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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 | ||
20002ded PM |
26 | |
27 | /* | |
28 | * Is sp valid as the address of the next kernel stack frame after prev_sp? | |
29 | * The next frame may be in a different stack area but should not go | |
30 | * back down in the same stack area. | |
31 | */ | |
32 | static int valid_next_sp(unsigned long sp, unsigned long prev_sp) | |
33 | { | |
34 | if (sp & 0xf) | |
35 | return 0; /* must be 16-byte aligned */ | |
36 | if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) | |
37 | return 0; | |
38 | if (sp >= prev_sp + STACK_FRAME_OVERHEAD) | |
39 | return 1; | |
40 | /* | |
41 | * sp could decrease when we jump off an interrupt stack | |
42 | * back to the regular process stack. | |
43 | */ | |
44 | if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1))) | |
45 | return 1; | |
46 | return 0; | |
47 | } | |
48 | ||
56962b44 FW |
49 | void |
50 | perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) | |
20002ded PM |
51 | { |
52 | unsigned long sp, next_sp; | |
53 | unsigned long next_ip; | |
54 | unsigned long lr; | |
55 | long level = 0; | |
56 | unsigned long *fp; | |
57 | ||
58 | lr = regs->link; | |
59 | sp = regs->gpr[1]; | |
70791ce9 | 60 | perf_callchain_store(entry, regs->nip); |
20002ded PM |
61 | |
62 | if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD)) | |
63 | return; | |
64 | ||
65 | for (;;) { | |
66 | fp = (unsigned long *) sp; | |
67 | next_sp = fp[0]; | |
68 | ||
69 | if (next_sp == sp + STACK_INT_FRAME_SIZE && | |
70 | fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) { | |
71 | /* | |
72 | * This looks like an interrupt frame for an | |
73 | * interrupt that occurred in the kernel | |
74 | */ | |
75 | regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD); | |
76 | next_ip = regs->nip; | |
77 | lr = regs->link; | |
78 | level = 0; | |
70791ce9 | 79 | perf_callchain_store(entry, PERF_CONTEXT_KERNEL); |
20002ded PM |
80 | |
81 | } else { | |
82 | if (level == 0) | |
83 | next_ip = lr; | |
84 | else | |
85 | next_ip = fp[STACK_FRAME_LR_SAVE]; | |
86 | ||
87 | /* | |
88 | * We can't tell which of the first two addresses | |
89 | * we get are valid, but we can filter out the | |
90 | * obviously bogus ones here. We replace them | |
91 | * with 0 rather than removing them entirely so | |
92 | * that userspace can tell which is which. | |
93 | */ | |
94 | if ((level == 1 && next_ip == lr) || | |
95 | (level <= 1 && !kernel_text_address(next_ip))) | |
96 | next_ip = 0; | |
97 | ||
98 | ++level; | |
99 | } | |
100 | ||
70791ce9 | 101 | perf_callchain_store(entry, next_ip); |
20002ded PM |
102 | if (!valid_next_sp(next_sp, sp)) |
103 | return; | |
104 | sp = next_sp; | |
105 | } | |
106 | } | |
107 | ||
108 | #ifdef CONFIG_PPC64 | |
20002ded PM |
109 | /* |
110 | * On 64-bit we don't want to invoke hash_page on user addresses from | |
111 | * interrupt context, so if the access faults, we read the page tables | |
112 | * to find which page (if any) is mapped and access it directly. | |
113 | */ | |
114 | static int read_user_stack_slow(void __user *ptr, void *ret, int nb) | |
115 | { | |
116 | pgd_t *pgdir; | |
117 | pte_t *ptep, pte; | |
a4fe3ce7 | 118 | unsigned shift; |
20002ded PM |
119 | unsigned long addr = (unsigned long) ptr; |
120 | unsigned long offset; | |
121 | unsigned long pfn; | |
122 | void *kaddr; | |
123 | ||
124 | pgdir = current->mm->pgd; | |
125 | if (!pgdir) | |
126 | return -EFAULT; | |
127 | ||
a4fe3ce7 DG |
128 | ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift); |
129 | if (!shift) | |
130 | shift = PAGE_SHIFT; | |
20002ded PM |
131 | |
132 | /* align address to page boundary */ | |
a4fe3ce7 | 133 | offset = addr & ((1UL << shift) - 1); |
20002ded PM |
134 | addr -= offset; |
135 | ||
20002ded PM |
136 | if (ptep == NULL) |
137 | return -EFAULT; | |
138 | pte = *ptep; | |
139 | if (!pte_present(pte) || !(pte_val(pte) & _PAGE_USER)) | |
140 | return -EFAULT; | |
141 | pfn = pte_pfn(pte); | |
