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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Copyright (C) 2015 Imagination Technologies
4 * Author: Alex Smith <alex.smith@imgtec.com>
5 */
6
7#ifndef __ASM_VDSO_H
8#define __ASM_VDSO_H
9
10#include <linux/mm_types.h>
11#include <vdso/datapage.h>
12
13#include <asm/barrier.h>
14
15/**
16 * struct mips_vdso_image - Details of a VDSO image.
17 * @data: Pointer to VDSO image data (page-aligned).
18 * @size: Size of the VDSO image data (page-aligned).
19 * @off_sigreturn: Offset of the sigreturn() trampoline.
20 * @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
21 * @mapping: Special mapping structure.
22 *
23 * This structure contains details of a VDSO image, including the image data
24 * and offsets of certain symbols required by the kernel. It is generated as
25 * part of the VDSO build process, aside from the mapping page array, which is
26 * populated at runtime.
27 */
28struct mips_vdso_image {
29 void *data;
30 unsigned long size;
31
32 unsigned long off_sigreturn;
33 unsigned long off_rt_sigreturn;
34
35 struct vm_special_mapping mapping;
36};
37
38/*
39 * The following structures are auto-generated as part of the build for each
40 * ABI by genvdso, see arch/mips/vdso/Makefile.
41 */
42
43extern struct mips_vdso_image vdso_image;
44
45#ifdef CONFIG_MIPS32_O32
46extern struct mips_vdso_image vdso_image_o32;
47#endif
48
49#ifdef CONFIG_MIPS32_N32
50extern struct mips_vdso_image vdso_image_n32;
51#endif
52
53union mips_vdso_data {
54 struct vdso_data data[CS_BASES];
55 u8 page[PAGE_SIZE];
56};
57
58#endif /* __ASM_VDSO_H */
1/*
2 * Copyright (C) 2015 Imagination Technologies
3 * Author: Alex Smith <alex.smith@imgtec.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version.
9 */
10
11#ifndef __ASM_VDSO_H
12#define __ASM_VDSO_H
13
14#include <linux/mm_types.h>
15
16#include <asm/barrier.h>
17
18/**
19 * struct mips_vdso_image - Details of a VDSO image.
20 * @data: Pointer to VDSO image data (page-aligned).
21 * @size: Size of the VDSO image data (page-aligned).
22 * @off_sigreturn: Offset of the sigreturn() trampoline.
23 * @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
24 * @mapping: Special mapping structure.
25 *
26 * This structure contains details of a VDSO image, including the image data
27 * and offsets of certain symbols required by the kernel. It is generated as
28 * part of the VDSO build process, aside from the mapping page array, which is
29 * populated at runtime.
30 */
31struct mips_vdso_image {
32 void *data;
33 unsigned long size;
34
35 unsigned long off_sigreturn;
36 unsigned long off_rt_sigreturn;
37
38 struct vm_special_mapping mapping;
39};
40
41/*
42 * The following structures are auto-generated as part of the build for each
43 * ABI by genvdso, see arch/mips/vdso/Makefile.
44 */
45
46extern struct mips_vdso_image vdso_image;
47
48#ifdef CONFIG_MIPS32_O32
49extern struct mips_vdso_image vdso_image_o32;
50#endif
51
52#ifdef CONFIG_MIPS32_N32
53extern struct mips_vdso_image vdso_image_n32;
54#endif
55
56/**
57 * union mips_vdso_data - Data provided by the kernel for the VDSO.
58 * @xtime_sec: Current real time (seconds part).
59 * @xtime_nsec: Current real time (nanoseconds part, shifted).
60 * @wall_to_mono_sec: Wall-to-monotonic offset (seconds part).
61 * @wall_to_mono_nsec: Wall-to-monotonic offset (nanoseconds part).
62 * @seq_count: Counter to synchronise updates (odd = updating).
63 * @cs_shift: Clocksource shift value.
64 * @clock_mode: Clocksource to use for time functions.
65 * @cs_mult: Clocksource multiplier value.
66 * @cs_cycle_last: Clock cycle value at last update.
67 * @cs_mask: Clocksource mask value.
68 * @tz_minuteswest: Minutes west of Greenwich (from timezone).
69 * @tz_dsttime: Type of DST correction (from timezone).
70 *
71 * This structure contains data needed by functions within the VDSO. It is
72 * populated by the kernel and mapped read-only into user memory. The time
73 * fields are mirrors of internal data from the timekeeping infrastructure.
74 *
75 * Note: Care should be taken when modifying as the layout must remain the same
76 * for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).
77 */
78union mips_vdso_data {
79 struct {
80 u64 xtime_sec;
81 u64 xtime_nsec;
82 u64 wall_to_mono_sec;
83 u64 wall_to_mono_nsec;
84 u32 seq_count;
85 u32 cs_shift;
86 u8 clock_mode;
87 u32 cs_mult;
88 u64 cs_cycle_last;
89 u64 cs_mask;
90 s32 tz_minuteswest;
91 s32 tz_dsttime;
92 };
93
94 u8 page[PAGE_SIZE];
95};
96
97static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)
98{
99 u32 seq;
100
101 while (true) {
102 seq = READ_ONCE(data->seq_count);
103 if (likely(!(seq & 1))) {
104 /* Paired with smp_wmb() in vdso_data_write_*(). */
105 smp_rmb();
106 return seq;
107 }
108
109 cpu_relax();
110 }
111}
112
113static inline bool vdso_data_read_retry(const union mips_vdso_data *data,
114 u32 start_seq)
115{
116 /* Paired with smp_wmb() in vdso_data_write_*(). */
117 smp_rmb();
118 return unlikely(data->seq_count != start_seq);
119}
120
121static inline void vdso_data_write_begin(union mips_vdso_data *data)
122{
123 ++data->seq_count;
124
125 /* Ensure sequence update is written before other data page values. */
126 smp_wmb();
127}
128
129static inline void vdso_data_write_end(union mips_vdso_data *data)
130{
131 /* Ensure data values are written before updating sequence again. */
132 smp_wmb();
133 ++data->seq_count;
134}
135
136#endif /* __ASM_VDSO_H */