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2874c5fd | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
c52d0d30 | 2 | /* |
ebb5e78c AS |
3 | * Copyright (C) 2015 Imagination Technologies |
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> |
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 | * |
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 |
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; |
77 | u64 xtime_nsec; | |
8ec7f15b GF |
78 | u64 wall_to_mono_sec; |
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 */ |