linux.git/include/linux/compiler.h, branch v6.13-rc4 Linux kernel source tree x86/static-call: provide a way to do very early static-call updates 2024-12-13T08:28:32+00:00 Juergen Gross jgross@suse.com 2024-11-29T15:15:54+00:00 0ef8047b737d7480a5d4c46d956e97c190f13050 Add static_call_update_early() for updating static-call targets in very early boot. This will be needed for support of Xen guest type specific hypercall functions. This is part of XSA-466 / CVE-2024-53241. Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Juergen Gross <jgross@suse.com> Co-developed-by: Peter Zijlstra <peterz@infradead.org> Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com> 
Add static_call_update_early() for updating static-call targets in
very early boot.

This will be needed for support of Xen guest type specific hypercall
functions.

This is part of XSA-466 / CVE-2024-53241.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Co-developed-by: Peter Zijlstra <peterz@infradead.org>
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
compiler.h: Fix undefined BUILD_BUG_ON_ZERO() 2024-11-17T05:15:41+00:00 Philipp Reisner philipp.reisner@linbit.com 2024-11-15T20:46:02+00:00 d7a516c6eeae29144649f1c3f586fa580ec9e040 <linux/compiler.h> defines __must_be_array() and __must_be_cstr() and both expand to BUILD_BUG_ON_ZERO(), but <linux/build_bug.h> defines BUILD_BUG_ON_ZERO(). Including <linux/build_bug.h> in <linux/compiler.h> would create a cyclic dependency as <linux/build_bug.h> already includes <linux/compiler.h>. Fix that by defining __BUILD_BUG_ON_ZERO_MSG() in <linux/compiler.h> and using that for __must_be_array() and __must_be_cstr(). Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Link: https://lore.kernel.org/r/20241115204602.249590-1-philipp.reisner@linbit.com Signed-off-by: Kees Cook <kees@kernel.org> 
<linux/compiler.h> defines __must_be_array() and __must_be_cstr() and
both expand to BUILD_BUG_ON_ZERO(), but <linux/build_bug.h> defines
BUILD_BUG_ON_ZERO(). Including <linux/build_bug.h> in
<linux/compiler.h> would create a cyclic dependency as
<linux/build_bug.h> already includes <linux/compiler.h>.

Fix that by defining __BUILD_BUG_ON_ZERO_MSG() in <linux/compiler.h>
and using that for __must_be_array() and __must_be_cstr().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Link: https://lore.kernel.org/r/20241115204602.249590-1-philipp.reisner@linbit.com
Signed-off-by: Kees Cook <kees@kernel.org>
compiler.h: specify correct attribute for .rodata..c_jump_table 2024-09-26T21:01:44+00:00 Tiezhu Yang yangtiezhu@loongson.cn 2024-09-24T06:27:10+00:00 c5b1184decc819756ae549ba54c63b6790c4ddfd Currently, there is an assembler message when generating kernel/bpf/core.o under CONFIG_OBJTOOL with LoongArch compiler toolchain: Warning: setting incorrect section attributes for .rodata..c_jump_table This is because the section ".rodata..c_jump_table" should be readonly, but there is a "W" (writable) part of the flags: $ readelf -S kernel/bpf/core.o | grep -A 1 "rodata..c" [34] .rodata..c_j[...] PROGBITS 0000000000000000 0000d2e0 0000000000000800 0000000000000000 WA 0 0 8 There is no above issue on x86 due to the generated section flag is only "A" (allocatable). In order to silence the warning on LoongArch, specify the attribute like ".rodata..c_jump_table,\"a\",@progbits #" explicitly, then the section attribute of ".rodata..c_jump_table" must be readonly in the kernel/bpf/core.o file. Before: $ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c" 21 .rodata..c_jump_table 00000800 0000000000000000 0000000000000000 0000d2e0 2**3 CONTENTS, ALLOC, LOAD, RELOC, DATA After: $ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c" 21 .rodata..c_jump_table 00000800 0000000000000000 0000000000000000 0000d2e0 2**3 CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA By the way, AFAICT, maybe the root cause is related with the different compiler behavior of various archs, so to some extent this change is a workaround for LoongArch, and also there is no effect for x86 which is the only port supported by objtool before LoongArch with this patch. Link: https://lkml.kernel.org/r/20240924062710.1243-1-yangtiezhu@loongson.cn Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> [6.9+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Currently, there is an assembler message when generating kernel/bpf/core.o
under CONFIG_OBJTOOL with LoongArch compiler toolchain:

