1 /* 2 * Kernel Debugger Architecture Independent Support Functions 3 * 4 * This file is subject to the terms and conditions of the GNU General Public 5 * License. See the file "COPYING" in the main directory of this archive 6 * for more details. 7 * 8 * Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved. 9 * Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved. 10 * 03/02/13 added new 2.5 kallsyms <xavier.bru@bull.net> 11 */ 12 13 #include <stdarg.h> 14 #include <linux/types.h> 15 #include <linux/sched.h> 16 #include <linux/mm.h> 17 #include <linux/kallsyms.h> 18 #include <linux/stddef.h> 19 #include <linux/vmalloc.h> 20 #include <linux/ptrace.h> 21 #include <linux/module.h> 22 #include <linux/highmem.h> 23 #include <linux/hardirq.h> 24 #include <linux/delay.h> 25 #include <linux/uaccess.h> 26 #include <linux/kdb.h> 27 #include <linux/slab.h> 28 #include "kdb_private.h" 29 30 /* 31 * kdbgetsymval - Return the address of the given symbol. 32 * 33 * Parameters: 34 * symname Character string containing symbol name 35 * symtab Structure to receive results 36 * Returns: 37 * 0 Symbol not found, symtab zero filled 38 * 1 Symbol mapped to module/symbol/section, data in symtab 39 */ 40 int kdbgetsymval(const char *symname, kdb_symtab_t *symtab) 41 { 42 if (KDB_DEBUG(AR)) 43 kdb_printf("kdbgetsymval: symname=%s, symtab=%px\n", symname, 44 symtab); 45 memset(symtab, 0, sizeof(*symtab)); 46 symtab->sym_start = kallsyms_lookup_name(symname); 47 if (symtab->sym_start) { 48 if (KDB_DEBUG(AR)) 49 kdb_printf("kdbgetsymval: returns 1, " 50 "symtab->sym_start=0x%lx\n", 51 symtab->sym_start); 52 return 1; 53 } 54 if (KDB_DEBUG(AR)) 55 kdb_printf("kdbgetsymval: returns 0\n"); 56 return 0; 57 } 58 EXPORT_SYMBOL(kdbgetsymval); 59 60 static char *kdb_name_table[100]; /* arbitrary size */ 61 62 /* 63 * kdbnearsym - Return the name of the symbol with the nearest address 64 * less than 'addr'. 65 * 66 * Parameters: 67 * addr Address to check for symbol near 68 * symtab Structure to receive results 69 * Returns: 70 * 0 No sections contain this address, symtab zero filled 71 * 1 Address mapped to module/symbol/section, data in symtab 72 * Remarks: 73 * 2.6 kallsyms has a "feature" where it unpacks the name into a 74 * string. If that string is reused before the caller expects it 75 * then the caller sees its string change without warning. To 76 * avoid cluttering up the main kdb code with lots of kdb_strdup, 77 * tests and kfree calls, kdbnearsym maintains an LRU list of the 78 * last few unique strings. The list is sized large enough to 79 * hold active strings, no kdb caller of kdbnearsym makes more 80 * than ~20 later calls before using a saved value. 81 */ 82 int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab) 83 { 84 int ret = 0; 85 unsigned long symbolsize = 0; 86 unsigned long offset = 0; 87 #define knt1_size 128 /* must be >= kallsyms table size */ 88 char *knt1 = NULL; 89 90 if (KDB_DEBUG(AR)) 91 kdb_printf("kdbnearsym: addr=0x%lx, symtab=%px\n", addr, symtab); 92 memset(symtab, 0, sizeof(*symtab)); 93 94 if (addr < 4096) 95 goto out; 96 knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC); 97 if (!knt1) { 98 kdb_printf("kdbnearsym: addr=0x%lx cannot kmalloc knt1\n", 99 addr); 100 goto out; 101 } 102 symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset, 103 (char **)(&symtab->mod_name), knt1); 104 if (offset > 8*1024*1024) { 105 symtab->sym_name = NULL; 106 addr = offset = symbolsize = 0; 107 } 108 symtab->sym_start = addr - offset; 109 symtab->sym_end = symtab->sym_start + symbolsize; 110 ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0'; 111 112 if (ret) { 113 int i; 114 /* Another 2.6 kallsyms "feature". Sometimes the sym_name is 115 * set but the buffer passed into kallsyms_lookup is not used, 116 * so it contains garbage. The caller has to work out which 117 * buffer needs to be saved. 118 * 119 * What was Rusty smoking when he wrote that code? 120 */ 121 if (symtab->sym_name != knt1) { 122 strncpy(knt1, symtab->sym_name, knt1_size); 123 knt1[knt1_size-1] = '\0'; 124 } 125 for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) { 126 if (kdb_name_table[i] && 127 strcmp(kdb_name_table[i], knt1) == 0) 128 break; 129 } 130 if (i >= ARRAY_SIZE(kdb_name_table)) { 131 debug_kfree(kdb_name_table[0]); 132 memmove(kdb_name_table, kdb_name_table+1, 133 sizeof(kdb_name_table[0]) * 134 (ARRAY_SIZE(kdb_name_table)-1)); 135 } else { 136 debug_kfree(knt1); 137 knt1 = kdb_name_table[i]; 138 memmove(kdb_name_table+i, kdb_name_table+i+1, 139 sizeof(kdb_name_table[0]) * 140 (ARRAY_SIZE(kdb_name_table)-i-1)); 141 } 142 i = ARRAY_SIZE(kdb_name_table) - 1; 143 kdb_name_table[i] = knt1; 144 symtab->sym_name = kdb_name_table[i]; 145 knt1 = NULL; 146 } 147 148 if (symtab->mod_name == NULL) 149 symtab->mod_name = "kernel"; 150 if (KDB_DEBUG(AR)) 151 kdb_printf("kdbnearsym: returns %d symtab->sym_start=0x%lx, " 152 "symtab->mod_name=%px, symtab->sym_name=%px (%s)\n", ret, 153 symtab->sym_start, symtab->mod_name, symtab->sym_name, 154 symtab->sym_name); 155 156 out: 157 debug_kfree(knt1); 158 return ret; 159 } 160 161 void kdbnearsym_cleanup(void) 162 { 163 int i; 164 for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) { 165 if (kdb_name_table[i]) { 166 debug_kfree(kdb_name_table[i]); 167 kdb_name_table[i] = NULL; 168 } 169 } 170 } 171 172 static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1]; 173 174 /* 175 * kallsyms_symbol_complete 176 * 177 * Parameters: 178 * prefix_name prefix of a symbol name to lookup 179 * max_len maximum length that can be returned 180 * Returns: 181 * Number of symbols which match the given prefix. 182 * Notes: 183 * prefix_name is changed to contain the longest unique prefix that 184 * starts with this prefix (tab completion). 185 */ 186 int kallsyms_symbol_complete(char *prefix_name, int max_len) 187 { 188 loff_t pos = 0; 189 int prefix_len = strlen(prefix_name), prev_len = 0; 190 int i, number = 0; 191 const char *name; 192 193 while ((name = kdb_walk_kallsyms(&pos))) { 194 if (strncmp(name, prefix_name, prefix_len) == 0) { 195 strscpy(ks_namebuf, name, sizeof(ks_namebuf)); 196 /* Work out the longest name that matches the prefix */ 197 if (++number == 1) { 198 prev_len = min_t(int, max_len-1, 199 strlen(ks_namebuf)); 200 memcpy(ks_namebuf_prev, ks_namebuf, prev_len); 201 ks_namebuf_prev[prev_len] = '\0'; 202 continue; 203 } 204 for (i = 0; i < prev_len; i++) { 205 if (ks_namebuf[i] != ks_namebuf_prev[i]) { 206 prev_len = i; 207 ks_namebuf_prev[i] = '\0'; 208 break; 209 } 210 } 211 } 212 } 213 if (prev_len > prefix_len) 214 memcpy(prefix_name, ks_namebuf_prev, prev_len+1); 215 return number; 216 } 217 218 /* 219 * kallsyms_symbol_next 220 * 221 * Parameters: 222 * prefix_name prefix of a symbol name to lookup 223 * flag 0 means search from the head, 1 means continue search. 