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sys/x86/x86/tsc.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 1998-2003 Poul-Henning Kamp 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include "opt_clock.h" 33 34 #include <sys/param.h> 35 #include <sys/systm.h> 36 #include <sys/bus.h> 37 #include <sys/cpu.h> 38 #include <sys/eventhandler.h> 39 #include <sys/limits.h> 40 #include <sys/malloc.h> 41 #include <sys/proc.h> 42 #include <sys/sched.h> 43 #include <sys/sysctl.h> 44 #include <sys/time.h> 45 #include <sys/timetc.h> 46 #include <sys/kernel.h> 47 #include <sys/smp.h> 48 #include <sys/vdso.h> 49 #include <machine/clock.h> 50 #include <machine/cputypes.h> 51 #include <machine/fpu.h> 52 #include <machine/md_var.h> 53 #include <machine/specialreg.h> 54 #include <x86/vmware.h> 55 #include <dev/acpica/acpi_hpet.h> 56 #include <contrib/dev/acpica/include/acpi.h> 57 58 #include "cpufreq_if.h" 59 60 uint64_t tsc_freq; 61 int tsc_is_invariant; 62 int tsc_perf_stat; 63 static int tsc_early_calib_exact; 64 65 static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag; 66 67 SYSCTL_INT(_kern_timecounter, OID_AUTO, invariant_tsc, CTLFLAG_RDTUN, 68 &tsc_is_invariant, 0, "Indicates whether the TSC is P-state invariant"); 69 70 #ifdef SMP 71 int smp_tsc; 72 SYSCTL_INT(_kern_timecounter, OID_AUTO, smp_tsc, CTLFLAG_RDTUN, &smp_tsc, 0, 73 "Indicates whether the TSC is safe to use in SMP mode"); 74 75 int smp_tsc_adjust = 0; 76 SYSCTL_INT(_kern_timecounter, OID_AUTO, smp_tsc_adjust, CTLFLAG_RDTUN, 77 &smp_tsc_adjust, 0, "Try to adjust TSC on APs to match BSP"); 78 #endif 79 80 static int tsc_shift = 1; 81 SYSCTL_INT(_kern_timecounter, OID_AUTO, tsc_shift, CTLFLAG_RDTUN, 82 &tsc_shift, 0, "Shift to pre-apply for the maximum TSC frequency"); 83 84 static int tsc_disabled; 85 SYSCTL_INT(_machdep, OID_AUTO, disable_tsc, CTLFLAG_RDTUN, &tsc_disabled, 0, 86 "Disable x86 Time Stamp Counter"); 87 88 static int tsc_skip_calibration; 89 SYSCTL_INT(_machdep, OID_AUTO, disable_tsc_calibration, CTLFLAG_RDTUN, 90 &tsc_skip_calibration, 0, 91 "Disable early TSC frequency calibration"); 92 93 static void tsc_freq_changed(void *arg, const struct cf_level *level, 94 int status); 95 static void tsc_freq_changing(void *arg, const struct cf_level *level, 96 int *status); 97 static u_int tsc_get_timecount(struct timecounter *tc); 98 static inline u_int tsc_get_timecount_low(struct timecounter *tc); 99 static u_int tsc_get_timecount_lfence(struct timecounter *tc); 100 static u_int tsc_get_timecount_low_lfence(struct timecounter *tc); 101 static u_int tsc_get_timecount_mfence(struct timecounter *tc); 102 static u_int tsc_get_timecount_low_mfence(struct timecounter *tc); 103 static u_int tscp_get_timecount(struct timecounter *tc); 104 static u_int tscp_get_timecount_low(struct timecounter *tc); 105 static void tsc_levels_changed(void *arg, int unit); 106 static uint32_t x86_tsc_vdso_timehands(struct vdso_timehands *vdso_th, 107 struct timecounter *tc); 108 #ifdef COMPAT_FREEBSD32 109 static uint32_t x86_tsc_vdso_timehands32(struct vdso_timehands32 *vdso_th32, 110 struct timecounter *tc); 111 #endif 112 113 static struct timecounter tsc_timecounter = { 114 .tc_get_timecount = tsc_get_timecount, 115 .tc_counter_mask = ~0u, 116 .tc_name = "TSC", 117 .tc_quality = 800, /* adjusted in code */ 118 .tc_fill_vdso_timehands = x86_tsc_vdso_timehands, 119 #ifdef COMPAT_FREEBSD32 