  Warning: setting incorrect section attributes for .rodata..c_jump_table

This is because the section ".rodata..c_jump_table" should be readonly,
but there is a "W" (writable) part of the flags:

  $ readelf -S kernel/bpf/core.o | grep -A 1 "rodata..c"
  [34] .rodata..c_j[...] PROGBITS         0000000000000000  0000d2e0
       0000000000000800  0000000000000000  WA       0     0     8

There is no above issue on x86 due to the generated section flag is only
"A" (allocatable). In order to silence the warning on LoongArch, specify
the attribute like ".rodata..c_jump_table,\"a\",@progbits #" explicitly,
then the section attribute of ".rodata..c_jump_table" must be readonly
in the kernel/bpf/core.o file.

Before:

  $ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c"
   21 .rodata..c_jump_table 00000800  0000000000000000  0000000000000000  0000d2e0  2**3
                  CONTENTS, ALLOC, LOAD, RELOC, DATA

After:

  $ objdump -h kernel/bpf/core.o | grep -A 1 "rodata..c"
   21 .rodata..c_jump_table 00000800  0000000000000000  0000000000000000  0000d2e0  2**3
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA

By the way, AFAICT, maybe the root cause is related with the different
compiler behavior of various archs, so to some extent this change is a
workaround for LoongArch, and also there is no effect for x86 which is the
only port supported by objtool before LoongArch with this patch.

Link: https://lkml.kernel.org/r/20240924062710.1243-1-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>	[6.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
string: Check for "nonstring" attribute on strscpy() arguments 2024-08-23T00:04:43+00:00 Kees Cook kees@kernel.org 2024-08-05T21:43:44+00:00 559048d156ff3391c4b793779a824c9193e20442 GCC already checks for arguments that are marked with the "nonstring"[1] attribute when used on standard C String API functions (e.g. strcpy). Gain this compile-time checking also for the kernel's primary string copying function, strscpy(). Note that Clang has neither "nonstring" nor __builtin_has_attribute(). Link: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute [1] Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20240805214340.work.339-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org> 
GCC already checks for arguments that are marked with the "nonstring"[1]
attribute when used on standard C String API functions (e.g. strcpy). Gain
this compile-time checking also for the kernel's primary string copying
function, strscpy().

Note that Clang has neither "nonstring" nor __builtin_has_attribute().

Link: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute [1]
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20240805214340.work.339-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
minmax: improve macro expansion and type checking 2024-07-30T17:36:47+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-07-30T17:36:47+00:00 22f5468731491e53356ba7c028f0fdea20b18e2c This clarifies the rules for min()/max()/clamp() type checking and makes them a much more efficient macro expansion. In particular, we now look at the type and range of the inputs to see whether they work together, generating a mask of acceptable comparisons, and then just verifying that the inputs have a shared case: - an expression with a signed type can be used for (1) signed comparisons (2) unsigned comparisons if it is statically known to have a non-negative value - an expression with an unsigned type can be used for (3) unsigned comparison (4) signed comparisons if the type is smaller than 'int' and thus the C integer promotion rules will make it signed anyway Here rule (1) and (3) are obvious, and rule (2) is important in order to allow obvious trivial constants to be used together with unsigned values. Rule (4) is not necessarily a good idea, but matches what we used to do, and we have extant cases of this situation in the kernel. Notably with bcachefs having an expression like min(bch2_bucket_sectors_dirty(a), ca->mi.bucket_size) where bch2_bucket_sectors_dirty() returns an 's64', and 'ca->mi.bucket_size' is of type 'u16'. Technically that bcachefs comparison is clearly sensible on a C type level, because the 'u16' will go through the normal C integer promotion, and become 'int', and then we're comparing two signed values and everything looks sane. However, it's not entirely clear that a 'min(s64,u16)' operation makes a lot of conceptual sense, and it's possible that we will remove rule (4). After all, the _reason_ we have these complicated type checks is exactly that the C type promotion rules are not very intuitive. But at least for now the rule is in place for backwards compatibility. Also note that rule (2) existed before, but is hugely relaxed by this commit. It used to be true only for the simplest compile-time non-negative integer constants. The new macro model will allow cases where the compiler can trivially see that an expression is non-negative even if it isn't necessarily a constant. For example, the amdgpu driver does min_t(size_t, sizeof(fru_info->serial), pia[addr] & 0x3F)); because our old 'min()' macro would see that 'pia[addr] & 0x3F' is of type 'int' and clearly not a C constant expression, so doing a 'min()' with a 'size_t' is a signedness violation. Our new 'min()' macro still sees that 'pia[addr] & 0x3F' is of type 'int', but is smart enough to also see that it is clearly non-negative, and thus would allow that case without any complaints. Cc: Arnd Bergmann <arnd@kernel.org> Cc: David Laight <David.Laight@aculab.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This clarifies the rules for min()/max()/clamp() type checking and makes
them a much more efficient macro expansion.

