[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PULL 13/15] include/qemu/atomic: add compile time asserts
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 13/15] include/qemu/atomic: add compile time asserts |
Date: |
Tue, 5 Apr 2016 11:50:16 +0200 |
From: Alex Bennée <address@hidden>
To be safely portable no atomic access should be trying to do more than
the natural word width of the host. The most common abuse is trying to
atomically access 64 bit values on a 32 bit host.
This patch adds some QEMU_BUILD_BUG_ON to the __atomic instrinsic paths
to create a build failure if (sizeof(*ptr) > sizeof(void *)).
Signed-off-by: Alex Bennée <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
include/qemu/atomic.h | 58 ++++++++++++++++++++++++++++++---------------------
1 file changed, 34 insertions(+), 24 deletions(-)
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index 8f1d8d9..5bc4d6c 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -42,30 +42,34 @@
* loads/stores past the atomic operation load/store. However there is
* no explicit memory barrier for the processor.
*/
-#define atomic_read(ptr) \
- ({ \
- typeof(*ptr) _val; \
- __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
- _val; \
+#define atomic_read(ptr) \
+ ({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val; \
+ __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
+ _val; \
})
-#define atomic_set(ptr, i) do { \
- typeof(*ptr) _val = (i); \
- __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
+#define atomic_set(ptr, i) do { \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val = (i); \
+ __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
} while(0)
/* Atomic RCU operations imply weak memory barriers */
-#define atomic_rcu_read(ptr) \
- ({ \
- typeof(*ptr) _val; \
- __atomic_load(ptr, &_val, __ATOMIC_CONSUME); \
- _val; \
+#define atomic_rcu_read(ptr) \
+ ({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val; \
+ __atomic_load(ptr, &_val, __ATOMIC_CONSUME); \
+ _val; \
})
-#define atomic_rcu_set(ptr, i) do { \
- typeof(*ptr) _val = (i); \
- __atomic_store(ptr, &_val, __ATOMIC_RELEASE); \
+#define atomic_rcu_set(ptr, i) do { \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val = (i); \
+ __atomic_store(ptr, &_val, __ATOMIC_RELEASE); \
} while(0)
/* atomic_mb_read/set semantics map Java volatile variables. They are
@@ -79,6 +83,7 @@
#if defined(_ARCH_PPC)
#define atomic_mb_read(ptr) \
({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val; \
__atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
smp_rmb(); \
@@ -86,22 +91,25 @@
})
#define atomic_mb_set(ptr, i) do { \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val = (i); \
smp_wmb(); \
__atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
smp_mb(); \
} while(0)
#else
-#define atomic_mb_read(ptr) \
- ({ \
- typeof(*ptr) _val; \
- __atomic_load(ptr, &_val, __ATOMIC_SEQ_CST); \
- _val; \
+#define atomic_mb_read(ptr) \
+ ({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val; \
+ __atomic_load(ptr, &_val, __ATOMIC_SEQ_CST); \
+ _val; \
})
-#define atomic_mb_set(ptr, i) do { \
- typeof(*ptr) _val = (i); \
- __atomic_store(ptr, &_val, __ATOMIC_SEQ_CST); \
+#define atomic_mb_set(ptr, i) do { \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
+ typeof(*ptr) _val = (i); \
+ __atomic_store(ptr, &_val, __ATOMIC_SEQ_CST); \
} while(0)
#endif
@@ -109,6 +117,7 @@
/* All the remaining operations are fully sequentially consistent */
#define atomic_xchg(ptr, i) ({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _new = (i), _old; \
__atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \
_old; \
@@ -117,6 +126,7 @@
/* Returns the eventual value, failed or not */
#define atomic_cmpxchg(ptr, old, new) \
({ \
+ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _old = (old), _new = (new); \
__atomic_compare_exchange(ptr, &_old, &_new, false, \
__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \
--
2.5.5
- [Qemu-devel] [PULL 09/15] char: ensure all clients are in non-blocking mode, (continued)
- [Qemu-devel] [PULL 09/15] char: ensure all clients are in non-blocking mode, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 08/15] char: fix broken EAGAIN retry on OS-X due to errno clobbering, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 10/15] doc/memory: update MMIO section, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 07/15] util: retry getaddrinfo if getting EAI_BADFLAGS with AI_V4MAPPED, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 11/15] nbd: don't request FUA on FLUSH, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 06/15] checkpatch: add target_ulong to typelist, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 14/15] nbd: Fix poor debug message, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 12/15] cpus: don't use atomic_read for vm_clock_warp_start, Paolo Bonzini, 2016/04/05
- [Qemu-devel] [PULL 13/15] include/qemu/atomic: add compile time asserts,
Paolo Bonzini <=
- [Qemu-devel] [PULL 15/15] net: fix missing include of qapi/error.h in netmap.c, Paolo Bonzini, 2016/04/05
- Re: [Qemu-devel] [PULL 00/15] Misc changes for QEMU 2.6.0-rc1, Peter Maydell, 2016/04/05