diff options
| -rw-r--r-- | include/qemu/atomic.h | 54 |
1 files changed, 48 insertions, 6 deletions
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 7e13fca351..43b06458f1 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -18,6 +18,48 @@ /* Compiler barrier */ #define barrier() ({ asm volatile("" ::: "memory"); (void)0; }) +/* The variable that receives the old value of an atomically-accessed + * variable must be non-qualified, because atomic builtins return values + * through a pointer-type argument as in __atomic_load(&var, &old, MODEL). + * + * This macro has to handle types smaller than int manually, because of + * implicit promotion. int and larger types, as well as pointers, can be + * converted to a non-qualified type just by applying a binary operator. + */ +#define typeof_strip_qual(expr) \ + typeof( \ + __builtin_choose_expr( \ + __builtin_types_compatible_p(typeof(expr), bool) || \ + __builtin_types_compatible_p(typeof(expr), const bool) || \ + __builtin_types_compatible_p(typeof(expr), volatile bool) || \ + __builtin_types_compatible_p(typeof(expr), const volatile bool), \ + (bool)1, \ + __builtin_choose_expr( \ + __builtin_types_compatible_p(typeof(expr), signed char) || \ + __builtin_types_compatible_p(typeof(expr), const signed char) || \ + __builtin_types_compatible_p(typeof(expr), volatile signed char) || \ + __builtin_types_compatible_p(typeof(expr), const volatile signed char), \ + (signed char)1, \ + __builtin_choose_expr( \ + __builtin_types_compatible_p(typeof(expr), unsigned char) || \ + __builtin_types_compatible_p(typeof(expr), const unsigned char) || \ + __builtin_types_compatible_p(typeof(expr), volatile unsigned char) || \ + __builtin_types_compatible_p(typeof(expr), const volatile unsigned char), \ + (unsigned char)1, \ + __builtin_choose_expr( \ + __builtin_types_compatible_p(typeof(expr), signed short) || \ + __builtin_types_compatible_p(typeof(expr), const signed short) || \ + __builtin_types_compatible_p(typeof(expr), volatile signed short) || \ + __builtin_types_compatible_p(typeof(expr), const volatile signed short), \ + (signed short)1, \ + __builtin_choose_expr( \ + __builtin_types_compatible_p(typeof(expr), unsigned short) || \ + __builtin_types_compatible_p(typeof(expr), const unsigned short) || \ + __builtin_types_compatible_p(typeof(expr), volatile unsigned short) || \ + __builtin_types_compatible_p(typeof(expr), const volatile unsigned short), \ + (unsigned short)1, \ + (expr)+0)))))) + #ifdef __ATOMIC_RELAXED /* For C11 atomic ops */ @@ -54,7 +96,7 @@ #define atomic_read(ptr) \ ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _val; \ + typeof_strip_qual(*ptr) _val; \ __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \ _val; \ }) @@ -80,7 +122,7 @@ #define atomic_rcu_read(ptr) \ ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _val; \ + typeof_strip_qual(*ptr) _val; \ atomic_rcu_read__nocheck(ptr, &_val); \ _val; \ }) @@ -103,7 +145,7 @@ #define atomic_mb_read(ptr) \ ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _val; \ + typeof_strip_qual(*ptr) _val; \ __atomic_load(ptr, &_val, __ATOMIC_RELAXED); \ smp_rmb(); \ _val; \ @@ -120,7 +162,7 @@ #define atomic_mb_read(ptr) \ ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _val; \ + typeof_strip_qual(*ptr) _val; \ __atomic_load(ptr, &_val, __ATOMIC_SEQ_CST); \ _val; \ }) @@ -137,7 +179,7 @@ #define atomic_xchg(ptr, i) ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _new = (i), _old; \ + typeof_strip_qual(*ptr) _new = (i), _old; \ __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \ _old; \ }) @@ -146,7 +188,7 @@ #define atomic_cmpxchg(ptr, old, new) \ ({ \ QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \ - typeof(*ptr) _old = (old), _new = (new); \ + typeof_strip_qual(*ptr) _old = (old), _new = (new); \ __atomic_compare_exchange(ptr, &_old, &_new, false, \ __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \ _old; \ |