142 | if (!page_is_ram(pfn)) | |
143 | return -EFAULT; | |
144 | ||
145 | /* no highmem to worry about here */ | |
146 | kaddr = pfn_to_kaddr(pfn); | |
147 | memcpy(ret, kaddr + offset, nb); | |
148 | return 0; | |
149 | } | |
150 | ||
151 | static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret) | |
152 | { | |
153 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) || | |
154 | ((unsigned long)ptr & 7)) | |
155 | return -EFAULT; | |
156 | ||
b59a1bfc DA |
157 | pagefault_disable(); |
158 | if (!__get_user_inatomic(*ret, ptr)) { | |
159 | pagefault_enable(); | |
20002ded | 160 | return 0; |
b59a1bfc DA |
161 | } |
162 | pagefault_enable(); | |
20002ded PM |
163 | |
164 | return read_user_stack_slow(ptr, ret, 8); | |
165 | } | |
166 | ||
167 | static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) | |
168 | { | |
169 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || | |
170 | ((unsigned long)ptr & 3)) | |
171 | return -EFAULT; | |
172 | ||
b59a1bfc DA |
173 | pagefault_disable(); |
174 | if (!__get_user_inatomic(*ret, ptr)) { | |
175 | pagefault_enable(); | |
20002ded | 176 | return 0; |
b59a1bfc DA |
177 | } |
178 | pagefault_enable(); | |
20002ded PM |
179 | |
180 | return read_user_stack_slow(ptr, ret, 4); | |
181 | } | |
182 | ||
183 | static inline int valid_user_sp(unsigned long sp, int is_64) | |
184 | { | |
185 | if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32) | |
186 | return 0; | |
187 | return 1; | |
188 | } | |
189 | ||
190 | /* | |
191 | * 64-bit user processes use the same stack frame for RT and non-RT signals. | |
192 | */ | |
193 | struct signal_frame_64 { | |
194 | char dummy[__SIGNAL_FRAMESIZE]; | |
195 | struct ucontext uc; | |
196 | unsigned long unused[2]; | |
197 | unsigned int tramp[6]; | |
198 | struct siginfo *pinfo; | |
199 | void *puc; | |
200 | struct siginfo info; | |
201 | char abigap[288]; | |
202 | }; | |
203 | ||
204 | static int is_sigreturn_64_address(unsigned long nip, unsigned long fp) | |
205 | { | |
206 | if (nip == fp + offsetof(struct signal_frame_64, tramp)) | |
207 | return 1; | |
208 | if (vdso64_rt_sigtramp && current->mm->context.vdso_base && | |
209 | nip == current->mm->context.vdso_base + vdso64_rt_sigtramp) | |
210 | return 1; | |
211 | return 0; | |
212 | } | |
213 | ||
214 | /* | |
215 | * Do some sanity checking on the signal frame pointed to by sp. | |
216 | * We check the pinfo and puc pointers in the frame. | |
217 | */ | |
218 | static int sane_signal_64_frame(unsigned long sp) | |
219 | { | |
220 | struct signal_frame_64 __user *sf; | |
221 | unsigned long pinfo, puc; | |
222 | ||
223 | sf = (struct signal_frame_64 __user *) sp; | |
224 | if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) || | |
225 | read_user_stack_64((unsigned long __user *) &sf->puc, &puc)) | |
226 | return 0; | |
227 | return pinfo == (unsigned long) &sf->info && | |
228 | puc == (unsigned long) &sf->uc; | |
229 | } | |
230 | ||
56962b44 FW |
231 | static void perf_callchain_user_64(struct perf_callchain_entry *entry, |
232 | struct pt_regs *regs) | |
20002ded PM |
233 | { |
234 | unsigned long sp, next_sp; | |
235 | unsigned long next_ip; | |
236 | unsigned long lr; | |
237 | long level = 0; | |
238 | struct signal_frame_64 __user *sigframe; | |
239 | unsigned long __user *fp, *uregs; | |
240 | ||
241 | next_ip = regs->nip; | |
242 | lr = regs->link; | |
243 | sp = regs->gpr[1]; | |
70791ce9 | 244 | perf_callchain_store(entry, next_ip); |
20002ded PM |
245 | |
246 | for (;;) { | |
247 | fp = (unsigned long __user *) sp; | |
248 | if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp)) | |
249 | return; | |
250 | if (level > 0 && read_user_stack_64(&fp[2], &next_ip)) | |
251 | return; | |
252 | ||
253 | /* | |
254 | * Note: the next_sp - sp >= signal frame size check | |
255 | * is true when next_sp < sp, which can happen when | |
256 | * transitioning from an alternate signal stack to the | |
257 | * normal stack. | |
258 | */ | |
259 | if (next_sp - sp >= sizeof(struct signal_frame_64) && | |