120 .tc_fill_vdso_timehands32 = x86_tsc_vdso_timehands32, 121 #endif 122 }; 123 124 static int 125 tsc_freq_cpuid_vm(void) 126 { 127 u_int regs[4]; 128 129 if (vm_guest == VM_GUEST_NO) 130 return (false); 131 if (hv_high < 0x40000010) 132 return (false); 133 do_cpuid(0x40000010, regs); 134 tsc_freq = (uint64_t)(regs[0]) * 1000; 135 tsc_early_calib_exact = 1; 136 return (true); 137 } 138 139 static void 140 tsc_freq_vmware(void) 141 { 142 u_int regs[4]; 143 144 vmware_hvcall(VMW_HVCMD_GETHZ, regs); 145 if (regs[1] != UINT_MAX) 146 tsc_freq = regs[0] | ((uint64_t)regs[1] << 32); 147 tsc_early_calib_exact = 1; 148 } 149 150 static void 151 tsc_freq_xen(void) 152 { 153 u_int regs[4]; 154 155 /* 156 * Must run *after* generic tsc_freq_cpuid_vm, so that when Xen is 157 * emulating Viridian support the Viridian leaf is used instead. 158 */ 159 KASSERT(hv_high >= 0x40000003, ("Invalid max hypervisor leaf on Xen")); 160 cpuid_count(0x40000003, 0, regs); 161 tsc_freq = (uint64_t)(regs[2]) * 1000; 162 tsc_early_calib_exact = 1; 163 } 164 165 /* 166 * Calculate TSC frequency using information from the CPUID leaf 0x15 'Time 167 * Stamp Counter and Nominal Core Crystal Clock'. If leaf 0x15 is not 168 * functional, as it is on Skylake/Kabylake, try 0x16 'Processor Frequency 169 * Information'. Leaf 0x16 is described in the SDM as informational only, but 170 * we can use this value until late calibration is complete. 171 */ 172 static bool 173 tsc_freq_cpuid(uint64_t *res) 174 { 175 u_int regs[4]; 176 177 if (cpu_high < 0x15) 178 return (false); 179 do_cpuid(0x15, regs); 180 if (regs[0] != 0 && regs[1] != 0 && regs[2] != 0) { 181 *res = (uint64_t)regs[2] * regs[1] / regs[0]; 182 return (true); 183 } 184 185 if (cpu_high < 0x16) 186 return (false); 187 do_cpuid(0x16, regs); 188 if (regs[0] != 0) { 189 *res = (uint64_t)regs[0] * 1000000; 190 return (true); 191 } 192 193 return (false); 194 } 195 196 static bool 197 tsc_freq_intel_brand(uint64_t *res) 198 { 199 char brand[48]; 200 u_int regs[4]; 201 uint64_t freq; 202 char *p; 203 u_int i; 204 205 /* 206 * Intel Processor Identification and the CPUID Instruction 207 * Application Note 485. 208 * http://www.intel.com/assets/pdf/appnote/241618.pdf 209 */ 210 if (cpu_exthigh >= 0x80000004) { 211 p = brand; 212 for (i = 0x80000002; i < 0x80000005; i++) { 213 do_cpuid(i, regs); 214 memcpy(p, regs, sizeof(regs)); 215 p += sizeof(regs); 216 } 217 p = NULL; 218 for (i = 0; i < sizeof(brand) - 1; i++) 219 if (brand[i] == 'H' && brand[i + 1] == 'z') 220 p = brand + i; 221 if (p != NULL) { 222 p -= 5; 223 switch (p[4]) { 224 case 'M': 225 i = 1; 226 break; 227 case 'G': 228 i = 1000; 229 break; 230 case 'T': 231 i = 1000000; 232 break; 233 default: 234 return (false); 235 } 236 #define C2D(c) ((c) - '') 237 if (p[1] == '.') { 238 freq = C2D(p[0]) * 1000; 239 freq += C2D(p[2]) * 100; 240 freq += C2D(p[3]) * 10; 241 freq *= i * 1000; 242 } else { 243 freq = C2D(p[0]) * 1000; 244 freq += C2D(p[1]) * 100; 245 freq += C2D(p[2]) * 10; 246 freq += C2D(p[3]); 247 freq *= i * 1000000; 248 } 249 #undef C2D 250 *res = freq; 251 return (true); 252 } 253 } 254 return (false); 255 } 256 257 static void 258 tsc_freq_tc(uint64_t *res) 259 { 260 uint64_t tsc1, tsc2; 261 int64_t overhead; 262 int count, i; 263 264 overhead = 0; 265 for (i = 0, count = 8; i < count; i++) { 266 tsc1 = rdtsc_ordered(); 267 DELAY(0); 268 tsc2 = rdtsc_ordered(); 