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20002ded PM |
1 | /* |
2 | * Performance counter callchain support - powerpc architecture code | |
3 | * | |
4 | * Copyright © 2009 Paul Mackerras, IBM Corporation. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/sched.h> | |
cdd6c482 | 13 | #include <linux/perf_event.h> |
20002ded PM |
14 | #include <linux/percpu.h> |
15 | #include <linux/uaccess.h> | |
16 | #include <linux/mm.h> | |
17 | #include <asm/ptrace.h> | |
18 | #include <asm/pgtable.h> | |
19 | #include <asm/sigcontext.h> | |
20 | #include <asm/ucontext.h> | |
21 | #include <asm/vdso.h> | |
22 | #ifdef CONFIG_PPC64 | |
23 | #include "ppc32.h" | |
24 | #endif | |
25 | ||
26 | /* | |
27 | * Store another value in a callchain_entry. | |
28 | */ | |
29 | static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip) | |
30 | { | |
31 | unsigned int nr = entry->nr; | |
32 | ||
33 | if (nr < PERF_MAX_STACK_DEPTH) { | |
34 | entry->ip[nr] = ip; | |
35 | entry->nr = nr + 1; | |
36 | } | |
37 | } | |
38 | ||
39 | /* | |
40 | * Is sp valid as the address of the next kernel stack frame after prev_sp? | |
41 | * The next frame may be in a different stack area but should not go | |
42 | * back down in the same stack area. | |
43 | */ | |
44 | static int valid_next_sp(unsigned long sp, unsigned long prev_sp) | |
45 | { | |
46 | if (sp & 0xf) | |
47 | return 0; /* must be 16-byte aligned */ | |
48 | if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) | |
49 | return 0; | |
50 | if (sp >= prev_sp + STACK_FRAME_OVERHEAD) | |
51 | return 1; | |
52 | /* | |
53 | * sp could decrease when we jump off an interrupt stack | |
54 | * back to the regular process stack. | |
55 | */ | |
56 | if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1))) | |
57 | return 1; | |
58 | return 0; | |
59 | } | |
60 | ||
61 | static void perf_callchain_kernel(struct pt_regs *regs, | |
62 | struct perf_callchain_entry *entry) | |
63 | { | |
64 | unsigned long sp, next_sp; | |
65 | unsigned long next_ip; | |
66 | unsigned long lr; | |
67 | long level = 0; | |
68 | unsigned long *fp; | |
69 | ||
70 | lr = regs->link; | |
71 | sp = regs->gpr[1]; | |
72 | callchain_store(entry, PERF_CONTEXT_KERNEL); | |
73 | callchain_store(entry, regs->nip); | |
74 | ||
75 | if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) | |
76 | return; | |
77 | ||
78 | for (;;) { | |
79 | fp = (unsigned long *) sp; | |
80 | next_sp = fp[0]; | |
81 | ||
82 | if (next_sp == sp + STACK_INT_FRAME_SIZE && | |
83 | fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) { | |
84 | /* | |
85 | * This looks like an interrupt frame for an | |
86 | * interrupt that occurred in the kernel | |
87 | */ | |
88 | regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD); | |
89 | next_ip = regs->nip; | |
90 | lr = regs->link; | |
91 | level = 0; | |
92 | callchain_store(entry, PERF_CONTEXT_KERNEL); | |
93 | ||
94 | } else { | |
95 | if (level == 0) | |
96 | next_ip = lr; | |
97 | else | |
98 | next_ip = fp[STACK_FRAME_LR_SAVE]; | |
99 | ||
100 | /* | |
101 | * We can't tell which of the first two addresses | |
102 | * we get are valid, but we can filter out the | |
103 | * obviously bogus ones here. We replace them | |
104 | * with 0 rather than removing them entirely so | |
105 | * that userspace can tell which is which. | |
106 | */ | |
107 | if ((level == 1 && next_ip == lr) || | |
108 | (level <= 1 && !kernel_text_address(next_ip))) | |
