Some compilers incorrectly inline small __no_kcsan functions, which then results in instrumenting the accesses. For this reason, the 'noinline' attribute was added to __no_kcsan_or_inline. All known versions of GCC are affected by this. Supported version of Clang are unaffected, and never inlines a no_sanitize function.
However, the attribute 'noinline' in __no_kcsan_or_inline causes unexpected code generation in functions that are __no_kcsan and call a __no_kcsan_or_inline function. In certain situations it is expected that the __no_kcsan_or_inline function is actually inlined by the __no_kcsan function, and *no* calls are emitted. By removing the 'noinline' attribute we give the compiler the ability to inline and generate the expected code in __no_kcsan functions. Link: https://lkml.kernel.org/r/canpmjnnopjk0tprxkb_deinav_ummorf1-2uajlhnlwqq1h...@mail.gmail.com Signed-off-by: Marco Elver <el...@google.com> --- include/linux/compiler.h | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index e24cc3a2bc3e..17c98b215572 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -276,11 +276,9 @@ do { \ #ifdef __SANITIZE_THREAD__ /* * Rely on __SANITIZE_THREAD__ instead of CONFIG_KCSAN, to avoid not inlining in - * compilation units where instrumentation is disabled. The attribute 'noinline' - * is required for older compilers, where implicit inlining of very small - * functions renders __no_sanitize_thread ineffective. + * compilation units where instrumentation is disabled. */ -# define __no_kcsan_or_inline __no_kcsan noinline notrace __maybe_unused +# define __no_kcsan_or_inline __no_kcsan notrace __maybe_unused # define __no_sanitize_or_inline __no_kcsan_or_inline #else # define __no_kcsan_or_inline __always_inline -- 2.26.2.761.g0e0b3e54be-goog
