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| author | Marco Elver <elver@google.com> | 2021-11-30 12:44:33 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-12-09 16:42:28 -0800 |
| commit | bd3d5bd1a0ad386475ea7a3de8a91e7d8a600536 (patch) | |
| tree | 0e66c5199f20a5757e3763a92be0158cccac35a2 /lib/Kconfig.kcsan | |
| parent | a015b7085979b12e55f67f3b86be0321fff6be3f (diff) | |
| download | lwn-bd3d5bd1a0ad386475ea7a3de8a91e7d8a600536.tar.gz lwn-bd3d5bd1a0ad386475ea7a3de8a91e7d8a600536.zip | |
kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
Clang and GCC behave a little differently when it comes to the
__no_sanitize_thread attribute, which has valid reasons, and depending
on context either one could be right.
Traditionally, user space ThreadSanitizer [1] still expects instrumented
builtin atomics (to avoid false positives) and __tsan_func_{entry,exit}
(to generate meaningful stack traces), even if the function has the
attribute no_sanitize("thread").
[1] https://clang.llvm.org/docs/ThreadSanitizer.html#attribute-no-sanitize-thread
GCC doesn't follow the same policy (for better or worse), and removes
all kinds of instrumentation if no_sanitize is added. Arguably, since
this may be a problem for user space ThreadSanitizer, we expect this may
change in future.
Since KCSAN != ThreadSanitizer, the likelihood of false positives even
without barrier instrumentation everywhere, is much lower by design.
At least for Clang, however, to fully remove all sanitizer
instrumentation, we must add the disable_sanitizer_instrumentation
attribute, which is available since Clang 14.0.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'lib/Kconfig.kcsan')
| -rw-r--r-- | lib/Kconfig.kcsan | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan index e4394ea8068b..63b70b8c5551 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -198,7 +198,7 @@ config KCSAN_WEAK_MEMORY # We can either let objtool nop __tsan_func_{entry,exit}() and builtin # atomics instrumentation in .noinstr.text, or use a compiler that can # implement __no_kcsan to really remove all instrumentation. - depends on STACK_VALIDATION || CC_IS_GCC + depends on STACK_VALIDATION || CC_IS_GCC || CLANG_VERSION >= 140000 help Enable support for modeling a subset of weak memory, which allows detecting a subset of data races due to missing memory barriers. |