1/*
 2 * This file is subject to the terms and conditions of the GNU General Public
 3 * License.  See the file "COPYING" in the main directory of this archive
 4 * for more details.
 5 *
 6 * Copyright (C) 2009 Cavium Networks
 
 
 
 7 */
 8
 9#ifndef __ASM_VDSO_H
10#define __ASM_VDSO_H
11
12#include <linux/types.h>
13
 
14
15#ifdef CONFIG_32BIT
16struct mips_vdso {
17	u32 signal_trampoline[2];
18	u32 rt_signal_trampoline[2];
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
19};
20#else  /* !CONFIG_32BIT */
21struct mips_vdso {
22	u32 o32_signal_trampoline[2];
23	u32 o32_rt_signal_trampoline[2];
24	u32 rt_signal_trampoline[2];
25	u32 n32_rt_signal_trampoline[2];
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
26};
27#endif /* CONFIG_32BIT */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
28
29#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		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;
 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 = 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
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 */