224 * buf_size maximum length that can be written to prefix_name 225 * buffer 226 * Returns: 227 * 1 if a symbol matches the given prefix. 228 * 0 if no string found 229 */ 230 int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size) 231 { 232 int prefix_len = strlen(prefix_name); 233 static loff_t pos; 234 const char *name; 235 236 if (!flag) 237 pos = 0; 238 239 while ((name = kdb_walk_kallsyms(&pos))) { 240 if (!strncmp(name, prefix_name, prefix_len)) 241 return strscpy(prefix_name, name, buf_size); 242 } 243 return 0; 244 } 245 246 /* 247 * kdb_symbol_print - Standard method for printing a symbol name and offset. 248 * Inputs: 249 * addr Address to be printed. 250 * symtab Address of symbol data, if NULL this routine does its 251 * own lookup. 252 * punc Punctuation for string, bit field. 253 * Remarks: 254 * The string and its punctuation is only printed if the address 255 * is inside the kernel, except that the value is always printed 256 * when requested. 257 */ 258 void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p, 259 unsigned int punc) 260 { 261 kdb_symtab_t symtab, *symtab_p2; 262 if (symtab_p) { 263 symtab_p2 = (kdb_symtab_t *)symtab_p; 264 } else { 265 symtab_p2 = &symtab; 266 kdbnearsym(addr, symtab_p2); 267 } 268 if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE))) 269 return; 270 if (punc & KDB_SP_SPACEB) 271 kdb_printf(" "); 272 if (punc & KDB_SP_VALUE) 273 kdb_printf(kdb_machreg_fmt0, addr); 274 if (symtab_p2->sym_name) { 275 if (punc & KDB_SP_VALUE) 276 kdb_printf(" "); 277 if (punc & KDB_SP_PAREN) 278 kdb_printf("("); 279 if (strcmp(symtab_p2->mod_name, "kernel")) 280 kdb_printf("[%s]", symtab_p2->mod_name); 281 kdb_printf("%s", symtab_p2->sym_name); 282 if (addr != symtab_p2->sym_start) 283 kdb_printf("+0x%lx", addr - symtab_p2->sym_start); 284 if (punc & KDB_SP_SYMSIZE) 285 kdb_printf("/0x%lx", 286 symtab_p2->sym_end - symtab_p2->sym_start); 287 if (punc & KDB_SP_PAREN) 288 kdb_printf(")"); 289 } 290 if (punc & KDB_SP_SPACEA) 291 kdb_printf(" "); 292 if (punc & KDB_SP_NEWLINE) 293 kdb_printf("\n"); 294 } 295 296 /* 297 * kdb_strdup - kdb equivalent of strdup, for disasm code. 298 * Inputs: 299 * str The string to duplicate. 300 * type Flags to kmalloc for the new string. 301 * Returns: 302 * Address of the new string, NULL if storage could not be allocated. 303 * Remarks: 304 * This is not in lib/string.c because it uses kmalloc which is not 305 * available when string.o is used in boot loaders. 306 */ 307 char *kdb_strdup(const char *str, gfp_t type) 308 { 309 int n = strlen(str)+1; 310 char *s = kmalloc(n, type); 311 if (!s) 312 return NULL; 313 return strcpy(s, str); 314 } 315 316 /* 317 * kdb_getarea_size - Read an area of data. The kdb equivalent of 318 * copy_from_user, with kdb messages for invalid addresses. 319 * Inputs: 320 * res Pointer to the area to receive the result. 321 * addr Address of the area to copy. 322 * size Size of the area. 323 * Returns: 324 * 0 for success, < 0 for error. 