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[Qemu-devel] [PULL for-4.1 3/7] include/qemu/atomic.h: Add signal_barrie
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PULL for-4.1 3/7] include/qemu/atomic.h: Add signal_barrier |
Date: |
Sun, 14 Jul 2019 11:12:45 +0000 |
We have some potential race conditions vs our user-exec signal
handler that will be solved with this barrier.
Reviewed-by: Alex Bennée <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
include/qemu/atomic.h | 11 +++++++++++
1 file changed, 11 insertions(+)
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
*/
--
2.17.1
- [Qemu-devel] [PULL for-4.1 0/7] tcg patch queue, Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 1/7] tcg: Fix constant folding of INDEX_op_extract2_i32, Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 3/7] include/qemu/atomic.h: Add signal_barrier,
Richard Henderson <=
- [Qemu-devel] [PULL for-4.1 2/7] tcg/aarch64: Fix output of extract2 opcodes, Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 5/7] tcg: Remove cpu_ld*_code_ra, Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 4/7] tcg: Introduce set/clear_helper_retaddr, Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 6/7] tcg: Remove duplicate #if !defined(CODE_ACCESS), Richard Henderson, 2019/07/14
- [Qemu-devel] [PULL for-4.1 7/7] tcg: Release mmap_lock on translation fault, Richard Henderson, 2019/07/14
- Re: [Qemu-devel] [PULL for-4.1 0/7] tcg patch queue, Peter Maydell, 2019/07/15