Commit | Line | Data |
---|---|---|
7664c5a1 JF |
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. | |
b93a531e JB |
8 | CONFIG_GENERIC_BUG_RELATIVE_POINTERS - use 32-bit pointers relative to |
9 | the containing struct bug_entry for bug_addr and file. | |
7664c5a1 JF |
10 | CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG |
11 | ||
12 | CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable | |
13 | (though they're generally always on). | |
14 | ||
15 | CONFIG_GENERIC_BUG is set by each architecture using this code. | |
16 | ||
17 | To use this, your architecture must: | |
18 | ||
19 | 1. Set up the config options: | |
20 | - Enable CONFIG_GENERIC_BUG if CONFIG_BUG | |
21 | ||
22 | 2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON) | |
23 | - Define HAVE_ARCH_BUG | |
24 | - Implement BUG() to generate a faulting instruction | |
25 | - NOTE: struct bug_entry does not have "file" or "line" entries | |
26 | when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate | |
27 | the values accordingly. | |
28 | ||
29 | 3. Implement the trap | |
30 | - In the illegal instruction trap handler (typically), verify | |
31 | that the fault was in kernel mode, and call report_bug() | |
32 | - report_bug() will return whether it was a false alarm, a warning, | |
33 | or an actual bug. | |
34 | - You must implement the is_valid_bugaddr(bugaddr) callback which | |
35 | returns true if the eip is a real kernel address, and it points | |
36 | to the expected BUG trap instruction. | |
37 | ||
38 | Jeremy Fitzhardinge <jeremy@goop.org> 2006 | |
39 | */ | |
c56ba703 FF |
40 | |
41 | #define pr_fmt(fmt) fmt | |
42 | ||
7664c5a1 JF |
43 | #include <linux/list.h> |
44 | #include <linux/module.h> | |
da9eac89 | 45 | #include <linux/kernel.h> |
7664c5a1 | 46 | #include <linux/bug.h> |
608e2619 | 47 | #include <linux/sched.h> |
7664c5a1 | 48 | |
1cac41cb MB |
49 | #ifdef CONFIG_SEC_DEBUG |
50 | #include <linux/sec_debug.h> | |
51 | #endif | |
52 | ||
7664c5a1 JF |
53 | extern const struct bug_entry __start___bug_table[], __stop___bug_table[]; |
54 | ||
b93a531e JB |
55 | static inline unsigned long bug_addr(const struct bug_entry *bug) |
56 | { | |
57 | #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS | |
58 | return bug->bug_addr; | |
59 | #else | |
60 | return (unsigned long)bug + bug->bug_addr_disp; | |
61 | #endif | |
62 | } | |
63 | ||
7664c5a1 | 64 | #ifdef CONFIG_MODULES |
1fb9341a | 65 | /* Updates are protected by module mutex */ |
7664c5a1 JF |
66 | static LIST_HEAD(module_bug_list); |
67 | ||
68 | static const struct bug_entry *module_find_bug(unsigned long bugaddr) | |
69 | { | |
70 | struct module *mod; | |
0286b5ea | 71 | const struct bug_entry *bug = NULL; |
7664c5a1 | 72 | |
0be964be | 73 | rcu_read_lock_sched(); |
0286b5ea | 74 | list_for_each_entry_rcu(mod, &module_bug_list, bug_list) { |
7664c5a1 JF |
75 | unsigned i; |
76 | ||
0286b5ea | 77 | bug = mod->bug_table; |
7664c5a1 | 78 | for (i = 0; i < mod->num_bugs; ++i, ++bug) |
b93a531e | 79 | if (bugaddr == bug_addr(bug)) |
0286b5ea | 80 | goto out; |
7664c5a1 | 81 | } |
0286b5ea MH |
82 | bug = NULL; |
83 | out: | |
0be964be | 84 | rcu_read_unlock_sched(); |
0286b5ea MH |
85 | |
86 | return bug; | |
7664c5a1 JF |
87 | } |
88 | ||
5336377d LT |
89 | void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, |
90 | struct module *mod) | |
7664c5a1 JF |
91 | { |
92 | char *secstrings; | |
93 | unsigned int i; | |
94 | ||
0be964be PZ |
95 | lockdep_assert_held(&module_mutex); |
96 | ||
7664c5a1 JF |
97 | mod->bug_table = NULL; |
98 | mod->num_bugs = 0; | |
99 | ||
100 | /* Find the __bug_table section, if present */ | |
