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867e359b CM |
1 | /* |
2 | * Copyright 2010 Tilera Corporation. All Rights Reserved. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation, version 2. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but | |
9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or | |
11 | * NON INFRINGEMENT. See the GNU General Public License for | |
12 | * more details. | |
13 | */ | |
14 | ||
15 | #include <linux/sched.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/kprobes.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/pfn.h> | |
20 | #include <linux/kallsyms.h> | |
21 | #include <linux/stacktrace.h> | |
22 | #include <linux/uaccess.h> | |
23 | #include <linux/mmzone.h> | |
24 | #include <asm/backtrace.h> | |
25 | #include <asm/page.h> | |
26 | #include <asm/tlbflush.h> | |
27 | #include <asm/ucontext.h> | |
28 | #include <asm/sigframe.h> | |
29 | #include <asm/stack.h> | |
30 | #include <arch/abi.h> | |
31 | #include <arch/interrupts.h> | |
32 | ||
dabe98c9 CM |
33 | #define KBT_ONGOING 0 /* Backtrace still ongoing */ |
34 | #define KBT_DONE 1 /* Backtrace cleanly completed */ | |
35 | #define KBT_RUNNING 2 /* Can't run backtrace on a running task */ | |
36 | #define KBT_LOOP 3 /* Backtrace entered a loop */ | |
867e359b CM |
37 | |
38 | /* Is address on the specified kernel stack? */ | |
93013a0f | 39 | static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp) |
867e359b CM |
40 | { |
41 | ulong kstack_base = (ulong) kbt->task->stack; | |
42 | if (kstack_base == 0) /* corrupt task pointer; just follow stack... */ | |
43 | return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory; | |
44 | return sp >= kstack_base && sp < kstack_base + THREAD_SIZE; | |
45 | } | |
46 | ||
867e359b | 47 | /* Is address valid for reading? */ |
93013a0f | 48 | static int valid_address(struct KBacktraceIterator *kbt, unsigned long address) |
867e359b CM |
49 | { |
50 | HV_PTE *l1_pgtable = kbt->pgtable; | |
51 | HV_PTE *l2_pgtable; | |
52 | unsigned long pfn; | |
53 | HV_PTE pte; | |
54 | struct page *page; | |
55 | ||
0707ad30 CM |
56 | if (l1_pgtable == NULL) |
57 | return 0; /* can't read user space in other tasks */ | |
58 | ||
3cebbafd CM |
59 | #ifdef CONFIG_64BIT |
60 | /* Find the real l1_pgtable by looking in the l0_pgtable. */ | |
61 | pte = l1_pgtable[HV_L0_INDEX(address)]; | |
62 | if (!hv_pte_get_present(pte)) | |
63 | return 0; | |
64 | pfn = hv_pte_get_pfn(pte); | |
65 | if (pte_huge(pte)) { | |
66 | if (!pfn_valid(pfn)) { | |
67 | pr_err("L0 huge page has bad pfn %#lx\n", pfn); | |
68 | return 0; | |
69 | } | |
70 | return hv_pte_get_present(pte) && hv_pte_get_readable(pte); | |
71 | } | |
72 | page = pfn_to_page(pfn); | |
73 | BUG_ON(PageHighMem(page)); /* No HIGHMEM on 64-bit. */ | |
74 | l1_pgtable = (HV_PTE *)pfn_to_kaddr(pfn); | |
75 | #endif | |
867e359b CM |
76 | pte = l1_pgtable[HV_L1_INDEX(address)]; |
77 | if (!hv_pte_get_present(pte)) | |
78 | return 0; | |
79 | pfn = hv_pte_get_pfn(pte); | |
80 | if (pte_huge(pte)) { | |
81 | if (!pfn_valid(pfn)) { | |
0707ad30 | 82 | pr_err("huge page has bad pfn %#lx\n", pfn); |
867e359b CM |
83 | return 0; |
84 | } | |
85 | return hv_pte_get_present(pte) && hv_pte_get_readable(pte); | |
86 | } | |
87 | ||
88 | page = pfn_to_page(pfn); | |
89 | if (PageHighMem(page)) { | |
0707ad30 | 90 | pr_err("L2 page table not in LOWMEM (%#llx)\n", |
867e359b CM |
91 | HV_PFN_TO_CPA(pfn)); |
92 | return 0; | |
93 | } | |
94 | l2_pgtable = (HV_PTE *)pfn_to_kaddr(pfn); | |
95 | pte = l2_pgtable[HV_L2_INDEX(address)]; | |
96 | return hv_pte_get_present(pte) && hv_pte_get_readable(pte); | |
97 | } | |
98 | ||
99 | /* Callback for backtracer; basically a glorified memcpy */ | |
