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