101 | secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; | |
102 | for (i = 1; i < hdr->e_shnum; i++) { | |
103 | if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) | |
104 | continue; | |
105 | mod->bug_table = (void *) sechdrs[i].sh_addr; | |
106 | mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); | |
107 | break; | |
108 | } | |
109 | ||
110 | /* | |
111 | * Strictly speaking this should have a spinlock to protect against | |
112 | * traversals, but since we only traverse on BUG()s, a spinlock | |
113 | * could potentially lead to deadlock and thus be counter-productive. | |
0286b5ea MH |
114 | * Thus, this uses RCU to safely manipulate the bug list, since BUG |
115 | * must run in non-interruptive state. | |
7664c5a1 | 116 | */ |
0286b5ea | 117 | list_add_rcu(&mod->bug_list, &module_bug_list); |
7664c5a1 JF |
118 | } |
119 | ||
120 | void module_bug_cleanup(struct module *mod) | |
121 | { | |
0be964be | 122 | lockdep_assert_held(&module_mutex); |
0286b5ea | 123 | list_del_rcu(&mod->bug_list); |
7664c5a1 JF |
124 | } |
125 | ||
126 | #else | |
127 | ||
128 | static inline const struct bug_entry *module_find_bug(unsigned long bugaddr) | |
129 | { | |
130 | return NULL; | |
131 | } | |
132 | #endif | |
133 | ||
134 | const struct bug_entry *find_bug(unsigned long bugaddr) | |
135 | { | |
136 | const struct bug_entry *bug; | |
137 | ||
138 | for (bug = __start___bug_table; bug < __stop___bug_table; ++bug) | |
b93a531e | 139 | if (bugaddr == bug_addr(bug)) |
7664c5a1 JF |
140 | return bug; |
141 | ||
142 | return module_find_bug(bugaddr); | |
143 | } | |
144 | ||
608e2619 | 145 | enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) |
7664c5a1 JF |
146 | { |
147 | const struct bug_entry *bug; | |
148 | const char *file; | |
149 | unsigned line, warning; | |
150 | ||
151 | if (!is_valid_bugaddr(bugaddr)) | |
152 | return BUG_TRAP_TYPE_NONE; | |
153 | ||
154 | bug = find_bug(bugaddr); | |
155 | ||
7664c5a1 JF |
156 | file = NULL; |
157 | line = 0; | |
158 | warning = 0; | |
159 | ||
160 | if (bug) { | |
161 | #ifdef CONFIG_DEBUG_BUGVERBOSE | |
b93a531e | 162 | #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS |
7664c5a1 | 163 | file = bug->file; |
b93a531e JB |
164 | #else |
165 | file = (const char *)bug + bug->file_disp; | |
166 | #endif | |
7664c5a1 JF |
167 | line = bug->line; |
168 | #endif | |
169 | warning = (bug->flags & BUGFLAG_WARNING) != 0; | |
170 | } | |
171 | ||
172 | if (warning) { | |
173 | /* this is a WARN_ON rather than BUG/BUG_ON */ | |
c56ba703 | 174 | pr_warn("------------[ cut here ]------------\n"); |
e2e7e093 | 175 | |
7664c5a1 | 176 | if (file) |
c56ba703 | 177 | pr_warn("WARNING: at %s:%u\n", file, line); |
7664c5a1 | 178 | else |
c56ba703 FF |
179 | pr_warn("WARNING: at %p [verbose debug info unavailable]\n", |
180 | (void *)bugaddr); | |
7664c5a1 | 181 | |
e2e7e093 | 182 | print_modules(); |
863a6049 | 183 | print_oops_end_marker(); |
373d4d09 RR |
184 | /* Just a warning, don't kill lockdep. */ |
185 | add_taint(BUG_GET_TAINT(bug), LOCKDEP_STILL_OK); | |
7664c5a1 JF |
186 | return BUG_TRAP_TYPE_WARN; |
187 | } | |
188 | ||
b0f4c4b3 | 189 | printk(KERN_DEFAULT "------------[ cut here ]------------\n"); |
e2e7e093 | 190 | |
1cac41cb MB |
191 | #ifdef CONFIG_SEC_DEBUG_EXTRA_INFO |
192 | if (file) | |
193 | sec_debug_set_extra_info_bug(file, line); | |
194 | #endif | |
195 | ||
7664c5a1 | 196 | if (file) |
1cac41cb | 197 | pr_auto(ASL1, "kernel BUG at %s:%u!\n", file, line); |
7664c5a1 | 198 | else |
1cac41cb | 199 | pr_auto(ASL1, "Kernel BUG at %p [verbose debug info unavailable]\n", |
c56ba703 | 200 | (void *)bugaddr); |
7664c5a1 JF |
201 | |
202 | return BUG_TRAP_TYPE_BUG; | |
203 | } |