1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2006 Andi Kleen, SUSE Labs.
4 *
5 * Fast user context implementation of clock_gettime, gettimeofday, and time.
6 *
7 * The code should have no internal unresolved relocations.
8 * Check with readelf after changing.
9 * Also alternative() doesn't work.
10 */
11 /*
12 * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
13 */
14
15 #include <linux/kernel.h>
16 #include <linux/time.h>
17 #include <linux/string.h>
18 #include <asm/io.h>
19 #include <asm/unistd.h>
20 #include <asm/timex.h>
21 #include <asm/clocksource.h>
22 #include <asm/vvar.h>
23
24 #ifdef CONFIG_SPARC64
25 #define SYSCALL_STRING \
26 "ta 0x6d;" \
27 "bcs,a 1f;" \
28 " sub %%g0, %%o0, %%o0;" \
29 "1:"
30 #else
31 #define SYSCALL_STRING \
32 "ta 0x10;" \
33 "bcs,a 1f;" \
34 " sub %%g0, %%o0, %%o0;" \
35 "1:"
36 #endif
37
38 #define SYSCALL_CLOBBERS \
39 "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
40 "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15", \
41 "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23", \
42 "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31", \
43 "f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46", \
44 "f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62", \
45 "cc", "memory"
46
47 /*
48 * Compute the vvar page's address in the process address space, and return it
49 * as a pointer to the vvar_data.
50 */
get_vvar_data(void)51 notrace static __always_inline struct vvar_data *get_vvar_data(void)
52 {
53 unsigned long ret;
54
55 /*
56 * vdso data page is the first vDSO page so grab the PC
57 * and move up a page to get to the data page.
58 */
59 __asm__("rd %%pc, %0" : "=r" (ret));
60 ret &= ~(8192 - 1);
61 ret -= 8192;
62
63 return (struct vvar_data *) ret;
64 }
65
vdso_fallback_gettime(long clock,struct __kernel_old_timespec * ts)66 notrace static long vdso_fallback_gettime(long clock, struct __kernel_old_timespec *ts)
67 {
68 register long num __asm__("g1") = __NR_clock_gettime;
69 register long o0 __asm__("o0") = clock;
70 register long o1 __asm__("o1") = (long) ts;
71
72 __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
73 "0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
74 return o0;
75 }
76
vdso_fallback_gettimeofday(struct __kernel_old_timeval * tv,struct timezone * tz)77 notrace static long vdso_fallback_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
78 {
79 register long num __asm__("g1") = __NR_gettimeofday;
80 register long o0 __asm__("o0") = (long) tv;
81 register long o1 __asm__("o1") = (long) tz;
82
83 __asm__ __volatile__(SYSCALL_STRING : "=r" (o0) : "r" (num),
84 "0" (o0), "r" (o1) : SYSCALL_CLOBBERS);
85 return o0;
86 }
87
88 #ifdef CONFIG_SPARC64
__shr64(u64 val,int amt)89 notrace static __always_inline u64 __shr64(u64 val, int amt)
90 {
91 return val >> amt;
92 }
93
vread_tick(void)94 notrace static __always_inline u64 vread_tick(void)
95 {
96 u64 ret;
97
98 __asm__ __volatile__("rd %%tick, %0" : "=r" (ret));
99 return ret;
100 }
101
vread_tick_stick(void)102 notrace static __always_inline u64 vread_tick_stick(void)
103 {
104 u64 ret;
105
106 __asm__ __volatile__("rd %%asr24, %0" : "=r" (ret));
107 return ret;
108 }
109 #else
__shr64(u64 val,int amt)110 notrace static __always_inline u64 __shr64(u64 val, int amt)
111 {
112 u64 ret;
113
114 __asm__ __volatile__("sllx %H1, 32, %%g1\n\t"
115 "srl %L1, 0, %L1\n\t"
116 "or %%g1, %L1, %%g1\n\t"
117 "srlx %%g1, %2, %L0\n\t"
118 "srlx %L0, 32, %H0"
119 : "=r" (ret)
120 : "r" (val), "r" (amt)
121 : "g1");
122 return ret;
123 }
124
vread_tick(void)125 notrace static __always_inline u64 vread_tick(void)
126 {
127 register unsigned long long ret asm("o4");
128
129 __asm__ __volatile__("rd %%tick, %L0\n\t"
130 "srlx %L0, 32, %H0"
131 : "=r" (ret));
132 return ret;
133 }
134
vread_tick_stick(void)135 notrace static __always_inline u64 vread_tick_stick(void)
136 {
137 register unsigned long long ret asm("o4");
138
139 __asm__ __volatile__("rd %%asr24, %L0\n\t"
140 "srlx %L0, 32, %H0"
141 : "=r" (ret));
142 return ret;
143 }
144 #endif
145
vgetsns(struct vvar_data * vvar)146 notrace static __always_inline u64 vgetsns(struct vvar_data *vvar)
147 {
148 u64 v;
149 u64 cycles;
150
151 cycles = vread_tick();
