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1#include <linux/perf_event.h>
2#include <linux/types.h>
3
4#include <asm/perf_event.h>
5#include <asm/msr.h>
6#include <asm/insn.h>
7
8#include "perf_event.h"
9
10enum {
11 LBR_FORMAT_32 = 0x00,
12 LBR_FORMAT_LIP = 0x01,
13 LBR_FORMAT_EIP = 0x02,
14 LBR_FORMAT_EIP_FLAGS = 0x03,
15};
16
17/*
18 * Intel LBR_SELECT bits
19 * Intel Vol3a, April 2011, Section 16.7 Table 16-10
20 *
21 * Hardware branch filter (not available on all CPUs)
22 */
23#define LBR_KERNEL_BIT 0 /* do not capture at ring0 */
24#define LBR_USER_BIT 1 /* do not capture at ring > 0 */
25#define LBR_JCC_BIT 2 /* do not capture conditional branches */
26#define LBR_REL_CALL_BIT 3 /* do not capture relative calls */
27#define LBR_IND_CALL_BIT 4 /* do not capture indirect calls */
28#define LBR_RETURN_BIT 5 /* do not capture near returns */
29#define LBR_IND_JMP_BIT 6 /* do not capture indirect jumps */
30#define LBR_REL_JMP_BIT 7 /* do not capture relative jumps */
31#define LBR_FAR_BIT 8 /* do not capture far branches */
32
33#define LBR_KERNEL (1 << LBR_KERNEL_BIT)
34#define LBR_USER (1 << LBR_USER_BIT)
35#define LBR_JCC (1 << LBR_JCC_BIT)
36#define LBR_REL_CALL (1 << LBR_REL_CALL_BIT)
37#define LBR_IND_CALL (1 << LBR_IND_CALL_BIT)
38#define LBR_RETURN (1 << LBR_RETURN_BIT)
39#define LBR_REL_JMP (1 << LBR_REL_JMP_BIT)
40#define LBR_IND_JMP (1 << LBR_IND_JMP_BIT)
41#define LBR_FAR (1 << LBR_FAR_BIT)
42
43#define LBR_PLM (LBR_KERNEL | LBR_USER)
44
45#define LBR_SEL_MASK 0x1ff /* valid bits in LBR_SELECT */
46#define LBR_NOT_SUPP -1 /* LBR filter not supported */
47#define LBR_IGN 0 /* ignored */
48
49#define LBR_ANY \
50 (LBR_JCC |\
51 LBR_REL_CALL |\
52 LBR_IND_CALL |\
53 LBR_RETURN |\
54 LBR_REL_JMP |\
55 LBR_IND_JMP |\
56 LBR_FAR)
57
58#define LBR_FROM_FLAG_MISPRED (1ULL << 63)
59
60#define for_each_branch_sample_type(x) \
61 for ((x) = PERF_SAMPLE_BRANCH_USER; \
62 (x) < PERF_SAMPLE_BRANCH_MAX; (x) <<= 1)
63
64/*
65 * x86control flow change classification
66 * x86control flow changes include branches, interrupts, traps, faults
67 */
68enum {
69 X86_BR_NONE = 0, /* unknown */
70
71 X86_BR_USER = 1 << 0, /* branch target is user */
72 X86_BR_KERNEL = 1 << 1, /* branch target is kernel */
73
74 X86_BR_CALL = 1 << 2, /* call */
75 X86_BR_RET = 1 << 3, /* return */
76 X86_BR_SYSCALL = 1 << 4, /* syscall */
77 X86_BR_SYSRET = 1 << 5, /* syscall return */
78 X86_BR_INT = 1 << 6, /* sw interrupt */
79 X86_BR_IRET = 1 << 7, /* return from interrupt */
80 X86_BR_JCC = 1 << 8, /* conditional */
81 X86_BR_JMP = 1 << 9, /* jump */
82 X86_BR_IRQ = 1 << 10,/* hw interrupt or trap or fault */
83 X86_BR_IND_CALL = 1 << 11,/* indirect calls */
84};
85
86#define X86_BR_PLM (X86_BR_USER | X86_BR_KERNEL)
87
88#define X86_BR_ANY \
89 (X86_BR_CALL |\
90 X86_BR_RET |\
91 X86_BR_SYSCALL |\
92 X86_BR_SYSRET |\
93 X86_BR_INT |\
94 X86_BR_IRET |\
95 X86_BR_JCC |\
96 X86_BR_JMP |\
97 X86_BR_IRQ |\
98 X86_BR_IND_CALL)
99
100#define X86_BR_ALL (X86_BR_PLM | X86_BR_ANY)
101
102#define X86_BR_ANY_CALL \
103 (X86_BR_CALL |\
104 X86_BR_IND_CALL |\
105 X86_BR_SYSCALL |\
106 X86_BR_IRQ |\
107 X86_BR_INT)
108
109static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc);
110
111/*
112 * We only support LBR implementations that have FREEZE_LBRS_ON_PMI
113 * otherwise it becomes near impossible to get a reliable stack.
