kernel/linux.git/include/linux/compiler-clang.h, branch v5.10.258

kmsan: introduce __no_sanitize_memory and __no_kmsan_checks

2026-01-19T12:11:28+00:00

[ Upstream commit 9b448bc25b776daab3215393c3ce6953dd3bb8ad ] __no_sanitize_memory is a function attribute that instructs KMSAN to skip a function during instrumentation. This is needed to e.g. implement the noinstr functions. __no_kmsan_checks is a function attribute that makes KMSAN ignore the uninitialized values coming from the function's inputs, and initialize the function's outputs. Functions marked with this attribute can't be inlined into functions not marked with it, and vice versa. This behavior is overridden by __always_inline. __SANITIZE_MEMORY__ is a macro that's defined iff the file is instrumented with KMSAN. This is not the same as CONFIG_KMSAN, which is defined for every file. Link: https://lkml.kernel.org/r/20220915150417.722975-8-glider@google.com Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver Cc: Alexander Viro Cc: Alexei Starovoitov Cc: Andrey Konovalov Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Eric Biggers Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Ilya Leoshkevich Cc: Ingo Molnar Cc: Jens Axboe Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Matthew Wilcox Cc: Michael S. Tsirkin Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Petr Mladek Cc: Stephen Rothwell Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vegard Nossum Cc: Vlastimil Babka Signed-off-by: Andrew Morton Stable-dep-of: ced37e9ceae5 ("x86/dumpstack: Prevent KASAN false positive warnings in __show_regs()") Signed-off-by: Sasha Levin

locking: Introduce __cleanup() based infrastructure

2025-10-29T13:01:15+00:00

[ Upstream commit 54da6a0924311c7cf5015533991e44fb8eb12773 ] Use __attribute__((__cleanup__(func))) to build: - simple auto-release pointers using __free() - 'classes' with constructor and destructor semantics for scope-based resource management. - lock guards based on the above classes. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

compiler-clang.h: define __SANITIZE_*__ macros only when undefined

2025-10-02T11:35:37+00:00

commit 3fac212fe489aa0dbe8d80a42a7809840ca7b0f9 upstream. Clang 22 recently added support for defining __SANITIZE__ macros similar to GCC [1], which causes warnings (or errors with CONFIG_WERROR=y or W=e) with the existing defines that the kernel creates to emulate this behavior with existing clang versions. In file included from :3: In file included from include/linux/compiler_types.h:171: include/linux/compiler-clang.h:37:9: error: '__SANITIZE_THREAD__' macro redefined [-Werror,-Wmacro-redefined] 37 | #define __SANITIZE_THREAD__ | ^ :352:9: note: previous definition is here 352 | #define __SANITIZE_THREAD__ 1 | ^ Refactor compiler-clang.h to only define the sanitizer macros when they are undefined and adjust the rest of the code to use these macros for checking if the sanitizers are enabled, clearing up the warnings and allowing the kernel to easily drop these defines when the minimum supported version of LLVM for building the kernel becomes 22.0.0 or newer. Link: https://lkml.kernel.org/r/20250902-clang-update-sanitize-defines-v1-1-cf3702ca3d92@kernel.org Link: https://github.com/llvm/llvm-project/commit/568c23bbd3303518c5056d7f03444dae4fdc8a9c [1] Signed-off-by: Nathan Chancellor Reviewed-by: Justin Stitt Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Bill Wendling Cc: Dmitriy Vyukov Cc: Marco Elver Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

compiler.h: drop fallback overflow checkers

2025-10-02T11:35:36+00:00

[ Upstream commit 4eb6bd55cfb22ffc20652732340c4962f3ac9a91 ] Once upgrading the minimum supported version of GCC to 5.1, we can drop the fallback code for !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW. This is effectively a revert of commit f0907827a8a9 ("compiler.h: enable builtin overflow checkers and add fallback code") Link: https://github.com/ClangBuiltLinux/linux/issues/1438#issuecomment-916745801 Suggested-by: Rasmus Villemoes Signed-off-by: Nick Desaulniers Acked-by: Kees Cook Reviewed-by: Nathan Chancellor Signed-off-by: Linus Torvalds Signed-off-by: Eliav Farber Signed-off-by: Greg Kroah-Hartman

