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kcsan: Remove 'noinline' from __no_kcsan_or_inline

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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 versions of Clang are unaffected, and
never inline 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, give the compiler
the ability to inline and generate the expected code in __no_kcsan
functions.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/CANpmjNNOpJk0tprXKB_deiNAv_UmmORf1-2uajLhnLWQQ1hvoA@mail.gmail.com
Link: https://lkml.kernel.org/r/20200521142047.169334-6-elver@google.com
This commit is contained in:
Marco Elver 2020-05-21 16:20:41 +02:00 committed by Thomas Gleixner
parent d31d4d6bb2
commit e3b779d9eb
1 changed files with 2 additions and 4 deletions
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6
include/linux/compiler.h
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@ -329,11 +329,9 @@ 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