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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_GENERIC_BUG_RELATIVE_POINTERS - use 32-bit pointers relative to
9 the containing struct bug_entry for bug_addr and file.
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 */
40#include <linux/list.h>
41#include <linux/module.h>
42#include <linux/kernel.h>
43#include <linux/bug.h>
44#include <linux/sched.h>
45
46extern const struct bug_entry __start___bug_table[], __stop___bug_table[];
47
48static inline unsigned long bug_addr(const struct bug_entry *bug)
49{
50#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
51 return bug->bug_addr;
52#else
53 return (unsigned long)bug + bug->bug_addr_disp;
54#endif
55}
56
57#ifdef CONFIG_MODULES
58static LIST_HEAD(module_bug_list);
59
60static const struct bug_entry *module_find_bug(unsigned long bugaddr)
61{
62 struct module *mod;
63
64 list_for_each_entry(mod, &module_bug_list, bug_list) {
65 const struct bug_entry *bug = mod->bug_table;
66 unsigned i;
67
68 for (i = 0; i < mod->num_bugs; ++i, ++bug)
69 if (bugaddr == bug_addr(bug))
70 return bug;
71 }
72 return NULL;
73}
74
75void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
76 struct module *mod)
77{
78 char *secstrings;
79 unsigned int i;
80
81 mod->bug_table = NULL;
82 mod->num_bugs = 0;
83
84 /* Find the __bug_table section, if present */
85 secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
86 for (i = 1; i < hdr->e_shnum; i++) {
87 if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
88 continue;
89 mod->bug_table = (void *) sechdrs[i].sh_addr;
90 mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
91 break;
92 }
93
94 /*
95 * Strictly speaking this should have a spinlock to protect against
96 * traversals, but since we only traverse on BUG()s, a spinlock
97 * could potentially lead to deadlock and thus be counter-productive.
98 */
99 list_add(&mod->bug_list, &module_bug_list);
100}
101
102void module_bug_cleanup(struct module *mod)
103{
104 list_del(&mod->bug_list);
105}
106
107#else
108
109static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
110{
111 return NULL;
112}
113#endif
114
115const struct bug_entry *find_bug(unsigned long bugaddr)
116{
117 const struct bug_entry *bug;
118
119 for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
120 if (bugaddr == bug_addr(bug))
121 return bug;
122
123 return module_find_bug(bugaddr);
124}
125
126enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
127{
128 const struct bug_entry *bug;
129 const char *file;
130 unsigned line, warning;
131
132 if (!is_valid_bugaddr(bugaddr))
133 return BUG_TRAP_TYPE_NONE;
134
135 bug = find_bug(bugaddr);
136
137 file = NULL;
138 line = 0;
139 warning = 0;
140
141 if (bug) {
142#ifdef CONFIG_DEBUG_BUGVERBOSE
143#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
144 file = bug->file;
145#else
146 file = (const char *)bug + bug->file_disp;
147#endif
148 line = bug->line;
149#endif
150 warning = (bug->flags & BUGFLAG_WARNING) != 0;
151 }
152
153 if (warning) {
154 /* this is a WARN_ON rather than BUG/BUG_ON */
155 printk(KERN_WARNING "------------[ cut here ]------------\n");
156
157 if (file)
158 printk(KERN_WARNING "WARNING: at %s:%u\n",
159 file, line);
160 else
161 printk(KERN_WARNING "WARNING: at %p "
162 "[verbose debug info unavailable]\n",
163 (void *)bugaddr);
164
165 print_modules();
166 show_regs(regs);
167 print_oops_end_marker();
168 add_taint(BUG_GET_TAINT(bug));
169 return BUG_TRAP_TYPE_WARN;
170 }
171
172 printk(KERN_EMERG "------------[ cut here ]------------\n");
173
174 if (file)
175 printk(KERN_CRIT "kernel BUG at %s:%u!\n",
176 file, line);
177 else
178 printk(KERN_CRIT "Kernel BUG at %p "
179 "[verbose debug info unavailable]\n",
180 (void *)bugaddr);
181
182 return BUG_TRAP_TYPE_BUG;
183}
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_GENERIC_BUG_RELATIVE_POINTERS - use 32-bit pointers relative to
9 the containing struct bug_entry for bug_addr and file.
