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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;
#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 = 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;
}
#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 %[p],%[seg]",
".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 */
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