114 */
115
116static void __intel_pmu_lbr_enable(void)
117{
118 u64 debugctl;
119 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
120
121 if (cpuc->lbr_sel)
122 wrmsrl(MSR_LBR_SELECT, cpuc->lbr_sel->config);
123
124 rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
125 debugctl |= (DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI);
126 wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
127}
128
129static void __intel_pmu_lbr_disable(void)
130{
131 u64 debugctl;
132
133 rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
134 debugctl &= ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI);
135 wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
136}
137
138static void intel_pmu_lbr_reset_32(void)
139{
140 int i;
141
142 for (i = 0; i < x86_pmu.lbr_nr; i++)
143 wrmsrl(x86_pmu.lbr_from + i, 0);
144}
145
146static void intel_pmu_lbr_reset_64(void)
147{
148 int i;
149
150 for (i = 0; i < x86_pmu.lbr_nr; i++) {
151 wrmsrl(x86_pmu.lbr_from + i, 0);
152 wrmsrl(x86_pmu.lbr_to + i, 0);
153 }
154}
155
156void intel_pmu_lbr_reset(void)
157{
158 if (!x86_pmu.lbr_nr)
159 return;
160
161 if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
162 intel_pmu_lbr_reset_32();
163 else
164 intel_pmu_lbr_reset_64();
165}
166
167void intel_pmu_lbr_enable(struct perf_event *event)
168{
169 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
170
171 if (!x86_pmu.lbr_nr)
172 return;
173
174 /*
175 * Reset the LBR stack if we changed task context to
176 * avoid data leaks.
177 */
178 if (event->ctx->task && cpuc->lbr_context != event->ctx) {
179 intel_pmu_lbr_reset();
180 cpuc->lbr_context = event->ctx;
181 }
182 cpuc->br_sel = event->hw.branch_reg.reg;
183
184 cpuc->lbr_users++;
185}
186
187void intel_pmu_lbr_disable(struct perf_event *event)
188{
189 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
190
191 if (!x86_pmu.lbr_nr)
192 return;
193
194 cpuc->lbr_users--;
195 WARN_ON_ONCE(cpuc->lbr_users < 0);
196
197 if (cpuc->enabled && !cpuc->lbr_users) {
198 __intel_pmu_lbr_disable();
199 /* avoid stale pointer */
200 cpuc->lbr_context = NULL;
201 }
202}
203
204void intel_pmu_lbr_enable_all(void)
205{
206 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
207
208 if (cpuc->lbr_users)
209 __intel_pmu_lbr_enable();
210}
211
212void intel_pmu_lbr_disable_all(void)
213{
214 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
215
216 if (cpuc->lbr_users)
217 __intel_pmu_lbr_disable();
218}
219
220/*
221 * TOS = most recently recorded branch
222 */
223static inline u64 intel_pmu_lbr_tos(void)
224{
225 u64 tos;
226
227 rdmsrl(x86_pmu.lbr_tos, tos);
228
229 return tos;
230}
231
232static void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc)
233{
234 unsigned long mask = x86_pmu.lbr_nr - 1;
235 u64 tos = intel_pmu_lbr_tos();
236 int i;
237
238 for (i = 0; i < x86_pmu.lbr_nr; i++) {
239 unsigned long lbr_idx = (tos - i) & mask;
240 union {
241 struct {
242 u32 from;
243 u32 to;
244 };
245 u64 lbr;
246 } msr_lastbranch;
247
248 rdmsrl(x86_pmu.lbr_from + lbr_idx, msr_lastbranch.lbr);
249
250 cpuc->lbr_entries[i].from = msr_lastbranch.from;
251 cpuc->lbr_entries[i].to = msr_lastbranch.to;
252 cpuc->lbr_entries[i].mispred = 0;
253 cpuc->lbr_entries[i].predicted = 0;
254 cpuc->lbr_entries[i].reserved = 0;
255 }
256 cpuc->lbr_stack.nr = i;
257}
258
259/*
260 * Due to lack of segmentation in Linux the effective address (offset)
261 * is the same as the linear address, allowing us to merge the LIP and EIP
262 * LBR formats.
