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 /* Bring in default accessors */
9 #include <vdso/vsyscall.h>
10
11 #ifndef vdso_calc_ns
12
13 #ifdef VDSO_DELTA_NOMASK
14 # define VDSO_DELTA_MASK(vd) ULLONG_MAX
15 #else
16 # define VDSO_DELTA_MASK(vd) (vd->mask)
17 #endif
18
19 #ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
vdso_delta_ok(const struct vdso_clock * vc,u64 delta)20 static __always_inline bool vdso_delta_ok(const struct vdso_clock *vc, u64 delta)
21 {
22 return delta < vc->max_cycles;
23 }
24 #else
vdso_delta_ok(const struct vdso_clock * vc,u64 delta)25 static __always_inline bool vdso_delta_ok(const struct vdso_clock *vc, u64 delta)
26 {
27 return true;
28 }
29 #endif
30
31 #ifndef vdso_shift_ns
vdso_shift_ns(u64 ns,u32 shift)32 static __always_inline u64 vdso_shift_ns(u64 ns, u32 shift)
33 {
34 return ns >> shift;
35 }
36 #endif
37
38 /*
39 * Default implementation which works for all sane clocksources. That
40 * obviously excludes x86/TSC.
41 */
vdso_calc_ns(const struct vdso_clock * vc,u64 cycles,u64 base)42 static __always_inline u64 vdso_calc_ns(const struct vdso_clock *vc, u64 cycles, u64 base)
43 {
44 u64 delta = (cycles - vc->cycle_last) & VDSO_DELTA_MASK(vc);
45
46 if (likely(vdso_delta_ok(vc, delta)))
47 return vdso_shift_ns((delta * vc->mult) + base, vc->shift);
48
49 return mul_u64_u32_add_u64_shr(delta, vc->mult, base, vc->shift);
50 }
51 #endif /* vdso_calc_ns */
52
53 #ifndef __arch_vdso_hres_capable
__arch_vdso_hres_capable(void)54 static inline bool __arch_vdso_hres_capable(void)
55 {
56 return true;
57 }
58 #endif
59
60 #ifndef vdso_clocksource_ok
vdso_clocksource_ok(const struct vdso_clock * vc)61 static inline bool vdso_clocksource_ok(const struct vdso_clock *vc)
62 {
63 return vc->clock_mode != VDSO_CLOCKMODE_NONE;
64 }
65 #endif
66
67 #ifndef vdso_cycles_ok
vdso_cycles_ok(u64 cycles)68 static inline bool vdso_cycles_ok(u64 cycles)
69 {
70 return true;
71 }
72 #endif
73
74 #ifdef CONFIG_TIME_NS
75
76 #ifdef CONFIG_GENERIC_VDSO_DATA_STORE
77 static __always_inline
__arch_get_vdso_u_timens_data(const struct vdso_time_data * vd)78 const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_time_data *vd)
79 {
80 return (void *)vd + PAGE_SIZE;
81 }
82 #endif /* CONFIG_GENERIC_VDSO_DATA_STORE */
83
84 static __always_inline
do_hres_timens(const struct vdso_time_data * vdns,const struct vdso_clock * vcns,clockid_t clk,struct __kernel_timespec * ts)85 int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
86 clockid_t clk, struct __kernel_timespec *ts)
87 {
88 const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns);
89 const struct timens_offset *offs = &vcns->offset[clk];
90 const struct vdso_clock *vc = vd->clock_data;
91 const struct vdso_timestamp *vdso_ts;
92 u64 cycles, ns;
93 u32 seq;
94 s64 sec;
95
96 if (clk != CLOCK_MONOTONIC_RAW)
97 vc = &vc[CS_HRES_COARSE];
98 else
99 vc = &vc[CS_RAW];
100 vdso_ts = &vc->basetime[clk];
101
102 do {
103 seq = vdso_read_begin(vc);
104
105 if (unlikely(!vdso_clocksource_ok(vc)))
106 return -1;
107
108 cycles = __arch_get_hw_counter(vc->clock_mode, vd);
109 if (unlikely(!vdso_cycles_ok(cycles)))
110 return -1;
111 ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);
112 sec = vdso_ts->sec;
113 } while (unlikely(vdso_read_retry(vc, seq)));
114
115 /* Add the namespace offset */
116 sec += offs->sec;
117 ns += offs->nsec;
118
119 /*
120 * Do this outside the loop: a race inside the loop could result
121 * in __iter_div_u64_rem() being extremely slow.