325 */ 326 int kdb_getarea_size(void *res, unsigned long addr, size_t size) 327 { 328 int ret = probe_kernel_read((char *)res, (char *)addr, size); 329 if (ret) { 330 if (!KDB_STATE(SUPPRESS)) { 331 kdb_printf("kdb_getarea: Bad address 0x%lx\n", addr); 332 KDB_STATE_SET(SUPPRESS); 333 } 334 ret = KDB_BADADDR; 335 } else { 336 KDB_STATE_CLEAR(SUPPRESS); 337 } 338 return ret; 339 } 340 341 /* 342 * kdb_putarea_size - Write an area of data. The kdb equivalent of 343 * copy_to_user, with kdb messages for invalid addresses. 344 * Inputs: 345 * addr Address of the area to write to. 346 * res Pointer to the area holding the data. 347 * size Size of the area. 348 * Returns: 349 * 0 for success, < 0 for error. 350 */ 351 int kdb_putarea_size(unsigned long addr, void *res, size_t size) 352 { 353 int ret = probe_kernel_read((char *)addr, (char *)res, size); 354 if (ret) { 355 if (!KDB_STATE(SUPPRESS)) { 356 kdb_printf("kdb_putarea: Bad address 0x%lx\n", addr); 357 KDB_STATE_SET(SUPPRESS); 358 } 359 ret = KDB_BADADDR; 360 } else { 361 KDB_STATE_CLEAR(SUPPRESS); 362 } 363 return ret; 364 } 365 366 /* 367 * kdb_getphys - Read data from a physical address. Validate the 368 * address is in range, use kmap_atomic() to get data 369 * similar to kdb_getarea() - but for phys addresses 370 * Inputs: 371 * res Pointer to the word to receive the result 372 * addr Physical address of the area to copy 373 * size Size of the area 374 * Returns: 375 * 0 for success, < 0 for error. 376 */ 377 static int kdb_getphys(void *res, unsigned long addr, size_t size) 378 { 379 unsigned long pfn; 380 void *vaddr; 381 struct page *page; 382 383 pfn = (addr >> PAGE_SHIFT); 384 if (!pfn_valid(pfn)) 385 return 1; 386 page = pfn_to_page(pfn); 387 vaddr = kmap_atomic(page); 388 memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size); 389 kunmap_atomic(vaddr); 390 391 return 0; 392 } 393 394 /* 395 * kdb_getphysword 396 * Inputs: 397 * word Pointer to the word to receive the result. 398 * addr Address of the area to copy. 399 * size Size of the area. 400 * Returns: 401 * 0 for success, < 0 for error. 402 */ 403 int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size) 404 { 405 int diag; 406 __u8 w1; 407 __u16 w2; 408 __u32 w4; 409 __u64 w8; 410 *word = 0; /* Default value if addr or size is invalid */ 411 412 switch (size) { 413 case 1: 414 diag = kdb_getphys(&w1, addr, sizeof(w1)); 415 if (!diag) 416 *word = w1; 417 break; 418 case 2: 419 diag = kdb_getphys(&w2, addr, sizeof(w2)); 420 if (!diag) 421 *word = w2; 422 break; 423 case 4: 424 diag = kdb_getphys(&w4, addr, sizeof(w4)); 425 if (!diag) 426 *word = w4; 427 break; 428 case 8: 429 if (size <= sizeof(*word)) { 430 diag = kdb_getphys(&w8, addr, sizeof(w8)); 431 if (!diag) 432 *word = w8; 433 break; 434 } 435 /* fall through */ 436 default: 437 diag = KDB_BADWIDTH; 438 kdb_printf("kdb_getphysword: bad width %ld\n", (long) size); 439 } 440 return diag; 441 } 442 443 /* 444 * kdb_getword - Read a binary value. Unlike kdb_getarea, this treats 445 * data as numbers. 446 * Inputs: 447 * word Pointer to the word to receive the result. 448 * addr Address of the area to copy. 449 * size Size of the area. 450 * Returns: 451 * 0 for success, < 0 for error. 