93013a0f | 100 | static bool read_memory_func(void *result, unsigned long address, |
867e359b CM |
101 | unsigned int size, void *vkbt) |
102 | { | |
103 | int retval; | |
104 | struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt; | |
3cebbafd | 105 | if (__kernel_text_address(address)) { |
867e359b CM |
106 | /* OK to read kernel code. */ |
107 | } else if (address >= PAGE_OFFSET) { | |
108 | /* We only tolerate kernel-space reads of this task's stack */ | |
109 | if (!in_kernel_stack(kbt, address)) | |
110 | return 0; | |
867e359b CM |
111 | } else if (!valid_address(kbt, address)) { |
112 | return 0; /* invalid user-space address */ | |
113 | } | |
114 | pagefault_disable(); | |
0707ad30 CM |
115 | retval = __copy_from_user_inatomic(result, |
116 | (void __user __force *)address, | |
867e359b CM |
117 | size); |
118 | pagefault_enable(); | |
119 | return (retval == 0); | |
120 | } | |
121 | ||
122 | /* Return a pt_regs pointer for a valid fault handler frame */ | |
123 | static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) | |
124 | { | |
867e359b CM |
125 | const char *fault = NULL; /* happy compiler */ |
126 | char fault_buf[64]; | |
93013a0f | 127 | unsigned long sp = kbt->it.sp; |
867e359b CM |
128 | struct pt_regs *p; |
129 | ||
130 | if (!in_kernel_stack(kbt, sp)) | |
131 | return NULL; | |
132 | if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1)) | |
133 | return NULL; | |
134 | p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE); | |
135 | if (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN) | |
136 | fault = "syscall"; | |
137 | else { | |
138 | if (kbt->verbose) { /* else we aren't going to use it */ | |
139 | snprintf(fault_buf, sizeof(fault_buf), | |
140 | "interrupt %ld", p->faultnum); | |
141 | fault = fault_buf; | |
142 | } | |
143 | } | |
144 | if (EX1_PL(p->ex1) == KERNEL_PL && | |
3cebbafd | 145 | __kernel_text_address(p->pc) && |
867e359b CM |
146 | in_kernel_stack(kbt, p->sp) && |
147 | p->sp >= sp) { | |
148 | if (kbt->verbose) | |
0707ad30 | 149 | pr_err(" <%s while in kernel mode>\n", fault); |
867e359b CM |
150 | } else if (EX1_PL(p->ex1) == USER_PL && |
151 | p->pc < PAGE_OFFSET && | |
152 | p->sp < PAGE_OFFSET) { | |
153 | if (kbt->verbose) | |
0707ad30 | 154 | pr_err(" <%s while in user mode>\n", fault); |
867e359b | 155 | } else if (kbt->verbose) { |
0707ad30 | 156 | pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n", |
867e359b CM |
157 | p->pc, p->sp, p->ex1); |
158 | p = NULL; | |
159 | } | |
160 | if (!kbt->profile || (INT_MASK(p->faultnum) & QUEUED_INTERRUPTS) == 0) | |
161 | return p; | |
867e359b CM |
162 | return NULL; |
163 | } | |
164 | ||
165 | /* Is the pc pointing to a sigreturn trampoline? */ | |
93013a0f | 166 | static int is_sigreturn(unsigned long pc) |
867e359b CM |
167 | { |
168 | return (pc == VDSO_BASE); | |
169 | } | |
170 | ||
171 | /* Return a pt_regs pointer for a valid signal handler frame */ | |
172 | static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt) | |
173 | { | |
174 | BacktraceIterator *b = &kbt->it; | |
175 | ||
176 | if (b->pc == VDSO_BASE) { | |
177 | struct rt_sigframe *frame; | |
178 | unsigned long sigframe_top = | |
179 | b->sp + sizeof(struct rt_sigframe) - 1; | |
180 | if (!valid_address(kbt, b->sp) || | |
181 | !valid_address(kbt, sigframe_top)) { | |
182 | if (kbt->verbose) | |
0707ad30 | 183 | pr_err(" (odd signal: sp %#lx?)\n", |
867e359b CM |
184 | (unsigned long)(b->sp)); |
185 | return NULL; | |
186 | } | |
187 | frame = (struct rt_sigframe *)b->sp; | |
188 | if (kbt->verbose) { | |
0707ad30 | 189 | pr_err(" <received signal %d>\n", |
867e359b CM |
190 | frame->info.si_signo); |
191 | } | |
