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>
13 #include <linux/perf_event.h>
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 "../kernel/ppc32.h"
24 #endif
25
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 */
valid_next_sp(unsigned long sp,unsigned long prev_sp)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_MIN_SIZE)
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
49 void
perf_callchain_kernel(struct perf_callchain_entry * entry,struct pt_regs * regs)50 perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
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];
60 perf_callchain_store(entry, perf_instruction_pointer(regs));
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;
79 perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
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
101 perf_callchain_store(entry, next_ip);
102 if (!valid_next_sp(next_sp, sp))
103 return;
104 sp = next_sp;
105 }
106 }
107
108 #ifdef CONFIG_PPC64
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 */
read_user_stack_slow(void __user * ptr,void * ret,int nb)114 static int read_user_stack_slow(void __user *ptr, void *ret, int nb)
115 {
116 pgd_t *pgdir;
117 pte_t *ptep, pte;
118 unsigned shift;
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
128 ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
129 if (!shift)
130 shift = PAGE_SHIFT;
131
132 /* align address to page boundary */
133 offset = addr & ((1UL << shift) - 1);
134 addr -= offset;
135
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
read_user_stack_64(unsigned long __user * ptr,unsigned long * ret)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
157 pagefault_disable();
158 if (!__get_user_inatomic(*ret, ptr)) {
159 pagefault_enable();
160 return 0;
161 }
162 pagefault_enable();
163
164 return read_user_stack_slow(ptr, ret, 8);
165 }
166
read_user_stack_32(unsigned int __user * ptr,unsigned int * ret)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
173 pagefault_disable();
174 if (!__get_user_inatomic(*ret, ptr)) {
175 pagefault_enable();
176 return 0;
177 }
178 pagefault_enable();
179
180 return read_user_stack_slow(ptr, ret, 4);
181 }
182
valid_user_sp(unsigned long sp,int is_64)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
is_sigreturn_64_address(unsigned long nip,unsigned long fp)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 */
sane_signal_64_frame(unsigned long sp)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
perf_callchain_user_64(struct perf_callchain_entry * entry,struct pt_regs * regs)231 static void perf_callchain_user_64(struct perf_callchain_entry *entry,
232 struct pt_regs *regs)
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 = perf_instruction_pointer(regs);
242 lr = regs->link;
243 sp = regs->gpr[1];
244 perf_callchain_store(entry, next_ip);
245
246 while (entry->nr < PERF_MAX_STACK_DEPTH) {
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;
273 perf_callchain_store(entry, PERF_CONTEXT_USER);
274 perf_callchain_store(entry, next_ip);
275 continue;
276 }
277
278 if (level == 0)
279 next_ip = lr;
280 perf_callchain_store(entry, next_ip);
281 ++level;
282 sp = next_sp;
283 }
284 }
285
current_is_64bit(void)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 */
read_user_stack_32(unsigned int __user * ptr,unsigned int * ret)303 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
304 {
305 int rc;
306
307 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
308 ((unsigned long)ptr & 3))
309 return -EFAULT;
310
311 pagefault_disable();
312 rc = __get_user_inatomic(*ret, ptr);
313 pagefault_enable();
314
315 return rc;
316 }
317
perf_callchain_user_64(struct perf_callchain_entry * entry,struct pt_regs * regs)318 static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
319 struct pt_regs *regs)
320 {
321 }
322
current_is_64bit(void)323 static inline int current_is_64bit(void)
324 {
325 return 0;
326 }
327
valid_user_sp(unsigned long sp,int is_64)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
is_sigreturn_32_address(unsigned int nip,unsigned int fp)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
is_rt_sigreturn_32_address(unsigned int nip,unsigned int fp)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
sane_signal_32_frame(unsigned int sp)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
sane_rt_signal_32_frame(unsigned int sp)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
signal_frame_32_regs(unsigned int sp,unsigned int next_sp,unsigned int next_ip)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
perf_callchain_user_32(struct perf_callchain_entry * entry,struct pt_regs * regs)438 static void perf_callchain_user_32(struct perf_callchain_entry *entry,
439 struct pt_regs *regs)
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 = perf_instruction_pointer(regs);
448 lr = regs->link;
449 sp = regs->gpr[1];
450 perf_callchain_store(entry, next_ip);
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;
472 perf_callchain_store(entry, PERF_CONTEXT_USER);
473 perf_callchain_store(entry, next_ip);
474 continue;
475 }
476
477 if (level == 0)
478 next_ip = lr;
479 perf_callchain_store(entry, next_ip);
480 ++level;
481 sp = next_sp;
482 }
483 }
484
485 void
perf_callchain_user(struct perf_callchain_entry * entry,struct pt_regs * regs)486 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
487 {
488 if (current_is_64bit())
489 perf_callchain_user_64(entry, regs);
490 else
491 perf_callchain_user_32(entry, regs);
492 }
493