mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-12-27 11:06:41 -05:00
69562e4983
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>
21 lines
824 B
Makefile
21 lines
824 B
Makefile
# SPDX-License-Identifier: GPL-2.0
|
|
# 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.
|
|
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)
|