263 */
264static void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc)
265{
266 unsigned long mask = x86_pmu.lbr_nr - 1;
267 int lbr_format = x86_pmu.intel_cap.lbr_format;
268 u64 tos = intel_pmu_lbr_tos();
269 int i;
270
271 for (i = 0; i < x86_pmu.lbr_nr; i++) {
272 unsigned long lbr_idx = (tos - i) & mask;
273 u64 from, to, mis = 0, pred = 0;
274
275 rdmsrl(x86_pmu.lbr_from + lbr_idx, from);
276 rdmsrl(x86_pmu.lbr_to + lbr_idx, to);
277
278 if (lbr_format == LBR_FORMAT_EIP_FLAGS) {
279 mis = !!(from & LBR_FROM_FLAG_MISPRED);
280 pred = !mis;
281 from = (u64)((((s64)from) << 1) >> 1);
282 }
283
284 cpuc->lbr_entries[i].from = from;
285 cpuc->lbr_entries[i].to = to;
286 cpuc->lbr_entries[i].mispred = mis;
287 cpuc->lbr_entries[i].predicted = pred;
288 cpuc->lbr_entries[i].reserved = 0;
289 }
290 cpuc->lbr_stack.nr = i;
291}
292
293void intel_pmu_lbr_read(void)
294{
295 struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
296
297 if (!cpuc->lbr_users)
298 return;
299
300 if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
301 intel_pmu_lbr_read_32(cpuc);
302 else
303 intel_pmu_lbr_read_64(cpuc);
304
305 intel_pmu_lbr_filter(cpuc);
306}
307
308/*
309 * SW filter is used:
310 * - in case there is no HW filter
311 * - in case the HW filter has errata or limitations
312 */
313static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
314{
315 u64 br_type = event->attr.branch_sample_type;
316 int mask = 0;
317
318 if (br_type & PERF_SAMPLE_BRANCH_USER)
319 mask |= X86_BR_USER;
320
321 if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
322 mask |= X86_BR_KERNEL;
323
324 /* we ignore BRANCH_HV here */
325
326 if (br_type & PERF_SAMPLE_BRANCH_ANY)
327 mask |= X86_BR_ANY;
328
329 if (br_type & PERF_SAMPLE_BRANCH_ANY_CALL)
330 mask |= X86_BR_ANY_CALL;
331
332 if (br_type & PERF_SAMPLE_BRANCH_ANY_RETURN)
333 mask |= X86_BR_RET | X86_BR_IRET | X86_BR_SYSRET;
334
335 if (br_type & PERF_SAMPLE_BRANCH_IND_CALL)
336 mask |= X86_BR_IND_CALL;
337 /*
338 * stash actual user request into reg, it may
339 * be used by fixup code for some CPU
340 */
341 event->hw.branch_reg.reg = mask;
342}
343
344/*
345 * setup the HW LBR filter
346 * Used only when available, may not be enough to disambiguate
347 * all branches, may need the help of the SW filter
348 */
349static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
350{
351 struct hw_perf_event_extra *reg;
352 u64 br_type = event->attr.branch_sample_type;
353 u64 mask = 0, m;
354 u64 v;
355
356 for_each_branch_sample_type(m) {
357 if (!(br_type & m))
358 continue;
359
360 v = x86_pmu.lbr_sel_map[m];
361 if (v == LBR_NOT_SUPP)
362 return -EOPNOTSUPP;
363
364 if (v != LBR_IGN)
365 mask |= v;
366 }
367 reg = &event->hw.branch_reg;
368 reg->idx = EXTRA_REG_LBR;
369
370 /* LBR_SELECT operates in suppress mode so invert mask */
371 reg->config = ~mask & x86_pmu.lbr_sel_mask;
372
373 return 0;
374}
375
