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-rw-r--r--arch/tile/kernel/stack.c478
1 files changed, 478 insertions, 0 deletions
diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c
new file mode 100644
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+++ b/arch/tile/kernel/stack.c
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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
34/* Is address on the specified kernel stack? */
35static int in_kernel_stack(struct KBacktraceIterator *kbt, VirtualAddress sp)
36{
37 ulong kstack_base = (ulong) kbt->task->stack;
38 if (kstack_base == 0) /* corrupt task pointer; just follow stack... */
39 return sp >= PAGE_OFFSET && sp < (unsigned long)high_memory;
40 return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;
41}
42
43/* Is address in the specified kernel code? */
44static int in_kernel_text(VirtualAddress address)
45{
46 return (address >= MEM_SV_INTRPT &&
47 address < MEM_SV_INTRPT + HPAGE_SIZE);
48}
49
50/* Is address valid for reading? */
51static int valid_address(struct KBacktraceIterator *kbt, VirtualAddress address)
52{
53 HV_PTE *l1_pgtable = kbt->pgtable;
54 HV_PTE *l2_pgtable;
55 unsigned long pfn;
56 HV_PTE pte;
57 struct page *page;
58
59 if (l1_pgtable == NULL)
60 return 0; /* can't read user space in other tasks */
61
62 pte = l1_pgtable[HV_L1_INDEX(address)];
63 if (!hv_pte_get_present(pte))
64 return 0;
65 pfn = hv_pte_get_pfn(pte);
66 if (pte_huge(pte)) {
67 if (!pfn_valid(pfn)) {
68 pr_err("huge page has bad pfn %#lx\n", pfn);
69 return 0;
70 }
71 return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
72 }
73
74 page = pfn_to_page(pfn);
75 if (PageHighMem(page)) {
76 pr_err("L2 page table not in LOWMEM (%#llx)\n",
77 HV_PFN_TO_CPA(pfn));
78 return 0;
79 }
80 l2_pgtable = (HV_PTE *)pfn_to_kaddr(pfn);
81 pte = l2_pgtable[HV_L2_INDEX(address)];
82 return hv_pte_get_present(pte) && hv_pte_get_readable(pte);
83}
84
85/* Callback for backtracer; basically a glorified memcpy */
86static bool read_memory_func(void *result, VirtualAddress address,
87 unsigned int size, void *vkbt)
88{
89 int retval;
90 struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;
91 if (in_kernel_text(address)) {
92 /* OK to read kernel code. */
93 } else if (address >= PAGE_OFFSET) {
94 /* We only tolerate kernel-space reads of this task's stack */
95 if (!in_kernel_stack(kbt, address))
96 return 0;
97 } else if (!valid_address(kbt, address)) {
98 return 0; /* invalid user-space address */
99 }
100 pagefault_disable();
101 retval = __copy_from_user_inatomic(result,
102 (void __user __force *)address,
103 size);
104 pagefault_enable();
105 return (retval == 0);
106}
107
108/* Return a pt_regs pointer for a valid fault handler frame */
109static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
110{
111 const char *fault = NULL; /* happy compiler */
112 char fault_buf[64];
113 VirtualAddress sp = kbt->it.sp;
114 struct pt_regs *p;
115
116 if (!in_kernel_stack(kbt, sp))
117 return NULL;
118 if (!in_kernel_stack(kbt, sp + C_ABI_SAVE_AREA_SIZE + PTREGS_SIZE-1))
119 return NULL;
120 p = (struct pt_regs *)(sp + C_ABI_SAVE_AREA_SIZE);
121 if (p->faultnum == INT_SWINT_1 || p->faultnum == INT_SWINT_1_SIGRETURN)
122 fault = "syscall";
123 else {
124 if (kbt->verbose) { /* else we aren't going to use it */
125 snprintf(fault_buf, sizeof(fault_buf),
126 "interrupt %ld", p->faultnum);
127 fault = fault_buf;
128 }
129 }
130 if (EX1_PL(p->ex1) == KERNEL_PL &&
131 in_kernel_text(p->pc) &&
132 in_kernel_stack(kbt, p->sp) &&
133 p->sp >= sp) {
134 if (kbt->verbose)
135 pr_err(" <%s while in kernel mode>\n", fault);
136 } else if (EX1_PL(p->ex1) == USER_PL &&
