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[linux-2.6/next.git] / arch / powerpc / kernel / perf_callchain.c
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1 /*
2 * Performance counter callchain support - powerpc architecture code
4 * Copyright © 2009 Paul Mackerras, IBM Corporation.
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.
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 "ppc32.h"
24 #endif
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.
32 static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
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;
41 * sp could decrease when we jump off an interrupt stack
42 * back to the regular process stack.
44 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
45 return 1;
46 return 0;
49 void
50 perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
52 unsigned long sp, next_sp;
53 unsigned long next_ip;
54 unsigned long lr;
55 long level = 0;
56 unsigned long *fp;
58 lr = regs->link;
59 sp = regs->gpr[1];
60 perf_callchain_store(entry, regs->nip);
62 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
63 return;
65 for (;;) {
66 fp = (unsigned long *) sp;
67 next_sp = fp[0];
69 if (next_sp == sp + STACK_INT_FRAME_SIZE &&
70 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
72 * This looks like an interrupt frame for an
73 * interrupt that occurred in the kernel
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);
81 } else {
82 if (level == 0)
83 next_ip = lr;
84 else
85 next_ip = fp[STACK_FRAME_LR_SAVE];
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.
94 if ((level == 1 && next_ip == lr) ||
95 (level <= 1 && !kernel_text_address(next_ip)))
96 next_ip = 0;
98 ++level;
101 perf_callchain_store(entry, next_ip);
102 if (!valid_next_sp(next_sp, sp))
103 return;
104 sp = next_sp;
108 #ifdef CONFIG_PPC64
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.
114 static int read_user_stack_slow(void __user *ptr, void *ret, int nb)
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;
124 pgdir = current->mm->pgd;
125 if (!pgdir)
126 return -EFAULT;
128 ptep = find_linux_pte_or_hugepte(pgdir, addr, &shift);
129 if (!shift)
130 shift = PAGE_SHIFT;
132 /* align address to page boundary */
133 offset = addr & ((1UL << shift) - 1);
134 addr -= offset;
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;
145 /* no highmem to worry about here */
146 kaddr = pfn_to_kaddr(pfn);
147 memcpy(ret, kaddr + offset, nb);
148 return 0;
151 static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
153 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
154 ((unsigned long)ptr & 7))
155 return -EFAULT;
157 if (!__get_user_inatomic(*ret, ptr))
158 return 0;
160 return read_user_stack_slow(ptr, ret, 8);
163 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
165 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
166 ((unsigned long)ptr & 3))
167 return -EFAULT;
169 if (!__get_user_inatomic(*ret, ptr))
170 return 0;
172 return read_user_stack_slow(ptr, ret, 4);
175 static inline int valid_user_sp(unsigned long sp, int is_64)
177 if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
178 return 0;
179 return 1;
183 * 64-bit user processes use the same stack frame for RT and non-RT signals.
185 struct signal_frame_64 {
186 char dummy[__SIGNAL_FRAMESIZE];
187 struct ucontext uc;
188 unsigned long unused[2];
189 unsigned int tramp[6];
190 struct siginfo *pinfo;
191 void *puc;
192 struct siginfo info;
193 char abigap[288];
196 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
198 if (nip == fp + offsetof(struct signal_frame_64, tramp))
199 return 1;
200 if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
201 nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
202 return 1;
203 return 0;
207 * Do some sanity checking on the signal frame pointed to by sp.
208 * We check the pinfo and puc pointers in the frame.
210 static int sane_signal_64_frame(unsigned long sp)
212 struct signal_frame_64 __user *sf;
213 unsigned long pinfo, puc;
215 sf = (struct signal_frame_64 __user *) sp;
216 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
217 read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
218 return 0;
219 return pinfo == (unsigned long) &sf->info &&
220 puc == (unsigned long) &sf->uc;
223 static void perf_callchain_user_64(struct perf_callchain_entry *entry,
224 struct pt_regs *regs)
226 unsigned long sp, next_sp;
227 unsigned long next_ip;
228 unsigned long lr;
229 long level = 0;
230 struct signal_frame_64 __user *sigframe;
231 unsigned long __user *fp, *uregs;
233 next_ip = regs->nip;
234 lr = regs->link;
235 sp = regs->gpr[1];
236 perf_callchain_store(entry, next_ip);
238 for (;;) {
239 fp = (unsigned long __user *) sp;
240 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
241 return;
242 if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
243 return;
246 * Note: the next_sp - sp >= signal frame size check
247 * is true when next_sp < sp, which can happen when
248 * transitioning from an alternate signal stack to the
249 * normal stack.
251 if (next_sp - sp >= sizeof(struct signal_frame_64) &&
252 (is_sigreturn_64_address(next_ip, sp) ||
253 (level <= 1 && is_sigreturn_64_address(lr, sp))) &&
254 sane_signal_64_frame(sp)) {
256 * This looks like an signal frame
258 sigframe = (struct signal_frame_64 __user *) sp;
259 uregs = sigframe->uc.uc_mcontext.gp_regs;
260 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
261 read_user_stack_64(&uregs[PT_LNK], &lr) ||
262 read_user_stack_64(&uregs[PT_R1], &sp))
263 return;
264 level = 0;
265 perf_callchain_store(entry, PERF_CONTEXT_USER);
266 perf_callchain_store(entry, next_ip);
267 continue;
270 if (level == 0)
271 next_ip = lr;
272 perf_callchain_store(entry, next_ip);
273 ++level;
274 sp = next_sp;
278 static inline int current_is_64bit(void)
281 * We can't use test_thread_flag() here because we may be on an
282 * interrupt stack, and the thread flags don't get copied over
283 * from the thread_info on the main stack to the interrupt stack.
