The following commit has been merged into the locking/kcsan branch of tip:
Commit-ID: f487a549ea30ee894055d8d20e81c1996a6e10a0
Gitweb: https://git.kernel.org/tip/f487a549ea30ee894055d8d20e81c1996a6e10a0
Author: Marco Elver <elver@xxxxxxxxxx>
AuthorDate: Thu, 21 May 2020 16:20:41 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Fri, 22 May 2020 15:12:39 +02:00
kcsan: Remove 'noinline' from __no_kcsan_or_inline
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@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/CANpmjNNOpJk0tprXKB_deiNAv_UmmORf1-2uajLhnLWQQ1hvoA@xxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20200521142047.169334-6-elver@xxxxxxxxxx
---
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 e24cc3a..17c98b2 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
|