In particular, we now look at the type and range of the inputs to see
whether they work together, generating a mask of acceptable comparisons,
and then just verifying that the inputs have a shared case:

 - an expression with a signed type can be used for
    (1) signed comparisons
    (2) unsigned comparisons if it is statically known to have a
        non-negative value

 - an expression with an unsigned type can be used for
    (3) unsigned comparison
    (4) signed comparisons if the type is smaller than 'int' and thus
        the C integer promotion rules will make it signed anyway

Here rule (1) and (3) are obvious, and rule (2) is important in order to
allow obvious trivial constants to be used together with unsigned
values.

Rule (4) is not necessarily a good idea, but matches what we used to do,
and we have extant cases of this situation in the kernel.  Notably with
bcachefs having an expression like

	min(bch2_bucket_sectors_dirty(a), ca->mi.bucket_size)

where bch2_bucket_sectors_dirty() returns an 's64', and
'ca->mi.bucket_size' is of type 'u16'.

Technically that bcachefs comparison is clearly sensible on a C type
level, because the 'u16' will go through the normal C integer promotion,
and become 'int', and then we're comparing two signed values and
everything looks sane.

However, it's not entirely clear that a 'min(s64,u16)' operation makes a
lot of conceptual sense, and it's possible that we will remove rule (4).
After all, the _reason_ we have these complicated type checks is exactly
that the C type promotion rules are not very intuitive.

But at least for now the rule is in place for backwards compatibility.

Also note that rule (2) existed before, but is hugely relaxed by this
commit.  It used to be true only for the simplest compile-time
non-negative integer constants.  The new macro model will allow cases
where the compiler can trivially see that an expression is non-negative
even if it isn't necessarily a constant.

For example, the amdgpu driver does

	min_t(size_t, sizeof(fru_info->serial), pia[addr] & 0x3F));

because our old 'min()' macro would see that 'pia[addr] & 0x3F' is of
type 'int' and clearly not a C constant expression, so doing a 'min()'
with a 'size_t' is a signedness violation.

Our new 'min()' macro still sees that 'pia[addr] & 0x3F' is of type
'int', but is smart enough to also see that it is clearly non-negative,
and thus would allow that case without any complaints.

