atomics: Add __nocheck atomic operations

While the check against sizeof(void *) is appropriate for
normal usage within qemu, there are places in which we want
wider operaions and have checked for their existance.
Reviewed-by: NEmilio G. Cota <cota@braap.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

include/qemu/atomic.h

@@ -99,15 +99,21 @@
  * no effect on the generated code but not using the atomic primitives
  * will get flagged by sanitizers as a violation.
  */
+#define atomic_read__nocheck(ptr) \
+    __atomic_load_n(ptr, __ATOMIC_RELAXED)
+
 #define atomic_read(ptr)                              \
     ({                                                \
     QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
-    __atomic_load_n(ptr, __ATOMIC_RELAXED);           \
+    atomic_read__nocheck(ptr);                        \
     })
 
+#define atomic_set__nocheck(ptr, i) \
+    __atomic_store_n(ptr, i, __ATOMIC_RELAXED)
+
 #define atomic_set(ptr, i)  do {                      \
     QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *)); \
-    __atomic_store_n(ptr, i, __ATOMIC_RELAXED);       \
+    atomic_set__nocheck(ptr, i);                      \
 } while(0)
 
 /* See above: most compilers currently treat consume and acquire the
@@ -151,20 +157,27 @@
 
 /* All the remaining operations are fully sequentially consistent */
 
+#define atomic_xchg__nocheck(ptr, i)    ({                  \
+    __atomic_exchange_n(ptr, (i), __ATOMIC_SEQ_CST);        \
+})
+
 #define atomic_xchg(ptr, i)    ({                           \
     QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *));       \
-    __atomic_exchange_n(ptr, i, __ATOMIC_SEQ_CST);          \
+    atomic_xchg__nocheck(ptr, i);                           \
 })
 
 /* Returns the eventual value, failed or not */
-#define atomic_cmpxchg(ptr, old, new)                                   \
-    ({                                                                  \
-    QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *));                   \
+#define atomic_cmpxchg__nocheck(ptr, old, new)    ({                    \
     typeof_strip_qual(*ptr) _old = (old);                               \
     __atomic_compare_exchange_n(ptr, &_old, new, false,                 \
                               __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);      \
     _old;                                                               \
-    })
+})
+
+#define atomic_cmpxchg(ptr, old, new)    ({                             \
+    QEMU_BUILD_BUG_ON(sizeof(*ptr) > sizeof(void *));                   \
+    atomic_cmpxchg__nocheck(ptr, old, new);                             \
+})
 
 /* Provide shorter names for GCC atomic builtins, return old value */
 #define atomic_fetch_inc(ptr)  __atomic_fetch_add(ptr, 1, __ATOMIC_SEQ_CST)
@@ -279,8 +292,11 @@
 /* These will only be atomic if the processor does the fetch or store
  * in a single issue memory operation
  */
-#define atomic_read(ptr)       (*(__typeof__(*ptr) volatile*) (ptr))
-#define atomic_set(ptr, i)     ((*(__typeof__(*ptr) volatile*) (ptr)) = (i))
+#define atomic_read__nocheck(p)   (*(__typeof__(*(p)) volatile*) (p))
+#define atomic_set__nocheck(p, i) ((*(__typeof__(*(p)) volatile*) (p)) = (i))
+
+#define atomic_read(ptr)       atomic_read__nocheck(ptr)
+#define atomic_set(ptr, i)     atomic_set__nocheck(ptr,i)
 
 /**
  * atomic_rcu_read - reads a RCU-protected pointer to a local variable
@@ -341,6 +357,7 @@
 #define atomic_xchg(ptr, i)    (smp_mb(), __sync_lock_test_and_set(ptr, i))
 #endif
 #endif
+#define atomic_xchg__nocheck  atomic_xchg
 
 /* Provide shorter names for GCC atomic builtins.  */
 #define atomic_fetch_inc(ptr)  __sync_fetch_and_add(ptr, 1)
@@ -360,6 +377,7 @@
 #define atomic_xor_fetch(ptr, n) __sync_xor_and_fetch(ptr, n)
 
 #define atomic_cmpxchg(ptr, old, new) __sync_val_compare_and_swap(ptr, old, new)
+#define atomic_cmpxchg__nocheck(ptr, old, new)  atomic_cmpxchg(ptr, old, new)
 
 /* And even shorter names that return void.  */
 #define atomic_inc(ptr)        ((void) __sync_fetch_and_add(ptr, 1))