lkml.org 
[lkml]   [2020]   [May]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH -tip v3 04/11] kcsan: Pass option tsan-instrument-read-before-write to Clang
From
Clang (unlike GCC) removes reads before writes with matching addresses
in the same basic block. This is an optimization for TSAN, since writes
will always cause conflict if the preceding read would have.

However, for KCSAN we cannot rely on this option, because we apply
several special rules to writes, in particular when the
KCSAN_ASSUME_PLAIN_WRITES_ATOMIC option is selected. To avoid missing
potential data races, pass the -tsan-instrument-read-before-write option
to Clang if it is available [1].

[1] https://github.com/llvm/llvm-project/commit/151ed6aa38a3ec6c01973b35f684586b6e1c0f7e

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marco Elver <elver@google.com>
---
scripts/Makefile.kcsan | 1 +
1 file changed, 1 insertion(+)

diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index 75d2942b9437..bd4da1af5953 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -13,6 +13,7 @@ endif
# 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-read-before-write=1)) \
$(call cc-param,tsan-distinguish-volatile=1)

endif # CONFIG_KCSAN
--
2.26.2.761.g0e0b3e54be-goog
\
 
 \ /
  Last update: 2020-05-21 16:23    [W:0.102 / U:2.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site