137 lines
3.7 KiB
C
137 lines
3.7 KiB
C
/*
|
|
* Copyright (C) 2015 Imagination Technologies
|
|
* Author: Alex Smith <alex.smith@imgtec.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License as published by the
|
|
* Free Software Foundation; either version 2 of the License, or (at your
|
|
* option) any later version.
|
|
*/
|
|
|
|
#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;
|
|
u32 wall_to_mono_sec;
|
|
u32 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 = ACCESS_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 */
|