2 Generic support for BUG()
4 This respects the following config options:
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
12 CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable
13 (though they're generally always on).
15 CONFIG_GENERIC_BUG is set by each architecture using this code.
17 To use this, your architecture must:
19 1. Set up the config options:
20 - Enable CONFIG_GENERIC_BUG if CONFIG_BUG
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.
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,
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.
38 Jeremy Fitzhardinge <jeremy@goop.org> 2006
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>
46 extern const struct bug_entry __start___bug_table
[], __stop___bug_table
[];
48 static inline unsigned long bug_addr(const struct bug_entry
*bug
)
50 #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
53 return (unsigned long)bug
+ bug
->bug_addr_disp
;
58 static LIST_HEAD(module_bug_list
);
60 static const struct bug_entry
*module_find_bug(unsigned long bugaddr
)
64 list_for_each_entry(mod
, &module_bug_list
, bug_list
) {
65 const struct bug_entry
*bug
= mod
->bug_table
;
68 for (i
= 0; i
< mod
->num_bugs
; ++i
, ++bug
)
69 if (bugaddr
== bug_addr(bug
))
75 int module_bug_finalize(const Elf_Ehdr
*hdr
, const Elf_Shdr
*sechdrs
,
81 mod
->bug_table
= NULL
;
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"))
89 mod
->bug_table
= (void *) sechdrs
[i
].sh_addr
;
90 mod
->num_bugs
= sechdrs
[i
].sh_size
/ sizeof(struct bug_entry
);
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.
99 list_add(&mod
->bug_list
, &module_bug_list
);
104 void module_bug_cleanup(struct module
*mod
)
106 list_del(&mod
->bug_list
);
111 static inline const struct bug_entry
*module_find_bug(unsigned long bugaddr
)
117 const struct bug_entry
*find_bug(unsigned long bugaddr
)
119 const struct bug_entry
*bug
;
121 for (bug
= __start___bug_table
; bug
< __stop___bug_table
; ++bug
)
122 if (bugaddr
== bug_addr(bug
))
125 return module_find_bug(bugaddr
);
128 enum bug_trap_type
report_bug(unsigned long bugaddr
, struct pt_regs
*regs
)
130 const struct bug_entry
*bug
;
132 unsigned line
, warning
;
134 if (!is_valid_bugaddr(bugaddr
))
135 return BUG_TRAP_TYPE_NONE
;
137 bug
= find_bug(bugaddr
);
139 printk(KERN_EMERG
"------------[ cut here ]------------\n");
146 #ifdef CONFIG_DEBUG_BUGVERBOSE
147 #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
150 file
= (const char *)bug
+ bug
->file_disp
;
154 warning
= (bug
->flags
& BUGFLAG_WARNING
) != 0;
158 /* this is a WARN_ON rather than BUG/BUG_ON */
160 printk(KERN_ERR
"Badness at %s:%u\n",
163 printk(KERN_ERR
"Badness at %p "
164 "[verbose debug info unavailable]\n",
168 add_taint(TAINT_WARN
);
169 return BUG_TRAP_TYPE_WARN
;
173 printk(KERN_CRIT
"kernel BUG at %s:%u!\n",
176 printk(KERN_CRIT
"Kernel BUG at %p "
177 "[verbose debug info unavailable]\n",
180 return BUG_TRAP_TYPE_BUG
;