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Tiezhu Yang e2bc9a5d7a LoongArch: Extend the maximum number of watchpoints 
commit 531936dee5 upstream.

The maximum number of load/store watchpoints and fetch instruction
watchpoints is 14 each according to LoongArch Reference Manual, so
extend the maximum number of watchpoints from 8 to 14 for ptrace.

By the way, just simply change 8 to 14 for the definition in struct
user_watch_state at the beginning, but it may corrupt uapi, then add
a new struct user_watch_state_v2 directly.

As far as I can tell, the only users for this struct in the userspace
are GDB and LLDB, there are no any problems of software compatibility
between the application and kernel according to the analysis.

The compatibility problem has been considered while developing and
testing. When the applications in the userspace get watchpoint state,
the length will be specified which is no bigger than the sizeof struct
user_watch_state or user_watch_state_v2, the actual length is assigned
as the minimal value of the application and kernel in the generic code
of ptrace:

kernel/ptrace.c: ptrace_regset():

	kiov->iov_len = min(kiov->iov_len,
			   (__kernel_size_t) (regset->n * regset->size));

	if (req == PTRACE_GETREGSET)
		return copy_regset_to_user(task, view, regset_no, 0,
					  kiov->iov_len, kiov->iov_base);
	else
		return copy_regset_from_user(task, view, regset_no, 0,
					  kiov->iov_len, kiov->iov_base);

For example, there are four kind of combinations, all of them work well.

(1) "older kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200;
(2) "newer kernel + newer gdb", the actual length is 8+(8+8+4+4)*14=344;
(3) "older kernel + newer gdb", the actual length is 8+(8+8+4+4)*8=200;
(4) "newer kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200.

Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints
Cc: stable@vger.kernel.org
Fixes: 1a69f7a161 ("LoongArch: ptrace: Expose hardware breakpoints to debuggers")
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-02-17 10:05:18 +01:00
arch LoongArch: Extend the maximum number of watchpoints 2025-02-17 10:05:18 +01:00
block blk-cgroup: Fix class @block_class's subsystem refcount leakage 2025-02-17 10:05:12 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: api - Fix boot-up self-test race 2025-02-08 09:57:28 +01:00
Documentation arm64: Filter out SVE hwcaps when FEAT_SVE isn't implemented 2025-02-17 10:05:04 +01:00
drivers serial: sh-sci: Do not probe the serial port if its slot in sci_ports[] is in use 2025-02-17 10:05:18 +01:00
fs ksmbd: fix integer overflows on 32 bit systems 2025-02-17 10:05:06 +01:00
include scsi: ufs: core: Fix the HIGH/LOW_TEMP Bit Definitions 2025-02-17 10:05:12 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-05 14:02:45 +01:00
io_uring io_uring/uring_cmd: use cached cmd_op in io_uring_cmd_sock() 2025-02-08 09:58:10 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel ring-buffer: Do not allow events in NMI with generic atomic64 cmpxchg() 2025-02-17 10:05:14 +01:00
lib atomic64: Use arch_spin_locks instead of raw_spin_locks 2025-02-17 10:05:14 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm memcg: fix soft lockup in the OOM process 2025-02-08 09:58:19 +01:00
net Bluetooth: L2CAP: accept zero as a special value for MTU auto-selection 2025-02-17 10:05:09 +01:00
rust rust: kbuild: set bindgen's Rust target version 2024-12-19 18:13:22 +01:00
samples samples/landlock: Fix possible NULL dereference in parse_path() 2025-02-08 09:57:11 +01:00
scripts kbuild: switch from lz4c to lz4 for compression 2025-02-08 09:58:12 +01:00
security KEYS: trusted: dcp: fix improper sg use with CONFIG_VMAP_STACK=y 2025-02-17 10:05:09 +01:00
sound ASoC: acp: Support microphone from Lenovo Go S 2025-02-17 10:05:18 +01:00
tools perf bench: Fix undefined behavior in cmpworker() 2025-02-17 10:05:12 +01:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: update location of media main tree 2024-12-05 14:02:42 +01:00
Makefile Linux 6.12.13 2025-02-08 09:58:20 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.