452 */ 453 int kdb_getword(unsigned long *word, unsigned long addr, size_t size) 454 { 455 int diag; 456 __u8 w1; 457 __u16 w2; 458 __u32 w4; 459 __u64 w8; 460 *word = 0; /* Default value if addr or size is invalid */ 461 switch (size) { 462 case 1: 463 diag = kdb_getarea(w1, addr); 464 if (!diag) 465 *word = w1; 466 break; 467 case 2: 468 diag = kdb_getarea(w2, addr); 469 if (!diag) 470 *word = w2; 471 break; 472 case 4: 473 diag = kdb_getarea(w4, addr); 474 if (!diag) 475 *word = w4; 476 break; 477 case 8: 478 if (size <= sizeof(*word)) { 479 diag = kdb_getarea(w8, addr); 480 if (!diag) 481 *word = w8; 482 break; 483 } 484 /* fall through */ 485 default: 486 diag = KDB_BADWIDTH; 487 kdb_printf("kdb_getword: bad width %ld\n", (long) size); 488 } 489 return diag; 490 } 491 492 /* 493 * kdb_putword - Write a binary value. Unlike kdb_putarea, this 494 * treats data as numbers. 495 * Inputs: 496 * addr Address of the area to write to.. 497 * word The value to set. 498 * size Size of the area. 499 * Returns: 500 * 0 for success, < 0 for error. 501 */ 502 int kdb_putword(unsigned long addr, unsigned long word, size_t size) 503 { 504 int diag; 505 __u8 w1; 506 __u16 w2; 507 __u32 w4; 508 __u64 w8; 509 switch (size) { 510 case 1: 511 w1 = word; 512 diag = kdb_putarea(addr, w1); 513 break; 514 case 2: 515 w2 = word; 516 diag = kdb_putarea(addr, w2); 517 break; 518 case 4: 519 w4 = word; 520 diag = kdb_putarea(addr, w4); 521 break; 522 case 8: 523 if (size <= sizeof(word)) { 524 w8 = word; 525 diag = kdb_putarea(addr, w8); 526 break; 527 } 528 /* fall through */ 529 default: 530 diag = KDB_BADWIDTH; 531 kdb_printf("kdb_putword: bad width %ld\n", (long) size); 532 } 533 return diag; 534 } 535 536 /* 537 * kdb_task_state_string - Convert a string containing any of the 538 * letters DRSTCZEUIMA to a mask for the process state field and 539 * return the value. If no argument is supplied, return the mask 540 * that corresponds to environment variable PS, DRSTCZEU by 541 * default. 542 * Inputs: 543 * s String to convert 544 * Returns: 545 * Mask for process state. 546 * Notes: 547 * The mask folds data from several sources into a single long value, so 548 * be careful not to overlap the bits. TASK_* bits are in the LSB, 549 * special cases like UNRUNNABLE are in the MSB. As of 2.6.10-rc1 there 550 * is no overlap between TASK_* and EXIT_* but that may not always be 551 * true, so EXIT_* bits are shifted left 16 bits before being stored in 552 * the mask. 553 */ 554 555 /* unrunnable is < 0 */ 556 #define UNRUNNABLE (1UL << (8*sizeof(unsigned long) - 1)) 557 #define RUNNING (1UL << (8*sizeof(unsigned long) - 2)) 558 #define IDLE (1UL << (8*sizeof(unsigned long) - 3)) 559 #define DAEMON (1UL << (8*sizeof(unsigned long) - 4)) 560 561 unsigned long kdb_task_state_string(const char *s) 562 { 563 long res = 0; 564 if (!s) { 565 s = kdbgetenv("PS"); 566 if (!s) 567 s = "DRSTCZEU"; /* default value for ps */ 568 } 569 while (*s) { 570 switch (*s) { 571 case 'D': 572 res |= TASK_UNINTERRUPTIBLE; 573 break; 574 case 'R': 575 res |= RUNNING; 576 break; 577 case 'S': 578 res |= TASK_INTERRUPTIBLE; 579 break; 580 case 'T': 581 res |= TASK_STOPPED; 582 break; 583 case 'C': 584 res |= TASK_TRACED; 585 break; 586 case 'Z': 587 res |= EXIT_ZOMBIE << 16; 588 break; 589 case 'E': 590 res |= EXIT_DEAD << 16; 591 break; 592 case 'U': 593 res |= UNRUNNABLE; 594 break; 595 case 'I': 596 res |= IDLE; 597 break; 598 case 'M': 599 res |= DAEMON; 600 break; 601 case 'A': 602 res = ~0UL; 603 break; 604 default: 605 kdb_printf("%s: unknown flag '%c' ignored\n", 606 __func__, *s); 607 break; 608 } 609 ++s; 610 } 611 return res; 612 } 613 614 /* 615 * kdb_task_state_char - Return the character that represents the task state. 