122 */
123 ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
124 ts->tv_nsec = ns;
125
126 return 0;
127 }
128 #else
129 static __always_inline
__arch_get_vdso_u_timens_data(const struct vdso_time_data * vd)130 const struct vdso_time_data *__arch_get_vdso_u_timens_data(const struct vdso_time_data *vd)
131 {
132 return NULL;
133 }
134
135 static __always_inline
do_hres_timens(const struct vdso_time_data * vdns,const struct vdso_clock * vcns,clockid_t clk,struct __kernel_timespec * ts)136 int do_hres_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
137 clockid_t clk, struct __kernel_timespec *ts)
138 {
139 return -EINVAL;
140 }
141 #endif
142
143 static __always_inline
do_hres(const struct vdso_time_data * vd,const struct vdso_clock * vc,clockid_t clk,struct __kernel_timespec * ts)144 int do_hres(const struct vdso_time_data *vd, const struct vdso_clock *vc,
145 clockid_t clk, struct __kernel_timespec *ts)
146 {
147 const struct vdso_timestamp *vdso_ts = &vc->basetime[clk];
148 u64 cycles, sec, ns;
149 u32 seq;
150
151 /* Allows to compile the high resolution parts out */
152 if (!__arch_vdso_hres_capable())
153 return -1;
154
155 do {
156 /*
157 * Open coded function vdso_read_begin() to handle
158 * VDSO_CLOCKMODE_TIMENS. Time namespace enabled tasks have a
159 * special VVAR page installed which has vc->seq set to 1 and
160 * vc->clock_mode set to VDSO_CLOCKMODE_TIMENS. For non time
161 * namespace affected tasks this does not affect performance
162 * because if vc->seq is odd, i.e. a concurrent update is in
163 * progress the extra check for vc->clock_mode is just a few
164 * extra instructions while spin waiting for vc->seq to become
165 * even again.
166 */
167 while (unlikely((seq = READ_ONCE(vc->seq)) & 1)) {
168 if (IS_ENABLED(CONFIG_TIME_NS) &&
169 vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
170 return do_hres_timens(vd, vc, clk, ts);
171 cpu_relax();
172 }
173 smp_rmb();
174
175 if (unlikely(!vdso_clocksource_ok(vc)))
176 return -1;
177
178 cycles = __arch_get_hw_counter(vc->clock_mode, vd);
179 if (unlikely(!vdso_cycles_ok(cycles)))
180 return -1;
181 ns = vdso_calc_ns(vc, cycles, vdso_ts->nsec);
182 sec = vdso_ts->sec;
183 } while (unlikely(vdso_read_retry(vc, seq)));
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(ns, NSEC_PER_SEC, &ns);
190 ts->tv_nsec = ns;
191
192 return 0;
193 }
194
195 #ifdef CONFIG_TIME_NS
196 static __always_inline
do_coarse_timens(const struct vdso_time_data * vdns,const struct vdso_clock * vcns,clockid_t clk,struct __kernel_timespec * ts)197 int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
198 clockid_t clk, struct __kernel_timespec *ts)
199 {
200 const struct vdso_time_data *vd = __arch_get_vdso_u_timens_data(vdns);
201 const struct timens_offset *offs = &vcns->offset[clk];
202 const struct vdso_clock *vc = vd->clock_data;
203 const struct vdso_timestamp *vdso_ts;
204 u64 nsec;
205 s64 sec;
206 s32 seq;
207
208 vdso_ts = &vc->basetime[clk];
209
210 do {
211 seq = vdso_read_begin(vc);
212 sec = vdso_ts->sec;
213 nsec = vdso_ts->nsec;
214 } while (unlikely(vdso_read_retry(vc, seq)));
215
216 /* Add the namespace offset */
217 sec += offs->sec;
218 nsec += offs->nsec;
219
220 /*
221 * Do this outside the loop: a race inside the loop could result
222 * in __iter_div_u64_rem() being extremely slow.
223 */
224 ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
225 ts->tv_nsec = nsec;
226 return 0;
227 }
228 #else
229 static __always_inline
do_coarse_timens(const struct vdso_time_data * vdns,const struct vdso_clock * vcns,clockid_t clk,struct __kernel_timespec * ts)230 int do_coarse_timens(const struct vdso_time_data *vdns, const struct vdso_clock *vcns,
231 clockid_t clk, struct __kernel_timespec *ts)
232 {
233 return -1;
234 }
235 #endif
236
237 static __always_inline
do_coarse(const struct vdso_time_data * vd,const struct vdso_clock * vc,clockid_t clk,struct __kernel_timespec * ts)238 int do_coarse(const struct vdso_time_data *vd, const struct vdso_clock *vc,
239 clockid_t clk, struct __kernel_timespec *ts)
240 {
241 const struct vdso_timestamp *vdso_ts = &vc->basetime[clk];
242 u32 seq;
243
244 do {
245 /*
246 * Open coded function vdso_read_begin() to handle
247 * VDSO_CLOCK_TIMENS. See comment in do_hres().
