arch/tile/kernel/stack.c

   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? */
  35 static 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? */
  44 static 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? */
  51 static 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 */
  86 static 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 */
 109 static 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? */
 152 static 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 */
 158 static 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 &frame->uc.uc_mcontext.regs;
 179         }
 180         return NULL;
 181 }
 182
 183 static int KBacktraceIterator_is_sigreturn(struct KBacktraceIterator *kbt)
 184 {
 185         return is_sigreturn(kbt->it.pc);
 186 }
 187
 188 static 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. */
 204 static 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  */
 226 static 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
 246 void 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 }
 310 EXPORT_SYMBOL(KBacktraceIterator_init);
 311
 312 int KBacktraceIterator_end(struct KBacktraceIterator *kbt)
 313 {
 314         return kbt->end;
 315 }
 316 EXPORT_SYMBOL(KBacktraceIterator_end);
 317
 318 void 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 }
 329 EXPORT_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  */
 336 void 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 }
 393 EXPORT_SYMBOL(tile_show_stack);
 394
 395
 396 /* This is called from show_regs() and _dump_stack() */
 397 void 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 }
 403 EXPORT_SYMBOL(dump_stack_regs);
 404
 405 static 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 */
 417 void _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() */
 424 void _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 */
 433 void 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
 447 void 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 }
 468 EXPORT_SYMBOL(save_stack_trace_tsk);
 469
 470 void save_stack_trace(struct stack_trace *trace)
 471 {
 472         save_stack_trace_tsk(NULL, trace);
 473 }
 474
 475 #endif
 476
 477 /* In entry.S */
 478 EXPORT_SYMBOL(KBacktraceIterator_init_current);