1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Generic userspace implementations of gettimeofday() and similar.
4 */
5 #include <vdso/datapage.h>
6 #include <vdso/helpers.h>
7
8 #ifndef vdso_calc_delta
9 /*
10 * Default implementation which works for all sane clocksources. That
11 * obviously excludes x86/TSC.
12 */
13 static __always_inline
vdso_calc_delta(u64 cycles,u64 last,u64 mask,u32 mult)14 u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
15 {
16 return ((cycles - last) & mask) * mult;
17 }
18 #endif
19
20 #ifndef vdso_shift_ns
vdso_shift_ns(u64 ns,u32 shift)21 static __always_inline u64 vdso_shift_ns(u64 ns, u32 shift)
22 {
23 return ns >> shift;
24 }
25 #endif
26
27 #ifndef __arch_vdso_hres_capable
__arch_vdso_hres_capable(void)28 static inline bool __arch_vdso_hres_capable(void)
29 {
30 return true;
31 }
32 #endif
33
34 #ifndef vdso_clocksource_ok
vdso_clocksource_ok(const struct vdso_data * vd)35 static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
36 {
37 return vd->clock_mode != VDSO_CLOCKMODE_NONE;
38 }
39 #endif
40
41 #ifndef vdso_cycles_ok
vdso_cycles_ok(u64 cycles)42 static inline bool vdso_cycles_ok(u64 cycles)
43 {
44 return true;
45 }
46 #endif
47
48 #ifdef CONFIG_TIME_NS
do_hres_timens(const struct vdso_data * vdns,clockid_t clk,struct __kernel_timespec * ts)49 static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
50 struct __kernel_timespec *ts)
51 {
52 const struct vdso_data *vd;
53 const struct timens_offset *offs = &vdns->offset[clk];
54 const struct vdso_timestamp *vdso_ts;
55 u64 cycles, last, ns;
56 u32 seq;
57 s64 sec;
58
59 vd = vdns - (clk == CLOCK_MONOTONIC_RAW ? CS_RAW : CS_HRES_COARSE);
60 vd = __arch_get_timens_vdso_data(vd);
61 if (clk != CLOCK_MONOTONIC_RAW)
62 vd = &vd[CS_HRES_COARSE];
63 else
64 vd = &vd[CS_RAW];
65 vdso_ts = &vd->basetime[clk];
66
67 do {
68 seq = vdso_read_begin(vd);
69
70 if (unlikely(!vdso_clocksource_ok(vd)))
71 return -1;
72
73 cycles = __arch_get_hw_counter(vd->clock_mode, vd);
74 if (unlikely(!vdso_cycles_ok(cycles)))
75 return -1;
76 ns = vdso_ts->nsec;
77 last = vd->cycle_last;
78 ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
79 ns = vdso_shift_ns(ns, vd->shift);
80 sec = vdso_ts->sec;
81 } while (unlikely(vdso_read_retry(vd, seq)));
82
83 /* Add the namespace offset */
84 sec += offs->sec;
85 ns += offs->nsec;
86
87 /*
88 * Do this outside the loop: a race inside the loop could result
89 * in __iter_div_u64_rem() being extremely slow.
90 */
91 ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
92 ts->tv_nsec = ns;
93
94 return 0;
95 }
96 #else
97 static __always_inline
__arch_get_timens_vdso_data(const struct vdso_data * vd)98 const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
99 {
100 return NULL;
101 }
102
do_hres_timens(const struct vdso_data * vdns,clockid_t clk,struct __kernel_timespec * ts)103 static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
104 struct __kernel_timespec *ts)
105 {
106 return -EINVAL;
107 }
108 #endif
109
do_hres(const struct vdso_data * vd,clockid_t clk,struct __kernel_timespec * ts)110 static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
111 struct __kernel_timespec *ts)
112 {
113 const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
114 u64 cycles, last, sec, ns;
115 u32 seq;
116
117 /* Allows to compile the high resolution parts out */
118 if (!__arch_vdso_hres_capable())
119 return -1;
120
121 do {
122 /*
123 * Open coded to handle VDSO_CLOCKMODE_TIMENS. Time namespace
124 * enabled tasks have a special VVAR page installed which
125 * has vd->seq set to 1 and vd->clock_mode set to
126 * VDSO_CLOCKMODE_TIMENS. For non time namespace affected tasks
127 * this does not affect performance because if vd->seq is
128 * odd, i.e. a concurrent update is in progress the extra
129 * check for vd->clock_mode is just a few extra
130 * instructions while spin waiting for vd->seq to become
131 * even again.
132 */
133 while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
134 if (IS_ENABLED(CONFIG_TIME_NS) &&
135 vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
136 return do_hres_timens(vd, clk, ts);
137 cpu_relax();
138 }
139 smp_rmb();
140
141 if (unlikely(!vdso_clocksource_ok(vd)))
142 return -1;
143
144 cycles = __arch_get_hw_counter(vd->clock_mode, vd);
145 if (unlikely(!vdso_cycles_ok(cycles)))
146 return -1;
147 ns = vdso_ts->nsec;
148 last = vd->cycle_last;
149 ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
150 ns = vdso_shift_ns(ns, vd->shift);
151 sec = vdso_ts->sec;
152 } while (unlikely(vdso_read_retry(vd, seq)));
153
154 /*
155 * Do this outside the loop: a race inside the loop could result
156 * in __iter_div_u64_rem() being extremely slow.
