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include/qemu/atomic: add compile time asserts 

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 <alex.bennee@linaro.org>
Message-Id: <1459780549-12942-3-git-send-email-alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Alex Bennée 2016-04-04 15:35:49 +01:00 committed by Paolo Bonzini
parent ccffff48c9
commit ca47a926ad
1 changed files with 34 additions and 24 deletions
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10
include/qemu/atomic.h
View File

@ -44,12 +44,14 @@
*/ */
#define atomic_read(ptr) \ #define atomic_read(ptr) \
({ \ ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val; \ typeof(*ptr) _val; \
__atomic_load(ptr, &_val, __ATOMIC_RELAXED); \ __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
_val; \ _val; \
}) })
#define atomic_set(ptr, i) do { \ #define atomic_set(ptr, i) do { \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val = (i); \ typeof(*ptr) _val = (i); \
__atomic_store(ptr, &_val, __ATOMIC_RELAXED); \ __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
} while(0) } while(0)
@ -58,12 +60,14 @@
#define atomic_rcu_read(ptr) \ #define atomic_rcu_read(ptr) \
({ \ ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val; \ typeof(*ptr) _val; \
__atomic_load(ptr, &_val, __ATOMIC_CONSUME); \ __atomic_load(ptr, &_val, __ATOMIC_CONSUME); \
_val; \ _val; \
}) })
#define atomic_rcu_set(ptr, i) do { \ #define atomic_rcu_set(ptr, i) do { \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val = (i); \ typeof(*ptr) _val = (i); \
__atomic_store(ptr, &_val, __ATOMIC_RELEASE); \ __atomic_store(ptr, &_val, __ATOMIC_RELEASE); \
} while(0) } while(0)
@ -79,6 +83,7 @@
#if defined(_ARCH_PPC) #if defined(_ARCH_PPC)
#define atomic_mb_read(ptr) \ #define atomic_mb_read(ptr) \
({ \ ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val; \ typeof(*ptr) _val; \
__atomic_load(ptr, &_val, __ATOMIC_RELAXED); \ __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \
smp_rmb(); \ smp_rmb(); \
@ -86,6 +91,7 @@
}) })
#define atomic_mb_set(ptr, i) do { \ #define atomic_mb_set(ptr, i) do { \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val = (i); \ typeof(*ptr) _val = (i); \
smp_wmb(); \ smp_wmb(); \
__atomic_store(ptr, &_val, __ATOMIC_RELAXED); \ __atomic_store(ptr, &_val, __ATOMIC_RELAXED); \
@ -94,12 +100,14 @@
#else #else
#define atomic_mb_read(ptr) \ #define atomic_mb_read(ptr) \
({ \ ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val; \ typeof(*ptr) _val; \
__atomic_load(ptr, &_val, __ATOMIC_SEQ_CST); \ __atomic_load(ptr, &_val, __ATOMIC_SEQ_CST); \
_val; \ _val; \
}) })
#define atomic_mb_set(ptr, i) do { \ #define atomic_mb_set(ptr, i) do { \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _val = (i); \ typeof(*ptr) _val = (i); \
__atomic_store(ptr, &_val, __ATOMIC_SEQ_CST); \ __atomic_store(ptr, &_val, __ATOMIC_SEQ_CST); \
} while(0) } while(0)
@ -109,6 +117,7 @@
/* All the remaining operations are fully sequentially consistent */ /* All the remaining operations are fully sequentially consistent */
#define atomic_xchg(ptr, i) ({ \ #define atomic_xchg(ptr, i) ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _new = (i), _old; \ typeof(*ptr) _new = (i), _old; \
__atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \ __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \
_old; \ _old; \
@ -117,6 +126,7 @@
/* Returns the eventual value, failed or not */ /* Returns the eventual value, failed or not */
#define atomic_cmpxchg(ptr, old, new) \ #define atomic_cmpxchg(ptr, old, new) \
({ \ ({ \
QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
typeof(*ptr) _old = (old), _new = (new); \ typeof(*ptr) _old = (old), _new = (new); \
__atomic_compare_exchange(ptr, &_old, &_new, false, \ __atomic_compare_exchange(ptr, &_old, &_new, false, \
__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \ __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \