kernel/unwind.c

   1 /*
   2  * Copyright (C) 2002-2006 Novell, Inc.
   3  *      Jan Beulich <jbeulich@novell.com>
   4  * This code is released under version 2 of the GNU GPL.
   5  *
   6  * A simple API for unwinding kernel stacks.  This is used for
   7  * debugging and error reporting purposes.  The kernel doesn't need
   8  * full-blown stack unwinding with all the bells and whistles, so there
   9  * is not much point in implementing the full Dwarf2 unwind API.
  10  */
  11
  12 #include <linux/unwind.h>
  13 #include <linux/module.h>
  14 #include <linux/bootmem.h>
  15 #include <linux/sort.h>
  16 #include <linux/stop_machine.h>
  17 #include <linux/uaccess.h>
  18 #include <asm/sections.h>
  19 #include <asm/uaccess.h>
  20 #include <asm/unaligned.h>
  21
  22 extern const char __start_unwind[], __end_unwind[];
  23 extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];
  24
  25 #define MAX_STACK_DEPTH 8
  26
  27 #define EXTRA_INFO(f) { \
  28                 BUILD_BUG_ON_ZERO(offsetof(struct unwind_frame_info, f) \
  29                                   % FIELD_SIZEOF(struct unwind_frame_info, f)) \
  30                 + offsetof(struct unwind_frame_info, f) \
  31                   / FIELD_SIZEOF(struct unwind_frame_info, f), \
  32                 FIELD_SIZEOF(struct unwind_frame_info, f) \
  33         }
  34 #define PTREGS_INFO(f) EXTRA_INFO(regs.f)
  35
  36 static const struct {
  37         unsigned offs:BITS_PER_LONG / 2;
  38         unsigned width:BITS_PER_LONG / 2;
  39 } reg_info[] = {
  40         UNW_REGISTER_INFO
  41 };
  42
  43 #undef PTREGS_INFO
  44 #undef EXTRA_INFO
  45
  46 #ifndef REG_INVALID
  47 #define REG_INVALID(r) (reg_info[r].width == 0)
  48 #endif
  49
  50 #define DW_CFA_nop                          0x00
  51 #define DW_CFA_set_loc                      0x01
  52 #define DW_CFA_advance_loc1                 0x02
  53 #define DW_CFA_advance_loc2                 0x03
  54 #define DW_CFA_advance_loc4                 0x04
  55 #define DW_CFA_offset_extended              0x05
  56 #define DW_CFA_restore_extended             0x06
  57 #define DW_CFA_undefined                    0x07
  58 #define DW_CFA_same_value                   0x08
  59 #define DW_CFA_register                     0x09
  60 #define DW_CFA_remember_state               0x0a
  61 #define DW_CFA_restore_state                0x0b
  62 #define DW_CFA_def_cfa                      0x0c
  63 #define DW_CFA_def_cfa_register             0x0d
  64 #define DW_CFA_def_cfa_offset               0x0e
  65 #define DW_CFA_def_cfa_expression           0x0f
  66 #define DW_CFA_expression                   0x10
  67 #define DW_CFA_offset_extended_sf           0x11
  68 #define DW_CFA_def_cfa_sf                   0x12
  69 #define DW_CFA_def_cfa_offset_sf            0x13
  70 #define DW_CFA_val_offset                   0x14
  71 #define DW_CFA_val_offset_sf                0x15
  72 #define DW_CFA_val_expression               0x16
  73 #define DW_CFA_lo_user                      0x1c
  74 #define DW_CFA_GNU_window_save              0x2d
  75 #define DW_CFA_GNU_args_size                0x2e
  76 #define DW_CFA_GNU_negative_offset_extended 0x2f
  77 #define DW_CFA_hi_user                      0x3f
  78
  79 #define DW_EH_PE_FORM     0x07
  80 #define DW_EH_PE_native   0x00
  81 #define DW_EH_PE_leb128   0x01
  82 #define DW_EH_PE_data2    0x02
  83 #define DW_EH_PE_data4    0x03
  84 #define DW_EH_PE_data8    0x04
  85 #define DW_EH_PE_signed   0x08
  86 #define DW_EH_PE_ADJUST   0x70
  87 #define DW_EH_PE_abs      0x00
  88 #define DW_EH_PE_pcrel    0x10
  89 #define DW_EH_PE_textrel  0x20
  90 #define DW_EH_PE_datarel  0x30
  91 #define DW_EH_PE_funcrel  0x40
  92 #define DW_EH_PE_aligned  0x50
  93 #define DW_EH_PE_indirect 0x80
  94 #define DW_EH_PE_omit     0xff
  95
  96 typedef unsigned long uleb128_t;
  97 typedef   signed long sleb128_t;
  98 #define sleb128abs __builtin_labs
  99
 100 static struct unwind_table {
 101         struct {
 102                 unsigned long pc;
 103                 unsigned long range;
 104         } core, init;
 105         const void *address;
 106         unsigned long size;
 107         const unsigned char *header;
 108         unsigned long hdrsz;
 109         struct unwind_table *link;
 110         const char *name;
 111 } root_table;
 112
 113 struct unwind_item {
 114         enum item_location {
 115                 Nowhere,
 116                 Memory,
 117                 Register,
 118                 Value
 119         } where;
 120         uleb128_t value;
 121 };
 122
 123 struct unwind_state {
 124         uleb128_t loc, org;
 125         const u8 *cieStart, *cieEnd;
 126         uleb128_t codeAlign;
 127         sleb128_t dataAlign;
 128         struct cfa {
 129                 uleb128_t reg, offs;
 130         } cfa;
 131         struct unwind_item regs[ARRAY_SIZE(reg_info)];
 132         unsigned stackDepth:8;
 133         unsigned version:8;
 134         const u8 *label;
 135         const u8 *stack[MAX_STACK_DEPTH];
 136 };
 137
 138 static const struct cfa badCFA = { ARRAY_SIZE(reg_info), 1 };
 139
 140 static unsigned unwind_debug;
 141 static int __init unwind_debug_setup(char *s)
 142 {
 143         unwind_debug = simple_strtoul(s, NULL, 0);
 144         return 1;
 145 }
 146 __setup("unwind_debug=", unwind_debug_setup);
 147 #define dprintk(lvl, fmt, args...) \
 148         ((void)(lvl > unwind_debug \
 149          || printk(KERN_DEBUG "unwind: " fmt "\n", ##args)))
 150
 151 static struct unwind_table *find_table(unsigned long pc)
 152 {
 153         struct unwind_table *table;
 154
 155         for (table = &root_table; table; table = table->link)
 156                 if ((pc >= table->core.pc
 157                      && pc < table->core.pc + table->core.range)
 158                     || (pc >= table->init.pc
 159                         && pc < table->init.pc + table->init.range))
 160                         break;
 161
 162         return table;
 163 }
 164
 165 static unsigned long read_pointer(const u8 **pLoc,
 166                                   const void *end,
 167                                   signed ptrType,
 168                                   unsigned long text_base,
 169                                   unsigned long data_base);
 170
 171 static void init_unwind_table(struct unwind_table *table,
 172                               const char *name,
 173                               const void *core_start,
 174                               unsigned long core_size,
 175                               const void *init_start,
 176                               unsigned long init_size,
 177                               const void *table_start,
 178                               unsigned long table_size,
 179                               const u8 *header_start,
 180                               unsigned long header_size)
 181 {
 182         const u8 *ptr = header_start + 4;
 183         const u8 *end = header_start + header_size;
 184
 185         table->core.pc = (unsigned long)core_start;