109 | next_ip = 0; | |
110 | ||
111 | ++level; | |
112 | } | |
113 | ||
114 | callchain_store(entry, next_ip); | |
115 | if (!valid_next_sp(next_sp, sp)) | |
116 | return; | |
117 | sp = next_sp; | |
118 | } | |
119 | } | |
120 | ||
121 | #ifdef CONFIG_PPC64 | |
20002ded PM |
122 | /* |
123 | * On 64-bit we don't want to invoke hash_page on user addresses from | |
124 | * interrupt context, so if the access faults, we read the page tables | |
125 | * to find which page (if any) is mapped and access it directly. | |
126 | */ | |
127 | static int read_user_stack_slow(void __user *ptr, void *ret, int nb) | |
128 | { | |
129 | pgd_t *pgdir; | |
130 | pte_t *ptep, pte; | |
a4fe3ce7 | 131 | unsigned shift; |
20002ded PM |
132 | unsigned long addr = (unsigned long) ptr; |
133 | unsigned long offset; | |
134 | unsigned long pfn; | |
135 | void *kaddr; | |
136 | ||
137 | pgdir = current->mm->pgd; | |
138 | if (!pgdir) | |
139 | return -EFAULT; | |
140 | ||
a4fe3ce7 DG |
141 | ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift); |
142 | if (!shift) | |
143 | shift = PAGE_SHIFT; | |
20002ded PM |
144 | |
145 | /* align address to page boundary */ | |
a4fe3ce7 | 146 | offset = addr & ((1UL << shift) - 1); |
20002ded PM |
147 | addr -= offset; |
148 | ||
20002ded PM |
149 | if (ptep == NULL) |
150 | return -EFAULT; | |
151 | pte = *ptep; | |
152 | if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER)) | |
153 | return -EFAULT; | |
154 | pfn = pte_pfn(pte); | |
155 | if (!page_is_ram(pfn)) | |
156 | return -EFAULT; | |
157 | ||
158 | /* no highmem to worry about here */ | |
159 | kaddr = pfn_to_kaddr(pfn); | |
160 | memcpy(ret, kaddr + offset, nb); | |
161 | return 0; | |
162 | } | |
163 | ||
164 | static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) | |
165 | { | |
166 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) || | |
167 | ((unsigned long)ptr & 7)) | |
168 | return -EFAULT; | |
169 | ||
170 | if (!__get_user_inatomic(*ret, ptr)) | |
171 | return 0; | |
172 | ||
173 | return read_user_stack_slow(ptr, ret, 8); | |
174 | } | |
175 | ||
176 | static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) | |
177 | { | |
178 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || | |
179 | ((unsigned long)ptr & 3)) | |
180 | return -EFAULT; | |
181 | ||
182 | if (!__get_user_inatomic(*ret, ptr)) | |
183 | return 0; | |
184 | ||
185 | return read_user_stack_slow(ptr, ret, 4); | |
186 | } | |
187 | ||
188 | static inline int valid_user_sp(unsigned long sp, int is_64) | |
189 | { | |
190 | if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32) | |
191 | return 0; | |
192 | return 1; | |
193 | } | |
194 | ||
195 | /* | |
196 | * 64-bit user processes use the same stack frame for RT and non-RT signals. | |
197 | */ | |
198 | struct signal_frame_64 { | |
199 | char dummy[__SIGNAL_FRAMESIZE]; | |
200 | struct ucontext uc; | |
201 | unsigned long unused[2]; | |
202 | unsigned int tramp[6]; | |
203 | struct siginfo *pinfo; | |
204 | void *puc; | |
205 | struct siginfo info; | |
206 | char abigap[288]; | |
207 | }; | |
208 | ||
209 | static int is_sigreturn_64_address(unsigned long nip, unsigned long fp) | |
210 | { | |
211 | if (nip == fp + offsetof(struct signal_frame_64, tramp)) | |
212 | return 1; | |
213 | if (vdso64_rt_sigtramp && current->mm->context.vdso_base && | |
214 | nip == current->mm->context.vdso_base + vdso64_rt_sigtramp) | |
