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v3.5.6
  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_DEFAULT "------------[ 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}
v3.15
  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
 58/* Updates are protected by module mutex */
 59static LIST_HEAD(module_bug_list);
 60
 61static const struct bug_entry *module_find_bug(unsigned long bugaddr)
 62{
 63	struct module *mod;
 64
 65	list_for_each_entry(mod, &module_bug_list, bug_list) {
 66		const struct bug_entry *bug = mod->bug_table;
 67		unsigned i;
 68
 69		for (i = 0; i < mod->num_bugs; ++i, ++bug)
 70			if (bugaddr == bug_addr(bug))
 71				return bug;
 72	}
 73	return NULL;
 74}
 75
 76void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 77			 struct module *mod)
 78{
 79	char *secstrings;
 80	unsigned int i;
 81
 82	mod->bug_table = NULL;
 83	mod->num_bugs = 0;
 84
 85	/* Find the __bug_table section, if present */
 86	secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 87	for (i = 1; i < hdr->e_shnum; i++) {
 88		if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))
 89			continue;
 90		mod->bug_table = (void *) sechdrs[i].sh_addr;
 91		mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);
 92		break;
 93	}
 94
 95	/*
 96	 * Strictly speaking this should have a spinlock to protect against
 97	 * traversals, but since we only traverse on BUG()s, a spinlock
 98	 * could potentially lead to deadlock and thus be counter-productive.
 99	 */
100	list_add(&mod->bug_list, &module_bug_list);
101}
102
103void module_bug_cleanup(struct module *mod)
104{
105	list_del(&mod->bug_list);
106}
107
108#else
109
110static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)
111{
112	return NULL;
113}
114#endif
115
116const struct bug_entry *find_bug(unsigned long bugaddr)
117{
118	const struct bug_entry *bug;
119
120	for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
121		if (bugaddr == bug_addr(bug))
122			return bug;
123
124	return module_find_bug(bugaddr);
125}
126
127enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
128{
129	const struct bug_entry *bug;
130	const char *file;
131	unsigned line, warning;
132
133	if (!is_valid_bugaddr(bugaddr))
134		return BUG_TRAP_TYPE_NONE;
135
136	bug = find_bug(bugaddr);
137
138	file = NULL;
139	line = 0;
140	warning = 0;
141
142	if (bug) {
143#ifdef CONFIG_DEBUG_BUGVERBOSE
144#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
145		file = bug->file;
146#else
147		file = (const char *)bug + bug->file_disp;
148#endif
149		line = bug->line;
150#endif
151		warning = (bug->flags & BUGFLAG_WARNING) != 0;
152	}
153
154	if (warning) {
155		/* this is a WARN_ON rather than BUG/BUG_ON */
156		printk(KERN_WARNING "------------[ cut here ]------------\n");
157
158		if (file)
159			printk(KERN_WARNING "WARNING: at %s:%u\n",
160			       file, line);
161		else
162			printk(KERN_WARNING "WARNING: at %p "
163			       "[verbose debug info unavailable]\n",
164			       (void *)bugaddr);
165
166		print_modules();
167		show_regs(regs);
168		print_oops_end_marker();
169		/* Just a warning, don't kill lockdep. */
170		add_taint(BUG_GET_TAINT(bug), LOCKDEP_STILL_OK);
171		return BUG_TRAP_TYPE_WARN;
172	}
173
174	printk(KERN_DEFAULT "------------[ cut here ]------------\n");
175
176	if (file)
177		printk(KERN_CRIT "kernel BUG at %s:%u!\n",
178		       file, line);
179	else
180		printk(KERN_CRIT "Kernel BUG at %p "
181		       "[verbose debug info unavailable]\n",
182		       (void *)bugaddr);
183
184	return BUG_TRAP_TYPE_BUG;
185}