260 | (is_sigreturn_64_address(next_ip, sp) || | |
261 | (level <= 1 && is_sigreturn_64_address(lr, sp))) && | |
262 | sane_signal_64_frame(sp)) { | |
263 | /* | |
264 | * This looks like an signal frame | |
265 | */ | |
266 | sigframe = (struct signal_frame_64 __user *) sp; | |
267 | uregs = sigframe->uc.uc_mcontext.gp_regs; | |
268 | if (read_user_stack_64(&uregs[PT_NIP], &next_ip) || | |
269 | read_user_stack_64(&uregs[PT_LNK], &lr) || | |
270 | read_user_stack_64(&uregs[PT_R1], &sp)) | |
271 | return; | |
272 | level = 0; | |
70791ce9 FW |
273 | perf_callchain_store(entry, PERF_CONTEXT_USER); |
274 | perf_callchain_store(entry, next_ip); | |
20002ded PM |
275 | continue; |
276 | } | |
277 | ||
278 | if (level == 0) | |
279 | next_ip = lr; | |
70791ce9 | 280 | perf_callchain_store(entry, next_ip); |
20002ded PM |
281 | ++level; |
282 | sp = next_sp; | |
283 | } | |
284 | } | |
285 | ||
286 | static inline int current_is_64bit(void) | |
287 | { | |
288 | /* | |
289 | * We can't use test_thread_flag() here because we may be on an | |
290 | * interrupt stack, and the thread flags don't get copied over | |
291 | * from the thread_info on the main stack to the interrupt stack. | |
292 | */ | |
293 | return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT); | |
294 | } | |
295 | ||
296 | #else /* CONFIG_PPC64 */ | |
297 | /* | |
298 | * On 32-bit we just access the address and let hash_page create a | |
299 | * HPTE if necessary, so there is no need to fall back to reading | |
300 | * the page tables. Since this is called at interrupt level, | |
301 | * do_page_fault() won't treat a DSI as a page fault. | |
302 | */ | |
303 | static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret) | |
304 | { | |
b59a1bfc DA |
305 | int rc; |
306 | ||
20002ded PM |
307 | if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) || |
308 | ((unsigned long)ptr & 3)) | |
309 | return -EFAULT; | |
310 | ||
b59a1bfc DA |
311 | pagefault_disable(); |
312 | rc = __get_user_inatomic(*ret, ptr); | |
313 | pagefault_enable(); | |
314 | ||
315 | return rc; | |
20002ded PM |
316 | } |
317 | ||
56962b44 FW |
318 | static inline void perf_callchain_user_64(struct perf_callchain_entry *entry, |
319 | struct pt_regs *regs) | |
20002ded PM |
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 | ||
56962b44 FW |
438 | static void perf_callchain_user_32(struct perf_callchain_entry *entry, |
439 | struct pt_regs *regs) | |
20002ded PM |
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]; | |
70791ce9 | 450 | perf_callchain_store(entry, next_ip); |
20002ded PM |
451 | |
452 | while (entry->nr < PERF_MAX_STACK_DEPTH) { | |
453 | fp = (unsigned int __user *) (unsigned long) sp; | |
454 | if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp)) | |
455 | return; | |
456 | if (level > 0 && read_user_stack_32(&fp[1], &next_ip)) | |
457 | return; | |
458 | ||
459 | uregs = signal_frame_32_regs(sp, next_sp, next_ip); | |
460 | if (!uregs && level <= 1) | |
461 | uregs = signal_frame_32_regs(sp, next_sp, lr); | |
462 | if (uregs) { | |
463 | /* | |
464 | * This looks like an signal frame, so restart | |
465 | * the stack trace with the values in it. | |
466 | */ | |
467 | if (read_user_stack_32(&uregs[PT_NIP], &next_ip) || | |
468 | read_user_stack_32(&uregs[PT_LNK], &lr) || | |
469 | read_user_stack_32(&uregs[PT_R1], &sp)) | |
470 | return; | |
471 | level = 0; | |
70791ce9 FW |
472 | perf_callchain_store(entry, PERF_CONTEXT_USER); |
473 | perf_callchain_store(entry, next_ip); | |
20002ded PM |
474 | continue; |
475 | } | |
476 | ||
477 | if (level == 0) | |
478 | next_ip = lr; | |
70791ce9 | 479 | perf_callchain_store(entry, next_ip); |
20002ded PM |
480 | ++level; |
481 | sp = next_sp; | |
482 | } | |
483 | } | |
484 | ||
56962b44 FW |
485 | void |
486 | perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) | |
20002ded | 487 | { |
56962b44 FW |
488 | if (current_is_64bit()) |
489 | perf_callchain_user_64(entry, regs); | |
490 | else | |
491 | perf_callchain_user_32(entry, regs); | |
20002ded | 492 | } |