157 */
158 ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
159 ts->tv_nsec = ns;
160
161 return 0;
162 }
163
164 #ifdef CONFIG_TIME_NS
do_coarse_timens(const struct vdso_data * vdns,clockid_t clk,struct __kernel_timespec * ts)165 static __always_inline int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
166 struct __kernel_timespec *ts)
167 {
168 const struct vdso_data *vd = __arch_get_timens_vdso_data(vdns);
169 const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
170 const struct timens_offset *offs = &vdns->offset[clk];
171 u64 nsec;
172 s64 sec;
173 s32 seq;
174
175 do {
176 seq = vdso_read_begin(vd);
177 sec = vdso_ts->sec;
178 nsec = vdso_ts->nsec;
179 } while (unlikely(vdso_read_retry(vd, seq)));
180
181 /* Add the namespace offset */
182 sec += offs->sec;
183 nsec += offs->nsec;
184
185 /*
186 * Do this outside the loop: a race inside the loop could result
187 * in __iter_div_u64_rem() being extremely slow.
188 */
189 ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
190 ts->tv_nsec = nsec;
191 return 0;
192 }
193 #else
do_coarse_timens(const struct vdso_data * vdns,clockid_t clk,struct __kernel_timespec * ts)194 static __always_inline int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
195 struct __kernel_timespec *ts)
196 {
197 return -1;
198 }
199 #endif
200
do_coarse(const struct vdso_data * vd,clockid_t clk,struct __kernel_timespec * ts)201 static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
202 struct __kernel_timespec *ts)
203 {
204 const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
205 u32 seq;
206
207 do {
208 /*
209 * Open coded to handle VDSO_CLOCK_TIMENS. See comment in
210 * do_hres().
211 */
212 while ((seq = READ_ONCE(vd->seq)) & 1) {
213 if (IS_ENABLED(CONFIG_TIME_NS) &&
214 vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
215 return do_coarse_timens(vd, clk, ts);
216 cpu_relax();
217 }
218 smp_rmb();
219
220 ts->tv_sec = vdso_ts->sec;
221 ts->tv_nsec = vdso_ts->nsec;
222 } while (unlikely(vdso_read_retry(vd, seq)));
223
224 return 0;
225 }
226
227 static __always_inline int
__cvdso_clock_gettime_common(const struct vdso_data * vd,clockid_t clock,struct __kernel_timespec * ts)228 __cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
229 struct __kernel_timespec *ts)
230 {
231 u32 msk;
232
233 /* Check for negative values or invalid clocks */
234 if (unlikely((u32) clock >= MAX_CLOCKS))
235 return -1;
236
237 /*
238 * Convert the clockid to a bitmask and use it to check which
239 * clocks are handled in the VDSO directly.
240 */
241 msk = 1U << clock;
242 if (likely(msk & VDSO_HRES))
243 vd = &vd[CS_HRES_COARSE];
244 else if (msk & VDSO_COARSE)
245 return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
246 else if (msk & VDSO_RAW)
247 vd = &vd[CS_RAW];
248 else
249 return -1;
250
251 return do_hres(vd, clock, ts);
252 }
253
254 static __maybe_unused int
__cvdso_clock_gettime_data(const struct vdso_data * vd,clockid_t clock,struct __kernel_timespec * ts)255 __cvdso_clock_gettime_data(const struct vdso_data *vd, clockid_t clock,
256 struct __kernel_timespec *ts)
257 {
258 int ret = __cvdso_clock_gettime_common(vd, clock, ts);
259
260 if (unlikely(ret))
261 return clock_gettime_fallback(clock, ts);
262 return 0;
263 }
264
265 static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock,struct __kernel_timespec * ts)266 __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
267 {
268 return __cvdso_clock_gettime_data(__arch_get_vdso_data(), clock, ts);
269 }
270
271 #ifdef BUILD_VDSO32
272 static __maybe_unused int
__cvdso_clock_gettime32_data(const struct vdso_data * vd,clockid_t clock,struct old_timespec32 * res)273 __cvdso_clock_gettime32_data(const struct vdso_data *vd, clockid_t clock,
274 struct old_timespec32 *res)
275 {
276 struct __kernel_timespec ts;
277 int ret;
278
279 ret = __cvdso_clock_gettime_common(vd, clock, &ts);
280
281 if (unlikely(ret))
282 return clock_gettime32_fallback(clock, res);
283
284 /* For ret == 0 */
285 res->tv_sec = ts.tv_sec;
286 res->tv_nsec = ts.tv_nsec;
287
288 return ret;
289 }
290
291 static __maybe_unused int
__cvdso_clock_gettime32(clockid_t clock,struct old_timespec32 * res)292 __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
293 {
294 return __cvdso_clock_gettime32_data(__arch_get_vdso_data(), clock, res);
295 }
296 #endif /* BUILD_VDSO32 */
297
298 static __maybe_unused int
