Re: [PATCH 4/8] kcsan: Add missing CONFIG_KCSAN_IGNORE_ATOMICS checks
From: Peter Zijlstra
Date: Tue Jul 21 2020 - 10:09:39 EST
On Tue, Jul 21, 2020 at 12:30:12PM +0200, Marco Elver wrote:
> Add missing CONFIG_KCSAN_IGNORE_ATOMICS checks for the builtin atomics
> instrumentation.
>
> Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> ---
> Added to this series, as it would otherwise cause patch conflicts.
> ---
> kernel/kcsan/core.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
> index 4633baebf84e..f53524ea0292 100644
> --- a/kernel/kcsan/core.c
> +++ b/kernel/kcsan/core.c
> @@ -892,14 +892,17 @@ EXPORT_SYMBOL(__tsan_init);
> u##bits __tsan_atomic##bits##_load(const u##bits *ptr, int memorder); \
> u##bits __tsan_atomic##bits##_load(const u##bits *ptr, int memorder) \
> { \
> - check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_ATOMIC); \
> + if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) \
> + check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_ATOMIC); \
> return __atomic_load_n(ptr, memorder); \
> } \
> EXPORT_SYMBOL(__tsan_atomic##bits##_load); \
> void __tsan_atomic##bits##_store(u##bits *ptr, u##bits v, int memorder); \
> void __tsan_atomic##bits##_store(u##bits *ptr, u##bits v, int memorder) \
> { \
> - check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
> + if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) \
> + check_access(ptr, bits / BITS_PER_BYTE, \
> + KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
> __atomic_store_n(ptr, v, memorder); \
> } \
> EXPORT_SYMBOL(__tsan_atomic##bits##_store)
> @@ -908,8 +911,10 @@ EXPORT_SYMBOL(__tsan_init);
> u##bits __tsan_atomic##bits##_##op(u##bits *ptr, u##bits v, int memorder); \
> u##bits __tsan_atomic##bits##_##op(u##bits *ptr, u##bits v, int memorder) \
> { \
> - check_access(ptr, bits / BITS_PER_BYTE, \
> - KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
> + if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) \
> + check_access(ptr, bits / BITS_PER_BYTE, \
> + KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
> + KCSAN_ACCESS_ATOMIC); \
> return __atomic_##op##suffix(ptr, v, memorder); \
> } \
> EXPORT_SYMBOL(__tsan_atomic##bits##_##op)
> @@ -937,8 +942,10 @@ EXPORT_SYMBOL(__tsan_init);
> int __tsan_atomic##bits##_compare_exchange_##strength(u##bits *ptr, u##bits *exp, \
> u##bits val, int mo, int fail_mo) \
> { \
> - check_access(ptr, bits / BITS_PER_BYTE, \
> - KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
> + if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) \
> + check_access(ptr, bits / BITS_PER_BYTE, \
> + KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
> + KCSAN_ACCESS_ATOMIC); \
> return __atomic_compare_exchange_n(ptr, exp, val, weak, mo, fail_mo); \
> } \
> EXPORT_SYMBOL(__tsan_atomic##bits##_compare_exchange_##strength)
> @@ -949,8 +956,10 @@ EXPORT_SYMBOL(__tsan_init);
> u##bits __tsan_atomic##bits##_compare_exchange_val(u##bits *ptr, u##bits exp, u##bits val, \
> int mo, int fail_mo) \
> { \
> - check_access(ptr, bits / BITS_PER_BYTE, \
> - KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
> + if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) \
> + check_access(ptr, bits / BITS_PER_BYTE, \
> + KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
> + KCSAN_ACCESS_ATOMIC); \
> __atomic_compare_exchange_n(ptr, &exp, val, 0, mo, fail_mo); \
> return exp; \
> } \
*groan*, that could really do with a bucket of '{', '}'. Also, it is
inconsistent in style with the existing use in
DEFINE_TSAN_VOLATILE_READ_WRITE() where the define causes an early
return.