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/*

  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_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 <jeremy@goop.org> 2006

 */

#include <linux/list.h>

#include <linux/module.h>

#include <linux/bug.h>

#include <linux/sched.h>

extern const struct bug_entry __start___bug_table[], __stop___bug_table[];

#ifdef CONFIG_MODULES

static LIST_HEAD(module_bug_list);

static const struct bug_entry *module_find_bug(unsigned long bugaddr)

{

        struct module *mod;

        list_for_each_entry(mod, &module_bug_list, bug_list) {

                const struct bug_entry *bug = mod->bug_table;

                unsigned i;

                for (i = 0; i < mod->num_bugs; ++i, ++bug)

                        if (bugaddr == bug->bug_addr)

                                return bug;

        }

        return NULL;

}

int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,

                        struct module *mod)

{

        char *secstrings;

        unsigned int i;

        mod->bug_table = NULL;

        mod->num_bugs = 0;

        /* Find the __bug_table section, if present */

        secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

        for (i = 1; i < hdr->e_shnum; i++) {

                if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table"))

                        continue;

                mod->bug_table = (void *) sechdrs[i].sh_addr;

                mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);

                break;

        }

        /*

         * Strictly speaking this should have a spinlock to protect against

         * traversals, but since we only traverse on BUG()s, a spinlock

         * could potentially lead to deadlock and thus be counter-productive.

         */

        list_add(&mod->bug_list, &module_bug_list);

        return 0;

}

void module_bug_cleanup(struct module *mod)

{

        list_del(&mod->bug_list);

}

#else

static inline const struct bug_entry *module_find_bug(unsigned long bugaddr)

{

        return NULL;

}

#endif

const struct bug_entry *find_bug(unsigned long bugaddr)

{

        const struct bug_entry *bug;

        for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)

                if (bugaddr == bug->bug_addr)

                        return bug;

        return module_find_bug(bugaddr);

}

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

{

        const struct bug_entry *bug;

        const char *file;

        unsigned line, warning;

        if (!is_valid_bugaddr(bugaddr))

                return BUG_TRAP_TYPE_NONE;

        bug = find_bug(bugaddr);

        printk(KERN_EMERG "------------[ cut here ]------------\n");

        file = NULL;

        line = 0;

        warning = 0;

        if (bug) {

#ifdef CONFIG_DEBUG_BUGVERBOSE

                file = bug->file;

                line = bug->line;

#endif

                warning = (bug->flags & BUGFLAG_WARNING) != 0;

        }

        if (warning) {

                /* this is a WARN_ON rather than BUG/BUG_ON */

                if (file)

                        printk(KERN_ERR "Badness at %s:%u\n",

                               file, line);

                else

                        printk(KERN_ERR "Badness at %p "

                               "[verbose debug info unavailable]\n",

                               (void *)bugaddr);

                show_regs(regs);

                return BUG_TRAP_TYPE_WARN;

        }

        if (file)

                printk(KERN_CRIT "kernel BUG at %s:%u!\n",

                       file, line);

        else

                printk(KERN_CRIT "Kernel BUG at %p "

                       "[verbose debug info unavailable]\n",

                       (void *)bugaddr);

        return BUG_TRAP_TYPE_BUG;

}