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 */
kdbgetsymval(const char * symname,kdb_symtab_t * symtab)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 */
kdbnearsym(unsigned long addr,kdb_symtab_t * symtab)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
kdbnearsym_cleanup(void)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 */
kallsyms_symbol_complete(char * prefix_name,int max_len)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 */
kallsyms_symbol_next(char * prefix_name,int flag,int buf_size)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 */
kdb_symbol_print(unsigned long addr,const kdb_symtab_t * symtab_p,unsigned int punc)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 */
kdb_strdup(const char * str,gfp_t type)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 */
kdb_getarea_size(void * res,unsigned long addr,size_t size)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 */
kdb_putarea_size(unsigned long addr,void * res,size_t size)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 */
kdb_getphys(void * res,unsigned long addr,size_t size)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 */
kdb_getphysword(unsigned long * word,unsigned long addr,size_t size)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 */
kdb_getword(unsigned long * word,unsigned long addr,size_t size)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 */
kdb_putword(unsigned long addr,unsigned long word,size_t size)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
kdb_task_state_string(const char * s)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 */
kdb_task_state_char(const struct task_struct * p)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 */
kdb_task_state(const struct task_struct * p,unsigned long mask)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 */
kdb_print_nameval(const char * name,unsigned long val)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);
get_dap_lock(void)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
debug_kmalloc(size_t size,gfp_t flags)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
debug_kfree(void * p)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
debug_kusage(void)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
kdb_save_flags(void)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
kdb_restore_flags(void)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