kcov: add __no_sanitize_coverage to fix noinstr for all architectures

2021-07-20T14:05:46+00:00

[ Upstream commit 540540d06e9d9b3769b46d88def90f7e7c002322 ] Until now no compiler supported an attribute to disable coverage instrumentation as used by KCOV. To work around this limitation on x86, noinstr functions have their coverage instrumentation turned into nops by objtool. However, this solution doesn't scale automatically to other architectures, such as arm64, which are migrating to use the generic entry code. Clang [1] and GCC [2] have added support for the attribute recently. [1] https://github.com/llvm/llvm-project/commit/280333021e9550d80f5c1152a34e33e81df1e178 [2] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=cec4d4a6782c9bd8d071839c50a239c49caca689 The changes will appear in Clang 13 and GCC 12. Add __no_sanitize_coverage for both compilers, and add it to noinstr. Note: In the Clang case, __has_feature(coverage_sanitizer) is only true if the feature is enabled, and therefore we do not require an additional defined(CONFIG_KCOV) (like in the GCC case where __has_attribute(..) is always true) to avoid adding redundant attributes to functions if KCOV is off. That being said, compilers that support the attribute will not generate errors/warnings if the attribute is redundantly used; however, where possible let's avoid it as it reduces preprocessed code size and associated compile-time overheads. [elver@google.com: Implement __has_feature(coverage_sanitizer) in Clang] Link: https://lkml.kernel.org/r/20210527162655.3246381-1-elver@google.com [elver@google.com: add comment explaining __has_feature() in Clang] Link: https://lkml.kernel.org/r/20210527194448.3470080-1-elver@google.com Link: https://lkml.kernel.org/r/20210525175819.699786-1-elver@google.com Signed-off-by: Marco Elver Acked-by: Peter Zijlstra (Intel) Reviewed-by: Miguel Ojeda Reviewed-by: Nathan Chancellor Cc: Nick Desaulniers Cc: Kees Cook Cc: Will Deacon Cc: Ard Biesheuvel Cc: Luc Van Oostenryck Cc: Arvind Sankar Cc: Masahiro Yamada Cc: Sami Tolvanen Cc: Arnd Bergmann Cc: Dmitry Vyukov Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*

2021-03-17T16:06:35+00:00

commit 97e4910232fa1f81e806aa60c25a0450276d99a2 upstream. Separating compiler-clang.h from compiler-gcc.h inadventently dropped the definitions of the three HAVE_BUILTIN_BSWAP macros, which requires falling back to the open-coded version and hoping that the compiler detects it. Since all versions of clang support the __builtin_bswap interfaces, add back the flags and have the headers pick these up automatically. This results in a 4% improvement of compilation speed for arm defconfig. Note: it might also be worth revisiting which architectures set CONFIG_ARCH_USE_BUILTIN_BSWAP for one compiler or the other, today this is set on six architectures (arm32, csky, mips, powerpc, s390, x86), while another ten architectures define custom helpers (alpha, arc, ia64, m68k, mips, nios2, parisc, sh, sparc, xtensa), and the rest (arm64, h8300, hexagon, microblaze, nds32, openrisc, riscv) just get the unoptimized version and rely on the compiler to detect it. A long time ago, the compiler builtins were architecture specific, but nowadays, all compilers that are able to build the kernel have correct implementations of them, though some may not be as optimized as the inline asm versions. The patch that dropped the optimization landed in v4.19, so as discussed it would be fairly safe to backport this revert to stable kernels to the 4.19/5.4/5.10 stable kernels, but there is a remaining risk for regressions, and it has no known side-effects besides compile speed. Link: https://lkml.kernel.org/r/20210226161151.2629097-1-arnd@kernel.org Link: https://lore.kernel.org/lkml/20210225164513.3667778-1-arnd@kernel.org/ Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Kees Cook Acked-by: Miguel Ojeda Acked-by: Nick Desaulniers Acked-by: Luc Van Oostenryck Cc: Masahiro Yamada Cc: Nick Hu Cc: Greentime Hu Cc: Vincent Chen Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Guo Ren Cc: Randy Dunlap Cc: Sami Tolvanen Cc: Marco Elver Cc: Arvind Sankar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

