1 files changed, 106 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
new file mode 100644
index 000000000..53748541c
--- /dev/null
+++ b/arch/x86/include/asm/vgtod.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#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;
+	u64	cycle_last;
+	u64	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;
+
+extern int vclocks_used;
+static inline bool vclock_was_used(int vclock)
+{
+	return READ_ONCE(vclocks_used) & (1 << vclock);
+}
+
+static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
+{
+	unsigned ret;
+
+repeat:
+	ret = READ_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;
+}
+
+#ifdef CONFIG_X86_64
+
+#define VGETCPU_CPU_MASK 0xfff
+
+static inline unsigned int __getcpu(void)
+{
+	unsigned int p;
+
+	/*
+	 * Load per CPU data from GDT.  LSL is faster than RDTSCP and
+	 * works on all CPUs.  This is volatile so that it orders
+	 * correctly wrt barrier() and to keep gcc from cleverly
+	 * hoisting it out of the calling function.
+	 *
+	 * If RDPID is available, use it.
+	 */
+	alternative_io ("lsl %[seg],%[p]",
+			".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
+			X86_FEATURE_RDPID,
+			[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));
+
+	return p;
+}
+
+#endif /* CONFIG_X86_64 */
+
+#endif /* _ASM_X86_VGTOD_H */