215 | return 1; | |
216 | return 0; | |
217 | } | |
218 | ||
219 | /* | |
220 | * Do some sanity checking on the signal frame pointed to by sp. | |
221 | * We check the pinfo and puc pointers in the frame. | |
222 | */ | |
223 | static int sane_signal_64_frame(unsigned long sp) | |
224 | { | |
225 | struct signal_frame_64 __user *sf; | |
226 | unsigned long pinfo, puc; | |
227 | ||
228 | sf = (struct signal_frame_64 __user *) sp; | |
229 | if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) || | |
230 | read_user_stack_64((unsigned long __user *) &sf->puc, &puc)) | |
231 | return 0; | |
232 | return pinfo == (unsigned long) &sf->info && | |
233 | puc == (unsigned long) &sf->uc; | |
234 | } | |
235 | ||
236 | static void perf_callchain_user_64(struct pt_regs *regs, | |
237 | struct perf_callchain_entry *entry) | |
238 | { | |
239 | unsigned long sp, next_sp; | |
240 | unsigned long next_ip; | |
241 | unsigned long lr; | |
242 | long level = 0; | |
243 | struct signal_frame_64 __user *sigframe; | |
244 | unsigned long __user *fp, *uregs; | |
245 | ||
246 | next_ip = regs->nip; | |
247 | lr = regs->link; | |
248 | sp = regs->gpr[1]; | |
249 | callchain_store(entry, PERF_CONTEXT_USER); | |
250 | callchain_store(entry, next_ip); | |
251 | ||
252 | for (;;) { | |
253 | fp = (unsigned long __user *) sp; | |
254 | if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp)) | |
255 | return; | |
256 | if (level > 0 && read_user_stack_64(&fp[2], &next_ip)) | |
257 | return; | |
258 | ||
259 | /* | |
260 | * Note: the next_sp - sp >= signal frame size check | |
261 | * is true when next_sp < sp, which can happen when | |
262 | * transitioning from an alternate signal stack to the | |
263 | * normal stack. | |
264 | */ | |
265 | if (next_sp - sp >= sizeof(struct signal_frame_64) && | |
266 | (is_sigreturn_64_address(next_ip, sp) || | |
267 | (level <= 1 && is_sigreturn_64_address(lr, sp))) && | |
268 | sane_signal_64_frame(sp)) { | |
269 | /* | |
270 | * This looks like an signal frame | |
271 | */ | |
272 | sigframe = (struct signal_frame_64 __user *) sp; | |
273 | uregs = sigframe->uc.uc_mcontext.gp_regs; | |
274 | if (read_user_stack_64(&uregs[PT_NIP], &next_ip) || | |
275 | read_user_stack_64(&uregs[PT_LNK], &lr) || | |
276 | read_user_stack_64(&uregs[PT_R1], &sp)) | |
277 | return; | |
278 | level = 0; | |
279 | callchain_store(entry, PERF_CONTEXT_USER); | |
280 | callchain_store(entry, next_ip); | |
281 | continue; | |
282 | } | |
283 | ||
284 | if (level == 0) | |
285 | next_ip = lr; | |
286 | callchain_store(entry, next_ip); | |
287 | ++level; | |
288 | sp = next_sp; | |
289 | } | |
290 | } | |
291 | ||
292 | static inline int current_is_64bit(void) | |
293 | { | |
294 | /* | |
295 | * We can't use test_thread_flag() here because we may be on an | |
296 | * interrupt stack, and the thread flags don't get copied over | |
297 | * from the thread_info on the main stack to the interrupt stack. | |
298 | */ | |
299 | return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT); | |
300 | } | |
301 | ||
302 | #else /* CONFIG_PPC64 */ | |
303 | /* | |
304 | * On 32-bit we just access the address and let hash_page create a | |
305 | * HPTE if necessary, so there is no need to fall back to reading | |
306 | * the page tables. Since this is called at interrupt level, | |
307 | * do_page_fault() won't treat a DSI as a page fault. | |
308 | */ | |