137 p->pc < PAGE_OFFSET &&
138 p->sp < PAGE_OFFSET) {
139 if (kbt->verbose)
140 pr_err(" <%s while in user mode>\n", fault);
141 } else if (kbt->verbose) {
142 pr_err(" (odd fault: pc %#lx, sp %#lx, ex1 %#lx?)\n",
143 p->pc, p->sp, p->ex1);
144 p = NULL;
145 }
146 if (!kbt->profile || (INT_MASK(p->faultnum) & QUEUED_INTERRUPTS) == 0)
147 return p;
148 return NULL;
149}
150
151/* Is the pc pointing to a sigreturn trampoline? */
152static int is_sigreturn(VirtualAddress pc)
153{
154 return (pc == VDSO_BASE);
155}
156
157/* Return a pt_regs pointer for a valid signal handler frame */
158static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt)
159{
160 BacktraceIterator *b = &kbt->it;
161
162 if (b->pc == VDSO_BASE) {
163 struct rt_sigframe *frame;
164 unsigned long sigframe_top =
165 b->sp + sizeof(struct rt_sigframe) - 1;
166 if (!valid_address(kbt, b->sp) ||
167 !valid_address(kbt, sigframe_top)) {
168 if (kbt->verbose)
169 pr_err(" (odd signal: sp %#lx?)\n",
170 (unsigned long)(b->sp));
171 return NULL;
172 }
173 frame = (struct rt_sigframe *)b->sp;
174 if (kbt->verbose) {
175 pr_err(" <received signal %d>\n",
176 frame->info.si_signo);
177 }
178 return (struct pt_regs *)&frame->uc.uc_mcontext;
179 }
180 return NULL;
181}
182
183static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
184{
185 return is_sigreturn(kbt->it.pc);
186}
187
188static int KBacktraceIterator_restart(struct KBacktraceIterator *kbt)
189{
190 struct pt_regs *p;
191
192 p = valid_fault_handler(kbt);
193 if (p == NULL)
194 p = valid_sigframe(kbt);
195 if (p == NULL)
196 return 0;
197 backtrace_init(&kbt->it, read_memory_func, kbt,
198 p->pc, p->lr, p->sp, p->regs[52]);
199 kbt->new_context = 1;
200 return 1;
201}
202
203/* Find a frame that isn't a sigreturn, if there is one. */
204static int KBacktraceIterator_next_item_inclusive(
205 struct KBacktraceIterator *kbt)
206{
207 for (;;) {
208 do {
209 if (!KBacktraceIterator_is_sigreturn(kbt))
210 return 1;
211 } while (backtrace_next(&kbt->it));
212
213 if (!KBacktraceIterator_restart(kbt))
214 return 0;
215 }
216}
217
218/*
219 * If the current sp is on a page different than what we recorded
220 * as the top-of-kernel-stack last time we context switched, we have
221 * probably blown the stack, and nothing is going to work out well.
222 * If we can at least get out a warning, that may help the debug,
223 * though we probably won't be able to backtrace into the code that
224 * actually did the recursive damage.
225 */
226static void validate_stack(struct pt_regs *regs)
227{
228 int cpu = smp_processor_id();
229 unsigned long ksp0 = get_current_ksp0();
230 unsigned long ksp0_base = ksp0 - THREAD_SIZE;
231 unsigned long sp = stack_pointer;
232
233 if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
234 pr_err("WARNING: cpu %d: kernel stack page %#lx underrun!\n"
235 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
236 cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
237 }
238
239 else if (sp < ksp0_base + sizeof(struct thread_info)) {
240 pr_err("WARNING: cpu %d: kernel stack page %#lx overrun!\n"
241 " sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
242 cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
243 }
244}
245
246void KBacktraceIterator_init(struct KBacktraceIterator *kbt,
247 struct task_struct *t, struct pt_regs *regs)
248{
249 VirtualAddress pc, lr, sp, r52;
250 int is_current;
251
252 /*
253 * Set up callback information. We grab the kernel stack base
254 * so we will allow reads of that address range, and if we're
255 * asking about the current process we grab the page table
256 * so we can check user accesses before trying to read them.