__cvdso_gettimeofday_data(const struct vdso_data * vd,struct __kernel_old_timeval * tv,struct timezone * tz)299 __cvdso_gettimeofday_data(const struct vdso_data *vd,
300 struct __kernel_old_timeval *tv, struct timezone *tz)
301 {
302
303 if (likely(tv != NULL)) {
304 struct __kernel_timespec ts;
305
306 if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
307 return gettimeofday_fallback(tv, tz);
308
309 tv->tv_sec = ts.tv_sec;
310 tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
311 }
312
313 if (unlikely(tz != NULL)) {
314 if (IS_ENABLED(CONFIG_TIME_NS) &&
315 vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
316 vd = __arch_get_timens_vdso_data(vd);
317
318 tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
319 tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
320 }
321
322 return 0;
323 }
324
325 static __maybe_unused int
__cvdso_gettimeofday(struct __kernel_old_timeval * tv,struct timezone * tz)326 __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
327 {
328 return __cvdso_gettimeofday_data(__arch_get_vdso_data(), tv, tz);
329 }
330
331 #ifdef VDSO_HAS_TIME
332 static __maybe_unused __kernel_old_time_t
__cvdso_time_data(const struct vdso_data * vd,__kernel_old_time_t * time)333 __cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
334 {
335 __kernel_old_time_t t;
336
337 if (IS_ENABLED(CONFIG_TIME_NS) &&
338 vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
339 vd = __arch_get_timens_vdso_data(vd);
340
341 t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
342
343 if (time)
344 *time = t;
345
346 return t;
347 }
348
__cvdso_time(__kernel_old_time_t * time)349 static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
350 {
351 return __cvdso_time_data(__arch_get_vdso_data(), time);
352 }
353 #endif /* VDSO_HAS_TIME */
354
355 #ifdef VDSO_HAS_CLOCK_GETRES
356 static __maybe_unused
__cvdso_clock_getres_common(const struct vdso_data * vd,clockid_t clock,struct __kernel_timespec * res)357 int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
358 struct __kernel_timespec *res)
359 {
360 u32 msk;
361 u64 ns;
362
363 /* Check for negative values or invalid clocks */
364 if (unlikely((u32) clock >= MAX_CLOCKS))
365 return -1;
366
367 if (IS_ENABLED(CONFIG_TIME_NS) &&
368 vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
369 vd = __arch_get_timens_vdso_data(vd);
370
371 /*
372 * Convert the clockid to a bitmask and use it to check which
373 * clocks are handled in the VDSO directly.
374 */
375 msk = 1U << clock;
376 if (msk & (VDSO_HRES | VDSO_RAW)) {
377 /*
378 * Preserves the behaviour of posix_get_hrtimer_res().
379 */
380 ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
381 } else if (msk & VDSO_COARSE) {
382 /*
383 * Preserves the behaviour of posix_get_coarse_res().
384 */
385 ns = LOW_RES_NSEC;
386 } else {
387 return -1;
388 }
389
390 if (likely(res)) {
391 res->tv_sec = 0;
392 res->tv_nsec = ns;
393 }
394 return 0;
395 }
396
397 static __maybe_unused
__cvdso_clock_getres_data(const struct vdso_data * vd,clockid_t clock,struct __kernel_timespec * res)398 int __cvdso_clock_getres_data(const struct vdso_data *vd, clockid_t clock,
399 struct __kernel_timespec *res)
400 {
401 int ret = __cvdso_clock_getres_common(vd, clock, res);
402
403 if (unlikely(ret))
404 return clock_getres_fallback(clock, res);
405 return 0;
406 }
407
408 static __maybe_unused
__cvdso_clock_getres(clockid_t clock,struct __kernel_timespec * res)409 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
410 {
411 return __cvdso_clock_getres_data(__arch_get_vdso_data(), clock, res);
412 }
413
414 #ifdef BUILD_VDSO32
415 static __maybe_unused int
__cvdso_clock_getres_time32_data(const struct vdso_data * vd,clockid_t clock,struct old_timespec32 * res)416 __cvdso_clock_getres_time32_data(const struct vdso_data *vd, clockid_t clock,
417 struct old_timespec32 *res)
418 {
419 struct __kernel_timespec ts;
420 int ret;
421
422 ret = __cvdso_clock_getres_common(vd, clock, &ts);
423
424 if (unlikely(ret))
425 return clock_getres32_fallback(clock, res);
426
427 if (likely(res)) {
428 res->tv_sec = ts.tv_sec;
429 res->tv_nsec = ts.tv_nsec;
430 }
431 return ret;
432 }
433
434 static __maybe_unused int
__cvdso_clock_getres_time32(clockid_t clock,struct old_timespec32 * res)435 __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
436 {
437 return __cvdso_clock_getres_time32_data(__arch_get_vdso_data(),
438 clock, res);
439 }
440 #endif /* BUILD_VDSO32 */
441 #endif /* VDSO_HAS_CLOCK_GETRES */
442