1 files changed, 73 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
new file mode 100644
index 00000000000..3c3366c2e37
--- /dev/null
+++ b/arch/x86/include/asm/vgtod.h
@@ -0,0 +1,73 @@
+#ifndef _ASM_X86_VGTOD_H
+#define _ASM_X86_VGTOD_H
+
+#include <linux/compiler.h>
+#include <linux/clocksource.h>
+
+#ifdef BUILD_VDSO32_64
+typedef u64 gtod_long_t;
+#else
+typedef unsigned long gtod_long_t;
+#endif
+/*
+ * vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time
+ * so be carefull by modifying this structure.
+ */
+struct vsyscall_gtod_data {
+	unsigned seq;
+
+	int vclock_mode;
+	cycle_t	cycle_last;
+	cycle_t	mask;
+	u32	mult;
+	u32	shift;
+
+	/* open coded 'struct timespec' */
+	u64		wall_time_snsec;
+	gtod_long_t	wall_time_sec;
+	gtod_long_t	monotonic_time_sec;
+	u64		monotonic_time_snsec;
+	gtod_long_t	wall_time_coarse_sec;
+	gtod_long_t	wall_time_coarse_nsec;
+	gtod_long_t	monotonic_time_coarse_sec;
+	gtod_long_t	monotonic_time_coarse_nsec;
+
+	int		tz_minuteswest;
+	int		tz_dsttime;
+};
+extern struct vsyscall_gtod_data vsyscall_gtod_data;
+
+static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
+{
+	unsigned ret;
+
+repeat:
+	ret = ACCESS_ONCE(s->seq);
+	if (unlikely(ret & 1)) {
+		cpu_relax();
+		goto repeat;
+	}
+	smp_rmb();
+	return ret;
+}
+
+static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
+					unsigned start)
+{
+	smp_rmb();
+	return unlikely(s->seq != start);
+}
+
+static inline void gtod_write_begin(struct vsyscall_gtod_data *s)
+{
+	++s->seq;
+	smp_wmb();
+}
+
+static inline void gtod_write_end(struct vsyscall_gtod_data *s)
+{
+	smp_wmb();
+	++s->seq;
+}
+
+#endif /* _ASM_X86_VGTOD_H */