Cc: Arnd Bergmann <arnd@kernel.org>
Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2024-07-22T00:56:22+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-07-22T00:56:22+00:00 527eff227d4321c6ea453db1083bc4fdd4d3a3e8 Pull non-MM updates from Andrew Morton: - In the series "treewide: Refactor heap related implementation", Kuan-Wei Chiu has significantly reworked the min_heap library code and has taught bcachefs to use the new more generic implementation. - Yury Norov's series "Cleanup cpumask.h inclusion in core headers" reworks the cpumask and nodemask headers to make things generally more rational. - Kuan-Wei Chiu has sent along some maintenance work against our sorting library code in the series "lib/sort: Optimizations and cleanups". - More library maintainance work from Christophe Jaillet in the series "Remove usage of the deprecated ida_simple_xx() API". - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the series "nilfs2: eliminate the call to inode_attach_wb()". - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix GDB command error". - Plus the usual shower of singleton patches all over the place. Please see the relevant changelogs for details. * tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits) ia64: scrub ia64 from poison.h watchdog/perf: properly initialize the turbo mode timestamp and rearm counter tsacct: replace strncpy() with strscpy() lib/bch.c: use swap() to improve code test_bpf: convert comma to semicolon init/modpost: conditionally check section mismatch to __meminit* init: remove unused __MEMINIT* macros nilfs2: Constify struct kobj_type nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro math: rational: add missing MODULE_DESCRIPTION() macro lib/zlib: add missing MODULE_DESCRIPTION() macro fs: ufs: add MODULE_DESCRIPTION() lib/rbtree.c: fix the example typo ocfs2: add bounds checking to ocfs2_check_dir_entry() fs: add kernel-doc comments to ocfs2_prepare_orphan_dir() coredump: simplify zap_process() selftests/fpu: add missing MODULE_DESCRIPTION() macro compiler.h: simplify data_race() macro build-id: require program headers to be right after ELF header resource: add missing MODULE_DESCRIPTION() ... 
Pull non-MM updates from Andrew Morton:

 - In the series "treewide: Refactor heap related implementation",
   Kuan-Wei Chiu has significantly reworked the min_heap library code
   and has taught bcachefs to use the new more generic implementation.

 - Yury Norov's series "Cleanup cpumask.h inclusion in core headers"
   reworks the cpumask and nodemask headers to make things generally
   more rational.

 - Kuan-Wei Chiu has sent along some maintenance work against our
   sorting library code in the series "lib/sort: Optimizations and
   cleanups".

 - More library maintainance work from Christophe Jaillet in the series
   "Remove usage of the deprecated ida_simple_xx() API".

 - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the
   series "nilfs2: eliminate the call to inode_attach_wb()".

 - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix
   GDB command error".

 - Plus the usual shower of singleton patches all over the place. Please
   see the relevant changelogs for details.

* tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits)
  ia64: scrub ia64 from poison.h
  watchdog/perf: properly initialize the turbo mode timestamp and rearm counter
  tsacct: replace strncpy() with strscpy()
  lib/bch.c: use swap() to improve code
  test_bpf: convert comma to semicolon
  init/modpost: conditionally check section mismatch to __meminit*
  init: remove unused __MEMINIT* macros
  nilfs2: Constify struct kobj_type
  nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro
  math: rational: add missing MODULE_DESCRIPTION() macro
  lib/zlib: add missing MODULE_DESCRIPTION() macro
  fs: ufs: add MODULE_DESCRIPTION()
  lib/rbtree.c: fix the example typo
  ocfs2: add bounds checking to ocfs2_check_dir_entry()
  fs: add kernel-doc comments to ocfs2_prepare_orphan_dir()
  coredump: simplify zap_process()
  selftests/fpu: add missing MODULE_DESCRIPTION() macro
  compiler.h: simplify data_race() macro
  build-id: require program headers to be right after ELF header
  resource: add missing MODULE_DESCRIPTION()
  ...
compiler.h: simplify data_race() macro 2024-06-29T02:36:30+00:00 Alexey Dobriyan adobriyan@gmail.com 2024-06-24T15:39:49+00:00 7c812814e8c34a41bff6fe49987760ffaf8702af -Wdeclaration-after-statement used since forever required statement expressions to inject __kcsan_disable_current(), __kcsan_enable_current() to mark data race. Now that it is gone, make macro expansion simpler. __unqual_scalar_typeof() is wordy macro by itself. "expr" is expanded twice. Link: https://lkml.kernel.org/r/fb62163f-ba21-4661-be5b-bb5124abc87d@p183 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
-Wdeclaration-after-statement used since forever required statement
expressions to inject __kcsan_disable_current(), __kcsan_enable_current()
to mark data race. Now that it is gone, make macro expansion simpler.

