1 files changed, 95 insertions, 0 deletions
diff --git a/backport-include/linux/compiler.h b/backport-include/linux/compiler.h
new file mode 100644
index 0000000..53c069d
--- /dev/null
+++ b/backport-include/linux/compiler.h
@@ -0,0 +1,95 @@
+#ifndef __BACKPORT_LINUX_COMPILER_H
+#define __BACKPORT_LINUX_COMPILER_H
+#include_next <linux/compiler.h>
+
+#ifndef __rcu
+#define __rcu
+#endif
+
+#ifndef __always_unused
+#ifdef __GNUC__
+#define __always_unused			__attribute__((unused))
+#else
+#define __always_unused			/* unimplemented */
+#endif
+#endif
+
+#ifndef __PASTE
+/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
+#define ___PASTE(a,b) a##b
+#define __PASTE(a,b) ___PASTE(a,b)
+#endif
+
+/* Not-quite-unique ID. */
+#ifndef __UNIQUE_ID
+# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
+#endif
+
+#ifndef barrier_data
+#ifdef __GNUC__
+#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
+#else /* __GNUC__ */
+# define barrier_data(ptr) barrier()
+#endif /* __GNUC__ */
+#endif
+
+#ifndef READ_ONCE
+#include <linux/types.h>
+
+#define __READ_ONCE_SIZE						\
+({									\
+	switch (size) {							\
+	case 1: *(__u8 *)res = *(volatile __u8 *)p; break;		\
+	case 2: *(__u16 *)res = *(volatile __u16 *)p; break;		\
+	case 4: *(__u32 *)res = *(volatile __u32 *)p; break;		\
+	case 8: *(__u64 *)res = *(volatile __u64 *)p; break;		\
+	default:							\
+		barrier();						\
+		__builtin_memcpy((void *)res, (const void *)p, size);	\
+		barrier();						\
+	}								\
+})
+
+static __always_inline
+void __read_once_size(const volatile void *p, void *res, int size)
+{
+	__READ_ONCE_SIZE;
+}
+
+#define __READ_ONCE(x, check)						\
+({									\
+	union { typeof(x) __val; char __c[1]; } __u;			\
+	__read_once_size(&(x), __u.__c, sizeof(x));			\
+	__u.__val;							\
+})
+
+#define READ_ONCE(x) __READ_ONCE(x, 1)
+
+static __always_inline void __write_once_size(volatile void *p, void *res, int size)
+{
+	switch (size) {
+	case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
+	case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
+	case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
+	case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
+	default:
+		barrier();
+		__builtin_memcpy((void *)p, (const void *)res, size);
+		barrier();
+	}
+}
+
+#define WRITE_ONCE(x, val) \
+({							\
+	union { typeof(x) __val; char __c[1]; } __u =	\
+		{ .__val = (__force typeof(x)) (val) }; \
+	__write_once_size(&(x), __u.__c, sizeof(x));	\
+	__u.__val;					\
+})
+#endif
+
+#ifndef OPTIMIZER_HIDE_VAR
+#define OPTIMIZER_HIDE_VAR(var) barrier()
+#endif
+
+#endif /* __BACKPORT_LINUX_COMPILER_H */