376int intel_pmu_setup_lbr_filter(struct perf_event *event)
377{
378 int ret = 0;
379
380 /*
381 * no LBR on this PMU
382 */
383 if (!x86_pmu.lbr_nr)
384 return -EOPNOTSUPP;
385
386 /*
387 * setup SW LBR filter
388 */
389 intel_pmu_setup_sw_lbr_filter(event);
390
391 /*
392 * setup HW LBR filter, if any
393 */
394 if (x86_pmu.lbr_sel_map)
395 ret = intel_pmu_setup_hw_lbr_filter(event);
396
397 return ret;
398}
399
400/*
401 * return the type of control flow change at address "from"
402 * intruction is not necessarily a branch (in case of interrupt).
403 *
404 * The branch type returned also includes the priv level of the
405 * target of the control flow change (X86_BR_USER, X86_BR_KERNEL).
406 *
407 * If a branch type is unknown OR the instruction cannot be
408 * decoded (e.g., text page not present), then X86_BR_NONE is
409 * returned.
410 */
411static int branch_type(unsigned long from, unsigned long to)
412{
413 struct insn insn;
414 void *addr;
415 int bytes, size = MAX_INSN_SIZE;
416 int ret = X86_BR_NONE;
417 int ext, to_plm, from_plm;
418 u8 buf[MAX_INSN_SIZE];
419 int is64 = 0;
420
421 to_plm = kernel_ip(to) ? X86_BR_KERNEL : X86_BR_USER;
422 from_plm = kernel_ip(from) ? X86_BR_KERNEL : X86_BR_USER;
423
424 /*
425 * maybe zero if lbr did not fill up after a reset by the time
426 * we get a PMU interrupt
427 */
428 if (from == 0 || to == 0)
429 return X86_BR_NONE;
430
431 if (from_plm == X86_BR_USER) {
432 /*
433 * can happen if measuring at the user level only
434 * and we interrupt in a kernel thread, e.g., idle.
435 */
436 if (!current->mm)
437 return X86_BR_NONE;
438
439 /* may fail if text not present */
440 bytes = copy_from_user_nmi(buf, (void __user *)from, size);
441 if (bytes != size)
442 return X86_BR_NONE;
443
444 addr = buf;
445 } else
446 addr = (void *)from;
447
448 /*
449 * decoder needs to know the ABI especially
450 * on 64-bit systems running 32-bit apps
451 */
452#ifdef CONFIG_X86_64
453 is64 = kernel_ip((unsigned long)addr) || !test_thread_flag(TIF_IA32);
454#endif
455 insn_init(&insn, addr, is64);
456 insn_get_opcode(&insn);
457
458 switch (insn.opcode.bytes[0]) {
459 case 0xf:
460 switch (insn.opcode.bytes[1]) {
461 case 0x05: /* syscall */
462 case 0x34: /* sysenter */
463 ret = X86_BR_SYSCALL;
464 break;
465 case 0x07: /* sysret */
466 case 0x35: /* sysexit */
467 ret = X86_BR_SYSRET;
468 break;
469 case 0x80 ... 0x8f: /* conditional */
470 ret = X86_BR_JCC;
471 break;
472 default:
473 ret = X86_BR_NONE;
474 }
475 break;
476 case 0x70 ... 0x7f: /* conditional */
477 ret = X86_BR_JCC;
478 break;
479 case 0xc2: /* near ret */
480 case 0xc3: /* near ret */
481 case 0xca: /* far ret */
482 case 0xcb: /* far ret */
483 ret = X86_BR_RET;
484 break;
485 case 0xcf: /* iret */
486 ret = X86_BR_IRET;
487 break;
488 case 0xcc ... 0xce: /* int */
489 ret = X86_BR_INT;
490 break;
491 case 0xe8: /* call near rel */
492 case 0x9a: /* call far absolute */
493 ret = X86_BR_CALL;
494 break;
