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kcsan: Turn barrier instrumentation into macros

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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>
This commit is contained in:
Marco Elver 2021-12-04 13:57:03 +01:00 committed by Paul E. McKenney
parent a70d36e6a0
commit 80d7476fa2
1 changed files with 13 additions and 11 deletions
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24
include/linux/kcsan-checks.h
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@ -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 && ... */
/**