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| author | Richard Henderson <richard.henderson@linaro.org> | 2019-07-09 10:40:00 +0200 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2019-07-14 12:19:00 +0200 |
| commit | 359896dfa4e9707e1acea99129d324250fccab04 (patch) | |
| tree | da1df5ec403c4fcb42452ac9acd8c7853e143226 | |
| parent | 1789d4274b851fb8fdf4a947ce5474c63e813d0d (diff) | |
include/qemu/atomic.h: Add signal_barrier
We have some potential race conditions vs our user-exec signal
handler that will be solved with this barrier.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
| -rw-r--r-- | include/qemu/atomic.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index a6ac188188..f9cd24c899 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -88,6 +88,13 @@ #define smp_read_barrier_depends() barrier() #endif +/* + * A signal barrier forces all pending local memory ops to be observed before + * a SIGSEGV is delivered to the *same* thread. In practice this is exactly + * the same as barrier(), but since we have the correct builtin, use it. + */ +#define signal_barrier() __atomic_signal_fence(__ATOMIC_SEQ_CST) + /* Sanity check that the size of an atomic operation isn't "overly large". * Despite the fact that e.g. i686 has 64-bit atomic operations, we do not * want to use them because we ought not need them, and this lets us do a @@ -308,6 +315,10 @@ #define smp_read_barrier_depends() barrier() #endif +#ifndef signal_barrier +#define signal_barrier() barrier() +#endif + /* These will only be atomic if the processor does the fetch or store * in a single issue memory operation */ |