309 | static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) | |
310 | { | |
311 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || | |
312 | ((unsigned long)ptr & 3)) | |
313 | return -EFAULT; | |
314 | ||
315 | return __get_user_inatomic(*ret, ptr); | |
316 | } | |
317 | ||
318 | static inline void perf_callchain_user_64(struct pt_regs *regs, | |
319 | struct perf_callchain_entry *entry) | |
320 | { | |
321 | } | |
322 | ||
323 | static inline int current_is_64bit(void) | |
324 | { | |
325 | return 0; | |
326 | } | |
327 | ||
328 | static inline int valid_user_sp(unsigned long sp, int is_64) | |
329 | { | |
330 | if (!sp || (sp & 7) || sp > TASK_SIZE - 32) | |
331 | return 0; | |
332 | return 1; | |
333 | } | |
334 | ||
335 | #define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE | |
336 | #define sigcontext32 sigcontext | |
337 | #define mcontext32 mcontext | |
338 | #define ucontext32 ucontext | |
339 | #define compat_siginfo_t struct siginfo | |
340 | ||
341 | #endif /* CONFIG_PPC64 */ | |
342 | ||
343 | /* | |
344 | * Layout for non-RT signal frames | |
345 | */ | |
346 | struct signal_frame_32 { | |
347 | char dummy[__SIGNAL_FRAMESIZE32]; | |
348 | struct sigcontext32 sctx; | |
349 | struct mcontext32 mctx; | |
350 | int abigap[56]; | |
351 | }; | |
352 | ||
353 | /* | |
354 | * Layout for RT signal frames | |
355 | */ | |
356 | struct rt_signal_frame_32 { | |
357 | char dummy[__SIGNAL_FRAMESIZE32 + 16]; | |
358 | compat_siginfo_t info; | |
359 | struct ucontext32 uc; | |
360 | int abigap[56]; | |
361 | }; | |
362 | ||
363 | static int is_sigreturn_32_address(unsigned int nip, unsigned int fp) | |
364 | { | |
365 | if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad)) | |
366 | return 1; | |
367 | if (vdso32_sigtramp && current->mm->context.vdso_base && | |
368 | nip == current->mm->context.vdso_base + vdso32_sigtramp) | |
369 | return 1; | |
370 | return 0; | |
371 | } | |
372 | ||
373 | static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp) | |
374 | { | |
375 | if (nip == fp + offsetof(struct rt_signal_frame_32, | |
376 | uc.uc_mcontext.mc_pad)) | |
377 | return 1; | |
378 | if (vdso32_rt_sigtramp && current->mm->context.vdso_base && | |
379 | nip == current->mm->context.vdso_base + vdso32_rt_sigtramp) | |
380 | return 1; | |
381 | return 0; | |
382 | } | |
383 | ||
384 | static int sane_signal_32_frame(unsigned int sp) | |
385 | { | |
386 | struct signal_frame_32 __user *sf; | |
387 | unsigned int regs; | |
388 | ||
389 | sf = (struct signal_frame_32 __user *) (unsigned long) sp; | |
390 | if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s)) | |
391 | return 0; | |
392 | return regs == (unsigned long) &sf->mctx; | |
393 | } | |
394 | ||
395 | static int sane_rt_signal_32_frame(unsigned int sp) | |
396 | { | |
397 | struct rt_signal_frame_32 __user *sf; | |
398 | unsigned int regs; | |
399 | ||
400 | sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; | |
401 | if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s)) | |
402 | return 0; | |
403 | return regs == (unsigned long) &sf->uc.uc_mcontext; | |
404 | } | |
405 | ||
406 | static unsigned int __user *signal_frame_32_regs(unsigned int sp, | |
407 | unsigned int next_sp, unsigned int next_ip) | |
408 | { | |
409 | struct mcontext32 __user *mctx = NULL; | |
410 | struct signal_frame_32 __user *sf; | |
411 | struct rt_signal_frame_32 __user *rt_sf; | |
412 | ||
413 | /* | |
