1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2011 The University of Melbourne 5 * All rights reserved. 6 * 7 * This software was developed by Julien Ridoux at the University of Melbourne 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_ffclock.h" 36 37 #include <sys/param.h> 38 #include <sys/bus.h> 39 #include <sys/kernel.h> 40 #include <sys/lock.h> 41 #include <sys/module.h> 42 #include <sys/mutex.h> 43 #include <sys/priv.h> 44 #include <sys/proc.h> 45 #include <sys/sbuf.h> 46 #include <sys/sysent.h> 47 #include <sys/sysproto.h> 48 #include <sys/sysctl.h> 49 #include <sys/systm.h> 50 #include <sys/timeffc.h> 51 52 #ifdef FFCLOCK 53 54 FEATURE(ffclock, "Feed-forward clock support"); 55 56 extern struct ffclock_estimate ffclock_estimate; 57 extern struct bintime ffclock_boottime; 58 extern int8_t ffclock_updated; 59 extern struct mtx ffclock_mtx; 60 61 /* 62 * Feed-forward clock absolute time. This should be the preferred way to read 63 * the feed-forward clock for "wall-clock" type time. The flags allow to compose 64 * various flavours of absolute time (e.g. with or without leap seconds taken 65 * into account). If valid pointers are provided, the ffcounter value and an 66 * upper bound on clock error associated with the bintime are provided. 67 * NOTE: use ffclock_convert_abs() to differ the conversion of a ffcounter value 68 * read earlier. 69 */ 70 void 71 ffclock_abstime(ffcounter *ffcount, struct bintime *bt, 72 struct bintime *error_bound, uint32_t flags) 73 { 74 struct ffclock_estimate cest; 75 ffcounter ffc; 76 ffcounter update_ffcount; 77 ffcounter ffdelta_error; 78 79 /* Get counter and corresponding time. */ 80 if ((flags & FFCLOCK_FAST) == FFCLOCK_FAST) 81 ffclock_last_tick(&ffc, bt, flags); 82 else { 83 ffclock_read_counter(&ffc); 84 ffclock_convert_abs(ffc, bt, flags); 85 } 86 87 /* Current ffclock estimate, use update_ffcount as generation number. */ 88 do { 89 update_ffcount = ffclock_estimate.update_ffcount; 90 bcopy(&ffclock_estimate, &cest, sizeof(struct ffclock_estimate)); 91 } while (update_ffcount != ffclock_estimate.update_ffcount); 92 93 /* 94 * Leap second adjustment. Total as seen by synchronisation algorithm 95 * since it started. cest.leapsec_next is the ffcounter prediction of 96 * when the next leapsecond occurs. 97 */ 98 if ((flags & FFCLOCK_LEAPSEC) == FFCLOCK_LEAPSEC) { 99 bt->sec -= cest.leapsec_total; 100 if (ffc > cest.leapsec_next) 101 bt->sec -= cest.leapsec; 102 } 103 104 /* Boot time adjustment, for uptime/monotonic clocks. */ 105 if ((flags & FFCLOCK_UPTIME) == FFCLOCK_UPTIME) { 106 bintime_sub(bt, &ffclock_boottime); 107 } 108 109 /* Compute error bound if a valid pointer has been passed. */ 110 if (error_bound) { 111 ffdelta_error = ffc - cest.update_ffcount; 112 ffclock_convert_diff(ffdelta_error, error_bound); 113 /* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s] */ 114 bintime_mul(error_bound, cest.errb_rate * 115 (uint64_t)18446744073709LL); 116 /* 18446744073 = int(2^64 / 1e9), since err_abs in [ns] */ 117 bintime_addx(error_bound, cest.errb_abs * 118 (uint64_t)18446744073LL); 119 } 120 121 if (ffcount) 122 *ffcount = ffc; 123 } 124 125 /* 126 * Feed-forward difference clock. This should be the preferred way to convert a 127 * time interval in ffcounter values into a time interval in seconds. If a valid 128 * pointer is passed, an upper bound on the error in computing the time interval 129 * in seconds is provided. 130 */ 131 void 132 ffclock_difftime(ffcounter ffdelta, struct bintime *bt, 133 struct bintime *error_bound) 134 { 135 ffcounter update_ffcount; 136 uint32_t err_rate; 137 138 ffclock_convert_diff(ffdelta, bt); 139 140 if (error_bound) { 141 do { 142 update_ffcount = ffclock_estimate.update_ffcount; 143 err_rate = ffclock_estimate.errb_rate; 144 } while (update_ffcount != ffclock_estimate.update_ffcount); 145 146 ffclock_convert_diff(ffdelta, error_bound); 147 /* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s] */ 148 bintime_mul(error_bound, err_rate * (uint64_t)18446744073709LL); 149 } 150 } 151 152 /* 153 * Create a new kern.sysclock sysctl node, which will be home to some generic 154 * sysclock configuration variables. Feed-forward clock specific variables will 155 * live under the ffclock subnode. 