269 if (i > 0) 270 overhead += tsc2 - tsc1; 271 } 272 overhead /= count; 273 274 tsc1 = rdtsc_ordered(); 275 DELAY(100000); 276 tsc2 = rdtsc_ordered(); 277 tsc_freq = (tsc2 - tsc1 - overhead) * 10; 278 } 279 280 /* 281 * Try to determine the TSC frequency using CPUID or hypercalls. If successful, 282 * this lets use the TSC for early DELAY() calls instead of the 8254 timer, 283 * which may be unreliable or entirely absent on contemporary systems. However, 284 * avoid calibrating using the 8254 here so as to give hypervisors a chance to 285 * register a timecounter that can be used instead. 286 */ 287 static void 288 probe_tsc_freq_early(void) 289 { 290 #ifdef __i386__ 291 /* The TSC is known to be broken on certain CPUs. */ 292 switch (cpu_vendor_id) { 293 case CPU_VENDOR_AMD: 294 switch (cpu_id & 0xFF0) { 295 case 0x500: 296 /* K5 Model 0 */ 297 tsc_disabled = 1; 298 return; 299 } 300 break; 301 case CPU_VENDOR_CENTAUR: 302 switch (cpu_id & 0xff0) { 303 case 0x540: 304 /* 305 * http://www.centtech.com/c6_data_sheet.pdf 306 * 307 * I-12 RDTSC may return incoherent values in EDX:EAX 308 * I-13 RDTSC hangs when certain event counters are used 309 */ 310 tsc_disabled = 1; 311 return; 312 } 313 break; 314 case CPU_VENDOR_NSC: 315 switch (cpu_id & 0xff0) { 316 case 0x540: 317 if ((cpu_id & CPUID_STEPPING) == 0) { 318 tsc_disabled = 1; 319 return; 320 } 321 break; 322 } 323 break; 324 } 325 #endif 326 327 switch (cpu_vendor_id) { 328 case CPU_VENDOR_AMD: 329 case CPU_VENDOR_HYGON: 330 if ((amd_pminfo & AMDPM_TSC_INVARIANT) != 0 || 331 (vm_guest == VM_GUEST_NO && 332 CPUID_TO_FAMILY(cpu_id) >= 0x10)) 333 tsc_is_invariant = 1; 334 if (cpu_feature & CPUID_SSE2) { 335 tsc_timecounter.tc_get_timecount = 336 tsc_get_timecount_mfence; 337 } 338 break; 339 case CPU_VENDOR_INTEL: 340 if ((amd_pminfo & AMDPM_TSC_INVARIANT) != 0 || 341 (vm_guest == VM_GUEST_NO && 342 ((CPUID_TO_FAMILY(cpu_id) == 0x6 && 343 CPUID_TO_MODEL(cpu_id) >= 0xe) || 344 (CPUID_TO_FAMILY(cpu_id) == 0xf && 345 CPUID_TO_MODEL(cpu_id) >= 0x3)))) 346 tsc_is_invariant = 1; 347 if (cpu_feature & CPUID_SSE2) { 348 tsc_timecounter.tc_get_timecount = 349 tsc_get_timecount_lfence; 350 } 351 break; 352 case CPU_VENDOR_CENTAUR: 353 if (vm_guest == VM_GUEST_NO && 354 CPUID_TO_FAMILY(cpu_id) == 0x6 && 355 CPUID_TO_MODEL(cpu_id) >= 0xf && 356 (rdmsr(0x1203) & 0x100000000ULL) == 0) 357 tsc_is_invariant = 1; 358 if (cpu_feature & CPUID_SSE2) { 359 tsc_timecounter.tc_get_timecount = 360 tsc_get_timecount_lfence; 361 } 362 break; 363 } 364 365 if (tsc_freq_cpuid_vm()) { 366 if (bootverbose) 367 printf( 368 "Early TSC frequency %juHz derived from hypervisor CPUID\n", 369 (uintmax_t)tsc_freq); 370 } else if (vm_guest == VM_GUEST_VMWARE) { 371 tsc_freq_vmware(); 372 if (bootverbose) 373 printf( 374 "Early TSC frequency %juHz derived from VMWare hypercall\n", 375 (uintmax_t)tsc_freq); 376 } else if (vm_guest == VM_GUEST_XEN) { 377 tsc_freq_xen(); 378 if (bootverbose) 379 printf( 380 "Early TSC frequency %juHz derived from Xen CPUID\n", 381 (uintmax_t)tsc_freq); 382 } else if (tsc_freq_cpuid(&tsc_freq)) { 383 /* 384 * If possible, use the value obtained from CPUID as the initial 385 * frequency. This will be refined later during boot but is 386 * good enough for now. The 8254 PIT is not functional on some 387 * newer platforms anyway, so don't delay our boot for what 388 * might be a garbage result. Late calibration is required if 389 * the initial frequency was obtained from CPUID.16H, as the 390 * derived value may be off by as much as 1%. 