74fca9da | 192 | return (struct pt_regs *)&frame->uc.uc_mcontext; |
867e359b CM |
193 | } |
194 | return NULL; | |
195 | } | |
196 | ||
0707ad30 | 197 | static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt) |
867e359b CM |
198 | { |
199 | return is_sigreturn(kbt->it.pc); | |
200 | } | |
201 | ||
202 | static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt) | |
203 | { | |
204 | struct pt_regs *p; | |
205 | ||
206 | p = valid_fault_handler(kbt); | |
207 | if (p == NULL) | |
208 | p = valid_sigframe(kbt); | |
209 | if (p == NULL) | |
210 | return 0; | |
211 | backtrace_init(&kbt->it, read_memory_func, kbt, | |
212 | p->pc, p->lr, p->sp, p->regs[52]); | |
213 | kbt->new_context = 1; | |
214 | return 1; | |
215 | } | |
216 | ||
217 | /* Find a frame that isn't a sigreturn, if there is one. */ | |
218 | static int KBacktraceIterator_next_item_inclusive( | |
219 | struct KBacktraceIterator *kbt) | |
220 | { | |
221 | for (;;) { | |
222 | do { | |
223 | if (!KBacktraceIterator_is_sigreturn(kbt)) | |
dabe98c9 | 224 | return KBT_ONGOING; |
867e359b CM |
225 | } while (backtrace_next(&kbt->it)); |
226 | ||
227 | if (!KBacktraceIterator_restart(kbt)) | |
dabe98c9 | 228 | return KBT_DONE; |
867e359b CM |
229 | } |
230 | } | |
231 | ||
232 | /* | |
233 | * If the current sp is on a page different than what we recorded | |
234 | * as the top-of-kernel-stack last time we context switched, we have | |
235 | * probably blown the stack, and nothing is going to work out well. | |
236 | * If we can at least get out a warning, that may help the debug, | |
237 | * though we probably won't be able to backtrace into the code that | |
238 | * actually did the recursive damage. | |
239 | */ | |
240 | static void validate_stack(struct pt_regs *regs) | |
241 | { | |
242 | int cpu = smp_processor_id(); | |
243 | unsigned long ksp0 = get_current_ksp0(); | |
244 | unsigned long ksp0_base = ksp0 - THREAD_SIZE; | |
245 | unsigned long sp = stack_pointer; | |
246 | ||
247 | if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) { | |
0707ad30 | 248 | pr_err("WARNING: cpu %d: kernel stack page %#lx underrun!\n" |
867e359b CM |
249 | " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n", |
250 | cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr); | |
251 | } | |
252 | ||
253 | else if (sp < ksp0_base + sizeof(struct thread_info)) { | |
0707ad30 | 254 | pr_err("WARNING: cpu %d: kernel stack page %#lx overrun!\n" |
867e359b CM |
255 | " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n", |
256 | cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr); | |
257 | } | |
258 | } | |
259 | ||
260 | void KBacktraceIterator_init(struct KBacktraceIterator *kbt, | |
261 | struct task_struct *t, struct pt_regs *regs) | |
262 | { | |
93013a0f | 263 | unsigned long pc, lr, sp, r52; |
867e359b CM |
264 | int is_current; |
265 | ||
266 | /* | |
267 | * Set up callback information. We grab the kernel stack base | |
268 | * so we will allow reads of that address range, and if we're | |
269 | * asking about the current process we grab the page table | |
270 | * so we can check user accesses before trying to read them. | |
271 | * We flush the TLB to avoid any weird skew issues. | |
272 | */ | |
273 | is_current = (t == NULL); | |
274 | kbt->is_current = is_current; | |
275 | if (is_current) | |
276 | t = validate_current(); | |
277 | kbt->task = t; | |
278 | kbt->pgtable = NULL; | |
279 | kbt->verbose = 0; /* override in caller if desired */ | |
280 | kbt->profile = 0; /* override in caller if desired */ | |
dabe98c9 | 281 | kbt->end = KBT_ONGOING; |
867e359b CM |
282 | kbt->new_context = 0; |
283 | if (is_current) { | |
284 | HV_PhysAddr pgdir_pa = hv_inquire_context().page_table; | |