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 */
40
41#define pr_fmt(fmt) fmt
42
43#include <linux/list.h>
44#include <linux/module.h>
45#include <linux/kernel.h>
46#include <linux/bug.h>
47#include <linux/sched.h>
48
49extern const struct bug_entry __start___bug_table[], __stop___bug_table[];
50
51static inline unsigned long bug_addr(const struct bug_entry *bug)
52{
53#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
54 return bug->bug_addr;
55#else
56 return (unsigned long)bug + bug->bug_addr_disp;
57#endif
58}
59
60#ifdef CONFIG_MODULES
61/* Updates are protected by module mutex */
62static LIST_HEAD(module_bug_list);
63
64static const struct bug_entry *module_find_bug(unsigned long bugaddr)
65{
66 struct module *mod;
67 const struct bug_entry *bug = NULL;
68
69 rcu_read_lock_sched();
70 list_for_each_entry_rcu(mod, &module_bug_list, bug_list) {
71 unsigned i;
72
73 bug = mod->bug_table;
74 for (i = 0; i < mod->num_bugs; ++i, ++bug)
75 if (bugaddr == bug_addr(bug))
76 goto out;
77 }
78 bug = NULL;
79out:
80 rcu_read_unlock_sched();
81
82 return bug;
83}
84
85void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
86 struct module *mod)
87{
88 char *secstrings;
89 unsigned int i;
90
91 lockdep_assert_held(&module_mutex);
92
93 mod->bug_table = NULL;
94 mod->num_bugs = 0;
95
96 /* Find the __bug_table section, if present */
97 secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
98 for (i = 1; i < hdr->e_shnum; i++) {
99 if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
100 continue;
101 mod->bug_table = (void *) sechdrs[i].sh_addr;
102 mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
103 break;
104 }
105
106 /*
107 * Strictly speaking this should have a spinlock to protect against
108 * traversals, but since we only traverse on BUG()s, a spinlock
109 * could potentially lead to deadlock and thus be counter-productive.
110 * Thus, this uses RCU to safely manipulate the bug list, since BUG
111 * must run in non-interruptive state.
112 */
113 list_add_rcu(&mod->bug_list, &module_bug_list);
114}
115
116void module_bug_cleanup(struct module *mod)
117{
118 lockdep_assert_held(&module_mutex);
119 list_del_rcu(&mod->bug_list);
120}
121
122#else
123
124static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
125{
126 return NULL;
127}
128#endif
129
130const struct bug_entry *find_bug(unsigned long bugaddr)
131{
132 const struct bug_entry *bug;
133
134 for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
135 if (bugaddr == bug_addr(bug))
136 return bug;
137
138 return module_find_bug(bugaddr);
139}
140
141enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
142{
143 const struct bug_entry *bug;
144 const char *file;
145 unsigned line, warning;
146
147 if (!is_valid_bugaddr(bugaddr))
148 return BUG_TRAP_TYPE_NONE;
149
150 bug = find_bug(bugaddr);
151
152 file = NULL;
153 line = 0;
154 warning = 0;
155
156 if (bug) {
157#ifdef CONFIG_DEBUG_BUGVERBOSE
158#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
159 file = bug->file;
160#else
161 file = (const char *)bug + bug->file_disp;
162#endif
163 line = bug->line;
164#endif
165 warning = (bug->flags & BUGFLAG_WARNING) != 0;
166 }
167
168 if (warning) {
169 /* this is a WARN_ON rather than BUG/BUG_ON */
170 __warn(file, line, (void *)bugaddr, BUG_GET_TAINT(bug), regs,
171 NULL);
172 return BUG_TRAP_TYPE_WARN;
173 }
174
175 printk(KERN_DEFAULT "------------[ cut here ]------------\n");
176
177 if (file)
178 pr_crit("kernel BUG at %s:%u!\n", file, line);
179 else
180 pr_crit("Kernel BUG at %p [verbose debug info unavailable]\n",
181 (void *)bugaddr);
182
183 return BUG_TRAP_TYPE_BUG;
184}