 186         table->core.range = core_size;
 187         table->init.pc = (unsigned long)init_start;
 188         table->init.range = init_size;
 189         table->address = table_start;
 190         table->size = table_size;
 191         /* See if the linker provided table looks valid. */
 192         if (header_size <= 4
 193             || header_start[0] != 1
 194             || (void *)read_pointer(&ptr, end, header_start[1], 0, 0)
 195                != table_start
 196             || !read_pointer(&ptr, end, header_start[2], 0, 0)
 197             || !read_pointer(&ptr, end, header_start[3], 0,
 198                              (unsigned long)header_start)
 199             || !read_pointer(&ptr, end, header_start[3], 0,
 200                              (unsigned long)header_start))
 201                 header_start = NULL;
 202         table->hdrsz = header_size;
 203         smp_wmb();
 204         table->header = header_start;
 205         table->link = NULL;
 206         table->name = name;
 207 }
 208
 209 void __init unwind_init(void)
 210 {
 211         init_unwind_table(&root_table, "kernel",
 212                           _text, _end - _text,
 213                           NULL, 0,
 214                           __start_unwind, __end_unwind - __start_unwind,
 215                           __start_unwind_hdr, __end_unwind_hdr - __start_unwind_hdr);
 216 }
 217
 218 static const u32 bad_cie, not_fde;
 219 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *);
 220 static signed fde_pointer_type(const u32 *cie);
 221
 222 struct eh_frame_hdr_table_entry {
 223         unsigned long start, fde;
 224 };
 225
 226 static int cmp_eh_frame_hdr_table_entries(const void *p1, const void *p2)
 227 {
 228         const struct eh_frame_hdr_table_entry *e1 = p1;
 229         const struct eh_frame_hdr_table_entry *e2 = p2;
 230
 231         return (e1->start > e2->start) - (e1->start < e2->start);
 232 }
 233
 234 static void swap_eh_frame_hdr_table_entries(void *p1, void *p2, int size)
 235 {
 236         struct eh_frame_hdr_table_entry *e1 = p1;
 237         struct eh_frame_hdr_table_entry *e2 = p2;
 238         unsigned long v;
 239
 240         v = e1->start;
 241         e1->start = e2->start;
 242         e2->start = v;
 243         v = e1->fde;
 244         e1->fde = e2->fde;
 245         e2->fde = v;
 246 }
 247
 248 static void __init setup_unwind_table(struct unwind_table *table,
 249                                         void *(*alloc)(unsigned long))
 250 {
 251         const u8 *ptr;
 252         unsigned long tableSize = table->size, hdrSize;
 253         unsigned n;
 254         const u32 *fde;
 255         struct {
 256                 u8 version;
 257                 u8 eh_frame_ptr_enc;
 258                 u8 fde_count_enc;
 259                 u8 table_enc;
 260                 unsigned long eh_frame_ptr;
 261                 unsigned int fde_count;
 262                 struct eh_frame_hdr_table_entry table[];
 263         } __attribute__((__packed__)) *header;
 264
 265         if (table->header)
 266                 return;
 267
 268         if (table->hdrsz)
 269                 printk(KERN_WARNING ".eh_frame_hdr for '%s' present but unusable\n",
 270                        table->name);
 271
 272         if (tableSize & (sizeof(*fde) - 1))
 273                 return;
 274
 275         for (fde = table->address, n = 0;
 276              tableSize > sizeof(*fde) && tableSize - sizeof(*fde) >= *fde;
 277              tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
 278                 const u32 *cie = cie_for_fde(fde, table);
 279                 signed ptrType;
 280
 281                 if (cie == &not_fde)
 282                         continue;
 283                 if (cie == NULL
 284                     || cie == &bad_cie
 285                     || (ptrType = fde_pointer_type(cie)) < 0)
 286                         return;
 287                 ptr = (const u8 *)(fde + 2);
 288                 if (!read_pointer(&ptr,
 289                                   (const u8 *)(fde + 1) + *fde,
 290                                   ptrType, 0, 0))
 291                         return;
 292                 ++n;
 293         }
 294
 295         if (tableSize || !n)
 296                 return;
 297
 298         hdrSize = 4 + sizeof(unsigned long) + sizeof(unsigned int)
 299                 + 2 * n * sizeof(unsigned long);
 300         dprintk(2, "Binary lookup table size for %s: %lu bytes", table->name, hdrSize);
 301         header = alloc(hdrSize);
 302         if (!header)
 303                 return;
 304         header->version          = 1;
 305         header->eh_frame_ptr_enc = DW_EH_PE_abs|DW_EH_PE_native;
 306         header->fde_count_enc    = DW_EH_PE_abs|DW_EH_PE_data4;
 307         header->table_enc        = DW_EH_PE_abs|DW_EH_PE_native;
 308         put_unaligned((unsigned long)table->address, &header->eh_frame_ptr);
 309         BUILD_BUG_ON(offsetof(typeof(*header), fde_count)
 310                      % __alignof(typeof(header->fde_count)));
 311         header->fde_count        = n;
 312
 313         BUILD_BUG_ON(offsetof(typeof(*header), table)
 314                      % __alignof(typeof(*header->table)));
 315         for (fde = table->address, tableSize = table->size, n = 0;
 316              tableSize;
 317              tableSize -= sizeof(*fde) + *fde, fde += 1 + *fde / sizeof(*fde)) {
 318                 const u32 *cie = fde + 1 - fde[1] / sizeof(*fde);
 319
 320                 if (!fde[1])
 321                         continue; /* this is a CIE */
 322                 ptr = (const u8 *)(fde + 2);
 323                 header->table[n].start = read_pointer(&ptr,
 324                                                       (const u8 *)(fde + 1) + *fde,
 325                                                       fde_pointer_type(cie), 0, 0);
 326                 header->table[n].fde = (unsigned long)fde;
 327                 ++n;
 328         }
 329         WARN_ON(n != header->fde_count);
 330
 331         sort(header->table,
 332              n,
 333              sizeof(*header->table),
 334              cmp_eh_frame_hdr_table_entries,
 335              swap_eh_frame_hdr_table_entries);
 336
 337         table->hdrsz = hdrSize;
 338         smp_wmb();
 339         table->header = (const void *)header;
 340 }
 341
 342 static void *__init balloc(unsigned long sz)
 343 {
 344         return __alloc_bootmem_nopanic(sz,
 345                                        sizeof(unsigned int),
 346                                        __pa(MAX_DMA_ADDRESS));
 347 }
 348
 349 void __init unwind_setup(void)
 350 {
 351         setup_unwind_table(&root_table, balloc);
 352 }
 353
 354 #ifdef CONFIG_MODULES
 355
 356 static struct unwind_table *last_table;
 357
 358 /* Must be called with module_mutex held. */
 359 void *unwind_add_table(struct module *module,
 360                        const void *table_start,
 361                        unsigned long table_size)
 362 {
 363         struct unwind_table *table;
 364
 365         if (table_size <= 0)
 366                 return NULL;
 367
 368         table = kmalloc(sizeof(*table), GFP_KERNEL);
 369         if (!table)
 370                 return NULL;
 371
 372         init_unwind_table(table, module->name,
 373                           module->module_core, module->core_size,
 374                           module->module_init, module->init_size,
 375                           table_start, table_size,
 376                           NULL, 0);
 377
 378         if (last_table)
 379                 last_table->link = table;
 380         else
 381                 root_table.link = table;
 382         last_table = table;
 383
 384         return table;
 385 }
 386
 387 struct unlink_table_info
 388 {
 389         struct unwind_table *table;
 390         int init_only;
 391 };
 392
 393 static int unlink_table(void *arg)
 394 {
 395         struct unlink_table_info *info = arg;
 396         struct unwind_table *table = info->table, *prev;
 397
 398         for (prev = &root_table; prev->link && prev->link != table; prev = prev->link)
 399                 ;
 400
 401         if (prev->link) {
 402                 if (info->init_only) {
 403                         table->init.pc = 0;
 404                         table->init.range = 0;
 405                         info->table = NULL;
 406                 } else {
 407                         prev->link = table->link;
 408                         if (!prev->link)
 409                                 last_table = prev;
 410                 }
 411         } else
 412                 info->table = NULL;
 413
 414         return 0;
 415 }
 416
 417 /* Must be called with module_mutex held. */
 418 void unwind_remove_table(void *handle, int init_only)
 419 {
 420         struct unwind_table *table = handle;
 421         struct unlink_table_info info;
 422
 423         if (!table || table == &root_table)
 424                 return;
 425
 426         if (init_only && table == last_table) {
 427                 table->init.pc = 0;
 428                 table->init.range = 0;
 429                 return;
 430         }
 431
 432         info.table = table;
 433         info.init_only = init_only;
 434         stop_machine_run(unlink_table, &info, NR_CPUS);
 435
 436         if (info.table)
 437                 kfree(table);
 438 }
 439
 440 #endif /* CONFIG_MODULES */
 441
 442 static uleb128_t get_uleb128(const u8 **pcur, const u8 *end)
 443 {
 444         const u8 *cur = *pcur;
 445         uleb128_t value;
 446         unsigned shift;
 447
 448         for (shift = 0, value = 0; cur < end; shift += 7) {
 449                 if (shift + 7 > 8 * sizeof(value)
 450                     && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
 451                         cur = end + 1;
 452                         break;
 453                 }
 454                 value |= (uleb128_t)(*cur & 0x7f) << shift;
 455                 if (!(*cur++ & 0x80))
 456                         break;
 457         }
 458         *pcur = cur;
 459
 460         return value;
 461 }
 462
 463 static sleb128_t get_sleb128(const u8 **pcur, const u8 *end)
 464 {
 465         const u8 *cur = *pcur;
 466         sleb128_t value;
 467         unsigned shift;
 468
 469         for (shift = 0, value = 0; cur < end; shift += 7) {
 470                 if (shift + 7 > 8 * sizeof(value)
 471                     && (*cur & 0x7fU) >= (1U << (8 * sizeof(value) - shift))) {
 472                         cur = end + 1;
 473                         break;
 474                 }
 475                 value |= (sleb128_t)(*cur & 0x7f) << shift;
 476                 if (!(*cur & 0x80)) {
 477                         value |= -(*cur++ & 0x40) << shift;
 478                         break;
 479                 }
 480         }
 481         *pcur = cur;
 482
 483         return value;
 484 }
 485
 486 static const u32 *cie_for_fde(const u32 *fde, const struct unwind_table *table)
 487 {
 488         const u32 *cie;
 489
 490         if (!*fde || (*fde & (sizeof(*fde) - 1)))
 491                 return &bad_cie;
 492         if (!fde[1])
 493                 return &not_fde; /* this is a CIE */
 494         if ((fde[1] & (sizeof(*fde) - 1))
 495             || fde[1] > (unsigned long)(fde + 1) - (unsigned long)table->address)
 496                 return NULL; /* this is not a valid FDE */
 497         cie = fde + 1 - fde[1] / sizeof(*fde);
 498         if (*cie <= sizeof(*cie) + 4
 499             || *cie >= fde[1] - sizeof(*fde)
 500             || (*cie & (sizeof(*cie) - 1))
 501             || cie[1])
 502                 return NULL; /* this is not a (valid) CIE */
 503         return cie;
 504 }
 505
 506 static unsigned long read_pointer(const u8 **pLoc,
 507                                   const void *end,
 508                                   signed ptrType,
 509                                   unsigned long text_base,
 510                                   unsigned long data_base)
 511 {
 512         unsigned long value = 0;
 513         union {
 514                 const u8 *p8;
 515                 const u16 *p16u;
 516                 const s16 *p16s;
 517                 const u32 *p32u;
 518                 const s32 *p32s;
 519                 const unsigned long *pul;
 520         } ptr;
 521
 522         if (ptrType < 0 || ptrType == DW_EH_PE_omit) {
 523                 dprintk(1, "Invalid pointer encoding %02X (%p,%p).", ptrType, *pLoc, end);
 524                 return 0;
 525         }
 526         ptr.p8 = *pLoc;
 527         switch(ptrType & DW_EH_PE_FORM) {
 528         case DW_EH_PE_data2:
 529                 if (end < (const void *)(ptr.p16u + 1)) {
 530                         dprintk(1, "Data16 overrun (%p,%p).", ptr.p8, end);
 531                         return 0;
 532                 }
 533                 if(ptrType & DW_EH_PE_signed)
 534                         value = get_unaligned(ptr.p16s++);
 535                 else
 536                         value = get_unaligned(ptr.p16u++);
 537                 break;
 538         case DW_EH_PE_data4:
 539 #ifdef CONFIG_64BIT
 540                 if (end < (const void *)(ptr.p32u + 1)) {
 541                         dprintk(1, "Data32 overrun (%p,%p).", ptr.p8, end);
 542                         return 0;
 543                 }
 544                 if(ptrType & DW_EH_PE_signed)
 545                         value = get_unaligned(ptr.p32s++);
 546                 else
 547                         value = get_unaligned(ptr.p32u++);
 548                 break;
 549         case DW_EH_PE_data8:
 550                 BUILD_BUG_ON(sizeof(u64) != sizeof(value));
 551 #else
 552                 BUILD_BUG_ON(sizeof(u32) != sizeof(value));
 553 #endif
 554         case DW_EH_PE_native:
 555                 if (end < (const void *)(ptr.pul + 1)) {
 556                         dprintk(1, "DataUL overrun (%p,%p).", ptr.p8, end);
 557                         return 0;
 558                 }
 559                 value = get_unaligned(ptr.pul++);
 560                 break;
 561         case DW_EH_PE_leb128:
 562                 BUILD_BUG_ON(sizeof(uleb128_t) > sizeof(value));
 563                 value = ptrType & DW_EH_PE_signed
 564                         ? get_sleb128(&ptr.p8, end)
 565                         : get_uleb128(&ptr.p8, end);
 566                 if ((const void *)ptr.p8 > end) {
 567                         dprintk(1, "DataLEB overrun (%p,%p).", ptr.p8, end);
 568                         return 0;
 569                 }
 570                 break;
 571         default:
 572                 dprintk(2, "Cannot decode pointer type %02X (%p,%p).",
 573                         ptrType, ptr.p8, end);
 574                 return 0;
 575         }
 576         switch(ptrType & DW_EH_PE_ADJUST) {
 577         case DW_EH_PE_abs:
 578                 break;
 579         case DW_EH_PE_pcrel:
 580                 value += (unsigned long)*pLoc;
 581                 break;
 582         case DW_EH_PE_textrel:
 583                 if (likely(text_base)) {
 584                         value += text_base;
 585                         break;
 586                 }
 587                 dprintk(2, "Text-relative encoding %02X (%p,%p), but zero text base.",
 588                         ptrType, *pLoc, end);
 589                 return 0;
 590         case DW_EH_PE_datarel:
 591                 if (likely(data_base)) {
 592                         value += data_base;
 593                         break;
 594                 }
 595                 dprintk(2, "Data-relative encoding %02X (%p,%p), but zero data base.",
 596                         ptrType, *pLoc, end);
 597                 return 0;
 598         default:
 599                 dprintk(2, "Cannot adjust pointer type %02X (%p,%p).",
 600                         ptrType, *pLoc, end);
 601                 return 0;
 602         }
 603         if ((ptrType & DW_EH_PE_indirect)
 604             && probe_kernel_address((unsigned long *)value, value)) {
 605                 dprintk(1, "Cannot read indirect value %lx (%p,%p).",
 606                         value, *pLoc, end);
 607                 return 0;
 608         }
 609         *pLoc = ptr.p8;
 610
 611         return value;
 612 }
 613
 614 static signed fde_pointer_type(const u32 *cie)
 615 {
 616         const u8 *ptr = (const u8 *)(cie + 2);
 617         unsigned version = *ptr;
 618
 619         if (version != 1)
 620                 return -1; /* unsupported */
 621         if (*++ptr) {
 622                 const char *aug;
 623                 const u8 *end = (const u8 *)(cie + 1) + *cie;
 624                 uleb128_t len;
 625
 626                 /* check if augmentation size is first (and thus present) */
 627                 if (*ptr != 'z')
 628                         return -1;
 629                 /* check if augmentation string is nul-terminated */
 630                 if ((ptr = memchr(aug = (const void *)ptr, 0, end - ptr)) == NULL)
 631                         return -1;
 632                 ++ptr; /* skip terminator */
 633                 get_uleb128(&ptr, end); /* skip code alignment */
 634                 get_sleb128(&ptr, end); /* skip data alignment */
 635                 /* skip return address column */
 636                 version <= 1 ? (void)++ptr : (void)get_uleb128(&ptr, end);
 637                 len = get_uleb128(&ptr, end); /* augmentation length */
 638                 if (ptr + len < ptr || ptr + len > end)
 639                         return -1;
 640                 end = ptr + len;
 641                 while (*++aug) {
 642                         if (ptr >= end)
 643                                 return -1;
 644                         switch(*aug) {
 645                         case 'L':
 646                                 ++ptr;
 647                                 break;
 648                         case 'P': {
 649                                         signed ptrType = *ptr++;
 650
 651                                         if (!read_pointer(&ptr, end, ptrType, 0, 0)
 652                                             || ptr > end)
 653                                                 return -1;
 654                                 }
 655                                 break;
 656                         case 'R':
 657                                 return *ptr;
 658                         default:
 659                                 return -1;
 660                         }
 661                 }
 662         }
 663         return DW_EH_PE_native|DW_EH_PE_abs;
 664 }
 665
 666 static int advance_loc(unsigned long delta, struct unwind_state *state)
 667 {
 668         state->loc += delta * state->codeAlign;
 669
 670         return delta > 0;
 671 }
 672
 673 static void set_rule(uleb128_t reg,
 674                      enum item_location where,
 675                      uleb128_t value,
 676                      struct unwind_state *state)
 677 {
 678         if (reg < ARRAY_SIZE(state->regs)) {
 679                 state->regs[reg].where = where;
 680                 state->regs[reg].value = value;
 681         }
 682 }
 683
 684 static int processCFI(const u8 *start,
 685                       const u8 *end,
 686                       unsigned long targetLoc,
 687                       signed ptrType,
 688                       struct unwind_state *state)
 689 {
 690         union {
 691                 const u8 *p8;
 692                 const u16 *p16;
 693                 const u32 *p32;
 694         } ptr;
 695         int result = 1;
 696
 697         if (start != state->cieStart) {
 698                 state->loc = state->org;
 699                 result = processCFI(state->cieStart, state->cieEnd, 0, ptrType, state);
 700                 if (targetLoc == 0 && state->label == NULL)
 701                         return result;
 702         }
 703         for (ptr.p8 = start; result && ptr.p8 < end; ) {
 704                 switch(*ptr.p8 >> 6) {
 705                         uleb128_t value;
 706
 707                 case 0:
 708                         switch(*ptr.p8++) {
 709                         case DW_CFA_nop:
 710                                 break;
 711                         case DW_CFA_set_loc:
 712                                 state->loc = read_pointer(&ptr.p8, end, ptrType, 0, 0);
 713                                 if (state->loc == 0)
 714                                         result = 0;
 715                                 break;
 716                         case DW_CFA_advance_loc1:
 717                                 result = ptr.p8 < end && advance_loc(*ptr.p8++, state);
 718                                 break;
 719                         case DW_CFA_advance_loc2:
 720                                 result = ptr.p8 <= end + 2
 721                                          && advance_loc(*ptr.p16++, state);
 722                                 break;
 723                         case DW_CFA_advance_loc4:
 724                                 result = ptr.p8 <= end + 4
 725                                          && advance_loc(*ptr.p32++, state);
 726                                 break;
 727                         case DW_CFA_offset_extended:
 728                                 value = get_uleb128(&ptr.p8, end);
 729                                 set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
 730                                 break;
 731                         case DW_CFA_val_offset:
 732                                 value = get_uleb128(&ptr.p8, end);
 733                                 set_rule(value, Value, get_uleb128(&ptr.p8, end), state);
 734                                 break;
 735                         case DW_CFA_offset_extended_sf:
 736                                 value = get_uleb128(&ptr.p8, end);
 737                                 set_rule(value, Memory, get_sleb128(&ptr.p8, end), state);
 738                                 break;
 739                         case DW_CFA_val_offset_sf:
 740                                 value = get_uleb128(&ptr.p8, end);
 741                                 set_rule(value, Value, get_sleb128(&ptr.p8, end), state);
 742                                 break;
 743                         case DW_CFA_restore_extended:
 744                         case DW_CFA_undefined:
 745                         case DW_CFA_same_value:
 746                                 set_rule(get_uleb128(&ptr.p8, end), Nowhere, 0, state);
 747                                 break;
 748                         case DW_CFA_register:
 749                                 value = get_uleb128(&ptr.p8, end);
 750                                 set_rule(value,
 751                                          Register,
 752                                          get_uleb128(&ptr.p8, end), state);
 753                                 break;
 754                         case DW_CFA_remember_state:
 755                                 if (ptr.p8 == state->label) {
 756                                         state->label = NULL;
 757                                         return 1;
 758                                 }
 759                                 if (state->stackDepth >= MAX_STACK_DEPTH) {
 760                                         dprintk(1, "State stack overflow (%p,%p).", ptr.p8, end);
 761                                         return 0;
 762                                 }
 763                                 state->stack[state->stackDepth++] = ptr.p8;
 764                                 break;
 765                         case DW_CFA_restore_state:
 766                                 if (state->stackDepth) {
 767                                         const uleb128_t loc = state->loc;
 768                                         const u8 *label = state->label;
 769
 770                                         state->label = state->stack[state->stackDepth - 1];
 771                                         memcpy(&state->cfa, &badCFA, sizeof(state->cfa));
 772                                         memset(state->regs, 0, sizeof(state->regs));
 773                                         state->stackDepth = 0;
 774                                         result = processCFI(start, end, 0, ptrType, state);
 775                                         state->loc = loc;
 776                                         state->label = label;
 777                                 } else {
 778                                         dprintk(1, "State stack underflow (%p,%p).", ptr.p8, end);
 779                                         return 0;
 780                                 }
 781                                 break;
 782                         case DW_CFA_def_cfa:
 783                                 state->cfa.reg = get_uleb128(&ptr.p8, end);
 784                                 /*nobreak*/
 785                         case DW_CFA_def_cfa_offset:
 786                                 state->cfa.offs = get_uleb128(&ptr.p8, end);
 787                                 break;
 788                         case DW_CFA_def_cfa_sf:
 789                                 state->cfa.reg = get_uleb128(&ptr.p8, end);
 790                                 /*nobreak*/
 791                         case DW_CFA_def_cfa_offset_sf:
 792                                 state->cfa.offs = get_sleb128(&ptr.p8, end)
 793                                                   * state->dataAlign;
 794                                 break;
 795                         case DW_CFA_def_cfa_register:
 796                                 state->cfa.reg = get_uleb128(&ptr.p8, end);
 797                                 break;
 798                         /*todo case DW_CFA_def_cfa_expression: */
 799                         /*todo case DW_CFA_expression: */
 800                         /*todo case DW_CFA_val_expression: */
 801                         case DW_CFA_GNU_args_size:
 802                                 get_uleb128(&ptr.p8, end);
 803                                 break;
 804                         case DW_CFA_GNU_negative_offset_extended:
 805                                 value = get_uleb128(&ptr.p8, end);
 806                                 set_rule(value,
 807                                          Memory,
 808                                          (uleb128_t)0 - get_uleb128(&ptr.p8, end), state);
 809                                 break;
 810                         case DW_CFA_GNU_window_save:
 811                         default:
 812                                 dprintk(1, "Unrecognized CFI op %02X (%p,%p).", ptr.p8[-1], ptr.p8 - 1, end);
 813                                 result = 0;
 814                                 break;
 815                         }
 816                         break;
 817                 case 1:
 818                         result = advance_loc(*ptr.p8++ & 0x3f, state);
 819                         break;
 820                 case 2:
 821                         value = *ptr.p8++ & 0x3f;
 822                         set_rule(value, Memory, get_uleb128(&ptr.p8, end), state);
 823                         break;
 824                 case 3:
 825                         set_rule(*ptr.p8++ & 0x3f, Nowhere, 0, state);
 826                         break;
 827                 }
 828                 if (ptr.p8 > end) {
 829                         dprintk(1, "Data overrun (%p,%p).", ptr.p8, end);
 830                         result = 0;
 831                 }
 832                 if (result && targetLoc != 0 && targetLoc < state->loc)
 833                         return 1;
 834         }
 835
 836         if (result && ptr.p8 < end)
 837                 dprintk(1, "Data underrun (%p,%p).", ptr.p8, end);
 838
 839         return result
 840            && ptr.p8 == end
 841            && (targetLoc == 0
 842             || (/*todo While in theory this should apply, gcc in practice omits
 843                   everything past the function prolog, and hence the location
 844                   never reaches the end of the function.