414 | * Note: the next_sp - sp >= signal frame size check | |
415 | * is true when next_sp < sp, for example, when | |
416 | * transitioning from an alternate signal stack to the | |
417 | * normal stack. | |
418 | */ | |
419 | if (next_sp - sp >= sizeof(struct signal_frame_32) && | |
420 | is_sigreturn_32_address(next_ip, sp) && | |
421 | sane_signal_32_frame(sp)) { | |
422 | sf = (struct signal_frame_32 __user *) (unsigned long) sp; | |
423 | mctx = &sf->mctx; | |
424 | } | |
425 | ||
426 | if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) && | |
427 | is_rt_sigreturn_32_address(next_ip, sp) && | |
428 | sane_rt_signal_32_frame(sp)) { | |
429 | rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp; | |
430 | mctx = &rt_sf->uc.uc_mcontext; | |
431 | } | |
432 | ||
433 | if (!mctx) | |
434 | return NULL; | |
435 | return mctx->mc_gregs; | |
436 | } | |
437 | ||
438 | static void perf_callchain_user_32(struct pt_regs *regs, | |
439 | struct perf_callchain_entry *entry) | |
440 | { | |
441 | unsigned int sp, next_sp; | |
442 | unsigned int next_ip; | |
443 | unsigned int lr; | |
444 | long level = 0; | |
445 | unsigned int __user *fp, *uregs; | |
446 | ||
447 | next_ip = regs->nip; | |
448 | lr = regs->link; | |
449 | sp = regs->gpr[1]; | |
450 | callchain_store(entry, PERF_CONTEXT_USER); | |
451 | callchain_store(entry, next_ip); | |
452 | ||
453 | while (entry->nr < PERF_MAX_STACK_DEPTH) { | |
454 | fp = (unsigned int __user *) (unsigned long) sp; | |
455 | if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp)) | |
456 | return; | |
457 | if (level > 0 && read_user_stack_32(&fp[1], &next_ip)) | |
458 | return; | |
459 | ||
460 | uregs = signal_frame_32_regs(sp, next_sp, next_ip); | |
461 | if (!uregs && level <= 1) | |
462 | uregs = signal_frame_32_regs(sp, next_sp, lr); | |
463 | if (uregs) { | |
464 | /* | |
465 | * This looks like an signal frame, so restart | |
466 | * the stack trace with the values in it. | |
467 | */ | |
468 | if (read_user_stack_32(&uregs[PT_NIP], &next_ip) || | |
469 | read_user_stack_32(&uregs[PT_LNK], &lr) || | |
470 | read_user_stack_32(&uregs[PT_R1], &sp)) | |
471 | return; | |
472 | level = 0; | |
473 | callchain_store(entry, PERF_CONTEXT_USER); | |
474 | callchain_store(entry, next_ip); | |
475 | continue; | |
476 | } | |
477 | ||
478 | if (level == 0) | |
479 | next_ip = lr; | |
480 | callchain_store(entry, next_ip); | |
481 | ++level; | |
482 | sp = next_sp; | |
483 | } | |
484 | } | |
485 | ||
486 | /* | |
487 | * Since we can't get PMU interrupts inside a PMU interrupt handler, | |
488 | * we don't need separate irq and nmi entries here. | |
489 | */ | |
6b7487fc | 490 | static DEFINE_PER_CPU(struct perf_callchain_entry, cpu_perf_callchain); |
20002ded PM |
491 | |
492 | struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) | |
493 | { | |
6b7487fc | 494 | struct perf_callchain_entry *entry = &__get_cpu_var(cpu_perf_callchain); |
20002ded PM |
495 | |
496 | entry->nr = 0; | |
497 | ||
20002ded PM |
498 | if (!user_mode(regs)) { |
499 | perf_callchain_kernel(regs, entry); | |
500 | if (current->mm) | |
501 | regs = task_pt_regs(current); | |
502 | else | |
503 | regs = NULL; | |
504 | } | |
505 | ||
506 | if (regs) { | |
507 | if (current_is_64bit()) | |
508 | perf_callchain_user_64(regs, entry); | |
509 | else | |
510 | perf_callchain_user_32(regs, entry); | |
511 | } | |
512 | ||
513 | return entry; | |
514 | } |