285 return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
288 #else /* CONFIG_PPC64 */
290 * On 32-bit we just access the address and let hash_page create a
291 * HPTE if necessary, so there is no need to fall back to reading
292 * the page tables. Since this is called at interrupt level,
293 * do_page_fault() won't treat a DSI as a page fault.
295 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
297 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
298 ((unsigned long)ptr & 3))
299 return -EFAULT;
301 return __get_user_inatomic(*ret, ptr);
304 static inline void perf_callchain_user_64(struct perf_callchain_entry *entry,
305 struct pt_regs *regs)
309 static inline int current_is_64bit(void)
311 return 0;
314 static inline int valid_user_sp(unsigned long sp, int is_64)
316 if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
317 return 0;
318 return 1;
321 #define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
322 #define sigcontext32 sigcontext
323 #define mcontext32 mcontext
324 #define ucontext32 ucontext
325 #define compat_siginfo_t struct siginfo
327 #endif /* CONFIG_PPC64 */
330 * Layout for non-RT signal frames
332 struct signal_frame_32 {
333 char dummy[__SIGNAL_FRAMESIZE32];
334 struct sigcontext32 sctx;
335 struct mcontext32 mctx;
336 int abigap[56];
340 * Layout for RT signal frames
342 struct rt_signal_frame_32 {
343 char dummy[__SIGNAL_FRAMESIZE32 + 16];
344 compat_siginfo_t info;
345 struct ucontext32 uc;
346 int abigap[56];
349 static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
351 if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
352 return 1;
353 if (vdso32_sigtramp && current->mm->context.vdso_base &&
354 nip == current->mm->context.vdso_base + vdso32_sigtramp)
355 return 1;
356 return 0;
359 static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
361 if (nip == fp + offsetof(struct rt_signal_frame_32,
362 uc.uc_mcontext.mc_pad))
363 return 1;
364 if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
365 nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
366 return 1;
367 return 0;
370 static int sane_signal_32_frame(unsigned int sp)
372 struct signal_frame_32 __user *sf;
373 unsigned int regs;
375 sf = (struct signal_frame_32 __user *) (unsigned long) sp;
376 if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, &regs))
377 return 0;
378 return regs == (unsigned long) &sf->mctx;
381 static int sane_rt_signal_32_frame(unsigned int sp)
383 struct rt_signal_frame_32 __user *sf;
384 unsigned int regs;
386 sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
387 if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, &regs))
388 return 0;
389 return regs == (unsigned long) &sf->uc.uc_mcontext;
392 static unsigned int __user *signal_frame_32_regs(unsigned int sp,
393 unsigned int next_sp, unsigned int next_ip)
395 struct mcontext32 __user *mctx = NULL;
396 struct signal_frame_32 __user *sf;
397 struct rt_signal_frame_32 __user *rt_sf;
400 * Note: the next_sp - sp >= signal frame size check
401 * is true when next_sp < sp, for example, when
402 * transitioning from an alternate signal stack to the
403 * normal stack.
405 if (next_sp - sp >= sizeof(struct signal_frame_32) &&
406 is_sigreturn_32_address(next_ip, sp) &&
407 sane_signal_32_frame(sp)) {
408 sf = (struct signal_frame_32 __user *) (unsigned long) sp;
409 mctx = &sf->mctx;
412 if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
413 is_rt_sigreturn_32_address(next_ip, sp) &&
414 sane_rt_signal_32_frame(sp)) {
415 rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
416 mctx = &rt_sf->uc.uc_mcontext;
419 if (!mctx)
420 return NULL;
421 return mctx->mc_gregs;
424 static void perf_callchain_user_32(struct perf_callchain_entry *entry,
425 struct pt_regs *regs)
427 unsigned int sp, next_sp;
428 unsigned int next_ip;
429 unsigned int lr;
430 long level = 0;
431 unsigned int __user *fp, *uregs;
433 next_ip = regs->nip;
434 lr = regs->link;
435 sp = regs->gpr[1];
436 perf_callchain_store(entry, next_ip);
438 while (entry->nr < PERF_MAX_STACK_DEPTH) {
439 fp = (unsigned int __user *) (unsigned long) sp;
440 if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
441 return;
442 if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
443 return;
445 uregs = signal_frame_32_regs(sp, next_sp, next_ip);
446 if (!uregs && level <= 1)
447 uregs = signal_frame_32_regs(sp, next_sp, lr);
448 if (uregs) {
450 * This looks like an signal frame, so restart
451 * the stack trace with the values in it.
453 if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
454 read_user_stack_32(&uregs[PT_LNK], &lr) ||
455 read_user_stack_32(&uregs[PT_R1], &sp))
456 return;
457 level = 0;
458 perf_callchain_store(entry, PERF_CONTEXT_USER);
459 perf_callchain_store(entry, next_ip);
460 continue;
463 if (level == 0)
464 next_ip = lr;
465 perf_callchain_store(entry, next_ip);
466 ++level;
467 sp = next_sp;
471 void
472 perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
474 if (current_is_64bit())
475 perf_callchain_user_64(entry, regs);
476 else
477 perf_callchain_user_32(entry, regs);