v4.19.13 snapshot.
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
new file mode 100644
index 0000000..5374854
--- /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 */