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c52d0d30 | 1 | /* |
ebb5e78c AS |
2 | * Copyright (C) 2015 Imagination Technologies |
3 | * Author: Alex Smith <alex.smith@imgtec.com> | |
c52d0d30 | 4 | * |
ebb5e78c AS |
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. | |
c52d0d30 DD |
9 | */ |
10 | ||
11 | #ifndef __ASM_VDSO_H | |
12 | #define __ASM_VDSO_H | |
13 | ||
ebb5e78c | 14 | #include <linux/mm_types.h> |
c52d0d30 | 15 | |
a7f4df4e AS |
16 | #include <asm/barrier.h> |
17 | ||
ebb5e78c AS |
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 | */ | |
31 | struct mips_vdso_image { | |
32 | void *data; | |
33 | unsigned long size; | |
c52d0d30 | 34 | |
ebb5e78c AS |
35 | unsigned long off_sigreturn; |
36 | unsigned long off_rt_sigreturn; | |
37 | ||
38 | struct vm_special_mapping mapping; | |
c52d0d30 | 39 | }; |
ebb5e78c AS |
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 | ||
46 | extern struct mips_vdso_image vdso_image; | |
47 | ||
48 | #ifdef CONFIG_MIPS32_O32 | |
49 | extern struct mips_vdso_image vdso_image_o32; | |
50 | #endif | |
51 | ||
52 | #ifdef CONFIG_MIPS32_N32 | |
53 | extern struct mips_vdso_image vdso_image_n32; | |
54 | #endif | |
55 | ||
56 | /** | |
57 | * union mips_vdso_data - Data provided by the kernel for the VDSO. | |
a7f4df4e AS |
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). | |
ebb5e78c AS |
70 | * |
71 | * This structure contains data needed by functions within the VDSO. It is | |
a7f4df4e AS |
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. | |
ebb5e78c AS |
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 | */ | |
78 | union mips_vdso_data { | |
79 | struct { | |
a7f4df4e AS |
80 | u64 xtime_sec; |
81 | u64 xtime_nsec; | |
82 | u32 wall_to_mono_sec; | |
83 | u32 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; | |
ebb5e78c AS |
92 | }; |
93 | ||
94 | u8 page[PAGE_SIZE]; | |
c52d0d30 | 95 | }; |
c52d0d30 | 96 | |
a7f4df4e AS |
97 | static inline u32 vdso_data_read_begin(const union mips_vdso_data *data) |
98 | { | |
99 | u32 seq; | |
100 | ||
101 | while (true) { | |
102 | seq = ACCESS_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 | ||
113 | static 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 | ||
121 | static 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 | ||
129 | static 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 | ||
c52d0d30 | 136 | #endif /* __ASM_VDSO_H */ |