616 * Inputs: 617 * p struct task for the process 618 * Returns: 619 * One character to represent the task state. 620 */ 621 char kdb_task_state_char (const struct task_struct *p) 622 { 623 int cpu; 624 char state; 625 unsigned long tmp; 626 627 if (!p || probe_kernel_read(&tmp, (char *)p, sizeof(unsigned long))) 628 return 'E'; 629 630 cpu = kdb_process_cpu(p); 631 state = (p->state == 0) ? 'R' : 632 (p->state < 0) ? 'U' : 633 (p->state & TASK_UNINTERRUPTIBLE) ? 'D' : 634 (p->state & TASK_STOPPED) ? 'T' : 635 (p->state & TASK_TRACED) ? 'C' : 636 (p->exit_state & EXIT_ZOMBIE) ? 'Z' : 637 (p->exit_state & EXIT_DEAD) ? 'E' : 638 (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?'; 639 if (is_idle_task(p)) { 640 /* Idle task. Is it really idle, apart from the kdb 641 * interrupt? */ 642 if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) { 643 if (cpu != kdb_initial_cpu) 644 state = 'I'; /* idle task */ 645 } 646 } else if (!p->mm && state == 'S') { 647 state = 'M'; /* sleeping system daemon */ 648 } 649 return state; 650 } 651 652 /* 653 * kdb_task_state - Return true if a process has the desired state 654 * given by the mask. 655 * Inputs: 656 * p struct task for the process 657 * mask mask from kdb_task_state_string to select processes 658 * Returns: 659 * True if the process matches at least one criteria defined by the mask. 660 */ 661 unsigned long kdb_task_state(const struct task_struct *p, unsigned long mask) 662 { 663 char state[] = { kdb_task_state_char(p), '\0' }; 664 return (mask & kdb_task_state_string(state)) != 0; 665 } 666 667 /* 668 * kdb_print_nameval - Print a name and its value, converting the 669 * value to a symbol lookup if possible. 670 * Inputs: 671 * name field name to print 672 * val value of field 673 */ 674 void kdb_print_nameval(const char *name, unsigned long val) 675 { 676 kdb_symtab_t symtab; 677 kdb_printf(" %-11.11s ", name); 678 if (kdbnearsym(val, &symtab)) 679 kdb_symbol_print(val, &symtab, 680 KDB_SP_VALUE|KDB_SP_SYMSIZE|KDB_SP_NEWLINE); 681 else 682 kdb_printf("0x%lx\n", val); 683 } 684 685 /* Last ditch allocator for debugging, so we can still debug even when 686 * the GFP_ATOMIC pool has been exhausted. The algorithms are tuned 687 * for space usage, not for speed. One smallish memory pool, the free 688 * chain is always in ascending address order to allow coalescing, 689 * allocations are done in brute force best fit. 690 */ 691 692 struct debug_alloc_header { 693 u32 next; /* offset of next header from start of pool */ 694 u32 size; 695 void *caller; 696 }; 697 698 /* The memory returned by this allocator must be aligned, which means 699 * so must the header size. Do not assume that sizeof(struct 700 * debug_alloc_header) is a multiple of the alignment, explicitly 701 * calculate the overhead of this header, including the alignment. 702 * The rest of this code must not use sizeof() on any header or 703 * pointer to a header. 