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-rw-r--r--tools/virtio/ringtest/main.h57
1 files changed, 57 insertions, 0 deletions
diff --git a/tools/virtio/ringtest/main.h b/tools/virtio/ringtest/main.h
index 5706e075adf2..593a3289c87d 100644
--- a/tools/virtio/ringtest/main.h
+++ b/tools/virtio/ringtest/main.h
@@ -134,4 +134,61 @@ static inline void busy_wait(void)
barrier(); \
} while (0)
+#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__)
+#define smp_wmb() barrier()
+#else
+#define smp_wmb() smp_release()
+#endif
+
+#ifdef __alpha__
+#define smp_read_barrier_depends() smp_acquire()
+#else
+#define smp_read_barrier_depends() do {} while(0)
+#endif
+
+static __always_inline
+void __read_once_size(const volatile void *p, void *res, int size)
+{
+ switch (size) { \
+ case 1: *(unsigned char *)res = *(volatile unsigned char *)p; break; \
+ case 2: *(unsigned short *)res = *(volatile unsigned short *)p; break; \
+ case 4: *(unsigned int *)res = *(volatile unsigned int *)p; break; \
+ case 8: *(unsigned long long *)res = *(volatile unsigned long long *)p; break; \
+ default: \
+ barrier(); \
+ __builtin_memcpy((void *)res, (const void *)p, size); \
+ barrier(); \
+ } \
+}
+
+static __always_inline void __write_once_size(volatile void *p, void *res, int size)
+{
+ switch (size) {
+ case 1: *(volatile unsigned char *)p = *(unsigned char *)res; break;
+ case 2: *(volatile unsigned short *)p = *(unsigned short *)res; break;
+ case 4: *(volatile unsigned int *)p = *(unsigned int *)res; break;
+ case 8: *(volatile unsigned long long *)p = *(unsigned long long *)res; break;
+ default:
+ barrier();
+ __builtin_memcpy((void *)p, (const void *)res, size);
+ barrier();
+ }
+}
+
+#define READ_ONCE(x) \
+({ \
+ union { typeof(x) __val; char __c[1]; } __u; \
+ __read_once_size(&(x), __u.__c, sizeof(x)); \
+ smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
+ __u.__val; \
+})
+
+#define WRITE_ONCE(x, val) \
+({ \
+ union { typeof(x) __val; char __c[1]; } __u = \
+ { .__val = (typeof(x)) (val) }; \
+ __write_once_size(&(x), __u.__c, sizeof(x)); \
+ __u.__val; \
+})
+
#endif