android_kernel_xiaomi_sm8350/arch/powerpc/include/asm/vdso_datapage.h
Paul Mackerras 597bc5c00b powerpc: Improve resolution of VDSO clock_gettime
Currently the clock_gettime implementation in the VDSO produces a
result with microsecond resolution for the cases that are handled
without a system call, i.e. CLOCK_REALTIME and CLOCK_MONOTONIC.  The
nanoseconds field of the result is obtained by computing a
microseconds value and multiplying by 1000.

This changes the code in the VDSO to do the computation for
clock_gettime with nanosecond resolution.  That means that the
resolution of the result will ultimately depend on the timebase
frequency.

Because the timestamp in the VDSO datapage (stamp_xsec, the real time
corresponding to the timebase count in tb_orig_stamp) is in units of
2^-20 seconds, it doesn't have sufficient resolution for computing a
result with nanosecond resolution.  Therefore this adds a copy of
xtime to the VDSO datapage and updates it in update_gtod() along with
the other time-related fields.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2008-11-06 09:49:22 +11:00

125 lines
4.2 KiB
C

#ifndef _VDSO_DATAPAGE_H
#define _VDSO_DATAPAGE_H
#ifdef __KERNEL__
/*
* Copyright (C) 2002 Peter Bergner <bergner@vnet.ibm.com>, IBM
* Copyright (C) 2005 Benjamin Herrenschmidy <benh@kernel.crashing.org>,
* IBM Corp.
*
* 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.
*/
/*
* Note about this structure:
*
* This structure was historically called systemcfg and exposed to
* userland via /proc/ppc64/systemcfg. Unfortunately, this became an
* ABI issue as some proprietary software started relying on being able
* to mmap() it, thus we have to keep the base layout at least for a
* few kernel versions.
*
* However, since ppc32 doesn't suffer from this backward handicap,
* a simpler version of the data structure is used there with only the
* fields actually used by the vDSO.
*
*/
/*
* If the major version changes we are incompatible.
* Minor version changes are a hint.
*/
#define SYSTEMCFG_MAJOR 1
#define SYSTEMCFG_MINOR 1
#ifndef __ASSEMBLY__
#include <linux/unistd.h>
#include <linux/time.h>
#define SYSCALL_MAP_SIZE ((__NR_syscalls + 31) / 32)
/*
* So here is the ppc64 backward compatible version
*/
#ifdef CONFIG_PPC64
struct vdso_data {
__u8 eye_catcher[16]; /* Eyecatcher: SYSTEMCFG:PPC64 0x00 */
struct { /* Systemcfg version numbers */
__u32 major; /* Major number 0x10 */
__u32 minor; /* Minor number 0x14 */
} version;
/* Note about the platform flags: it now only contains the lpar
* bit. The actual platform number is dead and burried
*/
__u32 platform; /* Platform flags 0x18 */
__u32 processor; /* Processor type 0x1C */
__u64 processorCount; /* # of physical processors 0x20 */
__u64 physicalMemorySize; /* Size of real memory(B) 0x28 */
__u64 tb_orig_stamp; /* Timebase at boot 0x30 */
__u64 tb_ticks_per_sec; /* Timebase tics / sec 0x38 */
__u64 tb_to_xs; /* Inverse of TB to 2^20 0x40 */
__u64 stamp_xsec; /* 0x48 */
__u64 tb_update_count; /* Timebase atomicity ctr 0x50 */
__u32 tz_minuteswest; /* Minutes west of Greenwich 0x58 */
__u32 tz_dsttime; /* Type of dst correction 0x5C */
__u32 dcache_size; /* L1 d-cache size 0x60 */
__u32 dcache_line_size; /* L1 d-cache line size 0x64 */
__u32 icache_size; /* L1 i-cache size 0x68 */
__u32 icache_line_size; /* L1 i-cache line size 0x6C */
/* those additional ones don't have to be located anywhere
* special as they were not part of the original systemcfg
*/
__u32 dcache_block_size; /* L1 d-cache block size */
__u32 icache_block_size; /* L1 i-cache block size */
__u32 dcache_log_block_size; /* L1 d-cache log block size */
__u32 icache_log_block_size; /* L1 i-cache log block size */
__s32 wtom_clock_sec; /* Wall to monotonic clock */
__s32 wtom_clock_nsec;
struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */
__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
};
#else /* CONFIG_PPC64 */
/*
* And here is the simpler 32 bits version
*/
struct vdso_data {
__u64 tb_orig_stamp; /* Timebase at boot 0x30 */
__u64 tb_ticks_per_sec; /* Timebase tics / sec 0x38 */
__u64 tb_to_xs; /* Inverse of TB to 2^20 0x40 */
__u64 stamp_xsec; /* 0x48 */
__u32 tb_update_count; /* Timebase atomicity ctr 0x50 */
__u32 tz_minuteswest; /* Minutes west of Greenwich 0x58 */
__u32 tz_dsttime; /* Type of dst correction 0x5C */
__s32 wtom_clock_sec; /* Wall to monotonic clock */
__s32 wtom_clock_nsec;
struct timespec stamp_xtime; /* xtime as at tb_orig_stamp */
__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
__u32 dcache_block_size; /* L1 d-cache block size */
__u32 icache_block_size; /* L1 i-cache block size */
__u32 dcache_log_block_size; /* L1 d-cache log block size */
__u32 icache_log_block_size; /* L1 i-cache log block size */
};
#endif /* CONFIG_PPC64 */
#ifdef __KERNEL__
extern struct vdso_data *vdso_data;
#endif
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _SYSTEMCFG_H */