156 */ 157 158 SYSCTL_NODE(_kern, OID_AUTO, sysclock, CTLFLAG_RW, 0, 159 "System clock related configuration"); 160 SYSCTL_NODE(_kern_sysclock, OID_AUTO, ffclock, CTLFLAG_RW, 0, 161 "Feed-forward clock configuration"); 162 163 static char *sysclocks[] = {"feedback", "feed-forward"}; 164 #define MAX_SYSCLOCK_NAME_LEN 16 165 #define NUM_SYSCLOCKS nitems(sysclocks) 166 167 static int ffclock_version = 2; 168 SYSCTL_INT(_kern_sysclock_ffclock, OID_AUTO, version, CTLFLAG_RD, 169 &ffclock_version, 0, "Feed-forward clock kernel version"); 170 171 /* List available sysclocks. */ 172 static int 173 sysctl_kern_sysclock_available(SYSCTL_HANDLER_ARGS) 174 { 175 struct sbuf *s; 176 int clk, error; 177 178 s = sbuf_new_for_sysctl(NULL, NULL, 179 MAX_SYSCLOCK_NAME_LEN * NUM_SYSCLOCKS, req); 180 if (s == NULL) 181 return (ENOMEM); 182 183 for (clk = 0; clk < NUM_SYSCLOCKS; clk++) { 184 sbuf_cat(s, sysclocks[clk]); 185 if (clk + 1 < NUM_SYSCLOCKS) 186 sbuf_cat(s, " "); 187 } 188 error = sbuf_finish(s); 189 sbuf_delete(s); 190 191 return (error); 192 } 193 194 SYSCTL_PROC(_kern_sysclock, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 195 0, 0, sysctl_kern_sysclock_available, "A", 196 "List of available system clocks"); 197 198 /* 199 * Return the name of the active system clock if read, or attempt to change 200 * the active system clock to the user specified one if written to. The active 201 * system clock is read when calling any of the [get]{bin,nano,micro}[up]time() 202 * functions. 203 */ 204 static int 205 sysctl_kern_sysclock_active(SYSCTL_HANDLER_ARGS) 206 { 207 char newclock[MAX_SYSCLOCK_NAME_LEN]; 208 int error; 209 int clk; 210 211 /* Return the name of the current active sysclock. */ 212 strlcpy(newclock, sysclocks[sysclock_active], sizeof(newclock)); 213 error = sysctl_handle_string(oidp, newclock, sizeof(newclock), req); 214 215 /* Check for error or no change */ 216 if (error != 0 || req->newptr == NULL) 217 goto done; 218 219 /* Change the active sysclock to the user specified one: */ 220 error = EINVAL; 221 for (clk = 0; clk < NUM_SYSCLOCKS; clk++) { 222 if (strncmp(newclock, sysclocks[clk], 223 MAX_SYSCLOCK_NAME_LEN - 1)) { 224 continue; 225 } 226 sysclock_active = clk; 227 error = 0; 228 break; 229 } 230 done: 231 return (error); 232 } 233 234 SYSCTL_PROC(_kern_sysclock, OID_AUTO, active, CTLTYPE_STRING | CTLFLAG_RW, 235 0, 0, sysctl_kern_sysclock_active, "A", 236 "Name of the active system clock which is currently serving time"); 237 238 static int sysctl_kern_ffclock_ffcounter_bypass = 0; 239 SYSCTL_INT(_kern_sysclock_ffclock, OID_AUTO, ffcounter_bypass, CTLFLAG_RW, 240 &sysctl_kern_ffclock_ffcounter_bypass, 0, 241 "Use reliable hardware timecounter as the feed-forward counter"); 242 243 /* 244 * High level functions to access the Feed-Forward Clock. 245 */ 246 void 247 ffclock_bintime(struct bintime *bt) 248 { 249 250 ffclock_abstime(NULL, bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC); 251 } 252 253 void 254 ffclock_nanotime(struct timespec *tsp) 255 { 256 struct bintime bt; 257 258 ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC); 259 bintime2timespec(&bt, tsp); 260 } 261 262 void 263 ffclock_microtime(struct timeval *tvp) 264 { 265 struct bintime bt; 266 267 ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC); 268 bintime2timeval(&bt, tvp); 269 } 270 271 void 272 ffclock_getbintime(struct bintime *bt) 273 { 274 275 ffclock_abstime(NULL, bt, NULL, 276 FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST); 277 } 278 279 void 280 ffclock_getnanotime(struct timespec *tsp) 281 { 282 struct bintime bt; 283 284 ffclock_abstime(NULL, &bt, NULL, 285 FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST); 286 bintime2timespec(&bt, tsp); 287 } 288 289 void 290 ffclock_getmicrotime(struct timeval *tvp) 291 { 292 struct bintime bt; 293 294 ffclock_abstime(NULL, &bt, NULL, 295 FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST); 296 bintime2timeval(&bt, tvp); 297 } 298 299 void 300 ffclock_binuptime(struct bintime *bt) 301 { 302 303 ffclock_abstime(NULL, bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME); 304 } 305 306 void 307 ffclock_nanouptime(struct timespec *tsp) 308 { 309 struct bintime bt; 310 311 ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME); 312 bintime2timespec(&bt, tsp); 313 } 314 