 845                 targetLoc < state->loc &&*/ state->label == NULL));
 846 }
 847
 848 /* Unwind to previous to frame.  Returns 0 if successful, negative
 849  * number in case of an error. */
 850 int unwind(struct unwind_frame_info *frame)
 851 {
 852 #define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs])
 853         const u32 *fde = NULL, *cie = NULL;
 854         const u8 *ptr = NULL, *end = NULL;
 855         unsigned long pc = UNW_PC(frame) - frame->call_frame, sp;
 856         unsigned long startLoc = 0, endLoc = 0, cfa;
 857         unsigned i;
 858         signed ptrType = -1;
 859         uleb128_t retAddrReg = 0;
 860         const struct unwind_table *table;
 861         struct unwind_state state;
 862
 863         if (UNW_PC(frame) == 0)
 864                 return -EINVAL;
 865         if ((table = find_table(pc)) != NULL
 866             && !(table->size & (sizeof(*fde) - 1))) {
 867                 const u8 *hdr = table->header;
 868                 unsigned long tableSize;
 869
 870                 smp_rmb();
 871                 if (hdr && hdr[0] == 1) {
 872                         switch(hdr[3] & DW_EH_PE_FORM) {
 873                         case DW_EH_PE_native: tableSize = sizeof(unsigned long); break;
 874                         case DW_EH_PE_data2: tableSize = 2; break;
 875                         case DW_EH_PE_data4: tableSize = 4; break;
 876                         case DW_EH_PE_data8: tableSize = 8; break;
 877                         default: tableSize = 0; break;
 878                         }
 879                         ptr = hdr + 4;
 880                         end = hdr + table->hdrsz;
 881                         if (tableSize
 882                             && read_pointer(&ptr, end, hdr[1], 0, 0)
 883                                == (unsigned long)table->address
 884                             && (i = read_pointer(&ptr, end, hdr[2], 0, 0)) > 0
 885                             && i == (end - ptr) / (2 * tableSize)
 886                             && !((end - ptr) % (2 * tableSize))) {
 887                                 do {
 888                                         const u8 *cur = ptr + (i / 2) * (2 * tableSize);
 889
 890                                         startLoc = read_pointer(&cur,
 891                                                                 cur + tableSize,
 892                                                                 hdr[3], 0,
 893                                                                 (unsigned long)hdr);
 894                                         if (pc < startLoc)
 895                                                 i /= 2;
 896                                         else {
 897                                                 ptr = cur - tableSize;
 898                                                 i = (i + 1) / 2;
 899                                         }
 900                                 } while (startLoc && i > 1);
 901                                 if (i == 1
 902                                     && (startLoc = read_pointer(&ptr,
 903                                                                 ptr + tableSize,
 904                                                                 hdr[3], 0,
 905                                                                 (unsigned long)hdr)) != 0
 906                                     && pc >= startLoc)
 907                                         fde = (void *)read_pointer(&ptr,
 908                                                                    ptr + tableSize,
 909                                                                    hdr[3], 0,
 910                                                                    (unsigned long)hdr);
 911                         }
 912                 }
 913                 if(hdr && !fde)
 914                         dprintk(3, "Binary lookup for %lx failed.", pc);
 915
 916                 if (fde != NULL) {
 917                         cie = cie_for_fde(fde, table);
 918                         ptr = (const u8 *)(fde + 2);
 919                         if(cie != NULL
 920                            && cie != &bad_cie
 921                            && cie != &not_fde
 922                            && (ptrType = fde_pointer_type(cie)) >= 0
 923                            && read_pointer(&ptr,
 924                                            (const u8 *)(fde + 1) + *fde,
 925                                            ptrType, 0, 0) == startLoc) {
 926                                 if (!(ptrType & DW_EH_PE_indirect))
 927                                         ptrType &= DW_EH_PE_FORM|DW_EH_PE_signed;
 928                                 endLoc = startLoc
 929                                          + read_pointer(&ptr,
 930                                                         (const u8 *)(fde + 1) + *fde,
 931                                                         ptrType, 0, 0);
 932                                 if(pc >= endLoc)
 933                                         fde = NULL;
 934                         } else
 935                                 fde = NULL;
 936                         if(!fde)
 937                                 dprintk(1, "Binary lookup result for %lx discarded.", pc);
 938                 }
 939                 if (fde == NULL) {
 940                         for (fde = table->address, tableSize = table->size;
 941                              cie = NULL, tableSize > sizeof(*fde)
 942                              && tableSize - sizeof(*fde) >= *fde;
 943                              tableSize -= sizeof(*fde) + *fde,
 944                              fde += 1 + *fde / sizeof(*fde)) {
 945                                 cie = cie_for_fde(fde, table);
 946                                 if (cie == &bad_cie) {
 947                                         cie = NULL;
 948                                         break;
 949                                 }
 950                                 if (cie == NULL
 951                                     || cie == &not_fde
 952                                     || (ptrType = fde_pointer_type(cie)) < 0)
 953                                         continue;
 954                                 ptr = (const u8 *)(fde + 2);
 955                                 startLoc = read_pointer(&ptr,
 956                                                         (const u8 *)(fde + 1) + *fde,
 957                                                         ptrType, 0, 0);
 958                                 if (!startLoc)
 959                                         continue;
 960                                 if (!(ptrType & DW_EH_PE_indirect))
 961                                         ptrType &= DW_EH_PE_FORM|DW_EH_PE_signed;
 962                                 endLoc = startLoc
 963                                          + read_pointer(&ptr,
 964                                                         (const u8 *)(fde + 1) + *fde,
 965                                                         ptrType, 0, 0);
 966                                 if (pc >= startLoc && pc < endLoc)
 967                                         break;
 968                         }
 969                         if(!fde)
 970                                 dprintk(3, "Linear lookup for %lx failed.", pc);
 971                 }
 972         }
 973         if (cie != NULL) {
 974                 memset(&state, 0, sizeof(state));
 975                 state.cieEnd = ptr; /* keep here temporarily */
 976                 ptr = (const u8 *)(cie + 2);