704 */ 705 #define dah_align 8 706 #define dah_overhead ALIGN(sizeof(struct debug_alloc_header), dah_align) 707 708 static u64 debug_alloc_pool_aligned[256*1024/dah_align]; /* 256K pool */ 709 static char *debug_alloc_pool = (char *)debug_alloc_pool_aligned; 710 static u32 dah_first, dah_first_call = 1, dah_used, dah_used_max; 711 712 /* Locking is awkward. The debug code is called from all contexts, 713 * including non maskable interrupts. A normal spinlock is not safe 714 * in NMI context. Try to get the debug allocator lock, if it cannot 715 * be obtained after a second then give up. If the lock could not be 716 * previously obtained on this cpu then only try once. 717 * 718 * sparse has no annotation for "this function _sometimes_ acquires a 719 * lock", so fudge the acquire/release notation. 720 */ 721 static DEFINE_SPINLOCK(dap_lock); 722 static int get_dap_lock(void) 723 __acquires(dap_lock) 724 { 725 static int dap_locked = -1; 726 int count; 727 if (dap_locked == smp_processor_id()) 728 count = 1; 729 else 730 count = 1000; 731 while (1) { 732 if (spin_trylock(&dap_lock)) { 733 dap_locked = -1; 734 return 1; 735 } 736 if (!count--) 737 break; 738 udelay(1000); 739 } 740 dap_locked = smp_processor_id(); 741 __acquire(dap_lock); 742 return 0; 743 } 744 745 void *debug_kmalloc(size_t size, gfp_t flags) 746 { 747 unsigned int rem, h_offset; 748 struct debug_alloc_header *best, *bestprev, *prev, *h; 749 void *p = NULL; 750 if (!get_dap_lock()) { 751 __release(dap_lock); /* we never actually got it */ 752 return NULL; 753 } 754 h = (struct debug_alloc_header *)(debug_alloc_pool + dah_first); 755 if (dah_first_call) { 756 h->size = sizeof(debug_alloc_pool_aligned) - dah_overhead; 757 dah_first_call = 0; 758 } 759 size = ALIGN(size, dah_align); 760 prev = best = bestprev = NULL; 761 while (1) { 762 if (h->size >= size && (!best || h->size < best->size)) { 763 best = h; 764 bestprev = prev; 765 if (h->size == size) 766 break; 767 } 768 if (!h->next) 769 break; 770 prev = h; 771 h = (struct debug_alloc_header *)(debug_alloc_pool + h->next); 772 } 773 if (!best) 774 goto out; 775 rem = best->size - size; 776 /* The pool must always contain at least one header */ 777 if (best->next == 0 && bestprev == NULL && rem < dah_overhead) 778 goto out; 779 if (rem >= dah_overhead) { 780 best->size = size; 781 h_offset = ((char *)best - debug_alloc_pool) + 782 dah_overhead + best->size; 783 h = (struct debug_alloc_header *)(debug_alloc_pool + h_offset); 784 h->size = rem - dah_overhead; 785 h->next = best->next; 786 } else 787 h_offset = best->next; 788 best->caller = __builtin_return_address(0); 789 dah_used += best->size; 790 dah_used_max = max(dah_used, dah_used_max); 791 if (bestprev) 792 bestprev->next = h_offset; 793 else 794 dah_first = h_offset; 795 p = (char *)best + dah_overhead; 796 memset(p, POISON_INUSE, best->size - 1); 797 *((char *)p + best->size - 1) = POISON_END; 798 out: 799 spin_unlock(&dap_lock); 800 return p; 801 } 802 803 void debug_kfree(void *p) 804 { 805 struct debug_alloc_header *h; 806 unsigned int h_offset; 807 if (!p) 808 return; 809 if ((char *)p < debug_alloc_pool || 810 (char *)p >= debug_alloc_pool + sizeof(debug_alloc_pool_aligned)) { 811 kfree(p); 812 return; 813 } 814 if (!get_dap_lock()) { 815 __release(dap_lock); /* we never actually got it */ 816 return; /* memory leak, cannot be helped */ 817 } 818 h = (struct debug_alloc_header *)((char *)p - dah_overhead); 819 memset(p, POISON_FREE, h->size - 1); 820 *((char *)p + h->size - 1) = POISON_END; 821 h->caller = NULL; 822 dah_used -= h->size; 823 