152 v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
153 return v * vvar->clock.mult;
154 }
155
vgetsns_stick(struct vvar_data * vvar)156 notrace static __always_inline u64 vgetsns_stick(struct vvar_data *vvar)
157 {
158 u64 v;
159 u64 cycles;
160
161 cycles = vread_tick_stick();
162 v = (cycles - vvar->clock.cycle_last) & vvar->clock.mask;
163 return v * vvar->clock.mult;
164 }
165
do_realtime(struct vvar_data * vvar,struct __kernel_old_timespec * ts)166 notrace static __always_inline int do_realtime(struct vvar_data *vvar,
167 struct __kernel_old_timespec *ts)
168 {
169 unsigned long seq;
170 u64 ns;
171
172 do {
173 seq = vvar_read_begin(vvar);
174 ts->tv_sec = vvar->wall_time_sec;
175 ns = vvar->wall_time_snsec;
176 ns += vgetsns(vvar);
177 ns = __shr64(ns, vvar->clock.shift);
178 } while (unlikely(vvar_read_retry(vvar, seq)));
179
180 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
181 ts->tv_nsec = ns;
182
183 return 0;
184 }
185
do_realtime_stick(struct vvar_data * vvar,struct __kernel_old_timespec * ts)186 notrace static __always_inline int do_realtime_stick(struct vvar_data *vvar,
187 struct __kernel_old_timespec *ts)
188 {
189 unsigned long seq;
190 u64 ns;
191
192 do {
193 seq = vvar_read_begin(vvar);
194 ts->tv_sec = vvar->wall_time_sec;
195 ns = vvar->wall_time_snsec;
196 ns += vgetsns_stick(vvar);
197 ns = __shr64(ns, vvar->clock.shift);
198 } while (unlikely(vvar_read_retry(vvar, seq)));
199
200 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
201 ts->tv_nsec = ns;
202
203 return 0;
204 }
205
do_monotonic(struct vvar_data * vvar,struct __kernel_old_timespec * ts)206 notrace static __always_inline int do_monotonic(struct vvar_data *vvar,
207 struct __kernel_old_timespec *ts)
208 {
209 unsigned long seq;
210 u64 ns;
211
212 do {
213 seq = vvar_read_begin(vvar);
214 ts->tv_sec = vvar->monotonic_time_sec;
215 ns = vvar->monotonic_time_snsec;
216 ns += vgetsns(vvar);
217 ns = __shr64(ns, vvar->clock.shift);
218 } while (unlikely(vvar_read_retry(vvar, seq)));
219
220 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
221 ts->tv_nsec = ns;
222
223 return 0;
224 }
225
do_monotonic_stick(struct vvar_data * vvar,struct __kernel_old_timespec * ts)226 notrace static __always_inline int do_monotonic_stick(struct vvar_data *vvar,
227 struct __kernel_old_timespec *ts)
228 {
229 unsigned long seq;
230 u64 ns;
231
232 do {
233 seq = vvar_read_begin(vvar);
234 ts->tv_sec = vvar->monotonic_time_sec;
235 ns = vvar->monotonic_time_snsec;
236 ns += vgetsns_stick(vvar);
237 ns = __shr64(ns, vvar->clock.shift);
238 } while (unlikely(vvar_read_retry(vvar, seq)));
239
240 ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
241 ts->tv_nsec = ns;
242
243 return 0;
244 }
245
do_realtime_coarse(struct vvar_data * vvar,struct __kernel_old_timespec * ts)246 notrace static int do_realtime_coarse(struct vvar_data *vvar,
247 struct __kernel_old_timespec *ts)
248 {
249 unsigned long seq;
250
251 do {
252 seq = vvar_read_begin(vvar);
253 ts->tv_sec = vvar->wall_time_coarse_sec;
254 ts->tv_nsec = vvar->wall_time_coarse_nsec;
255 } while (unlikely(vvar_read_retry(vvar, seq)));
256 return 0;
257 }
258
do_monotonic_coarse(struct vvar_data * vvar,struct __kernel_old_timespec * ts)259 notrace static int do_monotonic_coarse(struct vvar_data *vvar,
260 struct __kernel_old_timespec *ts)
261 {
262 unsigned long seq;
263
264 do {
265 seq = vvar_read_begin(vvar);
266 ts->tv_sec = vvar->monotonic_time_coarse_sec;
267 ts->tv_nsec = vvar->monotonic_time_coarse_nsec;
268 } while (unlikely(vvar_read_retry(vvar, seq)));
269
270 return 0;
271 }
272
273 notrace int
__vdso_clock_gettime(clockid_t clock,struct __kernel_old_timespec * ts)274 __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
275 {
276 struct vvar_data *vvd = get_vvar_data();
277
278 switch (clock) {
279 case CLOCK_REALTIME:
280 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
281 break;
282 return do_realtime(vvd, ts);
283 case CLOCK_MONOTONIC:
284 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
285 break;
286 return do_monotonic(vvd, ts);
287 case CLOCK_REALTIME_COARSE:
288 return do_realtime_coarse(vvd, ts);
289 case CLOCK_MONOTONIC_COARSE:
290 return do_monotonic_coarse(vvd, ts);
291 }
292 /*
293 * Unknown clock ID ? Fall back to the syscall.