315 void 316 ffclock_microuptime(struct timeval *tvp) 317 { 318 struct bintime bt; 319 320 ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME); 321 bintime2timeval(&bt, tvp); 322 } 323 324 void 325 ffclock_getbinuptime(struct bintime *bt) 326 { 327 328 ffclock_abstime(NULL, bt, NULL, 329 FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST); 330 } 331 332 void 333 ffclock_getnanouptime(struct timespec *tsp) 334 { 335 struct bintime bt; 336 337 ffclock_abstime(NULL, &bt, NULL, 338 FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST); 339 bintime2timespec(&bt, tsp); 340 } 341 342 void 343 ffclock_getmicrouptime(struct timeval *tvp) 344 { 345 struct bintime bt; 346 347 ffclock_abstime(NULL, &bt, NULL, 348 FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST); 349 bintime2timeval(&bt, tvp); 350 } 351 352 void 353 ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt) 354 { 355 356 ffclock_difftime(ffdelta, bt, NULL); 357 } 358 359 void 360 ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp) 361 { 362 struct bintime bt; 363 364 ffclock_difftime(ffdelta, &bt, NULL); 365 bintime2timespec(&bt, tsp); 366 } 367 368 void 369 ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp) 370 { 371 struct bintime bt; 372 373 ffclock_difftime(ffdelta, &bt, NULL); 374 bintime2timeval(&bt, tvp); 375 } 376 377 /* 378 * System call allowing userland applications to retrieve the current value of 379 * the Feed-Forward Clock counter. 380 */ 381 #ifndef _SYS_SYSPROTO_H_ 382 struct ffclock_getcounter_args { 383 ffcounter *ffcount; 384 }; 385 #endif 386 /* ARGSUSED */ 387 int 388 sys_ffclock_getcounter(struct thread *td, struct ffclock_getcounter_args *uap) 389 { 390 ffcounter ffcount; 391 int error; 392 393 ffcount = 0; 394 ffclock_read_counter(&ffcount); 395 if (ffcount == 0) 396 return (EAGAIN); 397 error = copyout(&ffcount, uap->ffcount, sizeof(ffcounter)); 398 399 return (error); 400 } 401 402 /* 403 * System call allowing the synchronisation daemon to push new feed-foward clock 404 * estimates to the kernel. Acquire ffclock_mtx to prevent concurrent updates 405 * and ensure data consistency. 406 * NOTE: ffclock_updated signals the fftimehands that new estimates are 407 * available. The updated estimates are picked up by the fftimehands on next 408 * tick, which could take as long as 1/hz seconds (if ticks are not missed). 409 */ 410 #ifndef _SYS_SYSPROTO_H_ 411 struct ffclock_setestimate_args { 412 struct ffclock_estimate *cest; 413 }; 414 #endif 415 /* ARGSUSED */ 416 int 417 sys_ffclock_setestimate(struct thread *td, struct ffclock_setestimate_args *uap) 418 { 419 struct ffclock_estimate cest; 420 int error; 421 422 /* Reuse of PRIV_CLOCK_SETTIME. */ 423 if ((error = priv_check(td, PRIV_CLOCK_SETTIME)) != 0) 424 return (error); 425 426 if ((error = copyin(uap->cest, &cest, sizeof(struct ffclock_estimate))) 427 != 0) 428 return (error); 429 430 mtx_lock(&ffclock_mtx); 431 memcpy(&ffclock_estimate, &cest, sizeof(struct ffclock_estimate)); 432 ffclock_updated++; 433 mtx_unlock(&ffclock_mtx); 434 return (error); 435 } 436 437 /* 438 * System call allowing userland applications to retrieve the clock estimates 439 * stored within the kernel. It is useful to kickstart the synchronisation 440 * daemon with the kernel's knowledge of hardware timecounter. 441 */ 442 #ifndef _SYS_SYSPROTO_H_ 443 struct ffclock_getestimate_args { 444 struct ffclock_estimate *cest; 445 }; 446 #endif 447 /* ARGSUSED */ 448 int 449 sys_ffclock_getestimate(struct thread *td, struct ffclock_getestimate_args *uap) 450 { 451 struct ffclock_estimate cest; 452 int error; 453 454 mtx_lock(&ffclock_mtx); 455 memcpy(&cest, &ffclock_estimate, sizeof(struct ffclock_estimate)); 456 mtx_unlock(&ffclock_mtx); 457 error = copyout(&cest, uap->cest, sizeof(struct ffclock_estimate)); 458 return (error); 459 } 460 461 #else /* !FFCLOCK */ 462 463 int 464 sys_ffclock_getcounter(struct thread *td, struct ffclock_getcounter_args *uap) 465 { 466 467 return (ENOSYS); 468 } 469 470 int 471 sys_ffclock_setestimate(struct thread *td, struct ffclock_setestimate_args *uap) 472 { 473 474 return (ENOSYS); 475 } 476 477 int 478 sys_ffclock_getestimate(struct thread *td, struct ffclock_getestimate_args *uap) 479 { 480 481 return (ENOSYS); 482 } 483 484 #endif /* FFCLOCK */ 485