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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
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 */
37
38/* Is address on the specified kernel stack? */
39static int in_kernel_stack(struct KBacktraceIterator *kbt, unsigned long sp)
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
47/* Is address valid for reading? */
48static int valid_address(struct KBacktraceIterator *kbt, unsigned long address)
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
56 if (l1_pgtable == NULL)
57 return 0; /* can't read user space in other tasks */
58
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
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)) {
82 pr_err("huge page has bad pfn %#lx\n", pfn);
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)) {
90 pr_err("L2 page table not in LOWMEM (%#llx)\n",
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 */
100static bool read_memory_func(void *result, unsigned long address,
101 unsigned int size, void *vkbt)
102{
103 int retval;
104 struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
105 if (__kernel_text_address(address)) {
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;
111 } else if (!valid_address(kbt, address)) {
112 return 0; /* invalid user-space address */
113 }
114 pagefault_disable();
115 retval = __copy_from_user_inatomic(result,
116 (void __user __force *)address,
117 size);
118 pagefault_enable();
119 return (retval == 0);
120}
121
122/* Return a pt_regs pointer for a valid fault handler frame */
123static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
124{
125 const char *fault = NULL; /* happy compiler */
126 char fault_buf[64];
127 unsigned long sp = kbt->it.sp;
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 &&
145 __kernel_text_address(p->pc) &&
146 in_kernel_stack(kbt, p->sp) &&
147 p->sp >= sp) {
148 if (kbt->verbose)
149 pr_err(" <%s while in kernel mode>\n", fault);
150 } else if (EX1_PL(p->ex1) == USER_PL &&
151 p->pc < PAGE_OFFSET &&
152 p->sp < PAGE_OFFSET) {
153 if (kbt->verbose)
154 pr_err(" <%s while in user mode>\n", fault);
155 } else if (kbt->verbose) {
156 pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
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;
162 return NULL;
163}
164
165/* Is the pc pointing to a sigreturn trampoline? */
166static int is_sigreturn(unsigned long pc)
167{
168 return (pc == VDSO_BASE);
169}
170
171/* Return a pt_regs pointer for a valid signal handler frame */
172static 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)
183 pr_err(" (odd signal: sp %#lx?)\n",
184 (unsigned long)(b->sp));
185 return NULL;
186 }
187 frame = (struct rt_sigframe *)b->sp;
188 if (kbt->verbose) {
189 pr_err(" <received signal %d>\n",
190 frame->info.si_signo);
191 }
192 return (struct pt_regs *)&frame->uc.uc_mcontext;
193 }
194 return NULL;
195}
196
197static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
198{
199 return is_sigreturn(kbt->it.pc);
200}
201
202static 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. */
218static int KBacktraceIterator_next_item_inclusive(
219 struct KBacktraceIterator *kbt)
220{
221 for (;;) {
222 do {
223 if (!KBacktraceIterator_is_sigreturn(kbt))
224 return KBT_ONGOING;
225 } while (backtrace_next(&kbt->it));
226
227 if (!KBacktraceIterator_restart(kbt))
228 return KBT_DONE;
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 */
240static 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) {
248 pr_err("WARNING: cpu %d: kernel stack page %#lx underrun!\n"
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)) {
254 pr_err("WARNING: cpu %d: kernel stack page %#lx overrun!\n"
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
260void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
261 struct task_struct *t, struct pt_regs *regs)
262{
263 unsigned long pc, lr, sp, r52;
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 */
281 kbt->end = KBT_ONGOING;
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
297 pr_err("page table not in LOWMEM"
298 " (%#llx)\n", pgdir_pa);
299 }
300 local_flush_tlb_all();
301 validate_stack(regs);
302 }
303
304 if (regs == NULL) {
305 if (is_current || t->state == TASK_RUNNING) {
306 /* Can't do this; we need registers */
307 kbt->end = KBT_RUNNING;
308 return;
309 }
310 pc = get_switch_to_pc();
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);
322 kbt->end = KBacktraceIterator_next_item_inclusive(kbt);
323}
324EXPORT_SYMBOL(KBacktraceIterator_init);
325
326int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
327{
328 return kbt->end != KBT_ONGOING;
329}
330EXPORT_SYMBOL(KBacktraceIterator_end);
331
332void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
333{
334 unsigned long old_pc = kbt->it.pc, old_sp = kbt->it.sp;
335 kbt->new_context = 0;
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 }
345}
346EXPORT_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 */
353void 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 */
363 pr_err("\n");
364 pr_err("Starting stack dump of tid %d, pid %d (%s)"
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 }
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
398 pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
399 i++, address, namebuf, (unsigned long)(kbt->it.sp));
400
401 if (i >= 100) {
402 pr_err("Stack dump truncated"
403 " (%d frames)\n", i);
404 break;
405 }
406 }
407 if (kbt->end == KBT_LOOP)
408 pr_err("Stack dump stopped; next frame identical to this one\n");
409 if (headers)
410 pr_err("Stack dump complete\n");
411}
412EXPORT_SYMBOL(tile_show_stack);
413
414
415/* This is called from show_regs() and _dump_stack() */
416void 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}
422EXPORT_SYMBOL(dump_stack_regs);
423
424static 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 */
436void _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() */
443void _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 */
452void 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
466void 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}
487EXPORT_SYMBOL(save_stack_trace_tsk);
488
489void save_stack_trace(struct stack_trace *trace)
490{
491 save_stack_trace_tsk(NULL, trace);
492}
493
494#endif
495
496/* In entry.S */
497EXPORT_SYMBOL(KBacktraceIterator_init_current);