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/* 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;
typedef unsigned long gtod_long_t;
* 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;
ret = ACCESS_ONCE(s->seq);
if (unlikely(ret & 1)) {
goto repeat;
return ret;
static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
unsigned start)
return unlikely(s->seq != start);
static inline void gtod_write_begin(struct vsyscall_gtod_data *s)
static inline void gtod_write_end(struct vsyscall_gtod_data *s)
#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 */
[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));
return p;
#endif /* CONFIG_X86_64 */
#endif /* _ASM_X86_VGTOD_H */