495 case 0xe0 ... 0xe3: /* loop jmp */
496 ret = X86_BR_JCC;
497 break;
498 case 0xe9 ... 0xeb: /* jmp */
499 ret = X86_BR_JMP;
500 break;
501 case 0xff: /* call near absolute, call far absolute ind */
502 insn_get_modrm(&insn);
503 ext = (insn.modrm.bytes[0] >> 3) & 0x7;
504 switch (ext) {
505 case 2: /* near ind call */
506 case 3: /* far ind call */
507 ret = X86_BR_IND_CALL;
508 break;
509 case 4:
510 case 5:
511 ret = X86_BR_JMP;
512 break;
513 }
514 break;
515 default:
516 ret = X86_BR_NONE;
517 }
518 /*
519 * interrupts, traps, faults (and thus ring transition) may
520 * occur on any instructions. Thus, to classify them correctly,
521 * we need to first look at the from and to priv levels. If they
522 * are different and to is in the kernel, then it indicates
523 * a ring transition. If the from instruction is not a ring
524 * transition instr (syscall, systenter, int), then it means
525 * it was a irq, trap or fault.
526 *
527 * we have no way of detecting kernel to kernel faults.
528 */
529 if (from_plm == X86_BR_USER && to_plm == X86_BR_KERNEL
530 && ret != X86_BR_SYSCALL && ret != X86_BR_INT)
531 ret = X86_BR_IRQ;
532
533 /*
534 * branch priv level determined by target as
535 * is done by HW when LBR_SELECT is implemented
536 */
537 if (ret != X86_BR_NONE)
538 ret |= to_plm;
539
540 return ret;
541}
542
543/*
544 * implement actual branch filter based on user demand.
545 * Hardware may not exactly satisfy that request, thus
546 * we need to inspect opcodes. Mismatched branches are
547 * discarded. Therefore, the number of branches returned
548 * in PERF_SAMPLE_BRANCH_STACK sample may vary.
549 */
550static void
551intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
552{
553 u64 from, to;
554 int br_sel = cpuc->br_sel;
555 int i, j, type;
556 bool compress = false;
557
558 /* if sampling all branches, then nothing to filter */
559 if ((br_sel & X86_BR_ALL) == X86_BR_ALL)
560 return;
561
562 for (i = 0; i < cpuc->lbr_stack.nr; i++) {
563
564 from = cpuc->lbr_entries[i].from;
565 to = cpuc->lbr_entries[i].to;
566
567 type = branch_type(from, to);
568
569 /* if type does not correspond, then discard */
570 if (type == X86_BR_NONE || (br_sel & type) != type) {
571 cpuc->lbr_entries[i].from = 0;
572 compress = true;
573 }
574 }
575
576 if (!compress)
577 return;
578
579 /* remove all entries with from=0 */
580 for (i = 0; i < cpuc->lbr_stack.nr; ) {
581 if (!cpuc->lbr_entries[i].from) {
582 j = i;
583 while (++j < cpuc->lbr_stack.nr)
584 cpuc->lbr_entries[j-1] = cpuc->lbr_entries[j];
585 cpuc->lbr_stack.nr--;
586 if (!cpuc->lbr_entries[i].from)
587 continue;
588 }
589 i++;
590 }
591}
592
593/*
594 * Map interface branch filters onto LBR filters
595 */
596static const int nhm_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
597 [PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
598 [PERF_SAMPLE_BRANCH_USER] = LBR_USER,
599 [PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
