Jeremy Fitzhardinge | 7664c5a | 2006-12-08 02:36:19 -0800 | [diff] [blame^] | 1 | /* |
| 2 | Generic support for BUG() |
| 3 | |
| 4 | This respects the following config options: |
| 5 | |
| 6 | CONFIG_BUG - emit BUG traps. Nothing happens without this. |
| 7 | CONFIG_GENERIC_BUG - enable this code. |
| 8 | CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG |
| 9 | |
| 10 | CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable |
| 11 | (though they're generally always on). |
| 12 | |
| 13 | CONFIG_GENERIC_BUG is set by each architecture using this code. |
| 14 | |
| 15 | To use this, your architecture must: |
| 16 | |
| 17 | 1. Set up the config options: |
| 18 | - Enable CONFIG_GENERIC_BUG if CONFIG_BUG |
| 19 | |
| 20 | 2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON) |
| 21 | - Define HAVE_ARCH_BUG |
| 22 | - Implement BUG() to generate a faulting instruction |
| 23 | - NOTE: struct bug_entry does not have "file" or "line" entries |
| 24 | when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate |
| 25 | the values accordingly. |
| 26 | |
| 27 | 3. Implement the trap |
| 28 | - In the illegal instruction trap handler (typically), verify |
| 29 | that the fault was in kernel mode, and call report_bug() |
| 30 | - report_bug() will return whether it was a false alarm, a warning, |
| 31 | or an actual bug. |
| 32 | - You must implement the is_valid_bugaddr(bugaddr) callback which |
| 33 | returns true if the eip is a real kernel address, and it points |
| 34 | to the expected BUG trap instruction. |
| 35 | |
| 36 | Jeremy Fitzhardinge <jeremy@goop.org> 2006 |
| 37 | */ |
| 38 | #include <linux/list.h> |
| 39 | #include <linux/module.h> |
| 40 | #include <linux/bug.h> |
| 41 | |
| 42 | extern const struct bug_entry __start___bug_table[], __stop___bug_table[]; |
| 43 | |
| 44 | #ifdef CONFIG_MODULES |
| 45 | static LIST_HEAD(module_bug_list); |
| 46 | |
| 47 | static const struct bug_entry *module_find_bug(unsigned long bugaddr) |
| 48 | { |
| 49 | struct module *mod; |
| 50 | |
| 51 | list_for_each_entry(mod, &module_bug_list, bug_list) { |
| 52 | const struct bug_entry *bug = mod->bug_table; |
| 53 | unsigned i; |
| 54 | |
| 55 | for (i = 0; i < mod->num_bugs; ++i, ++bug) |
| 56 | if (bugaddr == bug->bug_addr) |
| 57 | return bug; |
| 58 | } |
| 59 | return NULL; |
| 60 | } |
| 61 | |
| 62 | int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, |
| 63 | struct module *mod) |
| 64 | { |
| 65 | char *secstrings; |
| 66 | unsigned int i; |
| 67 | |
| 68 | mod->bug_table = NULL; |
| 69 | mod->num_bugs = 0; |
| 70 | |
| 71 | /* Find the __bug_table section, if present */ |
| 72 | secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; |
| 73 | for (i = 1; i < hdr->e_shnum; i++) { |
| 74 | if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) |
| 75 | continue; |
| 76 | mod->bug_table = (void *) sechdrs[i].sh_addr; |
| 77 | mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); |
| 78 | break; |
| 79 | } |
| 80 | |
| 81 | /* |
| 82 | * Strictly speaking this should have a spinlock to protect against |
| 83 | * traversals, but since we only traverse on BUG()s, a spinlock |
| 84 | * could potentially lead to deadlock and thus be counter-productive. |
| 85 | */ |
| 86 | list_add(&mod->bug_list, &module_bug_list); |
| 87 | |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | void module_bug_cleanup(struct module *mod) |
| 92 | { |
| 93 | list_del(&mod->bug_list); |
| 94 | } |
| 95 | |
| 96 | #else |
| 97 | |
| 98 | static inline const struct bug_entry *module_find_bug(unsigned long bugaddr) |
| 99 | { |
| 100 | return NULL; |
| 101 | } |
| 102 | #endif |
| 103 | |
| 104 | const struct bug_entry *find_bug(unsigned long bugaddr) |
| 105 | { |
| 106 | const struct bug_entry *bug; |
| 107 | |
| 108 | for (bug = __start___bug_table; bug < __stop___bug_table; ++bug) |
| 109 | if (bugaddr == bug->bug_addr) |
| 110 | return bug; |
| 111 | |
| 112 | return module_find_bug(bugaddr); |
| 113 | } |
| 114 | |
| 115 | enum bug_trap_type report_bug(unsigned long bugaddr) |
| 116 | { |
| 117 | const struct bug_entry *bug; |
| 118 | const char *file; |
| 119 | unsigned line, warning; |
| 120 | |
| 121 | if (!is_valid_bugaddr(bugaddr)) |
| 122 | return BUG_TRAP_TYPE_NONE; |
| 123 | |
| 124 | bug = find_bug(bugaddr); |
| 125 | |
| 126 | printk(KERN_EMERG "------------[ cut here ]------------\n"); |
| 127 | |
| 128 | file = NULL; |
| 129 | line = 0; |
| 130 | warning = 0; |
| 131 | |
| 132 | if (bug) { |
| 133 | #ifdef CONFIG_DEBUG_BUGVERBOSE |
| 134 | file = bug->file; |
| 135 | line = bug->line; |
| 136 | #endif |
| 137 | warning = (bug->flags & BUGFLAG_WARNING) != 0; |
| 138 | } |
| 139 | |
| 140 | if (warning) { |
| 141 | /* this is a WARN_ON rather than BUG/BUG_ON */ |
| 142 | if (file) |
| 143 | printk(KERN_ERR "Badness at %s:%u\n", |
| 144 | file, line); |
| 145 | else |
| 146 | printk(KERN_ERR "Badness at %p " |
| 147 | "[verbose debug info unavailable]\n", |
| 148 | (void *)bugaddr); |
| 149 | |
| 150 | dump_stack(); |
| 151 | return BUG_TRAP_TYPE_WARN; |
| 152 | } |
| 153 | |
| 154 | if (file) |
| 155 | printk(KERN_CRIT "kernel BUG at %s:%u!\n", |
| 156 | file, line); |
| 157 | else |
| 158 | printk(KERN_CRIT "Kernel BUG at %p " |
| 159 | "[verbose debug info unavailable]\n", |
| 160 | (void *)bugaddr); |
| 161 | |
| 162 | return BUG_TRAP_TYPE_BUG; |
| 163 | } |