This series adds support for enabling compounded read-write instrumentation, if supported by the compiler (Clang 12 will be the first compiler to support the feature). The new instrumentation is emitted for sets of memory accesses in the same basic block to the same address with at least one read appearing before a write. These typically result from compound operations such as ++, --, +=, -=, |=, &=, etc. but also equivalent forms such as "var = var + 1".
We can then benefit from improved performance (fewer instrumentation calls) and better reporting for such accesses. In addition, existing explicit instrumentation via instrumented.h was updated to use explicit read-write instrumentation where appropriate, so we can also benefit from the better report generation. Marco Elver (8): kcsan: Support compounded read-write instrumentation objtool, kcsan: Add __tsan_read_write to uaccess whitelist kcsan: Skew delay to be longer for certain access types kcsan: Add missing CONFIG_KCSAN_IGNORE_ATOMICS checks kcsan: Test support for compound instrumentation instrumented.h: Introduce read-write instrumentation hooks asm-generic/bitops: Use instrument_read_write() where appropriate locking/atomics: Use read-write instrumentation for atomic RMWs include/asm-generic/atomic-instrumented.h | 330 +++++++++--------- .../asm-generic/bitops/instrumented-atomic.h | 6 +- .../asm-generic/bitops/instrumented-lock.h | 2 +- .../bitops/instrumented-non-atomic.h | 6 +- include/linux/instrumented.h | 30 ++ include/linux/kcsan-checks.h | 45 ++- kernel/kcsan/core.c | 46 ++- kernel/kcsan/kcsan-test.c | 65 +++- kernel/kcsan/report.c | 4 + lib/Kconfig.kcsan | 5 + scripts/Makefile.kcsan | 2 +- scripts/atomic/gen-atomic-instrumented.sh | 20 +- tools/objtool/check.c | 5 + 13 files changed, 348 insertions(+), 218 deletions(-) -- 2.28.0.rc0.105.gf9edc3c819-goog