294 */
295 return vdso_fallback_gettime(clock, ts);
296 }
297 int
298 clock_gettime(clockid_t, struct __kernel_old_timespec *)
299 __attribute__((weak, alias("__vdso_clock_gettime")));
300
301 notrace int
__vdso_clock_gettime_stick(clockid_t clock,struct __kernel_old_timespec * ts)302 __vdso_clock_gettime_stick(clockid_t clock, struct __kernel_old_timespec *ts)
303 {
304 struct vvar_data *vvd = get_vvar_data();
305
306 switch (clock) {
307 case CLOCK_REALTIME:
308 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
309 break;
310 return do_realtime_stick(vvd, ts);
311 case CLOCK_MONOTONIC:
312 if (unlikely(vvd->vclock_mode == VCLOCK_NONE))
313 break;
314 return do_monotonic_stick(vvd, ts);
315 case CLOCK_REALTIME_COARSE:
316 return do_realtime_coarse(vvd, ts);
317 case CLOCK_MONOTONIC_COARSE:
318 return do_monotonic_coarse(vvd, ts);
319 }
320 /*
321 * Unknown clock ID ? Fall back to the syscall.
322 */
323 return vdso_fallback_gettime(clock, ts);
324 }
325
326 notrace int
__vdso_gettimeofday(struct __kernel_old_timeval * tv,struct timezone * tz)327 __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
328 {
329 struct vvar_data *vvd = get_vvar_data();
330
331 if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
332 if (likely(tv != NULL)) {
333 union tstv_t {
334 struct __kernel_old_timespec ts;
335 struct __kernel_old_timeval tv;
336 } *tstv = (union tstv_t *) tv;
337 do_realtime(vvd, &tstv->ts);
338 /*
339 * Assign before dividing to ensure that the division is
340 * done in the type of tv_usec, not tv_nsec.
341 *
342 * There cannot be > 1 billion usec in a second:
343 * do_realtime() has already distributed such overflow
344 * into tv_sec. So we can assign it to an int safely.
345 */
346 tstv->tv.tv_usec = tstv->ts.tv_nsec;
347 tstv->tv.tv_usec /= 1000;
348 }
349 if (unlikely(tz != NULL)) {
350 /* Avoid memcpy. Some old compilers fail to inline it */
351 tz->tz_minuteswest = vvd->tz_minuteswest;
352 tz->tz_dsttime = vvd->tz_dsttime;
353 }
354 return 0;
355 }
356 return vdso_fallback_gettimeofday(tv, tz);
357 }
358 int
359 gettimeofday(struct __kernel_old_timeval *, struct timezone *)
360 __attribute__((weak, alias("__vdso_gettimeofday")));
361
362 notrace int
__vdso_gettimeofday_stick(struct __kernel_old_timeval * tv,struct timezone * tz)363 __vdso_gettimeofday_stick(struct __kernel_old_timeval *tv, struct timezone *tz)
364 {
365 struct vvar_data *vvd = get_vvar_data();
366
367 if (likely(vvd->vclock_mode != VCLOCK_NONE)) {
368 if (likely(tv != NULL)) {
369 union tstv_t {
370 struct __kernel_old_timespec ts;
371 struct __kernel_old_timeval tv;
372 } *tstv = (union tstv_t *) tv;
373 do_realtime_stick(vvd, &tstv->ts);
374 /*
375 * Assign before dividing to ensure that the division is
376 * done in the type of tv_usec, not tv_nsec.
377 *
378 * There cannot be > 1 billion usec in a second:
379 * do_realtime() has already distributed such overflow
380 * into tv_sec. So we can assign it to an int safely.
381 */
382 tstv->tv.tv_usec = tstv->ts.tv_nsec;
383 tstv->tv.tv_usec /= 1000;
384 }
385 if (unlikely(tz != NULL)) {
386 /* Avoid memcpy. Some old compilers fail to inline it */
387 tz->tz_minuteswest = vvd->tz_minuteswest;
388 tz->tz_dsttime = vvd->tz_dsttime;
389 }
390 return 0;
391 }
392 return vdso_fallback_gettimeofday(tv, tz);
393 }
394