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-rw-r--r--lib/bug.c163
1 files changed, 163 insertions, 0 deletions
diff --git a/lib/bug.c b/lib/bug.c
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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
42extern const struct bug_entry __start___bug_table[], __stop___bug_table[];
43
44#ifdef CONFIG_MODULES
45static LIST_HEAD(module_bug_list);
46
47static 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
62int 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
91void module_bug_cleanup(struct module *mod)
92{
93 list_del(&mod->bug_list);
94}
95
96#else
97
98static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
99{
100 return NULL;
101}
102#endif
103
104const 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
115enum 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}