248 */
249 while ((seq = READ_ONCE(vc->seq)) & 1) {
250 if (IS_ENABLED(CONFIG_TIME_NS) &&
251 vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
252 return do_coarse_timens(vd, vc, clk, ts);
253 cpu_relax();
254 }
255 smp_rmb();
256
257 ts->tv_sec = vdso_ts->sec;
258 ts->tv_nsec = vdso_ts->nsec;
259 } while (unlikely(vdso_read_retry(vc, seq)));
260
261 return 0;
262 }
263
264 static __always_inline int
__cvdso_clock_gettime_common(const struct vdso_time_data * vd,clockid_t clock,struct __kernel_timespec * ts)265 __cvdso_clock_gettime_common(const struct vdso_time_data *vd, clockid_t clock,
266 struct __kernel_timespec *ts)
267 {
268 const struct vdso_clock *vc = vd->clock_data;
269 u32 msk;
270
271 /* Check for negative values or invalid clocks */
272 if (unlikely((u32) clock >= MAX_CLOCKS))
273 return -1;
274
275 /*
276 * Convert the clockid to a bitmask and use it to check which
277 * clocks are handled in the VDSO directly.
278 */
279 msk = 1U << clock;
280 if (likely(msk & VDSO_HRES))
281 vc = &vc[CS_HRES_COARSE];
282 else if (msk & VDSO_COARSE)
283 return do_coarse(vd, &vc[CS_HRES_COARSE], clock, ts);
284 else if (msk & VDSO_RAW)
285 vc = &vc[CS_RAW];
286 else
287 return -1;
288
289 return do_hres(vd, vc, clock, ts);
290 }
291
292 static __maybe_unused int
__cvdso_clock_gettime_data(const struct vdso_time_data * vd,clockid_t clock,struct __kernel_timespec * ts)293 __cvdso_clock_gettime_data(const struct vdso_time_data *vd, clockid_t clock,
294 struct __kernel_timespec *ts)
295 {
296 int ret = __cvdso_clock_gettime_common(vd, clock, ts);
297
298 if (unlikely(ret))
299 return clock_gettime_fallback(clock, ts);
300 return 0;
301 }
302
303 static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock,struct __kernel_timespec * ts)304 __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
305 {
306 return __cvdso_clock_gettime_data(__arch_get_vdso_u_time_data(), clock, ts);
307 }
308
309 #ifdef BUILD_VDSO32
310 static __maybe_unused int
__cvdso_clock_gettime32_data(const struct vdso_time_data * vd,clockid_t clock,struct old_timespec32 * res)311 __cvdso_clock_gettime32_data(const struct vdso_time_data *vd, clockid_t clock,
312 struct old_timespec32 *res)
313 {
314 struct __kernel_timespec ts;
315 int ret;
316
317 ret = __cvdso_clock_gettime_common(vd, clock, &ts);
318
319 if (unlikely(ret))
320 return clock_gettime32_fallback(clock, res);
321
322 /* For ret == 0 */
323 res->tv_sec = ts.tv_sec;
324 res->tv_nsec = ts.tv_nsec;
325
326 return ret;
327 }
328
329 static __maybe_unused int
__cvdso_clock_gettime32(clockid_t clock,struct old_timespec32 * res)330 __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
331 {
332 return __cvdso_clock_gettime32_data(__arch_get_vdso_u_time_data(), clock, res);
333 }
334 #endif /* BUILD_VDSO32 */
335
336 static __maybe_unused int
__cvdso_gettimeofday_data(const struct vdso_time_data * vd,struct __kernel_old_timeval * tv,struct timezone * tz)337 __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
338 struct __kernel_old_timeval *tv, struct timezone *tz)
339 {
340 const struct vdso_clock *vc = vd->clock_data;
341
342 if (likely(tv != NULL)) {
343 struct __kernel_timespec ts;
344
345 if (do_hres(vd, &vc[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
346 return gettimeofday_fallback(tv, tz);
347
348 tv->tv_sec = ts.tv_sec;
349 tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
350 }
351
352 if (unlikely(tz != NULL)) {
353 if (IS_ENABLED(CONFIG_TIME_NS) &&
354 vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
355 vd = __arch_get_vdso_u_timens_data(vd);
356
357 tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
358 tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
359 }
360
361 return 0;
362 }
363
364 static __maybe_unused int