285 | if (pgdir_pa == (unsigned long)swapper_pg_dir - PAGE_OFFSET) { | |
286 | /* | |
287 | * Not just an optimization: this also allows | |
288 | * this to work at all before va/pa mappings | |
289 | * are set up. | |
290 | */ | |
291 | kbt->pgtable = swapper_pg_dir; | |
292 | } else { | |
293 | struct page *page = pfn_to_page(PFN_DOWN(pgdir_pa)); | |
294 | if (!PageHighMem(page)) | |
295 | kbt->pgtable = __va(pgdir_pa); | |
296 | else | |
0707ad30 | 297 | pr_err("page table not in LOWMEM" |
867e359b CM |
298 | " (%#llx)\n", pgdir_pa); |
299 | } | |
300 | local_flush_tlb_all(); | |
301 | validate_stack(regs); | |
302 | } | |
303 | ||
304 | if (regs == NULL) { | |
867e359b CM |
305 | if (is_current || t->state == TASK_RUNNING) { |
306 | /* Can't do this; we need registers */ | |
dabe98c9 | 307 | kbt->end = KBT_RUNNING; |
867e359b CM |
308 | return; |
309 | } | |
0707ad30 | 310 | pc = get_switch_to_pc(); |
867e359b CM |
311 | lr = t->thread.pc; |
312 | sp = t->thread.ksp; | |
313 | r52 = 0; | |
314 | } else { | |
315 | pc = regs->pc; | |
316 | lr = regs->lr; | |
317 | sp = regs->sp; | |
318 | r52 = regs->regs[52]; | |
319 | } | |
320 | ||
321 | backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52); | |
dabe98c9 | 322 | kbt->end = KBacktraceIterator_next_item_inclusive(kbt); |
867e359b CM |
323 | } |
324 | EXPORT_SYMBOL(KBacktraceIterator_init); | |
325 | ||
326 | int KBacktraceIterator_end(struct KBacktraceIterator *kbt) | |
327 | { | |
dabe98c9 | 328 | return kbt->end != KBT_ONGOING; |
867e359b CM |
329 | } |
330 | EXPORT_SYMBOL(KBacktraceIterator_end); | |
331 | ||
332 | void KBacktraceIterator_next(struct KBacktraceIterator *kbt) | |
333 | { | |
93013a0f | 334 | unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp; |
867e359b | 335 | kbt->new_context = 0; |
dabe98c9 CM |
336 | if (!backtrace_next(&kbt->it) && !KBacktraceIterator_restart(kbt)) { |
337 | kbt->end = KBT_DONE; | |
338 | return; | |
339 | } | |
340 | kbt->end = KBacktraceIterator_next_item_inclusive(kbt); | |
341 | if (old_pc == kbt->it.pc && old_sp == kbt->it.sp) { | |
342 | /* Trapped in a loop; give up. */ | |
343 | kbt->end = KBT_LOOP; | |
344 | } | |
867e359b CM |
345 | } |
346 | EXPORT_SYMBOL(KBacktraceIterator_next); | |
347 | ||
348 | /* | |
349 | * This method wraps the backtracer's more generic support. | |
350 | * It is only invoked from the architecture-specific code; show_stack() | |
351 | * and dump_stack() (in entry.S) are architecture-independent entry points. | |
352 | */ | |
353 | void tile_show_stack(struct KBacktraceIterator *kbt, int headers) | |
354 | { | |
355 | int i; | |
356 | ||
357 | if (headers) { | |
358 | /* | |
359 | * Add a blank line since if we are called from panic(), | |
360 | * then bust_spinlocks() spit out a space in front of us | |
361 | * and it will mess up our KERN_ERR. | |
362 | */ | |
0707ad30 CM |
363 | pr_err("\n"); |
364 | pr_err("Starting stack dump of tid %d, pid %d (%s)" | |
867e359b CM |
365 | " on cpu %d at cycle %lld\n", |
366 | kbt->task->pid, kbt->task->tgid, kbt->task->comm, | |
367 | smp_processor_id(), get_cycles()); | |
368 | } | |
867e359b CM |
369 | kbt->verbose = 1; |
370 | i = 0; | |
371 | for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) { | |
372 | char *modname; | |
373 | const char *name; | |
374 | unsigned long address = kbt->it.pc; | |
375 | unsigned long offset, size; | |
376 | char namebuf[KSYM_NAME_LEN+100]; | |
377 | ||
378 | if (address >= PAGE_OFFSET) | |
379 | name = kallsyms_lookup(address, &size, &offset, | |
380 | &modname, namebuf); | |
381 | else | |
382 | name = NULL; | |
383 | ||
384 | if (!name) | |
385 | namebuf[0] = '\0'; | |
386 | else { | |
387 | size_t namelen = strlen(namebuf); | |
388 | size_t remaining = (sizeof(namebuf) - 1) - namelen; | |