391 */ 392 if (bootverbose) 393 printf("Early TSC frequency %juHz derived from CPUID\n", 394 (uintmax_t)tsc_freq); 395 } 396 } 397 398 /* 399 * If we were unable to determine the TSC frequency via CPU registers, try 400 * to calibrate against a known clock. 401 */ 402 static void 403 probe_tsc_freq_late(void) 404 { 405 if (tsc_freq != 0) 406 return; 407 408 if (tsc_skip_calibration) { 409 /* 410 * Try to parse the brand string to obtain the nominal TSC 411 * frequency. 412 */ 413 if (cpu_vendor_id == CPU_VENDOR_INTEL && 414 tsc_freq_intel_brand(&tsc_freq)) { 415 if (bootverbose) 416 printf( 417 "Early TSC frequency %juHz derived from brand string\n", 418 (uintmax_t)tsc_freq); 419 } else { 420 tsc_disabled = 1; 421 } 422 } else { 423 /* 424 * Calibrate against a timecounter or the 8254 PIT. This 425 * estimate will be refined later in tsc_calib(). 426 */ 427 tsc_freq_tc(&tsc_freq); 428 if (bootverbose) 429 printf( 430 "Early TSC frequency %juHz calibrated from 8254 PIT\n", 431 (uintmax_t)tsc_freq); 432 } 433 } 434 435 void 436 start_TSC(void) 437 { 438 if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled) 439 return; 440 441 probe_tsc_freq_late(); 442 443 if (cpu_power_ecx & CPUID_PERF_STAT) { 444 /* 445 * XXX Some emulators expose host CPUID without actual support 446 * for these MSRs. We must test whether they really work. 447 */ 448 wrmsr(MSR_MPERF, 0); 449 wrmsr(MSR_APERF, 0); 450 DELAY(10); 451 if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0) 452 tsc_perf_stat = 1; 453 } 454 455 /* 456 * Inform CPU accounting about our boot-time clock rate. This will 457 * be updated if someone loads a cpufreq driver after boot that 458 * discovers a new max frequency. 459 * 460 * The frequency may also be updated after late calibration is complete; 461 * however, we register the TSC as the ticker now to avoid switching 462 * counters after much of the kernel has already booted and potentially 463 * sampled the CPU clock. 464 */ 465 if (tsc_freq != 0) 466 set_cputicker(rdtsc, tsc_freq, !tsc_is_invariant); 467 468 if (tsc_is_invariant) 469 return; 470 471 /* Register to find out about changes in CPU frequency. */ 472 tsc_pre_tag = EVENTHANDLER_REGISTER(cpufreq_pre_change, 473 tsc_freq_changing, NULL, EVENTHANDLER_PRI_FIRST); 474 tsc_post_tag = EVENTHANDLER_REGISTER(cpufreq_post_change, 475 tsc_freq_changed, NULL, EVENTHANDLER_PRI_FIRST); 476 tsc_levels_tag = EVENTHANDLER_REGISTER(cpufreq_levels_changed, 477 tsc_levels_changed, NULL, EVENTHANDLER_PRI_ANY); 478 } 479 480 #ifdef SMP 481 482 /* 483 * RDTSC is not a serializing instruction, and does not drain 484 * instruction stream, so we need to drain the stream before executing 485 * it. It could be fixed by use of RDTSCP, except the instruction is 486 * not available everywhere. 487 * 488 * Use CPUID for draining in the boot-time SMP constistency test. The 489 * timecounters use MFENCE for AMD CPUs, and LFENCE for others (Intel 490 * and VIA) when SSE2 is present, and nothing on older machines which 491 * also do not issue RDTSC prematurely. There, testing for SSE2 and 492 * vendor is too cumbersome, and we learn about TSC presence from CPUID. 493 * 494 * Do not use do_cpuid(), since we do not need CPUID results, which 495 * have to be written into memory with do_cpuid(). 