 977                 end = (const u8 *)(cie + 1) + *cie;
 978                 frame->call_frame = 1;
 979                 if ((state.version = *ptr) != 1)
 980                         cie = NULL; /* unsupported version */
 981                 else if (*++ptr) {
 982                         /* check if augmentation size is first (and thus present) */
 983                         if (*ptr == 'z') {
 984                                 while (++ptr < end && *ptr) {
 985                                         switch(*ptr) {
 986                                         /* check for ignorable (or already handled)
 987                                          * nul-terminated augmentation string */
 988                                         case 'L':
 989                                         case 'P':
 990                                         case 'R':
 991                                                 continue;
 992                                         case 'S':
 993                                                 frame->call_frame = 0;
 994                                                 continue;
 995                                         default:
 996                                                 break;
 997                                         }
 998                                         break;
 999                                 }
1000                         }
1001                         if (ptr >= end || *ptr)
1002                                 cie = NULL;
1003                 }
1004                 if(!cie)
1005                         dprintk(1, "CIE unusable (%p,%p).", ptr, end);
1006                 ++ptr;
1007         }
1008         if (cie != NULL) {
1009                 /* get code aligment factor */
1010                 state.codeAlign = get_uleb128(&ptr, end);
1011                 /* get data aligment factor */
1012                 state.dataAlign = get_sleb128(&ptr, end);
1013                 if (state.codeAlign == 0 || state.dataAlign == 0 || ptr >= end)
1014                         cie = NULL;
1015                 else if (UNW_PC(frame) % state.codeAlign
1016                          || UNW_SP(frame) % sleb128abs(state.dataAlign)) {
1017                         dprintk(1, "Input pointer(s) misaligned (%lx,%lx).",
1018                                 UNW_PC(frame), UNW_SP(frame));
1019                         return -EPERM;
1020                 } else {
1021                         retAddrReg = state.version <= 1 ? *ptr++ : get_uleb128(&ptr, end);
1022                         /* skip augmentation */
1023                         if (((const char *)(cie + 2))[1] == 'z') {
1024                                 uleb128_t augSize = get_uleb128(&ptr, end);
1025
1026                                 ptr += augSize;
1027                         }
1028                         if (ptr > end
1029                            || retAddrReg >= ARRAY_SIZE(reg_info)
1030                            || REG_INVALID(retAddrReg)
1031                            || reg_info[retAddrReg].width != sizeof(unsigned long))
1032                                 cie = NULL;
1033                 }
1034                 if(!cie)
1035                         dprintk(1, "CIE validation failed (%p,%p).", ptr, end);
1036         }
1037         if (cie != NULL) {
1038                 state.cieStart = ptr;
1039                 ptr = state.cieEnd;
1040                 state.cieEnd = end;
1041                 end = (const u8 *)(fde + 1) + *fde;
1042                 /* skip augmentation */
1043                 if (((const char *)(cie + 2))[1] == 'z') {
1044                         uleb128_t augSize = get_uleb128(&ptr, end);
1045
1046                         if ((ptr += augSize) > end)
1047                                 fde = NULL;
1048                 }
1049                 if(!fde)
1050                         dprintk(1, "FDE validation failed (%p,%p).", ptr, end);
1051         }
1052         if (cie == NULL || fde == NULL) {
1053 #ifdef CONFIG_FRAME_POINTER
1054                 unsigned long top, bottom;
1055
1056                 if ((UNW_SP(frame) | UNW_FP(frame)) % sizeof(unsigned long))
1057                         return -EPERM;
1058                 top = STACK_TOP(frame->task);
1059                 bottom = STACK_BOTTOM(frame->task);
1060 # if FRAME_RETADDR_OFFSET < 0
1061                 if (UNW_SP(frame) < top
1062                     && UNW_FP(frame) <= UNW_SP(frame)
1063                     && bottom < UNW_FP(frame)
1064 # else
1065                 if (UNW_SP(frame) > top
1066                     && UNW_FP(frame) >= UNW_SP(frame)
1067                     && bottom > UNW_FP(frame)
1068 # endif
1069                    && !((UNW_SP(frame) | UNW_FP(frame))
1070                         & (sizeof(unsigned long) - 1))) {
1071                         unsigned long link;
1072
1073                         if (!probe_kernel_address(
1074                                         (unsigned long *)(UNW_FP(frame)
1075                                                           + FRAME_LINK_OFFSET),
1076                                                   link)
1077 # if FRAME_RETADDR_OFFSET < 0
1078                            && link > bottom && link < UNW_FP(frame)
1079 # else
1080                            && link > UNW_FP(frame) && link < bottom
1081 # endif
1082                            && !(link & (sizeof(link) - 1))
1083                            && !probe_kernel_address(
1084                                           (unsigned long *)(UNW_FP(frame)
1085                                                             + FRAME_RETADDR_OFFSET), UNW_PC(frame))) {
1086                                 UNW_SP(frame) = UNW_FP(frame) + FRAME_RETADDR_OFFSET
1087 # if FRAME_RETADDR_OFFSET < 0
1088                                         -
1089 # else
1090                                         +
1091 # endif
1092                                           sizeof(UNW_PC(frame));
1093                                 UNW_FP(frame) = link;
1094                                 return 0;
1095                         }
1096                 }
1097 #endif
1098                 return -ENXIO;
1099         }
1100         state.org = startLoc;
1101         memcpy(&state.cfa, &badCFA, sizeof(state.cfa));
1102         /* process instructions */
1103         if (!processCFI(ptr, end, pc, ptrType, &state)
1104            || state.loc > endLoc
1105            || state.regs[retAddrReg].where == Nowhere
1106            || state.cfa.reg >= ARRAY_SIZE(reg_info)
1107            || reg_info[state.cfa.reg].width != sizeof(unsigned long)
1108            || FRAME_REG(state.cfa.reg, unsigned long) % sizeof(unsigned long)
1109            || state.cfa.offs % sizeof(unsigned long)) {
1110                 dprintk(1, "Unusable unwind info (%p,%p).", ptr, end);
1111                 return -EIO;
1112         }
1113         /* update frame */
1114 #ifndef CONFIG_AS_CFI_SIGNAL_FRAME
1115         if(frame->call_frame
1116            && !UNW_DEFAULT_RA(state.regs[retAddrReg], state.dataAlign))
1117                 frame->call_frame = 0;
1118 #endif
1119         cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs;
1120         startLoc = min((unsigned long)UNW_SP(frame), cfa);
1121         endLoc = max((unsigned long)UNW_SP(frame), cfa);
1122         if (STACK_LIMIT(startLoc) != STACK_LIMIT(endLoc)) {
1123                 startLoc = min(STACK_LIMIT(cfa), cfa);
1124                 endLoc = max(STACK_LIMIT(cfa), cfa);
1125         }
1126 #ifndef CONFIG_64BIT
1127 # define CASES CASE(8); CASE(16); CASE(32)
1128 #else
1129 # define CASES CASE(8); CASE(16); CASE(32); CASE(64)
1130 #endif
1131         pc = UNW_PC(frame);
