Forked from
Linaro / linux / kernel / torvalds / linux
411029 commits behind the upstream repository.
-
Marco Elver authored
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 Signed-off-by:
Marco Elver <elver@google.com> Signed-off-by:
Borislav Petkov <bp@suse.de> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Acked-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by:
Will Deacon <will@kernel.org> Link: https://lkml.kernel.org/r/20200521142047.169334-5-elver@google.com
d31d4d6b
Makefile.kcsan 706 B
# SPDX-License-Identifier: GPL-2.0
ifdef CONFIG_KCSAN
# GCC and Clang accept backend options differently. Do not wrap in cc-option,
# because Clang accepts "--param" even if it is unused.
ifdef CONFIG_CC_IS_CLANG
cc-param = -mllvm -$(1)
else
cc-param = --param -$(1)
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.
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