compiler-clang: remove version check for BPF Tracing

2020-11-22T18:48:22+00:00

bpftrace parses the kernel headers and uses Clang under the hood. Remove the version check when __BPF_TRACING__ is defined (as bpftrace does) so that this tool can continue to parse kernel headers, even with older clang sources. Fixes: commit 1f7a44f63e6c ("compiler-clang: add build check for clang 10.0.1") Reported-by: Chen Yu Reported-by: Jarkko Sakkinen Signed-off-by: Nick Desaulniers Signed-off-by: Andrew Morton Tested-by: Jarkko Sakkinen Acked-by: Jarkko Sakkinen Acked-by: Song Liu Acked-by: Nathan Chancellor Acked-by: Miguel Ojeda Link: https://lkml.kernel.org/r/20201104191052.390657-1-ndesaulniers@google.com Signed-off-by: Linus Torvalds

compiler.h: fix barrier_data() on clang

2020-11-14T19:26:03+00:00

Commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") neglected to copy barrier_data() from compiler-gcc.h into compiler-clang.h. The definition in compiler-gcc.h was really to work around clang's more aggressive optimization, so this broke barrier_data() on clang, and consequently memzero_explicit() as well. For example, this results in at least the memzero_explicit() call in lib/crypto/sha256.c:sha256_transform() being optimized away by clang. Fix this by moving the definition of barrier_data() into compiler.h. Also move the gcc/clang definition of barrier() into compiler.h, __memory_barrier() is icc-specific (and barrier() is already defined using it in compiler-intel.h) and doesn't belong in compiler.h. [rdunlap@infradead.org: fix ALPHA builds when SMP is not enabled] Link: https://lkml.kernel.org/r/20201101231835.4589-1-rdunlap@infradead.org Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Signed-off-by: Arvind Sankar Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Tested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Reviewed-by: Kees Cook Cc: Link: https://lkml.kernel.org/r/20201014212631.207844-1-nivedita@alum.mit.edu Signed-off-by: Linus Torvalds

compiler-clang: add build check for clang 10.0.1

2020-10-14T01:38:26+00:00

Patch series "set clang minimum version to 10.0.1", v3. Adds a compile time #error to compiler-clang.h setting the effective minimum supported version to clang 10.0.1. A separate patch has already been picked up into the Documentation/ tree also confirming the version. Next are a series of reverts. One for 32b arm is a partial revert. Then Marco suggested fixes to KASAN docs. Finally, improve the warning for GCC too as per Kees. This patch (of 7): During Plumbers 2020, we voted to just support the latest release of Clang for now. Add a compile time check for this. We plan to remove workarounds for older versions now, which will break in subtle and not so subtle ways. Suggested-by: Sedat Dilek Suggested-by: Nathan Chancellor Suggested-by: Kees Cook Signed-off-by: Nick Desaulniers Signed-off-by: Andrew Morton Tested-by: Sedat Dilek Reviewed-by: Kees Cook Reviewed-by: Miguel Ojeda Reviewed-by: Sedat Dilek Acked-by: Marco Elver Acked-by: Nathan Chancellor Acked-by: Sedat Dilek Cc: Andrey Konovalov Cc: Fangrui Song Cc: Masahiro Yamada Cc: Daniel Borkmann Cc: Alexei Starovoitov Cc: Will Deacon Cc: Vincenzo Frascino Link: https://lkml.kernel.org/r/20200902225911.209899-1-ndesaulniers@google.com Link: https://lkml.kernel.org/r/20200902225911.209899-2-ndesaulniers@google.com Link: https://github.com/ClangBuiltLinux/linux/issues/9 Link: https://github.com/ClangBuiltLinux/linux/issues/941 Signed-off-by: Linus Torvalds

include/linux/compiler-clang.h: drop duplicated word in a comment

2020-08-12T17:57:59+00:00

Drop the doubled word "the" in a comment. Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Reviewed-by: Nathan Chancellor Link: http://lkml.kernel.org/r/6a18c301-3505-742f-4dd7-0f38d0e537b9@infradead.org Signed-off-by: Linus Torvalds