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author | Richard Henderson <rth@twiddle.net> | 2017-04-26 10:41:55 -0700 |
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committer | Richard Henderson <rth@twiddle.net> | 2017-06-05 09:25:42 -0700 |
commit | 374aae653499f4d405caf32b7fff0c8639113fe4 (patch) | |
tree | 5da150e4bd37fb20e9a1965ccdd4cd976eaede16 /include/qemu | |
parent | f1079bb8f9a28495937408acc60a681a7b2536a8 (diff) | |
download | qemu-374aae653499f4d405caf32b7fff0c8639113fe4.zip qemu-374aae653499f4d405caf32b7fff0c8639113fe4.tar.gz qemu-374aae653499f4d405caf32b7fff0c8639113fe4.tar.bz2 |
qemu/atomic: Loosen restrictions for 64-bit ILP32 hosts
We need to coordinate with the TCG_OVERSIZED_GUEST test in cputlb.c,
and allow 64-bit atomics even though sizeof(void *) == 4.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'include/qemu')
-rw-r--r-- | include/qemu/atomic.h | 34 |
1 files changed, 26 insertions, 8 deletions
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 878fa07..e07c797 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -88,6 +88,24 @@ #define smp_read_barrier_depends() barrier() #endif +/* 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 + * bit of sanity checking that other 32-bit hosts might build. + * + * That said, we have a problem on 64-bit ILP32 hosts in that in order to + * sync with TCG_OVERSIZED_GUEST, this must match TCG_TARGET_REG_BITS. + * We'd prefer not want to pull in everything else TCG related, so handle + * those few cases by hand. + * + * Note that x32 is fully detected with __x64_64__ + _ILP32, and that for + * Sparc we always force the use of sparcv9 in configure. + */ +#if defined(__x86_64__) || defined(__sparc__) +# define ATOMIC_REG_SIZE 8 +#else +# define ATOMIC_REG_SIZE sizeof(void *) +#endif /* Weak atomic operations prevent the compiler moving other * loads/stores past the atomic operation load/store. However there is @@ -104,7 +122,7 @@ #define atomic_read(ptr) \ ({ \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ atomic_read__nocheck(ptr); \ }) @@ -112,7 +130,7 @@ __atomic_store_n(ptr, i, __ATOMIC_RELAXED) #define atomic_set(ptr, i) do { \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ atomic_set__nocheck(ptr, i); \ } while(0) @@ -130,27 +148,27 @@ #define atomic_rcu_read(ptr) \ ({ \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ typeof_strip_qual(*ptr) _val; \ atomic_rcu_read__nocheck(ptr, &_val); \ _val; \ }) #define atomic_rcu_set(ptr, i) do { \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ __atomic_store_n(ptr, i, __ATOMIC_RELEASE); \ } while(0) #define atomic_load_acquire(ptr) \ ({ \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ typeof_strip_qual(*ptr) _val; \ __atomic_load(ptr, &_val, __ATOMIC_ACQUIRE); \ _val; \ }) #define atomic_store_release(ptr, i) do { \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ __atomic_store_n(ptr, i, __ATOMIC_RELEASE); \ } while(0) @@ -162,7 +180,7 @@ }) #define atomic_xchg(ptr, i) ({ \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ atomic_xchg__nocheck(ptr, i); \ }) @@ -175,7 +193,7 @@ }) #define atomic_cmpxchg(ptr, old, new) ({ \ - QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ + QEMU_BUILD_BUG_ON(sizeof(*ptr) > ATOMIC_REG_SIZE); \ atomic_cmpxchg__nocheck(ptr, old, new); \ }) |