257 * We flush the TLB to avoid any weird skew issues.
258 */
259 is_current = (t == NULL);
260 kbt->is_current = is_current;
261 if (is_current)
262 t = validate_current();
263 kbt->task = t;
264 kbt->pgtable = NULL;
265 kbt->verbose = 0; /* override in caller if desired */
266 kbt->profile = 0; /* override in caller if desired */
267 kbt->end = 0;
268 kbt->new_context = 0;
269 if (is_current) {
270 HV_PhysAddr pgdir_pa = hv_inquire_context().page_table;
271 if (pgdir_pa == (unsigned long)swapper_pg_dir - PAGE_OFFSET) {
272 /*
273 * Not just an optimization: this also allows
274 * this to work at all before va/pa mappings
275 * are set up.
276 */
277 kbt->pgtable = swapper_pg_dir;
278 } else {
279 struct page *page = pfn_to_page(PFN_DOWN(pgdir_pa));
280 if (!PageHighMem(page))
281 kbt->pgtable = __va(pgdir_pa);
282 else
283 pr_err("page table not in LOWMEM"
284 " (%#llx)\n", pgdir_pa);
285 }
286 local_flush_tlb_all();
287 validate_stack(regs);
288 }
289
290 if (regs == NULL) {
291 if (is_current || t->state == TASK_RUNNING) {
292 /* Can't do this; we need registers */
293 kbt->end = 1;
294 return;
295 }
296 pc = get_switch_to_pc();
297 lr = t->thread.pc;
298 sp = t->thread.ksp;
299 r52 = 0;
300 } else {
301 pc = regs->pc;
302 lr = regs->lr;
303 sp = regs->sp;
304 r52 = regs->regs[52];
305 }
306
307 backtrace_init(&kbt->it, read_memory_func, kbt, pc, lr, sp, r52);
308 kbt->end = !KBacktraceIterator_next_item_inclusive(kbt);
309}
310EXPORT_SYMBOL(KBacktraceIterator_init);
311
312int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
313{
314 return kbt->end;
315}
316EXPORT_SYMBOL(KBacktraceIterator_end);
317
318void KBacktraceIterator_next(struct KBacktraceIterator *kbt)
319{
320 kbt->new_context = 0;
321 if (!backtrace_next(&kbt->it) &&
322 !KBacktraceIterator_restart(kbt)) {
323 kbt->end = 1;
324 return;
325 }
326
327 kbt->end = !KBacktraceIterator_next_item_inclusive(kbt);
328}
329EXPORT_SYMBOL(KBacktraceIterator_next);
330
331/*
332 * This method wraps the backtracer's more generic support.
333 * It is only invoked from the architecture-specific code; show_stack()
334 * and dump_stack() (in entry.S) are architecture-independent entry points.
335 */
336void tile_show_stack(struct KBacktraceIterator *kbt, int headers)
337{
338 int i;
339
340 if (headers) {
341 /*
342 * Add a blank line since if we are called from panic(),
343 * then bust_spinlocks() spit out a space in front of us
344 * and it will mess up our KERN_ERR.
