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/*
* Userspace implementations of gettimeofday() and friends.
*
* Copyright (C) 2012 ARM Limited
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#define NSEC_PER_SEC_LO16 0xca00
#define NSEC_PER_SEC_HI16 0x3b9a
vdso_data .req x6
seqcnt .req w7
w_tmp .req w8
x_tmp .req x8
/*
* Conventions for macro arguments:
* - An argument is write-only if its name starts with "res".
* - All other arguments are read-only, unless otherwise specified.
*/
.macro seqcnt_acquire
9999: ldr seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
tbnz seqcnt, #0, 9999b
dmb ishld
.endm
.macro seqcnt_check fail
dmb ishld
ldr w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT]
cmp w_tmp, seqcnt
b.ne \fail
.endm
.macro syscall_check fail
ldr w_tmp, [vdso_data, #VDSO_USE_SYSCALL]
cbnz w_tmp, \fail
.endm
.macro get_nsec_per_sec res
mov \res, #NSEC_PER_SEC_LO16
movk \res, #NSEC_PER_SEC_HI16, lsl #16
.endm
/*
* Returns the clock delta, in nanoseconds left-shifted by the clock
* shift.
*/
.macro get_clock_shifted_nsec res, cycle_last, mult
/* Read the virtual counter. */
isb
mrs x_tmp, cntvct_el0
/* Calculate cycle delta and convert to ns. */
sub \res, x_tmp, \cycle_last
/* We can only guarantee 56 bits of precision. */
movn x_tmp, #0xff00, lsl #48
and \res, x_tmp, \res
mul \res, \res, \mult
/*
* Fake address dependency from the value computed from the counter
* register to subsequent data page accesses so that the sequence
* locking also orders the read of the counter.
*/
and x_tmp, \res, xzr
add vdso_data, vdso_data, x_tmp
.endm
/*
* Returns in res_{sec,nsec} the REALTIME timespec, based on the
* "wall time" (xtime) and the clock_mono delta.
*/
.macro get_ts_realtime res_sec, res_nsec, \
clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec
add \res_nsec, \clock_nsec, \xtime_nsec
udiv x_tmp, \res_nsec, \nsec_to_sec
add \res_sec, \xtime_sec, x_tmp
msub \res_nsec, x_tmp, \nsec_to_sec, \res_nsec
.endm
/*
* Returns in res_{sec,nsec} the timespec based on the clock_raw delta,
* used for CLOCK_MONOTONIC_RAW.
*/
.macro get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec
udiv \res_sec, \clock_nsec, \nsec_to_sec
msub \res_nsec, \res_sec, \nsec_to_sec, \clock_nsec
.endm
/* sec and nsec are modified in place. */
.macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec
/* Add timespec. */
add \sec, \sec, \ts_sec
add \nsec, \nsec, \ts_nsec
/* Normalise the new timespec. */
cmp \nsec, \nsec_to_sec
b.lt 9999f
sub \nsec, \nsec, \nsec_to_sec
add \sec, \sec, #1
9999:
cmp \nsec, #0
b.ge 9998f
add \nsec, \nsec, \nsec_to_sec
sub \sec, \sec, #1
9998:
.endm
.macro clock_gettime_return, shift=0
.if \shift == 1
lsr x11, x11, x12
.endif
stp x10, x11, [x1, #TSPEC_TV_SEC]
mov x0, xzr
ret
.endm
.macro jump_slot jumptable, index, label
.if (. - \jumptable) != 4 * (\index)
.error "Jump slot index mismatch"
.endif
b \label
.endm
.text
/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
ENTRY(__kernel_gettimeofday)
.cfi_startproc
adr vdso_data, _vdso_data
/* If tv is NULL, skip to the timezone code. */
cbz x0, 2f
/* Compute the time of day. */
1: seqcnt_acquire
syscall_check fail=4f
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
seqcnt_check fail=1b
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
/* Convert ns to us. */
mov x13, #1000
lsl x13, x13, x12
udiv x11, x11, x13
stp x10, x11, [x0, #TVAL_TV_SEC]
2:
/* If tz is NULL, return 0. */
cbz x1, 3f
ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
stp w4, w5, [x1, #TZ_MINWEST]
3:
mov x0, xzr
ret
4:
/* Syscall fallback. */
mov x8, #__NR_gettimeofday
svc #0
ret
.cfi_endproc
ENDPROC(__kernel_gettimeofday)
#define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE
/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
ENTRY(__kernel_clock_gettime)
.cfi_startproc
cmp w0, #JUMPSLOT_MAX
b.hi syscall
adr vdso_data, _vdso_data
adr x_tmp, jumptable
add x_tmp, x_tmp, w0, uxtw #2
br x_tmp
ALIGN
jumptable:
jump_slot jumptable, CLOCK_REALTIME, realtime
jump_slot jumptable, CLOCK_MONOTONIC, monotonic
b syscall
b syscall
jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw
jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse
jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse
.if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1)
.error "Wrong jumptable size"
.endif
ALIGN
realtime:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
/* All computations are done with left-shifted nsecs. */
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
seqcnt_check fail=realtime
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
clock_gettime_return shift=1
ALIGN
monotonic:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
ldp x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC]
/* All computations are done with left-shifted nsecs. */
lsl x4, x4, x12
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
seqcnt_check fail=monotonic
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
clock_gettime_return shift=1
ALIGN
monotonic_raw:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
/* w11 = cs_raw_mult, w12 = cs_shift */
ldp w12, w11, [vdso_data, #VDSO_CS_SHIFT]
ldp x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC]
/* All computations are done with left-shifted nsecs. */
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
seqcnt_check fail=monotonic_raw
get_ts_clock_raw res_sec=x10, res_nsec=x11, \
clock_nsec=x15, nsec_to_sec=x9
add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
clock_gettime_return shift=1
ALIGN
realtime_coarse:
seqcnt_acquire
ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
seqcnt_check fail=realtime_coarse
clock_gettime_return
ALIGN
monotonic_coarse:
seqcnt_acquire
ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
seqcnt_check fail=monotonic_coarse
/* Computations are done in (non-shifted) nsecs. */
get_nsec_per_sec res=x9
add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
clock_gettime_return
ALIGN
syscall: /* Syscall fallback. */
mov x8, #__NR_clock_gettime
svc #0
ret
.cfi_endproc
ENDPROC(__kernel_clock_gettime)
/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
ENTRY(__kernel_clock_getres)
.cfi_startproc
cmp w0, #CLOCK_REALTIME
ccmp w0, #CLOCK_MONOTONIC, #0x4, ne
ccmp w0, #CLOCK_MONOTONIC_RAW, #0x4, ne
b.ne 1f
adr vdso_data, _vdso_data
ldr w2, [vdso_data, #CLOCK_REALTIME_RES]
b 2f
1:
cmp w0, #CLOCK_REALTIME_COARSE
ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
b.ne 4f
ldr x2, 5f
2:
cbz x1, 3f
stp xzr, x2, [x1]
3: /* res == NULL. */
mov w0, wzr
ret
4: /* Syscall fallback. */
mov x8, #__NR_clock_getres
svc #0
ret
5:
.quad CLOCK_COARSE_RES
.cfi_endproc
ENDPROC(__kernel_clock_getres)
|
