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 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 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 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 */ 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 54 static inline bool __arch_vdso_hres_capable(void) 55 { 56 return true; 57 } 58 #endif 59 60 #ifndef vdso_clocksource_ok 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 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 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 85 bool 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 false; 107 108 cycles = __arch_get_hw_counter(vc->clock_mode, vd); 109 if (unlikely(!vdso_cycles_ok(cycles))) 110 return false; 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 true; 127 } 128 #else 129 static __always_inline 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 136 bool 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 false; 140 } 141 #endif 142 143 static __always_inline 144 bool 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 false; 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 false; 177 178 cycles = __arch_get_hw_counter(vc->clock_mode, vd); 179 if (unlikely(!vdso_cycles_ok(cycles))) 180 return false; 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 true; 193 } 194 195 #ifdef CONFIG_TIME_NS 196 static __always_inline 197 bool 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 true; 227 } 228 #else 229 static __always_inline 230 bool 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 false; 234 } 235 #endif 236 237 static __always_inline 238 bool 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 true; 262 } 263 264 static __always_inline bool 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 false; 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 false; 288 289 return do_hres(vd, vc, clock, ts); 290 } 291 292 static __maybe_unused int 293 __cvdso_clock_gettime_data(const struct vdso_time_data *vd, clockid_t clock, 294 struct __kernel_timespec *ts) 295 { 296 bool ok; 297 298 ok = __cvdso_clock_gettime_common(vd, clock, ts); 299 300 if (unlikely(!ok)) 301 return clock_gettime_fallback(clock, ts); 302 return 0; 303 } 304 305 static __maybe_unused int 306 __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts) 307 { 308 return __cvdso_clock_gettime_data(__arch_get_vdso_u_time_data(), clock, ts); 309 } 310 311 #ifdef BUILD_VDSO32 312 static __maybe_unused int 313 __cvdso_clock_gettime32_data(const struct vdso_time_data *vd, clockid_t clock, 314 struct old_timespec32 *res) 315 { 316 struct __kernel_timespec ts; 317 bool ok; 318 319 ok = __cvdso_clock_gettime_common(vd, clock, &ts); 320 321 if (unlikely(!ok)) 322 return clock_gettime32_fallback(clock, res); 323 324 /* For ok == true */ 325 res->tv_sec = ts.tv_sec; 326 res->tv_nsec = ts.tv_nsec; 327 328 return 0; 329 } 330 331 static __maybe_unused int 332 __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res) 333 { 334 return __cvdso_clock_gettime32_data(__arch_get_vdso_u_time_data(), clock, res); 335 } 336 #endif /* BUILD_VDSO32 */ 337 338 static __maybe_unused int 339 __cvdso_gettimeofday_data(const struct vdso_time_data *vd, 340 struct __kernel_old_timeval *tv, struct timezone *tz) 341 { 342 const struct vdso_clock *vc = vd->clock_data; 343 344 if (likely(tv != NULL)) { 345 struct __kernel_timespec ts; 346 347 if (!do_hres(vd, &vc[CS_HRES_COARSE], CLOCK_REALTIME, &ts)) 348 return gettimeofday_fallback(tv, tz); 349 350 tv->tv_sec = ts.tv_sec; 351 tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC; 352 } 353 354 if (unlikely(tz != NULL)) { 355 if (IS_ENABLED(CONFIG_TIME_NS) && 356 vc->clock_mode == VDSO_CLOCKMODE_TIMENS) 357 vd = __arch_get_vdso_u_timens_data(vd); 358 359 tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest; 360 tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime; 361 } 362 363 return 0; 364 } 365 366 static __maybe_unused int 367 __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) 368 { 369 return __cvdso_gettimeofday_data(__arch_get_vdso_u_time_data(), tv, tz); 370 } 371 372 #ifdef VDSO_HAS_TIME 373 static __maybe_unused __kernel_old_time_t 374 __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time) 375 { 376 const struct vdso_clock *vc = vd->clock_data; 377 __kernel_old_time_t t; 378 379 if (IS_ENABLED(CONFIG_TIME_NS) && 380 vc->clock_mode == VDSO_CLOCKMODE_TIMENS) { 381 vd = __arch_get_vdso_u_timens_data(vd); 382 vc = vd->clock_data; 383 } 384 385 t = READ_ONCE(vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec); 386 387 if (time) 388 *time = t; 389 390 return t; 391 } 392 393 static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time) 394 { 395 return __cvdso_time_data(__arch_get_vdso_u_time_data(), time); 396 } 397 #endif /* VDSO_HAS_TIME */ 398 399 #ifdef VDSO_HAS_CLOCK_GETRES 400 static __maybe_unused 401 bool __cvdso_clock_getres_common(const struct vdso_time_data *vd, clockid_t clock, 402 struct __kernel_timespec *res) 403 { 404 const struct vdso_clock *vc = vd->clock_data; 405 u32 msk; 406 u64 ns; 407 408 /* Check for negative values or invalid clocks */ 409 if (unlikely((u32) clock >= MAX_CLOCKS)) 410 return false; 411 412 if (IS_ENABLED(CONFIG_TIME_NS) && 413 vc->clock_mode == VDSO_CLOCKMODE_TIMENS) 414 vd = __arch_get_vdso_u_timens_data(vd); 415 416 /* 417 * Convert the clockid to a bitmask and use it to check which 418 * clocks are handled in the VDSO directly. 419 */ 420 msk = 1U << clock; 421 if (msk & (VDSO_HRES | VDSO_RAW)) { 422 /* 423 * Preserves the behaviour of posix_get_hrtimer_res(). 424 */ 425 ns = READ_ONCE(vd->hrtimer_res); 426 } else if (msk & VDSO_COARSE) { 427 /* 428 * Preserves the behaviour of posix_get_coarse_res(). 429 */ 430 ns = LOW_RES_NSEC; 431 } else { 432 return false; 433 } 434 435 if (likely(res)) { 436 res->tv_sec = 0; 437 res->tv_nsec = ns; 438 } 439 return true; 440 } 441 442 static __maybe_unused 443 int __cvdso_clock_getres_data(const struct vdso_time_data *vd, clockid_t clock, 444 struct __kernel_timespec *res) 445 { 446 bool ok; 447 448 ok = __cvdso_clock_getres_common(vd, clock, res); 449 450 if (unlikely(!ok)) 451 return clock_getres_fallback(clock, res); 452 return 0; 453 } 454 455 static __maybe_unused 456 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res) 457 { 458 return __cvdso_clock_getres_data(__arch_get_vdso_u_time_data(), clock, res); 459 } 460 461 #ifdef BUILD_VDSO32 462 static __maybe_unused int 463 __cvdso_clock_getres_time32_data(const struct vdso_time_data *vd, clockid_t clock, 464 struct old_timespec32 *res) 465 { 466 struct __kernel_timespec ts; 467 bool ok; 468 469 ok = __cvdso_clock_getres_common(vd, clock, &ts); 470 471 if (unlikely(!ok)) 472 return clock_getres32_fallback(clock, res); 473 474 if (likely(res)) { 475 res->tv_sec = ts.tv_sec; 476 res->tv_nsec = ts.tv_nsec; 477 } 478 return 0; 479 } 480 481 static __maybe_unused int 482 __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res) 483 { 484 return __cvdso_clock_getres_time32_data(__arch_get_vdso_u_time_data(), 485 clock, res); 486 } 487 #endif /* BUILD_VDSO32 */ 488 #endif /* VDSO_HAS_CLOCK_GETRES */ 489