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-rw-r--r--kernel/kcsan/core.c43
-rw-r--r--scripts/Makefile.kcsan5
2 files changed, 47 insertions, 1 deletions
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index a73a66cf79df..15f67949d11e 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -790,6 +790,49 @@ void __tsan_write_range(void *ptr, size_t size)
EXPORT_SYMBOL(__tsan_write_range);
/*
+ * Use of explicit volatile is generally disallowed [1], however, volatile is
+ * still used in various concurrent context, whether in low-level
+ * synchronization primitives or for legacy reasons.
+ * [1] https://lwn.net/Articles/233479/
+ *
+ * We only consider volatile accesses atomic if they are aligned and would pass
+ * the size-check of compiletime_assert_rwonce_type().
+ */
+#define DEFINE_TSAN_VOLATILE_READ_WRITE(size) \
+ void __tsan_volatile_read##size(void *ptr) \
+ { \
+ const bool is_atomic = size <= sizeof(long long) && \
+ IS_ALIGNED((unsigned long)ptr, size); \
+ if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS) && is_atomic) \
+ return; \
+ check_access(ptr, size, is_atomic ? KCSAN_ACCESS_ATOMIC : 0); \
+ } \
+ EXPORT_SYMBOL(__tsan_volatile_read##size); \
+ void __tsan_unaligned_volatile_read##size(void *ptr) \
+ __alias(__tsan_volatile_read##size); \
+ EXPORT_SYMBOL(__tsan_unaligned_volatile_read##size); \
+ void __tsan_volatile_write##size(void *ptr) \
+ { \
+ const bool is_atomic = size <= sizeof(long long) && \
+ IS_ALIGNED((unsigned long)ptr, size); \
+ if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS) && is_atomic) \
+ return; \
+ check_access(ptr, size, \
+ KCSAN_ACCESS_WRITE | \
+ (is_atomic ? KCSAN_ACCESS_ATOMIC : 0)); \
+ } \
+ EXPORT_SYMBOL(__tsan_volatile_write##size); \
+ void __tsan_unaligned_volatile_write##size(void *ptr) \
+ __alias(__tsan_volatile_write##size); \
+ EXPORT_SYMBOL(__tsan_unaligned_volatile_write##size)
+
+DEFINE_TSAN_VOLATILE_READ_WRITE(1);
+DEFINE_TSAN_VOLATILE_READ_WRITE(2);
+DEFINE_TSAN_VOLATILE_READ_WRITE(4);
+DEFINE_TSAN_VOLATILE_READ_WRITE(8);
+DEFINE_TSAN_VOLATILE_READ_WRITE(16);
+
+/*
* The below are not required by KCSAN, but can still be emitted by the
* compiler.
*/
diff --git a/scripts/Makefile.kcsan b/scripts/Makefile.kcsan
index 20337a7ecf54..75d2942b9437 100644
--- a/scripts/Makefile.kcsan
+++ b/scripts/Makefile.kcsan
@@ -9,7 +9,10 @@ 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-func-entry-exit=0) -fno-optimize-sibling-calls) \
+ $(call cc-param,tsan-distinguish-volatile=1)
endif # CONFIG_KCSAN