path: root/scripts/Makefile.kcsan
diff options
authorMarco Elver <>2020-05-21 16:20:39 +0200
committerThomas Gleixner <>2020-06-11 20:04:01 +0200
commit75d75b7a4d5489cc6a5e91ace306f6c13f376f33 (patch)
tree3aa69e5ff92430125ce2678e5dd1a5d4976ca035 /scripts/Makefile.kcsan
parent0e1aa5b62160500bb2ed3150367fba83c0a194e5 (diff)
kcsan: Support distinguishing volatile accesses
In the kernel, the "volatile" keyword is used in various concurrent contexts, whether in low-level synchronization primitives or for legacy reasons. If supported by the compiler, it will be assumed that aligned volatile accesses up to sizeof(long long) (matching compiletime_assert_rwonce_type()) are atomic. Recent versions of Clang [1] (GCC tentative [2]) can instrument volatile accesses differently. Add the option (required) to enable the instrumentation, and provide the necessary runtime functions. None of the updated compilers are widely available yet (Clang 11 will be the first release to support the feature). [1] [2] This change allows removing of any explicit checks in primitives such as READ_ONCE() and WRITE_ONCE(). [ bp: Massage commit message a bit. ] Signed-off-by: Marco Elver <> Signed-off-by: Borislav Petkov <> Signed-off-by: Thomas Gleixner <> Acked-by: Will Deacon <> Acked-by: Peter Zijlstra (Intel) <> Link:
Diffstat (limited to 'scripts/Makefile.kcsan')
1 files changed, 4 insertions, 1 deletions
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index 20337a7ecf54..75d2942b9437 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -9,7 +9,10 @@ else
cc-param = --param -$(1)
+# Keep most options here optional, to allow enabling more compilers if absence
+# of some options does not break KCSAN nor causes false positive reports.
CFLAGS_KCSAN := -fsanitize=thread \
- $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls)
+ $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
+ $(call cc-param,tsan-distinguish-volatile=1)