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;