1132         sp = UNW_SP(frame);
1133         for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
1134                 if (REG_INVALID(i)) {
1135                         if (state.regs[i].where == Nowhere)
1136                                 continue;
1137                         dprintk(1, "Cannot restore register %u (%d).",
1138                                 i, state.regs[i].where);
1139                         return -EIO;
1140                 }
1141                 switch(state.regs[i].where) {
1142                 default:
1143                         break;
1144                 case Register:
1145                         if (state.regs[i].value >= ARRAY_SIZE(reg_info)
1146                            || REG_INVALID(state.regs[i].value)
1147                            || reg_info[i].width > reg_info[state.regs[i].value].width) {
1148                                 dprintk(1, "Cannot restore register %u from register %lu.",
1149                                         i, state.regs[i].value);
1150                                 return -EIO;
1151                         }
1152                         switch(reg_info[state.regs[i].value].width) {
1153 #define CASE(n) \
1154                         case sizeof(u##n): \
1155                                 state.regs[i].value = FRAME_REG(state.regs[i].value, \
1156                                                                 const u##n); \
1157                                 break
1158                         CASES;
1159 #undef CASE
1160                         default:
1161                                 dprintk(1, "Unsupported register size %u (%lu).",
1162                                         reg_info[state.regs[i].value].width,
1163                                         state.regs[i].value);
1164                                 return -EIO;
1165                         }
1166                         break;
1167                 }
1168         }
1169         for (i = 0; i < ARRAY_SIZE(state.regs); ++i) {
1170                 if (REG_INVALID(i))
1171                         continue;
1172                 switch(state.regs[i].where) {
1173                 case Nowhere:
1174                         if (reg_info[i].width != sizeof(UNW_SP(frame))
1175                            || &FRAME_REG(i, __typeof__(UNW_SP(frame)))
1176                               != &UNW_SP(frame))
1177                                 continue;
1178                         UNW_SP(frame) = cfa;
1179                         break;
1180                 case Register:
1181                         switch(reg_info[i].width) {
1182 #define CASE(n) case sizeof(u##n): \
1183                                 FRAME_REG(i, u##n) = state.regs[i].value; \
1184                                 break
1185                         CASES;
1186 #undef CASE
1187                         default:
1188                                 dprintk(1, "Unsupported register size %u (%u).",
1189                                         reg_info[i].width, i);
1190                                 return -EIO;
1191                         }
1192                         break;
1193                 case Value:
1194                         if (reg_info[i].width != sizeof(unsigned long)) {
1195                                 dprintk(1, "Unsupported value size %u (%u).",
1196                                         reg_info[i].width, i);
1197                                 return -EIO;
1198                         }
1199                         FRAME_REG(i, unsigned long) = cfa + state.regs[i].value
1200                                                             * state.dataAlign;
1201                         break;
1202                 case Memory: {
1203                                 unsigned long addr = cfa + state.regs[i].value
1204                                                            * state.dataAlign;
1205
1206                                 if ((state.regs[i].value * state.dataAlign)
1207                                     % sizeof(unsigned long)
1208                                     || addr < startLoc
1209                                     || addr + sizeof(unsigned long) < addr
1210                                     || addr + sizeof(unsigned long) > endLoc) {
1211                                         dprintk(1, "Bad memory location %lx (%lx).",
1212                                                 addr, state.regs[i].value);
1213                                         return -EIO;
1214                                 }
1215                                 switch(reg_info[i].width) {
1216 #define CASE(n)     case sizeof(u##n): \
1217                                         probe_kernel_address((u##n *)addr, FRAME_REG(i, u##n)); \
1218                                         break
1219                                 CASES;
1220 #undef CASE
1221                                 default:
1222                                         dprintk(1, "Unsupported memory size %u (%u).",
1223                                                 reg_info[i].width, i);
1224                                         return -EIO;
1225                                 }
1226                         }
1227                         break;
1228                 }
1229         }
1230
1231         if (UNW_PC(frame) % state.codeAlign
1232             || UNW_SP(frame) % sleb128abs(state.dataAlign)) {
1233                 dprintk(1, "Output pointer(s) misaligned (%lx,%lx).",
1234                         UNW_PC(frame), UNW_SP(frame));
1235                 return -EIO;
1236         }
1237         if (pc == UNW_PC(frame) && sp == UNW_SP(frame)) {
1238                 dprintk(1, "No progress (%lx,%lx).", pc, sp);
1239                 return -EIO;
1240         }
1241
1242         return 0;
1243 #undef CASES
1244 #undef FRAME_REG
1245 }
1246 EXPORT_SYMBOL(unwind);
1247
1248 int unwind_init_frame_info(struct unwind_frame_info *info,
1249                            struct task_struct *tsk,
1250                            /*const*/ struct pt_regs *regs)
1251 {
1252         info->task = tsk;
1253         info->call_frame = 0;
1254         arch_unw_init_frame_info(info, regs);
1255
1256         return 0;
1257 }
1258 EXPORT_SYMBOL(unwind_init_frame_info);
1259
1260 /*
1261  * Prepare to unwind a blocked task.
1262  */
1263 int unwind_init_blocked(struct unwind_frame_info *info,
1264                         struct task_struct *tsk)
1265 {
1266         info->task = tsk;
1267         info->call_frame = 0;
1268         arch_unw_init_blocked(info);
1269
1270         return 0;
1271 }
1272 EXPORT_SYMBOL(unwind_init_blocked);
1273
1274 /*
1275  * Prepare to unwind the currently running thread.
1276  */
1277 int unwind_init_running(struct unwind_frame_info *info,
1278                         asmlinkage int (*callback)(struct unwind_frame_info *,
1279                                                    void *arg),
1280                         void *arg)
1281 {
1282         info->task = current;
1283         info->call_frame = 0;
1284
1285         return arch_unwind_init_running(info, callback, arg);
1286 }
1287 EXPORT_SYMBOL(unwind_init_running);
1288
1289 /*
1290  * Unwind until the return pointer is in user-land (or until an error
1291  * occurs).  Returns 0 if successful, negative number in case of
1292  * error.
1293  */
1294 int unwind_to_user(struct unwind_frame_info *info)
1295 {
1296         while (!arch_unw_user_mode(info)) {
1297                 int err = unwind(info);
1298
1299                 if (err < 0)
1300                         return err;
1301         }
1302
1303         return 0;
1304 }
1305 EXPORT_SYMBOL(unwind_to_user);