Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH kcsan 27/29] kcsan: Turn barrier instrumentation into macros | Date | Tue, 14 Dec 2021 14:04:37 -0800 |
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From: Marco Elver <elver@google.com>
Some architectures use barriers in 'extern inline' functions, from which we should not refer to static inline functions.
For example, building Alpha with gcc and W=1 shows:
./include/asm-generic/barrier.h:70:30: warning: 'kcsan_rmb' is static but used in inline function 'pmd_offset' which is not static 70 | #define smp_rmb() do { kcsan_rmb(); __smp_rmb(); } while (0) | ^~~~~~~~~ ./arch/alpha/include/asm/pgtable.h:293:9: note: in expansion of macro 'smp_rmb' 293 | smp_rmb(); /* see above */ | ^~~~~~~
Which seems to warn about 6.7.4#3 of the C standard: "An inline definition of a function with external linkage shall not contain a definition of a modifiable object with static or thread storage duration, and shall not contain a reference to an identifier with internal linkage."
Fix it by turning barrier instrumentation into macros, which matches definitions in <asm/barrier.h>.
Perhaps we can revert this change in future, when there are no more 'extern inline' users left.
Link: https://lkml.kernel.org/r/202112041334.X44uWZXf-lkp@intel.com Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> --- include/linux/kcsan-checks.h | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/include/linux/kcsan-checks.h b/include/linux/kcsan-checks.h index 9d2c869167f2e..92f3843d9ebb8 100644 --- a/include/linux/kcsan-checks.h +++ b/include/linux/kcsan-checks.h @@ -241,28 +241,30 @@ static inline void __kcsan_disable_current(void) { } * disabled with the __no_kcsan function attribute. * * Also see definition of __tsan_atomic_signal_fence() in kernel/kcsan/core.c. + * + * These are all macros, like <asm/barrier.h>, since some architectures use them + * in non-static inline functions. */ #define __KCSAN_BARRIER_TO_SIGNAL_FENCE(name) \ - static __always_inline void kcsan_##name(void) \ - { \ + do { \ barrier(); \ __atomic_signal_fence(__KCSAN_BARRIER_TO_SIGNAL_FENCE_##name); \ barrier(); \ - } -__KCSAN_BARRIER_TO_SIGNAL_FENCE(mb) -__KCSAN_BARRIER_TO_SIGNAL_FENCE(wmb) -__KCSAN_BARRIER_TO_SIGNAL_FENCE(rmb) -__KCSAN_BARRIER_TO_SIGNAL_FENCE(release) + } while (0) +#define kcsan_mb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(mb) +#define kcsan_wmb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(wmb) +#define kcsan_rmb() __KCSAN_BARRIER_TO_SIGNAL_FENCE(rmb) +#define kcsan_release() __KCSAN_BARRIER_TO_SIGNAL_FENCE(release) #elif defined(CONFIG_KCSAN_WEAK_MEMORY) && defined(__KCSAN_INSTRUMENT_BARRIERS__) #define kcsan_mb __kcsan_mb #define kcsan_wmb __kcsan_wmb #define kcsan_rmb __kcsan_rmb #define kcsan_release __kcsan_release #else /* CONFIG_KCSAN_WEAK_MEMORY && ... */ -static inline void kcsan_mb(void) { } -static inline void kcsan_wmb(void) { } -static inline void kcsan_rmb(void) { } -static inline void kcsan_release(void) { } +#define kcsan_mb() do { } while (0) +#define kcsan_wmb() do { } while (0) +#define kcsan_rmb() do { } while (0) +#define kcsan_release() do { } while (0) #endif /* CONFIG_KCSAN_WEAK_MEMORY && ... */ /** -- 2.31.1.189.g2e36527f23
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