496 */ 497 #define TSC_READ(x) \ 498 static void \ 499 tsc_read_##x(void *arg) \ 500 { \ 501 uint64_t *tsc = arg; \ 502 u_int cpu = PCPU_GET(cpuid); \ 503 \ 504 __asm __volatile("cpuid" : : : "eax", "ebx", "ecx", "edx"); \ 505 tsc[cpu * 3 + x] = rdtsc(); \ 506 } 507 TSC_READ(0) 508 TSC_READ(1) 509 TSC_READ(2) 510 #undef TSC_READ 511 512 #define N 1000 513 514 static void 515 comp_smp_tsc(void *arg) 516 { 517 uint64_t *tsc; 518 int64_t d1, d2; 519 u_int cpu = PCPU_GET(cpuid); 520 u_int i, j, size; 521 522 size = (mp_maxid + 1) * 3; 523 for (i = 0, tsc = arg; i < N; i++, tsc += size) 524 CPU_FOREACH(j) { 525 if (j == cpu) 526 continue; 527 d1 = tsc[cpu * 3 + 1] - tsc[j * 3]; 528 d2 = tsc[cpu * 3 + 2] - tsc[j * 3 + 1]; 529 if (d1 <= 0 || d2 <= 0) { 530 smp_tsc = 0; 531 return; 532 } 533 } 534 } 535 536 static void 537 adj_smp_tsc(void *arg) 538 { 539 uint64_t *tsc; 540 int64_t d, min, max; 541 u_int cpu = PCPU_GET(cpuid); 542 u_int first, i, size; 543 544 first = CPU_FIRST(); 545 if (cpu == first) 546 return; 547 min = INT64_MIN; 548 max = INT64_MAX; 549 size = (mp_maxid + 1) * 3; 550 for (i = 0, tsc = arg; i < N; i++, tsc += size) { 551 d = tsc[first * 3] - tsc[cpu * 3 + 1]; 552 if (d > min) 553 min = d; 554 d = tsc[first * 3 + 1] - tsc[cpu * 3 + 2]; 555 if (d > min) 556 min = d; 557 d = tsc[first * 3 + 1] - tsc[cpu * 3]; 558 if (d < max) 559 max = d; 560 d = tsc[first * 3 + 2] - tsc[cpu * 3 + 1]; 561 if (d < max) 562 max = d; 563 } 564 if (min > max) 565 return; 566 d = min / 2 + max / 2; 567 __asm __volatile ( 568 "movl $0x10, %%ecx\n\t" 569 "rdmsr\n\t" 570 "addl %%edi, %%eax\n\t" 571 "adcl %%esi, %%edx\n\t" 572 "wrmsr\n" 573 : /* No output */ 574 : "D" ((uint32_t)d), "S" ((uint32_t)(d >> 32)) 575 : "ax", "cx", "dx", "cc" 576 ); 577 } 578 579 static int 580 test_tsc(int adj_max_count) 581 { 582 uint64_t *data, *tsc; 583 u_int i, size, adj; 584 585 if ((!smp_tsc && !tsc_is_invariant)) 586 return (-100); 587 /* 588 * Misbehavior of TSC under VirtualBox has been observed. In 589 * particular, threads doing small (~1 second) sleeps may miss their 590 * wakeup and hang around in sleep state, causing hangs on shutdown. 591 */ 592 if (vm_guest == VM_GUEST_VBOX) 593 return (0); 594 595 TSENTER(); 596 size = (mp_maxid + 1) * 3; 597 data = malloc(sizeof(*data) * size * N, M_TEMP, M_WAITOK); 598 adj = 0; 599 retry: 600 for (i = 0, tsc = data; i < N; i++, tsc += size) 601 smp_rendezvous(tsc_read_0, tsc_read_1, tsc_read_2, tsc); 602 smp_tsc = 1; /* XXX */ 603 smp_rendezvous(smp_no_rendezvous_barrier, comp_smp_tsc, 604 smp_no_rendezvous_barrier, data); 605 if (!smp_tsc && adj < adj_max_count) { 606 adj++; 607 smp_rendezvous(smp_no_rendezvous_barrier, adj_smp_tsc, 608 smp_no_rendezvous_barrier, data); 609 goto retry; 610 } 611 free(data, M_TEMP); 612 if (bootverbose) 613 printf("SMP: %sed TSC synchronization test%s\n", 614 smp_tsc ? "pass" : "fail", 615 adj > 0 ? " after adjustment" : ""); 616 TSEXIT(); 617 if (smp_tsc && tsc_is_invariant) { 618 switch (cpu_vendor_id) { 619 case CPU_VENDOR_AMD: 620 case CPU_VENDOR_HYGON: 621 /* 622 * Processor Programming Reference (PPR) for AMD 623 * Family 17h states that the TSC uses a common 624 * reference for all sockets, cores and threads. 625 */ 626 if (CPUID_TO_FAMILY(cpu_id) >= 0x17) 627 return (1000); 628 /* 629 * Starting with Family 15h processors, TSC clock 630 * source is in the north bridge. Check whether 631 * we have a single-socket/multi-core platform. 