pgtable->[root/mode] without lock. So its possible that in exteme corner case,
when increase_address_space() is updating pgtable->[root/mode], fetch_pte()
reads wrong page table level (pgtable->mode). It does compare the value with
level encoded in page table and returns NULL. This will result is
iommu_unmap ops to fail and upper layer may retry/log WARN_ON.
CPU 0 CPU 1
------ ------
map pages unmap pages
alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte()
pgtable->root = pte (new root value)
READ pgtable->[mode/root]
Reads new root, old mode
Updates mode (pgtable->mode += 1)
Since Page table level updates are infrequent and already synchronized with a
spinlock, implement seqcount to enable lock-free read operations on the read path.
Fixes: 754265bcab ("iommu/amd: Fix race in increase_address_space()")
Reported-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Cc: stable@vger.kernel.org
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
p9_read_work() doesn't set Rworksched and doesn't do schedule_work(m->rq)
if list_empty(&m->req_list).
However, if the pipe is full, we need to read more data and this used to
work prior to commit aaec5a95d5 ("pipe_read: don't wake up the writer
if the pipe is still full").
p9_read_work() does p9_fd_read() -> ... -> anon_pipe_read() which (before
the commit above) triggered the unnecessary wakeup. This wakeup calls
p9_pollwake() which kicks p9_poll_workfn() -> p9_poll_mux(), p9_poll_mux()
will notice EPOLLIN and schedule_work(&m->rq).
This no longer happens after the optimization above, change p9_fd_request()
to use p9_poll_mux() instead of only checking for EPOLLOUT.
Reported-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Tested-by: syzbot+d1b5dace43896bc386c3@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68a2de8f.050a0220.e29e5.0097.GAE@google.com/
Link: https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@google.com/
Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Message-ID: <20250819161013.GB11345@redhat.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Abstract ilk_display_irq_reset(), moving display related reset
there. This results in a slightly different order between GT and PCH
reset, hopefully with no impact.
v3: Reset display first (Ville)
v2: Also move GEN7_ERR_INT (Ville)
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/20250918133835.2412980-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
There are three groups of platforms using i915->irq_mask independently:
gen 2-4, VLV/CHV, and gen 5-7.
The gen 5-7 usage is primarily limited to display. Move its irq_mask
usage to struct intel_display as ilk_de_imr_mask for gen 5-7.
ilk_de_imr_mask could be put inside a union with with vlv_imr_mask and
de_irq_mask[], but keep them separate to avoid accidental aliasing of
the values.
With this, we can also drop the irq_mask member from struct xe_device.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/adf60e74b890d52dd20ab4673111ae2063d33b49.1758198300.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
There are three groups of platforms using i915->irq_mask independently:
gen 2-4, VLV/CHV, and gen 5-7.
The VLV/CHV usage is purely limited to display. Move its irq_mask usage
to struct intel_display as vlv_imr_mask for VLV/CHV.
vlv_imr_mask could be put inside a union with de_irq_mask[], but keep
them separate to avoid accidental aliasing of the values.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/cef6dee8d0b02ff76180c5879f3056e102947a57.1758198300.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
If copy_from_user() fails, the correct error code is -EFAULT, not
-EINVAL.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
The busy-waiting in `mdelay()` can cause CPU stalls and kernel timeouts
during boot.
Signed-off-by: Nirmoy Das <nirmoyd@nvidia.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Carol L Soto csoto@nvidia.com<mailto:csoto@nvidia.com>
Fixes: 594e9c04b5 ("drm/ast: Create the driver for ASPEED proprietory Display-Port")
Cc: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.19+
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250917194346.2905522-1-nirmoyd@nvidia.com
Re-order these checks to check if "i" is a valid array index before using
it. This prevents a potential off by one read access.
Fixes: d6e290837e ("tee: add Qualcomm TEE driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
i915 and xe do different things on the failure path; i915 calls
drm_gem_object_put() while xe calls xe_bo_unpin_map_no_vm(). Add a
helper to enable further refactoring.
v2: Call drm_gem_object_put() on intel_fbdev_fb_bo_destroy()
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/22bc3c3158f5a22ab258ada8684766fdf75fefec.1758184771.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
For reasons unknown, xe uses XE_PAGE_SIZE alignment for
stride. Presumably it's just a confusion between stride alignment and bo
allocation size alignment. Switch to 64 byte alignment to, uh, align
with i915.
This will also be helpful in deduplicating and unifying the xe and i915
framebuffer allocation.
Link: https://lore.kernel.org/r/aLqsC87Ol_zCXOkN@intel.com
Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/7f4972104de8b179d5724ae83892ee294d3f3fd3.1758184771.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Allow mhi_sync_power_up to handle SYS_ERR during power-up, reboot,
or recovery. This is to avoid premature exit when MHI_PM_IN_ERROR_STATE is
observed during above mentioned system states.
To achieve this, treat SYS_ERR as a valid state and let its handler process
the error and queue the next transition to Mission Mode instead of aborting
early.
Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
[mani: reworded description]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-uevent_vdev_next-20250911-v4-5-fa2f6ccd301b@quicinc.com
So, When the MHI driver is removed from the host side, it is essential to
ensure a clean and stable recovery of the device. This commit introduces
the following steps to achieve that:
1. Disable SR-IOV for any SR-IOV-enabled devices on the Physical Function.
2. Perform a SOC_RESET on the PF to fully reset the device.
Disabling SR-IOV ensures all Virtual Functions (VFs) are properly shutdown,
preventing issues during the reset process. The SOC_RESET guarantees that
the PF is restored to a known good state.