__cvdso_gettimeofday(struct __kernel_old_timeval * tv,struct timezone * tz)365 __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
366 {
367 return __cvdso_gettimeofday_data(__arch_get_vdso_u_time_data(), tv, tz);
368 }
369
370 #ifdef VDSO_HAS_TIME
371 static __maybe_unused __kernel_old_time_t
__cvdso_time_data(const struct vdso_time_data * vd,__kernel_old_time_t * time)372 __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time)
373 {
374 const struct vdso_clock *vc = vd->clock_data;
375 __kernel_old_time_t t;
376
377 if (IS_ENABLED(CONFIG_TIME_NS) &&
378 vc->clock_mode == VDSO_CLOCKMODE_TIMENS) {
379 vd = __arch_get_vdso_u_timens_data(vd);
380 vc = vd->clock_data;
381 }
382
383 t = READ_ONCE(vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
384
385 if (time)
386 *time = t;
387
388 return t;
389 }
390
__cvdso_time(__kernel_old_time_t * time)391 static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
392 {
393 return __cvdso_time_data(__arch_get_vdso_u_time_data(), time);
394 }
395 #endif /* VDSO_HAS_TIME */
396
397 #ifdef VDSO_HAS_CLOCK_GETRES
398 static __maybe_unused
__cvdso_clock_getres_common(const struct vdso_time_data * vd,clockid_t clock,struct __kernel_timespec * res)399 int __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock,
400 struct __kernel_timespec *res)
401 {
402 const struct vdso_clock *vc = vd->clock_data;
403 u32 msk;
404 u64 ns;
405
406 /* Check for negative values or invalid clocks */
407 if (unlikely((u32) clock >= MAX_CLOCKS))
408 return -1;
409
410 if (IS_ENABLED(CONFIG_TIME_NS) &&
411 vc->clock_mode == VDSO_CLOCKMODE_TIMENS)
412 vd = __arch_get_vdso_u_timens_data(vd);
413
414 /*
415 * Convert the clockid to a bitmask and use it to check which
416 * clocks are handled in the VDSO directly.
417 */
418 msk = 1U << clock;
419 if (msk & (VDSO_HRES | VDSO_RAW)) {
420 /*
421 * Preserves the behaviour of posix_get_hrtimer_res().
422 */
423 ns = READ_ONCE(vd->hrtimer_res);
424 } else if (msk & VDSO_COARSE) {
425 /*
426 * Preserves the behaviour of posix_get_coarse_res().
427 */
428 ns = LOW_RES_NSEC;
429 } else {
430 return -1;
431 }
432
433 if (likely(res)) {
434 res->tv_sec = 0;
435 res->tv_nsec = ns;
436 }
437 return 0;
438 }
439
440 static __maybe_unused
__cvdso_clock_getres_data(const struct vdso_time_data * vd,clockid_t clock,struct __kernel_timespec * res)441 int __cvdso_clock_getres_data(const struct vdso_time_data *vd, clockid_t clock,
442 struct __kernel_timespec *res)
443 {
444 int ret = __cvdso_clock_getres_common(vd, clock, res);
445
446 if (unlikely(ret))
447 return clock_getres_fallback(clock, res);
448 return 0;
449 }
450
451 static __maybe_unused
__cvdso_clock_getres(clockid_t clock,struct __kernel_timespec * res)452 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
453 {
454 return __cvdso_clock_getres_data(__arch_get_vdso_u_time_data(), clock, res);
455 }
456
457 #ifdef BUILD_VDSO32
458 static __maybe_unused int
__cvdso_clock_getres_time32_data(const struct vdso_time_data * vd,clockid_t clock,struct old_timespec32 * res)459 __cvdso_clock_getres_time32_data(const struct vdso_time_data *vd, clockid_t clock,
460 struct old_timespec32 *res)
461 {
462 struct __kernel_timespec ts;
463 int ret;
464
465 ret = __cvdso_clock_getres_common(vd, clock, &ts);
466
467 if (unlikely(ret))
468 return clock_getres32_fallback(clock, res);
469
470 if (likely(res)) {
471 res->tv_sec = ts.tv_sec;
472 res->tv_nsec = ts.tv_nsec;
473 }
474 return ret;
475 }
476
477 static __maybe_unused int
__cvdso_clock_getres_time32(clockid_t clock,struct old_timespec32 * res)478 __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
479 {
480 return __cvdso_clock_getres_time32_data(__arch_get_vdso_u_time_data(),
481 clock, res);
482 }
483 #endif /* BUILD_VDSO32 */
484 #endif /* VDSO_HAS_CLOCK_GETRES */
485