bug.c 4.0 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163
  1. /*
  2. Generic support for BUG()
  3. This respects the following config options:
  4. CONFIG_BUG - emit BUG traps. Nothing happens without this.
  5. CONFIG_GENERIC_BUG - enable this code.
  6. CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG
  7. CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable
  8. (though they're generally always on).
  9. CONFIG_GENERIC_BUG is set by each architecture using this code.
  10. To use this, your architecture must:
  11. 1. Set up the config options:
  12. - Enable CONFIG_GENERIC_BUG if CONFIG_BUG
  13. 2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON)
  14. - Define HAVE_ARCH_BUG
  15. - Implement BUG() to generate a faulting instruction
  16. - NOTE: struct bug_entry does not have "file" or "line" entries
  17. when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate
  18. the values accordingly.
  19. 3. Implement the trap
  20. - In the illegal instruction trap handler (typically), verify
  21. that the fault was in kernel mode, and call report_bug()
  22. - report_bug() will return whether it was a false alarm, a warning,
  23. or an actual bug.
  24. - You must implement the is_valid_bugaddr(bugaddr) callback which
  25. returns true if the eip is a real kernel address, and it points
  26. to the expected BUG trap instruction.
  27. Jeremy Fitzhardinge <jeremy@goop.org> 2006
  28. */
  29. #include <linux/list.h>
  30. #include <linux/module.h>
  31. #include <linux/bug.h>
  32. extern const struct bug_entry __start___bug_table[], __stop___bug_table[];
  33. #ifdef CONFIG_MODULES
  34. static LIST_HEAD(module_bug_list);
  35. static const struct bug_entry *module_find_bug(unsigned long bugaddr)
  36. {
  37. struct module *mod;
  38. list_for_each_entry(mod, &module_bug_list, bug_list) {
  39. const struct bug_entry *bug = mod->bug_table;
  40. unsigned i;
  41. for (i = 0; i < mod->num_bugs; ++i, ++bug)
  42. if (bugaddr == bug->bug_addr)
  43. return bug;
  44. }
  45. return NULL;
  46. }
  47. int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
  48. struct module *mod)
  49. {
  50. char *secstrings;
  51. unsigned int i;
  52. mod->bug_table = NULL;
  53. mod->num_bugs = 0;
  54. /* Find the __bug_table section, if present */
  55. secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
  56. for (i = 1; i < hdr->e_shnum; i++) {
  57. if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
  58. continue;
  59. mod->bug_table = (void *) sechdrs[i].sh_addr;
  60. mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
  61. break;
  62. }
  63. /*
  64. * Strictly speaking this should have a spinlock to protect against
  65. * traversals, but since we only traverse on BUG()s, a spinlock
  66. * could potentially lead to deadlock and thus be counter-productive.
  67. */
  68. list_add(&mod->bug_list, &module_bug_list);
  69. return 0;
  70. }
  71. void module_bug_cleanup(struct module *mod)
  72. {
  73. list_del(&mod->bug_list);
  74. }
  75. #else
  76. static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
  77. {
  78. return NULL;
  79. }
  80. #endif
  81. const struct bug_entry *find_bug(unsigned long bugaddr)
  82. {
  83. const struct bug_entry *bug;
  84. for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
  85. if (bugaddr == bug->bug_addr)
  86. return bug;
  87. return module_find_bug(bugaddr);
  88. }
  89. enum bug_trap_type report_bug(unsigned long bugaddr)
  90. {
  91. const struct bug_entry *bug;
  92. const char *file;
  93. unsigned line, warning;
  94. if (!is_valid_bugaddr(bugaddr))
  95. return BUG_TRAP_TYPE_NONE;
  96. bug = find_bug(bugaddr);
  97. printk(KERN_EMERG "------------[ cut here ]------------\n");
  98. file = NULL;
  99. line = 0;
  100. warning = 0;
  101. if (bug) {
  102. #ifdef CONFIG_DEBUG_BUGVERBOSE
  103. file = bug->file;
  104. line = bug->line;
  105. #endif
  106. warning = (bug->flags & BUGFLAG_WARNING) != 0;
  107. }
  108. if (warning) {
  109. /* this is a WARN_ON rather than BUG/BUG_ON */
  110. if (file)
  111. printk(KERN_ERR "Badness at %s:%u\n",
  112. file, line);
  113. else
  114. printk(KERN_ERR "Badness at %p "
  115. "[verbose debug info unavailable]\n",
  116. (void *)bugaddr);
  117. dump_stack();
  118. return BUG_TRAP_TYPE_WARN;
  119. }
  120. if (file)
  121. printk(KERN_CRIT "kernel BUG at %s:%u!\n",
  122. file, line);
  123. else
  124. printk(KERN_CRIT "Kernel BUG at %p "
  125. "[verbose debug info unavailable]\n",
  126. (void *)bugaddr);
  127. return BUG_TRAP_TYPE_BUG;
  128. }