If soc_reset is not performed device at driver remove, device will be
stuck in mission mode state and subsequent driver insert/power_up will not
proceed further.
Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
[mani: reworded subject]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-uevent_vdev_next-20250911-v4-4-fa2f6ccd301b@quicinc.com
pci_sriov_configure_simple() will enable or disable SR-IOV for devices
that don't require any specific PF setup before enabling SR-IOV.
Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-uevent_vdev_next-20250911-v4-3-fa2f6ccd301b@quicinc.com
In SR-IOV enabled devices, reading the VF DEVICE/VENDOR ID register
returns `FFFFh`, as specified in section 3.4.1.1 of the PCIe SR-IOV spec.
To accurately determine device activity, read the PCIe VENDOR_ID of
the Physical Function (PF) instead.
Health check monitoring for Virtual Functions (VFs) has been disabled,
since VFs are not physical functions and lack direct hardware control.
This change prevents unnecessary CPU cycles from being consumed by VF
health checks, which are both unintended and non-functional.
Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-uevent_vdev_next-20250911-v4-2-fa2f6ccd301b@quicinc.com
Implement support for separate controller configurations for both
Virtual Functions (VF) and Physical Functions (PF).
This enhancement allows for more flexible and efficient management of
resources. The PF takes on a supervisory role and will have bootup
information such as SAHARA, DIAG, and NDB (for file system sync data,
etc.). VFs can handle resources associated with the main data movement
of the Function are available to the SI (system image) as per PCIe SRIOV
spec (rev 0.9 1.Architectural overview)
Signed-off-by: Vivek Pernamitta <quic_vpernami@quicinc.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20250912-uevent_vdev_next-20250911-v4-1-fa2f6ccd301b@quicinc.com
devm_drm_bridge_alloc() returns ERR_PTR on failure instead of a
NULL pointer, so use IS_ERR() to check the returned pointer and
turn proper error code on failure by using PTR_ERR().
Fixes: dbdea37add ("drm: bridge: Add waveshare DSI2DPI unit driver")
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250806084121.510207-1-victor.liu@nxp.com
Add support for MIPS vendor extensions. Add support for the xmipsexectl
vendor extension.
Signed-off-by: Aleksa Paunovic <aleksa.paunovic@htecgroup.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250724-p8700-pause-v5-2-a6cbbe1c3412@htecgroup.com
[pjw@kernel.org: added the MIPS vendor ID from another patch to fix the build]
Signed-off-by: Paul Walmsley <pjw@kernel.org>
No functional changes, except for the addition of the headers for the
kfuncs so that they can be used for signature verification.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-8-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently only array maps are supported, but the implementation can be
extended for other maps and objects. The hash is memoized only for
exclusive and frozen maps as their content is stable until the exclusive
program modifies the map.
This is required for BPF signing, enabling a trusted loader program to
verify a map's integrity. The loader retrieves
the map's runtime hash from the kernel and compares it against an
expected hash computed at build time.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-7-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Implement setters and getters that allow map to be registered as
exclusive to the specified program. The registration should be done
before the exclusive program is loaded.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-5-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use AF_ALG sockets to not have libbpf depend on OpenSSL. The helper is
used for the loader generation code to embed the metadata hash in the
loader program and also by the bpf_map__make_exclusive API to calculate
the hash of the program the map is exclusive to.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-4-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Exclusive maps allow maps to only be accessed by program with a
program with a matching hash which is specified in the excl_prog_hash
attr.
For the signing use-case, this allows the trusted loader program
to load the map and verify the integrity
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-3-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Exclusive maps restrict map access to specific programs using a hash.
The current hash used for this is SHA1, which is prone to collisions.
This patch uses SHA256, which is more resilient against
collisions. This new hash is stored in bpf_prog and used by the verifier
to determine if a program can access a given exclusive map.
The original 64-bit tags are kept, as they are used by users as a short,
possibly colliding program identifier for non-security purposes.
Signed-off-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/r/20250914215141.15144-2-kpsingh@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These extensions depends on the F one. Add a validation callback
checking for the F extension to be present. Now that extensions are
correctly reported using the F/D presence, we can remove the
has_fpu() check in hwprobe_isa_ext0().
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250527100001.33284-1-cleger@rivosinc.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>
Add a README file for RISC-V specific kernel selftests under
tools/testing/selftests/riscv/. This mirrors the existing README
for arm64, providing clear guidance on how the tests are architecture
specific and skipped on non-riscv systems. It also includes
standard make commands for building, running and installing the
tests, along with a reference to general kselftest documentation.
Signed-off-by: Bala-Vignesh-Reddy <reddybalavignesh9979@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250815180724.14459-1-reddybalavignesh9979@gmail.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>
anx7625, and a mutex unlock fix for cdns-mhdp8546
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Merge tag 'drm-misc-fixes-2025-09-18' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixes
One fix for a documentation warning, a null pointer dereference fix for
anx7625, and a mutex unlock fix for cdns-mhdp8546
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Maxime Ripard <mripard@redhat.com>
Link: https://lore.kernel.org/r/20250918-orthodox-pretty-puma-1ddeea@houat
Current implementation stores the bus generation at which the bus manager
contending procedure finishes. The condition for the procedure is the
mismatch of the stored generation against current bus generation.
This commit refactors the code for the contending procedure. Two existing
branches are put into a new branch to detect the generation mismatch, thus
the most of change is indentation.
Link: https://lore.kernel.org/r/20250918235448.129705-4-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