345 */
346 pr_err("\n");
347 pr_err("Starting stack dump of tid %d, pid %d (%s)"
348 " on cpu %d at cycle %lld\n",
349 kbt->task->pid, kbt->task->tgid, kbt->task->comm,
350 smp_processor_id(), get_cycles());
351 }
352 kbt->verbose = 1;
353 i = 0;
354 for (; !KBacktraceIterator_end(kbt); KBacktraceIterator_next(kbt)) {
355 char *modname;
356 const char *name;
357 unsigned long address = kbt->it.pc;
358 unsigned long offset, size;
359 char namebuf[KSYM_NAME_LEN+100];
360
361 if (address >= PAGE_OFFSET)
362 name = kallsyms_lookup(address, &size, &offset,
363 &modname, namebuf);
364 else
365 name = NULL;
366
367 if (!name)
368 namebuf[0] = '\0';
369 else {
370 size_t namelen = strlen(namebuf);
371 size_t remaining = (sizeof(namebuf) - 1) - namelen;
372 char *p = namebuf + namelen;
373 int rc = snprintf(p, remaining, "+%#lx/%#lx ",
374 offset, size);
375 if (modname && rc < remaining)
376 snprintf(p + rc, remaining - rc,
377 "[%s] ", modname);
378 namebuf[sizeof(namebuf)-1] = '\0';
379 }
380
381 pr_err(" frame %d: 0x%lx %s(sp 0x%lx)\n",
382 i++, address, namebuf, (unsigned long)(kbt->it.sp));
383
384 if (i >= 100) {
385 pr_err("Stack dump truncated"
386 " (%d frames)\n", i);
387 break;
388 }
389 }
390 if (headers)
391 pr_err("Stack dump complete\n");
392}
393EXPORT_SYMBOL(tile_show_stack);
394
395
396/* This is called from show_regs() and _dump_stack() */
397void dump_stack_regs(struct pt_regs *regs)
398{
399 struct KBacktraceIterator kbt;
400 KBacktraceIterator_init(&kbt, NULL, regs);
401 tile_show_stack(&kbt, 1);
402}
403EXPORT_SYMBOL(dump_stack_regs);
404
405static struct pt_regs *regs_to_pt_regs(struct pt_regs *regs,
406 ulong pc, ulong lr, ulong sp, ulong r52)
407{
408 memset(regs, 0, sizeof(struct pt_regs));
409 regs->pc = pc;
410 regs->lr = lr;
411 regs->sp = sp;
412 regs->regs[52] = r52;
413 return regs;
414}
415
416/* This is called from dump_stack() and just converts to pt_regs */
417void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
418{
419 struct pt_regs regs;
420 dump_stack_regs(regs_to_pt_regs(&regs, pc, lr, sp, r52));
421}
422
423/* This is called from KBacktraceIterator_init_current() */
424void _KBacktraceIterator_init_current(struct KBacktraceIterator *kbt, ulong pc,
425 ulong lr, ulong sp, ulong r52)
426{
427 struct pt_regs regs;
428 KBacktraceIterator_init(kbt, NULL,
429 regs_to_pt_regs(&regs, pc, lr, sp, r52));
430}
431
432/* This is called only from kernel/sched.c, with esp == NULL */
433void show_stack(struct task_struct *task, unsigned long *esp)
434{
435 struct KBacktraceIterator kbt;
436 if (task == NULL || task == current)
437 KBacktraceIterator_init_current(&kbt);
438 else
439 KBacktraceIterator_init(&kbt, task, NULL);
440 tile_show_stack(&kbt, 0);
441}
442
443#ifdef CONFIG_STACKTRACE
444
445/* Support generic Linux stack API too */
446
447void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
448{
449 struct KBacktraceIterator kbt;
450 int skip = trace->skip;
451 int i = 0;
452
453 if (task == NULL || task == current)
454 KBacktraceIterator_init_current(&kbt);
455 else
456 KBacktraceIterator_init(&kbt, task, NULL);
457 for (; !KBacktraceIterator_end(&kbt); KBacktraceIterator_next(&kbt)) {
458 if (skip) {
459 --skip;
460 continue;
461 }
462 if (i >= trace->max_entries || kbt.it.pc < PAGE_OFFSET)
463 break;
464 trace->entries[i++] = kbt.it.pc;
465 }
466 trace->nr_entries = i;
467}
468EXPORT_SYMBOL(save_stack_trace_tsk);
469
470void save_stack_trace(struct stack_trace *trace)
471{
472 save_stack_trace_tsk(NULL, trace);
473}
474
475#endif
476
477/* In entry.S */
478EXPORT_SYMBOL(KBacktraceIterator_init_current);
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