[mirror_ubuntu-eoan-kernel.git] / arch / mips / include / asm / vdso.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2015 Imagination Technologies
 * Author: Alex Smith <alex.smith@imgtec.com>
 */

#ifndef __ASM_VDSO_H
#define __ASM_VDSO_H

#include <linux/mm_types.h>

#include <asm/barrier.h>

/**
 * struct mips_vdso_image - Details of a VDSO image.
 * @data: Pointer to VDSO image data (page-aligned).
 * @size: Size of the VDSO image data (page-aligned).
 * @off_sigreturn: Offset of the sigreturn() trampoline.
 * @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
 * @mapping: Special mapping structure.
 *
 * This structure contains details of a VDSO image, including the image data
 * and offsets of certain symbols required by the kernel. It is generated as
 * part of the VDSO build process, aside from the mapping page array, which is
 * populated at runtime.
 */
struct mips_vdso_image {
	void *data;
	unsigned long size;

	unsigned long off_sigreturn;
	unsigned long off_rt_sigreturn;

	struct vm_special_mapping mapping;
};

/*
 * The following structures are auto-generated as part of the build for each
 * ABI by genvdso, see arch/mips/vdso/Makefile.
 */

extern struct mips_vdso_image vdso_image;

#ifdef CONFIG_MIPS32_O32
extern struct mips_vdso_image vdso_image_o32;
#endif

#ifdef CONFIG_MIPS32_N32
extern struct mips_vdso_image vdso_image_n32;
#endif

/**
 * union mips_vdso_data - Data provided by the kernel for the VDSO.
 * @xtime_sec:		Current real time (seconds part).
 * @xtime_nsec:		Current real time (nanoseconds part, shifted).
 * @wall_to_mono_sec:	Wall-to-monotonic offset (seconds part).
 * @wall_to_mono_nsec:	Wall-to-monotonic offset (nanoseconds part).
 * @seq_count:		Counter to synchronise updates (odd = updating).
 * @cs_shift:		Clocksource shift value.
 * @clock_mode:		Clocksource to use for time functions.
 * @cs_mult:		Clocksource multiplier value.
 * @cs_cycle_last:	Clock cycle value at last update.
 * @cs_mask:		Clocksource mask value.
 * @tz_minuteswest:	Minutes west of Greenwich (from timezone).
 * @tz_dsttime:		Type of DST correction (from timezone).
 *
 * This structure contains data needed by functions within the VDSO. It is
 * populated by the kernel and mapped read-only into user memory. The time
 * fields are mirrors of internal data from the timekeeping infrastructure.
 *
 * Note: Care should be taken when modifying as the layout must remain the same
 * for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).
 */
union mips_vdso_data {
	struct {
		u64 xtime_sec;
		u64 xtime_nsec;
		u64 wall_to_mono_sec;
		u64 wall_to_mono_nsec;
		u32 seq_count;
		u32 cs_shift;
		u8 clock_mode;
		u32 cs_mult;
		u64 cs_cycle_last;
		u64 cs_mask;
		s32 tz_minuteswest;
		s32 tz_dsttime;
	};

	u8 page[PAGE_SIZE];
};

static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)
{
	u32 seq;

	while (true) {
		seq = READ_ONCE(data->seq_count);
		if (likely(!(seq & 1))) {
			/* Paired with smp_wmb() in vdso_data_write_*(). */
			smp_rmb();
			return seq;
		}

		cpu_relax();
	}
}

static inline bool vdso_data_read_retry(const union mips_vdso_data *data,
					u32 start_seq)
{
	/* Paired with smp_wmb() in vdso_data_write_*(). */
	smp_rmb();
	return unlikely(data->seq_count != start_seq);
}

static inline void vdso_data_write_begin(union mips_vdso_data *data)
{
	++data->seq_count;

	/* Ensure sequence update is written before other data page values. */
	smp_wmb();
}

static inline void vdso_data_write_end(union mips_vdso_data *data)
{
	/* Ensure data values are written before updating sequence again. */
	smp_wmb();
	++data->seq_count;
}

