2 * Userspace implementations of gettimeofday() and friends.
4 * Copyright (C) 2012 ARM Limited
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 * Author: Will Deacon <will.deacon@arm.com>
21 #include <linux/linkage.h>
22 #include <asm/asm-offsets.h>
23 #include <asm/unistd.h>
25 #define NSEC_PER_SEC_LO16 0xca00
26 #define NSEC_PER_SEC_HI16 0x3b9a
34 * Conventions for macro arguments:
35 * - An argument is write-only if its name starts with "res".
36 * - All other arguments are read-only, unless otherwise specified.
40 9999: ldr seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
41 tbnz seqcnt, #0, 9999b
45 .macro seqcnt_check fail
47 ldr w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT]
52 .macro syscall_check fail
53 ldr w_tmp, [vdso_data, #VDSO_USE_SYSCALL]
57 .macro get_nsec_per_sec res
58 mov \res, #NSEC_PER_SEC_LO16
59 movk \res, #NSEC_PER_SEC_HI16, lsl #16
63 * Returns the clock delta, in nanoseconds left-shifted by the clock
66 .macro get_clock_shifted_nsec res, cycle_last, mult
67 /* Read the virtual counter. */
70 /* Calculate cycle delta and convert to ns. */
71 sub \res, x_tmp, \cycle_last
72 /* We can only guarantee 56 bits of precision. */
73 movn x_tmp, #0xff00, lsl #48
77 * Fake address dependency from the value computed from the counter
78 * register to subsequent data page accesses so that the sequence
79 * locking also orders the read of the counter.
82 add vdso_data, vdso_data, x_tmp
86 * Returns in res_{sec,nsec} the REALTIME timespec, based on the
87 * "wall time" (xtime) and the clock_mono delta.
89 .macro get_ts_realtime res_sec, res_nsec, \
90 clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec
91 add \res_nsec, \clock_nsec, \xtime_nsec
92 udiv x_tmp, \res_nsec, \nsec_to_sec
93 add \res_sec, \xtime_sec, x_tmp
94 msub \res_nsec, x_tmp, \nsec_to_sec, \res_nsec
98 * Returns in res_{sec,nsec} the timespec based on the clock_raw delta,
99 * used for CLOCK_MONOTONIC_RAW.
101 .macro get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec
102 udiv \res_sec, \clock_nsec, \nsec_to_sec
103 msub \res_nsec, \res_sec, \nsec_to_sec, \clock_nsec
106 /* sec and nsec are modified in place. */
107 .macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec
109 add \sec, \sec, \ts_sec
110 add \nsec, \nsec, \ts_nsec
112 /* Normalise the new timespec. */
113 cmp \nsec, \nsec_to_sec
115 sub \nsec, \nsec, \nsec_to_sec
120 add \nsec, \nsec, \nsec_to_sec
125 .macro clock_gettime_return, shift=0
129 stp x10, x11, [x1, #TSPEC_TV_SEC]
134 .macro jump_slot jumptable, index, label
135 .if (. - \jumptable) != 4 * (\index)
136 .error "Jump slot index mismatch"
143 /* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
144 ENTRY(__kernel_gettimeofday)
146 adr vdso_data, _vdso_data
147 /* If tv is NULL, skip to the timezone code. */
150 /* Compute the time of day. */
152 syscall_check fail=4f
153 ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
154 /* w11 = cs_mono_mult, w12 = cs_shift */
155 ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
156 ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
158 get_nsec_per_sec res=x9
161 get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
163 get_ts_realtime res_sec=x10, res_nsec=x11, \
164 clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
166 /* Convert ns to us. */
170 stp x10, x11, [x0, #TVAL_TV_SEC]
172 /* If tz is NULL, return 0. */
174 ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
175 stp w4, w5, [x1, #TZ_MINWEST]
180 /* Syscall fallback. */
181 mov x8, #__NR_gettimeofday
185 ENDPROC(__kernel_gettimeofday)
187 #define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE
189 /* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
190 ENTRY(__kernel_clock_gettime)
192 cmp w0, #JUMPSLOT_MAX
194 adr vdso_data, _vdso_data
196 add x_tmp, x_tmp, w0, uxtw #2
201 jump_slot jumptable, CLOCK_REALTIME, realtime
202 jump_slot jumptable, CLOCK_MONOTONIC, monotonic
205 jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw
206 jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse
207 jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse
209 .if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1)
210 .error "Wrong jumptable size"
216 syscall_check fail=syscall
217 ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
218 /* w11 = cs_mono_mult, w12 = cs_shift */
219 ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
220 ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
222 /* All computations are done with left-shifted nsecs. */
223 get_nsec_per_sec res=x9
226 get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
227 seqcnt_check fail=realtime
228 get_ts_realtime res_sec=x10, res_nsec=x11, \
229 clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
230 clock_gettime_return, shift=1
235 syscall_check fail=syscall
236 ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
237 /* w11 = cs_mono_mult, w12 = cs_shift */
238 ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
239 ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
240 ldp x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC]
242 /* All computations are done with left-shifted nsecs. */
244 get_nsec_per_sec res=x9
247 get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
248 seqcnt_check fail=monotonic
249 get_ts_realtime res_sec=x10, res_nsec=x11, \
250 clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
252 add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
253 clock_gettime_return, shift=1
258 syscall_check fail=syscall
259 ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
260 /* w11 = cs_raw_mult, w12 = cs_shift */
261 ldp w12, w11, [vdso_data, #VDSO_CS_SHIFT]
262 ldp x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC]
264 /* All computations are done with left-shifted nsecs. */
265 get_nsec_per_sec res=x9
268 get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
269 seqcnt_check fail=monotonic_raw
270 get_ts_clock_raw res_sec=x10, res_nsec=x11, \
271 clock_nsec=x15, nsec_to_sec=x9
273 add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
274 clock_gettime_return, shift=1
279 ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
280 seqcnt_check fail=realtime_coarse
286 ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
287 ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
288 seqcnt_check fail=monotonic_coarse
290 /* Computations are done in (non-shifted) nsecs. */
291 get_nsec_per_sec res=x9
292 add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
296 syscall: /* Syscall fallback. */
297 mov x8, #__NR_clock_gettime
301 ENDPROC(__kernel_clock_gettime)
303 /* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
304 ENTRY(__kernel_clock_getres)
306 cmp w0, #CLOCK_REALTIME
307 ccmp w0, #CLOCK_MONOTONIC, #0x4, ne
308 ccmp w0, #CLOCK_MONOTONIC_RAW, #0x4, ne
311 adr vdso_data, _vdso_data
312 ldr w2, [vdso_data, #CLOCK_REALTIME_RES]
315 cmp w0, #CLOCK_REALTIME_COARSE
316 ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
323 3: /* res == NULL. */
327 4: /* Syscall fallback. */
328 mov x8, #__NR_clock_getres
332 .quad CLOCK_COARSE_RES
334 ENDPROC(__kernel_clock_getres)