600 [PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
601 [PERF_SAMPLE_BRANCH_ANY_RETURN] = LBR_RETURN | LBR_REL_JMP
602 | LBR_IND_JMP | LBR_FAR,
603 /*
604 * NHM/WSM erratum: must include REL_JMP+IND_JMP to get CALL branches
605 */
606 [PERF_SAMPLE_BRANCH_ANY_CALL] =
607 LBR_REL_CALL | LBR_IND_CALL | LBR_REL_JMP | LBR_IND_JMP | LBR_FAR,
608 /*
609 * NHM/WSM erratum: must include IND_JMP to capture IND_CALL
610 */
611 [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL | LBR_IND_JMP,
612};
613
614static const int snb_lbr_sel_map[PERF_SAMPLE_BRANCH_MAX] = {
615 [PERF_SAMPLE_BRANCH_ANY] = LBR_ANY,
616 [PERF_SAMPLE_BRANCH_USER] = LBR_USER,
617 [PERF_SAMPLE_BRANCH_KERNEL] = LBR_KERNEL,
618 [PERF_SAMPLE_BRANCH_HV] = LBR_IGN,
619 [PERF_SAMPLE_BRANCH_ANY_RETURN] = LBR_RETURN | LBR_FAR,
620 [PERF_SAMPLE_BRANCH_ANY_CALL] = LBR_REL_CALL | LBR_IND_CALL
621 | LBR_FAR,
622 [PERF_SAMPLE_BRANCH_IND_CALL] = LBR_IND_CALL,
623};
624
625/* core */
626void intel_pmu_lbr_init_core(void)
627{
628 x86_pmu.lbr_nr = 4;
629 x86_pmu.lbr_tos = MSR_LBR_TOS;
630 x86_pmu.lbr_from = MSR_LBR_CORE_FROM;
631 x86_pmu.lbr_to = MSR_LBR_CORE_TO;
632
633 /*
634 * SW branch filter usage:
635 * - compensate for lack of HW filter
636 */
637 pr_cont("4-deep LBR, ");
638}
639
640/* nehalem/westmere */
641void intel_pmu_lbr_init_nhm(void)
642{
643 x86_pmu.lbr_nr = 16;
644 x86_pmu.lbr_tos = MSR_LBR_TOS;
645 x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
646 x86_pmu.lbr_to = MSR_LBR_NHM_TO;
647
648 x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
649 x86_pmu.lbr_sel_map = nhm_lbr_sel_map;
650
651 /*
652 * SW branch filter usage:
653 * - workaround LBR_SEL errata (see above)
654 * - support syscall, sysret capture.
655 * That requires LBR_FAR but that means far
656 * jmp need to be filtered out
657 */
658 pr_cont("16-deep LBR, ");
659}
660
661/* sandy bridge */
662void intel_pmu_lbr_init_snb(void)
663{
664 x86_pmu.lbr_nr = 16;
665 x86_pmu.lbr_tos = MSR_LBR_TOS;
666 x86_pmu.lbr_from = MSR_LBR_NHM_FROM;
667 x86_pmu.lbr_to = MSR_LBR_NHM_TO;
668
669 x86_pmu.lbr_sel_mask = LBR_SEL_MASK;
670 x86_pmu.lbr_sel_map = snb_lbr_sel_map;
671
672 /*
673 * SW branch filter usage:
674 * - support syscall, sysret capture.
675 * That requires LBR_FAR but that means far
676 * jmp need to be filtered out
677 */
678 pr_cont("16-deep LBR, ");
679}
680
681/* atom */
682void intel_pmu_lbr_init_atom(void)
683{
684 /*
685 * only models starting at stepping 10 seems
686 * to have an operational LBR which can freeze
687 * on PMU interrupt
688 */
689 if (boot_cpu_data.x86_mask < 10) {
690 pr_cont("LBR disabled due to erratum");
691 return;
692 }
693
694 x86_pmu.lbr_nr = 8;
695 x86_pmu.lbr_tos = MSR_LBR_TOS;
696 x86_pmu.lbr_from = MSR_LBR_CORE_FROM;
697 x86_pmu.lbr_to = MSR_LBR_CORE_TO;
698
699 /*
700 * SW branch filter usage:
701 * - compensate for lack of HW filter
702 */
703 pr_cont("8-deep LBR, ");
704}