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authorMarco Elver <elver@google.com>2021-08-05 14:57:45 +0200
committerPaul E. McKenney <paulmck@kernel.org>2021-12-09 16:42:26 -0800
commit69562e4983d93e2791c0bf128b07462afbd7f4dc (patch)
tree3f09f093f4aea94918bd1ebb127f61a6f263d15d /scripts
parent9756f64c8f2d19c0029a5827bda8ac275302ec22 (diff)
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kcsan: Add core support for a subset of weak memory modeling
Add support for modeling a subset of weak memory, which will enable detection of a subset of data races due to missing memory barriers. KCSAN's approach to detecting missing memory barriers is based on modeling access reordering, and enabled if `CONFIG_KCSAN_WEAK_MEMORY=y`, which depends on `CONFIG_KCSAN_STRICT=y`. The feature can be enabled or disabled at boot and runtime via the `kcsan.weak_memory` boot parameter. Each memory access for which a watchpoint is set up, is also selected for simulated reordering within the scope of its function (at most 1 in-flight access). We are limited to modeling the effects of "buffering" (delaying the access), since the runtime cannot "prefetch" accesses (therefore no acquire modeling). Once an access has been selected for reordering, it is checked along every other access until the end of the function scope. If an appropriate memory barrier is encountered, the access will no longer be considered for reordering. When the result of a memory operation should be ordered by a barrier, KCSAN can then detect data races where the conflict only occurs as a result of a missing barrier due to reordering accesses. Suggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'scripts')
-rw-r--r--scripts/Makefile.kcsan9
1 files changed, 7 insertions, 2 deletions
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index 37cb504c77e1..4c7f0d282e42 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -9,7 +9,12 @@ endif
# Keep most options here optional, to allow enabling more compilers if absence
# of some options does not break KCSAN nor causes false positive reports.
-export CFLAGS_KCSAN := -fsanitize=thread \
- $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0) -fno-optimize-sibling-calls) \
+kcsan-cflags := -fsanitize=thread -fno-optimize-sibling-calls \
$(call cc-option,$(call cc-param,tsan-compound-read-before-write=1),$(call cc-option,$(call cc-param,tsan-instrument-read-before-write=1))) \
$(call cc-param,tsan-distinguish-volatile=1)
+
+ifndef CONFIG_KCSAN_WEAK_MEMORY
+kcsan-cflags += $(call cc-option,$(call cc-param,tsan-instrument-func-entry-exit=0))
+endif
+
+export CFLAGS_KCSAN := $(kcsan-cflags)