[linux-block.git] / arch / x86 / include / asm / vgtod.h

/* 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 */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1965aae3 PA	2	#ifndef _ASM_X86_VGTOD_H
1965aae3 PA	3	#define _ASM_X86_VGTOD_H
2aae950b	4
7c03156f	5	#include <linux/compiler.h>
2aae950b AK	6	#include <linux/clocksource.h>
2aae950b AK	7
7c03156f SS	8	#ifdef BUILD_VDSO32_64
	9	typedef u64 gtod_long_t;
	10	#else
	11	typedef unsigned long gtod_long_t;
	12	#endif
	13	/*
	14	* vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time
	15	* so be carefull by modifying this structure.
	16	*/
2aae950b	17	struct vsyscall_gtod_data {
7c03156f	18	unsigned seq;
2aae950b	19
7c03156f	20	int vclock_mode;
a5a1d1c2 TG	21	u64 cycle_last;
a5a1d1c2 TG	22	u64 mask;
7c03156f SS	23	u32 mult;
7c03156f SS	24	u32 shift;
91ec87d5 AL	25
91ec87d5 AL	26	/* open coded 'struct timespec' */
650ea024	27	u64 wall_time_snsec;
7c03156f SS	28	gtod_long_t wall_time_sec;
7c03156f SS	29	gtod_long_t monotonic_time_sec;
650ea024	30	u64 monotonic_time_snsec;
7c03156f SS	31	gtod_long_t wall_time_coarse_sec;
	32	gtod_long_t wall_time_coarse_nsec;
	33	gtod_long_t monotonic_time_coarse_sec;
	34	gtod_long_t monotonic_time_coarse_nsec;
91ec87d5	35
7c03156f SS	36	int tz_minuteswest;
7c03156f SS	37	int tz_dsttime;
2aae950b	38	};
2aae950b AK	39	extern struct vsyscall_gtod_data vsyscall_gtod_data;
2aae950b AK	40
bd902c53 AL	41	extern int vclocks_used;
	42	static inline bool vclock_was_used(int vclock)
	43	{
	44	return READ_ONCE(vclocks_used) & (1 << vclock);
	45	}
	46
7c03156f SS	47	static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
	48	{
	49	unsigned ret;
	50
	51	repeat:
	52	ret = ACCESS_ONCE(s->seq);
	53	if (unlikely(ret & 1)) {
	54	cpu_relax();
	55	goto repeat;
	56	}
	57	smp_rmb();
	58	return ret;
	59	}
	60
	61	static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
	62	unsigned start)
	63	{
	64	smp_rmb();
	65	return unlikely(s->seq != start);
	66	}
	67
	68	static inline void gtod_write_begin(struct vsyscall_gtod_data *s)
	69	{
	70	++s->seq;
	71	smp_wmb();
	72	}
	73
	74	static inline void gtod_write_end(struct vsyscall_gtod_data *s)
	75	{
	76	smp_wmb();
	77	++s->seq;
	78	}
	79
e76b027e AL	80	#ifdef CONFIG_X86_64
	81
	82	#define VGETCPU_CPU_MASK 0xfff
	83
	84	static inline unsigned int __getcpu(void)
	85	{
	86	unsigned int p;
	87
	88	/*
	89	* Load per CPU data from GDT. LSL is faster than RDTSCP and
1ddf0b1b AL	90	* works on all CPUs. This is volatile so that it orders
	91	* correctly wrt barrier() and to keep gcc from cleverly
	92	* hoisting it out of the calling function.
a582c540 AL	93	*
a582c540 AL	94	* If RDPID is available, use it.
e76b027e	95	*/
a582c540 AL	96	alternative_io ("lsl %[p],%[seg]",
	97	".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
	98	X86_FEATURE_RDPID,
	99	[p] "=a" (p), [seg] "r" (__PER_CPU_SEG));
e76b027e AL	100
	101	return p;
	102	}
	103
	104	#endif /* CONFIG_X86_64 */
	105
1965aae3	106	#endif /* _ASM_X86_VGTOD_H */