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Linux/kernel/debug/kdb/kdb_support.c

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

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