389 | char *p = namebuf + namelen; | |
390 | int rc = snprintf(p, remaining, "+%#lx/%#lx ", | |
391 | offset, size); | |
392 | if (modname && rc < remaining) | |
393 | snprintf(p + rc, remaining - rc, | |
394 | "[%s] ", modname); | |
395 | namebuf[sizeof(namebuf)-1] = '\0'; | |
396 | } | |
397 | ||
0707ad30 | 398 | pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n", |
867e359b CM |
399 | i++, address, namebuf, (unsigned long)(kbt->it.sp)); |
400 | ||
401 | if (i >= 100) { | |
0707ad30 | 402 | pr_err("Stack dump truncated" |
867e359b CM |
403 | " (%d frames)\n", i); |
404 | break; | |
405 | } | |
406 | } | |
dabe98c9 CM |
407 | if (kbt->end == KBT_LOOP) |
408 | pr_err("Stack dump stopped; next frame identical to this one\n"); | |
867e359b | 409 | if (headers) |
0707ad30 | 410 | pr_err("Stack dump complete\n"); |
867e359b CM |
411 | } |
412 | EXPORT_SYMBOL(tile_show_stack); | |
413 | ||
414 | ||
415 | /* This is called from show_regs() and _dump_stack() */ | |
416 | void dump_stack_regs(struct pt_regs *regs) | |
417 | { | |
418 | struct KBacktraceIterator kbt; | |
419 | KBacktraceIterator_init(&kbt, NULL, regs); | |
420 | tile_show_stack(&kbt, 1); | |
421 | } | |
422 | EXPORT_SYMBOL(dump_stack_regs); | |
423 | ||
424 | static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs, | |
425 | ulong pc, ulong lr, ulong sp, ulong r52) | |
426 | { | |
427 | memset(regs, 0, sizeof(struct pt_regs)); | |
428 | regs->pc = pc; | |
429 | regs->lr = lr; | |
430 | regs->sp = sp; | |
431 | regs->regs[52] = r52; | |
432 | return regs; | |
433 | } | |
434 | ||
435 | /* This is called from dump_stack() and just converts to pt_regs */ | |
436 | void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52) | |
437 | { | |
438 | struct pt_regs regs; | |
439 | dump_stack_regs(regs_to_pt_regs(®s, pc, lr, sp, r52)); | |
440 | } | |
441 | ||
442 | /* This is called from KBacktraceIterator_init_current() */ | |
443 | void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc, | |
444 | ulong lr, ulong sp, ulong r52) | |
445 | { | |
446 | struct pt_regs regs; | |
447 | KBacktraceIterator_init(kbt, NULL, | |
448 | regs_to_pt_regs(®s, pc, lr, sp, r52)); | |
449 | } | |
450 | ||
451 | /* This is called only from kernel/sched.c, with esp == NULL */ | |
452 | void show_stack(struct task_struct *task, unsigned long *esp) | |
453 | { | |
454 | struct KBacktraceIterator kbt; | |
455 | if (task == NULL || task == current) | |
456 | KBacktraceIterator_init_current(&kbt); | |
457 | else | |
458 | KBacktraceIterator_init(&kbt, task, NULL); | |
459 | tile_show_stack(&kbt, 0); | |
460 | } | |
461 | ||
462 | #ifdef CONFIG_STACKTRACE | |
463 | ||
464 | /* Support generic Linux stack API too */ | |
465 | ||
466 | void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace) | |
467 | { | |
468 | struct KBacktraceIterator kbt; | |
469 | int skip = trace->skip; | |
470 | int i = 0; | |
471 | ||
472 | if (task == NULL || task == current) | |
473 | KBacktraceIterator_init_current(&kbt); | |
474 | else | |
475 | KBacktraceIterator_init(&kbt, task, NULL); | |
476 | for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) { | |
477 | if (skip) { | |
478 | --skip; | |
479 | continue; | |
480 | } | |
481 | if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET) | |
482 | break; | |
483 | trace->entries[i++] = kbt.it.pc; | |
484 | } | |
485 | trace->nr_entries = i; | |
486 | } | |
487 | EXPORT_SYMBOL(save_stack_trace_tsk); | |
488 | ||
489 | void save_stack_trace(struct stack_trace *trace) | |
490 | { | |
491 | save_stack_trace_tsk(NULL, trace); | |
492 | } | |
493 | ||
494 | #endif | |
495 | ||
496 | /* In entry.S */ | |
497 | EXPORT_SYMBOL(KBacktraceIterator_init_current); |