#endif /* __ASM_VDSO_H */
Commit	Line	Data
2874c5fd	1	/* SPDX-License-Identifier: GPL-2.0-or-later */
c52d0d30	2	/*
ebb5e78c AS	3	* Copyright (C) 2015 Imagination Technologies
ebb5e78c AS	4	* Author: Alex Smith <alex.smith@imgtec.com>
c52d0d30 DD	5	*/
	6
	7	#ifndef __ASM_VDSO_H
	8	#define __ASM_VDSO_H
	9
ebb5e78c	10	#include <linux/mm_types.h>
c52d0d30	11
a7f4df4e AS	12	#include <asm/barrier.h>
a7f4df4e AS	13
ebb5e78c AS	14	/**
	15	* struct mips_vdso_image - Details of a VDSO image.
	16	* @data: Pointer to VDSO image data (page-aligned).
	17	* @size: Size of the VDSO image data (page-aligned).
	18	* @off_sigreturn: Offset of the sigreturn() trampoline.
	19	* @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
	20	* @mapping: Special mapping structure.
	21	*
	22	* This structure contains details of a VDSO image, including the image data
	23	* and offsets of certain symbols required by the kernel. It is generated as
	24	* part of the VDSO build process, aside from the mapping page array, which is
	25	* populated at runtime.
	26	*/
	27	struct mips_vdso_image {
	28	void *data;
	29	unsigned long size;
c52d0d30	30
ebb5e78c AS	31	unsigned long off_sigreturn;
	32	unsigned long off_rt_sigreturn;
	33
	34	struct vm_special_mapping mapping;
c52d0d30	35	};
ebb5e78c AS	36
	37	/*
	38	* The following structures are auto-generated as part of the build for each
	39	* ABI by genvdso, see arch/mips/vdso/Makefile.
	40	*/
	41
	42	extern struct mips_vdso_image vdso_image;
	43
	44	#ifdef CONFIG_MIPS32_O32
	45	extern struct mips_vdso_image vdso_image_o32;
	46	#endif
	47
	48	#ifdef CONFIG_MIPS32_N32
	49	extern struct mips_vdso_image vdso_image_n32;
	50	#endif
	51
	52	/**
	53	* union mips_vdso_data - Data provided by the kernel for the VDSO.
a7f4df4e AS	54	* @xtime_sec: Current real time (seconds part).
	55	* @xtime_nsec: Current real time (nanoseconds part, shifted).
	56	* @wall_to_mono_sec: Wall-to-monotonic offset (seconds part).
	57	* @wall_to_mono_nsec: Wall-to-monotonic offset (nanoseconds part).
	58	* @seq_count: Counter to synchronise updates (odd = updating).
	59	* @cs_shift: Clocksource shift value.
	60	* @clock_mode: Clocksource to use for time functions.
	61	* @cs_mult: Clocksource multiplier value.
	62	* @cs_cycle_last: Clock cycle value at last update.
	63	* @cs_mask: Clocksource mask value.
	64	* @tz_minuteswest: Minutes west of Greenwich (from timezone).
	65	* @tz_dsttime: Type of DST correction (from timezone).
ebb5e78c AS	66	*
ebb5e78c AS	67	* This structure contains data needed by functions within the VDSO. It is
a7f4df4e AS	68	* populated by the kernel and mapped read-only into user memory. The time
a7f4df4e AS	69	* fields are mirrors of internal data from the timekeeping infrastructure.
ebb5e78c AS	70	*
	71	* Note: Care should be taken when modifying as the layout must remain the same
	72	* for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).
	73	*/
	74	union mips_vdso_data {
	75	struct {
a7f4df4e AS	76	u64 xtime_sec;
a7f4df4e AS	77	u64 xtime_nsec;
8ec7f15b GF	78	u64 wall_to_mono_sec;
8ec7f15b GF	79	u64 wall_to_mono_nsec;
a7f4df4e AS	80	u32 seq_count;
	81	u32 cs_shift;
	82	u8 clock_mode;
	83	u32 cs_mult;
	84	u64 cs_cycle_last;
	85	u64 cs_mask;
	86	s32 tz_minuteswest;
	87	s32 tz_dsttime;
ebb5e78c AS	88	};
	89
	90	u8 page[PAGE_SIZE];
c52d0d30	91	};
c52d0d30	92
a7f4df4e AS	93	static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)
	94	{
	95	u32 seq;
	96
	97	while (true) {
6aa7de05	98	seq = READ_ONCE(data->seq_count);
a7f4df4e AS	99	if (likely(!(seq & 1))) {
	100	/* Paired with smp_wmb() in vdso_data_write_(). /
	101	smp_rmb();
	102	return seq;
	103	}
	104
	105	cpu_relax();
	106	}
	107	}
	108
	109	static inline bool vdso_data_read_retry(const union mips_vdso_data *data,
	110	u32 start_seq)
	111	{
	112	/* Paired with smp_wmb() in vdso_data_write_(). /
	113	smp_rmb();
	114	return unlikely(data->seq_count != start_seq);
	115	}
	116
	117	static inline void vdso_data_write_begin(union mips_vdso_data *data)
	118	{
	119	++data->seq_count;
	120
	121	/* Ensure sequence update is written before other data page values. */
	122	smp_wmb();
	123	}
	124
	125	static inline void vdso_data_write_end(union mips_vdso_data *data)
	126	{
	127	/* Ensure data values are written before updating sequence again. */
	128	smp_wmb();
	129	++data->seq_count;
	130	}
	131
c52d0d30	132	#endif /* __ASM_VDSO_H */