__unqual_scalar_typeof() is wordy macro by itself.
"expr" is expanded twice.

Link: https://lkml.kernel.org/r/fb62163f-ba21-4661-be5b-bb5124abc87d@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kcsan: Add example to data_race() kerneldoc header 2024-05-30T22:06:26+00:00 Paul E. McKenney paulmck@kernel.org 2024-05-10T22:36:57+00:00 020e6c22bd6e67592f38b47d0f1926a831482560 Although the data_race() kerneldoc header accurately states what it does, some of the implications and usage patterns are non-obvious. Therefore, add a brief locking example and also state how to have KCSAN ignore accesses while also preventing the compiler from folding, spindling, or otherwise mutilating the access. [ paulmck: Apply Bart Van Assche feedback. ] [ paulmck: Apply feedback from Marco Elver. ] Reported-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Marco Elver <elver@google.com> Cc: Breno Leitao <leitao@debian.org> Cc: Jens Axboe <axboe@kernel.dk> 
Although the data_race() kerneldoc header accurately states what it does,
some of the implications and usage patterns are non-obvious.  Therefore,
add a brief locking example and also state how to have KCSAN ignore
accesses while also preventing the compiler from folding, spindling,
or otherwise mutilating the access.

[ paulmck: Apply Bart Van Assche feedback. ]
[ paulmck: Apply feedback from Marco Elver. ]

Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Jens Axboe <axboe@kernel.dk>
compiler.h: Add missing quote in macro comment 2024-04-09T16:06:50+00:00 Thorsten Blum thorsten.blum@toblux.com 2024-04-09T15:46:23+00:00 d7a62d0a9a17e97ce2d4d40431094e09956a0568 Add a missing doublequote in the __is_constexpr() macro comment. Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Add a missing doublequote in the __is_constexpr() macro comment.

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'loongarch-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson 2024-03-22T17:22:45+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-03-22T17:22:45+00:00 1e3cd03c54b76b4cbc8b31256dc3f18c417a6876 Pull LoongArch updates from Huacai Chen: - Add objtool support for LoongArch - Add ORC stack unwinder support for LoongArch - Add kernel livepatching support for LoongArch - Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig - Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig - Some bug fixes and other small changes * tag 'loongarch-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: LoongArch/crypto: Clean up useless assignment operations LoongArch: Define the __io_aw() hook as mmiowb() LoongArch: Remove superfluous flush_dcache_page() definition LoongArch: Move {dmw,tlb}_virt_to_page() definition to page.h LoongArch: Change __my_cpu_offset definition to avoid mis-optimization LoongArch: Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig LoongArch: Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig LoongArch: Add kernel livepatching support LoongArch: Add ORC stack unwinder support objtool: Check local label in read_unwind_hints() objtool: Check local label in add_dead_ends() objtool/LoongArch: Enable orc to be built objtool/x86: Separate arch-specific and generic parts objtool/LoongArch: Implement instruction decoder objtool/LoongArch: Enable objtool to be built 
Pull LoongArch updates from Huacai Chen:

 - Add objtool support for LoongArch

 - Add ORC stack unwinder support for LoongArch

 - Add kernel livepatching support for LoongArch

 - Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig

 - Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig

 - Some bug fixes and other small changes

* tag 'loongarch-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
  LoongArch/crypto: Clean up useless assignment operations
  LoongArch: Define the __io_aw() hook as mmiowb()
  LoongArch: Remove superfluous flush_dcache_page() definition
  LoongArch: Move {dmw,tlb}_virt_to_page() definition to page.h
  LoongArch: Change __my_cpu_offset definition to avoid mis-optimization
  LoongArch: Select HAVE_ARCH_USERFAULTFD_MINOR in Kconfig
  LoongArch: Select ARCH_HAS_CURRENT_STACK_POINTER in Kconfig
  LoongArch: Add kernel livepatching support
  LoongArch: Add ORC stack unwinder support
  objtool: Check local label in read_unwind_hints()
  objtool: Check local label in add_dead_ends()
  objtool/LoongArch: Enable orc to be built
  objtool/x86: Separate arch-specific and generic parts
  objtool/LoongArch: Implement instruction decoder
  objtool/LoongArch: Enable objtool to be built