h_offset = (char *)h - debug_alloc_pool; 824 if (h_offset < dah_first) { 825 h->next = dah_first; 826 dah_first = h_offset; 827 } else { 828 struct debug_alloc_header *prev; 829 unsigned int prev_offset; 830 prev = (struct debug_alloc_header *)(debug_alloc_pool + 831 dah_first); 832 while (1) { 833 if (!prev->next || prev->next > h_offset) 834 break; 835 prev = (struct debug_alloc_header *) 836 (debug_alloc_pool + prev->next); 837 } 838 prev_offset = (char *)prev - debug_alloc_pool; 839 if (prev_offset + dah_overhead + prev->size == h_offset) { 840 prev->size += dah_overhead + h->size; 841 memset(h, POISON_FREE, dah_overhead - 1); 842 *((char *)h + dah_overhead - 1) = POISON_END; 843 h = prev; 844 h_offset = prev_offset; 845 } else { 846 h->next = prev->next; 847 prev->next = h_offset; 848 } 849 } 850 if (h_offset + dah_overhead + h->size == h->next) { 851 struct debug_alloc_header *next; 852 next = (struct debug_alloc_header *) 853 (debug_alloc_pool + h->next); 854 h->size += dah_overhead + next->size; 855 h->next = next->next; 856 memset(next, POISON_FREE, dah_overhead - 1); 857 *((char *)next + dah_overhead - 1) = POISON_END; 858 } 859 spin_unlock(&dap_lock); 860 } 861 862 void debug_kusage(void) 863 { 864 struct debug_alloc_header *h_free, *h_used; 865 #ifdef CONFIG_IA64 866 /* FIXME: using dah for ia64 unwind always results in a memory leak. 867 * Fix that memory leak first, then set debug_kusage_one_time = 1 for 868 * all architectures. 869 */ 870 static int debug_kusage_one_time; 871 #else 872 static int debug_kusage_one_time = 1; 873 #endif 874 if (!get_dap_lock()) { 875 __release(dap_lock); /* we never actually got it */ 876 return; 877 } 878 h_free = (struct debug_alloc_header *)(debug_alloc_pool + dah_first); 879 if (dah_first == 0 && 880 (h_free->size == sizeof(debug_alloc_pool_aligned) - dah_overhead || 881 dah_first_call)) 882 goto out; 883 if (!debug_kusage_one_time) 884 goto out; 885 debug_kusage_one_time = 0; 886 kdb_printf("%s: debug_kmalloc memory leak dah_first %d\n", 887 __func__, dah_first); 888 if (dah_first) { 889 h_used = (struct debug_alloc_header *)debug_alloc_pool; 890 kdb_printf("%s: h_used %px size %d\n", __func__, h_used, 891 h_used->size); 892 } 893 do { 894 h_used = (struct debug_alloc_header *) 895 ((char *)h_free + dah_overhead + h_free->size); 896 kdb_printf("%s: h_used %px size %d caller %px\n", 897 __func__, h_used, h_used->size, h_used->caller); 898 h_free = (struct debug_alloc_header *) 899 (debug_alloc_pool + h_free->next); 900 } while (h_free->next); 901 h_used = (struct debug_alloc_header *) 902 ((char *)h_free + dah_overhead + h_free->size); 903 if ((char *)h_used - debug_alloc_pool != 904 sizeof(debug_alloc_pool_aligned)) 905 kdb_printf("%s: h_used %px size %d caller %px\n", 906 __func__, h_used, h_used->size, h_used->caller); 907 out: 908 spin_unlock(&dap_lock); 909 } 910 911 /* Maintain a small stack of kdb_flags to allow recursion without disturbing 912 * the global kdb state. 913 */ 914 915 static int kdb_flags_stack[4], kdb_flags_index; 916 917 void kdb_save_flags(void) 918 { 919 BUG_ON(kdb_flags_index >= ARRAY_SIZE(kdb_flags_stack)); 920 kdb_flags_stack[kdb_flags_index++] = kdb_flags; 921 } 922 923 void kdb_restore_flags(void) 924 { 925 BUG_ON(kdb_flags_index <= 0); 926 kdb_flags = kdb_flags_stack[--kdb_flags_index]; 927 } 928