Commit 359896df authored by Richard Henderson's avatar Richard Henderson
Browse files

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: default avatarAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 1789d427

include/qemu/atomic.h

+11 −0
Original line number Diff line number Diff line
@@ -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

 */