linux/lib/bug.c

// SPDX-License-Identifier: GPL-2.0
/*
  Generic support for BUG()

  This respects the following config options:

  CONFIG_BUG - emit BUG traps.  Nothing happens without this.
  CONFIG_GENERIC_BUG - enable this code.
  CONFIG_GENERIC_BUG_RELATIVE_POINTERS - use 32-bit relative pointers for bug_addr and file
  CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG

  CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable
  (though they're generally always on).

  CONFIG_GENERIC_BUG is set by each architecture using this code.

  To use this, your architecture must:

  1. Set up the config options:
     - Enable CONFIG_GENERIC_BUG if CONFIG_BUG

  2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON)
     - Define HAVE_ARCH_BUG
     - Implement BUG() to generate a faulting instruction
     - NOTE: struct bug_entry does not have "file" or "line" entries
       when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate
       the values accordingly.

  3. Implement the trap
     - In the illegal instruction trap handler (typically), verify
       that the fault was in kernel mode, and call report_bug()
     - report_bug() will return whether it was a false alarm, a warning,
       or an actual bug.
     - You must implement the is_valid_bugaddr(bugaddr) callback which
       returns true if the eip is a real kernel address, and it points
       to the expected BUG trap instruction.

    Jeremy Fitzhardinge <[email protected]> 2006
 */

#define pr_fmt(fmt) …

#include <linux/list.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/sched.h>
#include <linux/rculist.h>
#include <linux/ftrace.h>
#include <linux/context_tracking.h>

extern struct bug_entry __start___bug_table[], __stop___bug_table[];

static inline unsigned long bug_addr(const struct bug_entry *bug)
{ … }

#ifdef CONFIG_MODULES
/* Updates are protected by module mutex */
static LIST_HEAD(module_bug_list);

static struct bug_entry *module_find_bug(unsigned long bugaddr)
{ … }

void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
			 struct module *mod)
{ … }

void module_bug_cleanup(struct module *mod)
{ … }

#else

static inline struct bug_entry *module_find_bug(unsigned long bugaddr)
{
	return NULL;
}
#endif

void bug_get_file_line(struct bug_entry *bug, const char **file,
		       unsigned int *line)
{ … }

struct bug_entry *find_bug(unsigned long bugaddr)
{ … }

static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *regs)
{ … }

enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
{ … }

static void clear_once_table(struct bug_entry *start, struct bug_entry *end)
{ … }

void generic_bug_clear_once(void)
{ … }