632 * XXX Need more work for complex cases. 633 */ 634 if (CPUID_TO_FAMILY(cpu_id) < 0x15 || 635 (amd_feature2 & AMDID2_CMP) == 0 || 636 smp_cpus > (cpu_procinfo2 & AMDID_CMP_CORES) + 1) 637 break; 638 return (1000); 639 case CPU_VENDOR_INTEL: 640 /* 641 * XXX Assume Intel platforms have synchronized TSCs. 642 */ 643 return (1000); 644 } 645 return (800); 646 } 647 return (-100); 648 } 649 650 #undef N 651 652 #endif /* SMP */ 653 654 static void 655 init_TSC_tc(void) 656 { 657 uint64_t max_freq; 658 int shift; 659 660 if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled) 661 return; 662 663 /* 664 * Limit timecounter frequency to fit in an int and prevent it from 665 * overflowing too fast. 666 */ 667 max_freq = UINT_MAX; 668 669 /* 670 * Intel CPUs without a C-state invariant TSC can stop the TSC 671 * in either C2 or C3. Disable use of C2 and C3 while using 672 * the TSC as the timecounter. The timecounter can be changed 673 * to enable C2 and C3. 674 * 675 * Note that the TSC is used as the cputicker for computing 676 * thread runtime regardless of the timecounter setting, so 677 * using an alternate timecounter and enabling C2 or C3 can 678 * result incorrect runtimes for kernel idle threads (but not 679 * for any non-idle threads). 680 */ 681 if (cpu_vendor_id == CPU_VENDOR_INTEL && 682 (amd_pminfo & AMDPM_TSC_INVARIANT) == 0) { 683 tsc_timecounter.tc_flags |= TC_FLAGS_C2STOP; 684 if (bootverbose) 685 printf("TSC timecounter disables C2 and C3.\n"); 686 } 687 688 /* 689 * We can not use the TSC in SMP mode unless the TSCs on all CPUs 690 * are synchronized. If the user is sure that the system has 691 * synchronized TSCs, set kern.timecounter.smp_tsc tunable to a 692 * non-zero value. The TSC seems unreliable in virtualized SMP 693 * environments, so it is set to a negative quality in those cases. 694 */ 695 #ifdef SMP 696 if (mp_ncpus > 1) 697 tsc_timecounter.tc_quality = test_tsc(smp_tsc_adjust); 698 else 699 #endif /* SMP */ 700 if (tsc_is_invariant) 701 tsc_timecounter.tc_quality = 1000; 702 max_freq >>= tsc_shift; 703 704 for (shift = 0; shift <= 31 && (tsc_freq >> shift) > max_freq; shift++) 705 ; 706 707 /* 708 * Timecounter implementation selection, top to bottom: 709 * - If RDTSCP is available, use RDTSCP. 710 * - If fence instructions are provided (SSE2), use LFENCE;RDTSC 711 * on Intel, and MFENCE;RDTSC on AMD. 712 * - For really old CPUs, just use RDTSC. 713 */ 714 if ((amd_feature & AMDID_RDTSCP) != 0) { 715 tsc_timecounter.tc_get_timecount = shift > 0 ? 716 tscp_get_timecount_low : tscp_get_timecount; 717 } else if ((cpu_feature & CPUID_SSE2) != 0 && mp_ncpus > 1) { 718 if (cpu_vendor_id == CPU_VENDOR_AMD || 719 cpu_vendor_id == CPU_VENDOR_HYGON) { 720 tsc_timecounter.tc_get_timecount = shift > 0 ? 721 tsc_get_timecount_low_mfence : 722 tsc_get_timecount_mfence; 723 } else { 724 tsc_timecounter.tc_get_timecount = shift > 0 ? 725 tsc_get_timecount_low_lfence : 726 tsc_get_timecount_lfence; 727 } 728 } else { 729 tsc_timecounter.tc_get_timecount = shift > 0 ? 730 tsc_get_timecount_low : tsc_get_timecount; 731 } 732 if (shift > 0) { 733 tsc_timecounter.tc_name = "TSC-low"; 734 if (bootverbose) 735 printf("TSC timecounter discards lower %d bit(s)\n", 736 shift); 737 } 738 if (tsc_freq != 0) { 739 tsc_timecounter.tc_frequency = tsc_freq >> shift; 740 tsc_timecounter.tc_priv = (void *)(intptr_t)shift; 741 742 /* 743 * Timecounter registration is deferred until after late 744 * calibration is finished. 745 */ 746 } 747 } 748 SYSINIT(tsc_tc, SI_SUB_SMP, SI_ORDER_ANY, init_TSC_tc, NULL); 749 750 static void 751 tsc_update_freq(uint64_t new_freq) 752 { 753 atomic_store_rel_64(&tsc_freq, new_freq); 754 atomic_store_rel_64(&tsc_timecounter.tc_frequency, 755 new_freq >> (int)(intptr_t)tsc_timecounter.tc_priv); 756 } 757 758 void 759 tsc_init(void) 760 { 761 if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled) 762 return; 763 764 probe_tsc_freq_early(); 765 } 766 767 /* 768 * Perform late calibration of the TSC frequency once ACPI-based timecounters 769 * are available. At this point timehands are not set up, so we read the 770 * highest-quality timecounter directly rather than using (s)binuptime(). 771 */ 772 void 773 tsc_calibrate(void) 774 { 775 uint64_t freq; 776 777 if (tsc_disabled) 778 return; 779 if (tsc_early_calib_exact) 780 goto calibrated; 781 782 fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX); 783 freq = clockcalib(rdtsc_ordered, "TSC"); 784 fpu_kern_leave(curthread, NULL); 785 tsc_update_freq(freq); 786 787 calibrated: 788 tc_init(&tsc_timecounter); 789 set_cputicker(rdtsc, tsc_freq, !tsc_is_invariant); 790 } 791 792 void 793 resume_TSC(void) 794 { 795 #ifdef SMP 796 int quality; 797 798 /* If TSC was not good on boot, it is unlikely to become good now. */ 799 if (tsc_timecounter.tc_quality < 0) 800 return; 801 /* Nothing to do with UP. */ 802 if (mp_ncpus < 2) 803 return; 804 805 /* 806 * If TSC was good, a single synchronization should be enough, 807 * but honour smp_tsc_adjust if it's set. 808 */ 809 quality = test_tsc(MAX(smp_tsc_adjust, 1)); 810 if (quality != tsc_timecounter.tc_quality) { 811 printf("TSC timecounter quality changed: %d -> %d\n", 812 tsc_timecounter.tc_quality, quality); 813 tsc_timecounter.tc_quality = quality; 814 } 815 #endif /* SMP */ 816 } 817 818 /* 819 * When cpufreq levels change, find out about the (new) max frequency. We 820 * use this to update CPU accounting in case it got a lower estimate at boot. 821 */ 822 static void 823 tsc_levels_changed(void *arg, int unit) 824 { 825 device_t cf_dev; 826 struct cf_level *levels; 827 int count, error; 828 uint64_t max_freq; 829 830 /* Only use values from the first CPU, assuming all are equal. */ 831 if (unit != 0) 832 return; 833 834 /* Find the appropriate cpufreq device instance. */ 835 cf_dev = devclass_get_device(devclass_find("cpufreq"), unit); 836 if (cf_dev == NULL) { 837 printf("tsc_levels_changed() called but no cpufreq device?\n"); 838 return; 839 } 840 841 /* Get settings from the device and find the max frequency. */ 842 count = 64; 843 levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT); 844 if (levels == NULL) 845 return; 846 error = CPUFREQ_LEVELS(cf_dev, levels, &count); 847 if (error == 0 && count != 0) { 848 max_freq = (uint64_t)levels[0].total_set.freq * 1000000; 849 set_cputicker(rdtsc, max_freq, true); 850 } else 851 printf("tsc_levels_changed: no max freq found\n"); 852 free(levels, M_TEMP); 853 } 854 855 /* 856 * If the TSC timecounter is in use, veto the pending change. It may be 857 * possible in the future to handle a dynamically-changing timecounter rate. 858 */ 859 static void 860 tsc_freq_changing(void *arg, const struct cf_level *level, int *status) 861 { 862 863 if (*status != 0 || timecounter != &tsc_timecounter) 864 return; 865 866 printf("timecounter TSC must not be in use when " 867 "changing frequencies; change denied\n"); 868 *status = EBUSY; 869 } 870 871 /* Update TSC freq with the value indicated by the caller. */ 872 static void 873 tsc_freq_changed(void *arg, const struct cf_level *level, int status) 874 { 875 uint64_t freq; 876 877 /* If there was an error during the transition, don't do anything. */ 878 if (tsc_disabled || status != 0) 879 return; 880 881 /* Total setting for this level gives the new frequency in MHz. */ 882 freq = (uint64_t)level->total_set.freq * 1000000; 883 tsc_update_freq(freq); 884 } 885 886 static int 887 sysctl_machdep_tsc_freq(SYSCTL_HANDLER_ARGS) 888 { 889 int error; 890 uint64_t freq; 891 892 freq = atomic_load_acq_64(&tsc_freq); 893 if (freq == 0) 894 return (EOPNOTSUPP); 895 error = sysctl_handle_64(oidp, &freq, 0, req); 896 if (error == 0 && req->newptr != NULL) 897 tsc_update_freq(freq); 898 return (error); 899 } 900 SYSCTL_PROC(_machdep, OID_AUTO, tsc_freq, 901 CTLTYPE_U64 | CTLFLAG_RW | CTLFLAG_MPSAFE, 902 0, 0, sysctl_machdep_tsc_freq, "QU", 903 "Time Stamp Counter frequency"); 904 905 static u_int 906 tsc_get_timecount(struct timecounter *tc __unused) 907 { 908 909 return (rdtsc32()); 910 } 911 912 static u_int 913 tscp_get_timecount(struct timecounter *tc __unused) 914 { 915 916 return (rdtscp32()); 917 } 918 919 static inline u_int 920 tsc_get_timecount_low(struct timecounter *tc) 921 { 922 uint32_t rv; 923 924 __asm __volatile("rdtsc; shrd %%cl, %%edx, %0" 925 : "=a" (rv) : "c" ((int)(intptr_t)tc->tc_priv) : "edx"); 926 return (rv); 927 } 928 929 static u_int 930 tscp_get_timecount_low(struct timecounter *tc) 931 { 932 uint32_t rv; 933 934 __asm __volatile("rdtscp; movl %1, %%ecx; shrd %%cl, %%edx, %0" 935 : "=&a" (rv) : "m" (tc->tc_priv) : "ecx", "edx"); 936 return (rv); 937 } 938 939 static u_int 940 tsc_get_timecount_lfence(struct timecounter *tc __unused) 941 { 942 943 lfence(); 944 return (rdtsc32()); 945 } 946 947 static u_int 948 tsc_get_timecount_low_lfence(struct timecounter *tc) 949 { 950 951 lfence(); 952 return (tsc_get_timecount_low(tc)); 953 } 954 955 static u_int 956 tsc_get_timecount_mfence(struct timecounter *tc __unused) 957 { 958 959 mfence(); 960 return (rdtsc32()); 961 } 962 963 static u_int 964 tsc_get_timecount_low_mfence(struct timecounter *tc) 965 { 966 967 mfence(); 968 return (tsc_get_timecount_low(tc)); 969 } 970 971 static uint32_t 972 x86_tsc_vdso_timehands(struct vdso_timehands *vdso_th, struct timecounter *tc) 973 { 974 975 vdso_th->th_algo = VDSO_TH_ALGO_X86_TSC; 976 vdso_th->th_x86_shift = (int)(intptr_t)tc->tc_priv; 977 vdso_th->th_x86_hpet_idx = 0xffffffff; 978 vdso_th->th_x86_pvc_last_systime = 0; 979 vdso_th->th_x86_pvc_stable_mask = 0; 980 bzero(vdso_th->th_res, sizeof(vdso_th->th_res)); 981 return (1); 982 } 983 984 #ifdef COMPAT_FREEBSD32 985 static uint32_t 986 x86_tsc_vdso_timehands32(struct vdso_timehands32 *vdso_th32, 987 struct timecounter *tc) 988 { 989 990 vdso_th32->th_algo = VDSO_TH_ALGO_X86_TSC; 991 vdso_th32->th_x86_shift = (int)(intptr_t)tc->tc_priv; 992 vdso_th32->th_x86_hpet_idx = 0xffffffff; 993 vdso_th32->th_x86_pvc_last_systime = 0; 994 vdso_th32->th_x86_pvc_stable_mask = 0; 995 bzero(vdso_th32->th_res, sizeof(vdso_th32->th_res)); 996 return (1); 997 } 998 #endif
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