cregit-Linux how code gets into the kernel

Release 4.9 lib/bug.c

Directory: lib
  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 pointers relative to
        the containing struct bug_entry 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:

  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 <> 2006

#define pr_fmt(fmt) fmt

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

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

static inline unsigned long bug_addr(const struct bug_entry *bug) { #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS return bug->bug_addr; #else return (unsigned long)bug + bug->bug_addr_disp; #endif }


jan beulichjan beulich37100.00%1100.00%

#ifdef CONFIG_MODULES /* Updates are protected by module mutex */ static LIST_HEAD(module_bug_list);
static const struct bug_entry *module_find_bug(unsigned long bugaddr) { struct module *mod; const struct bug_entry *bug = NULL; rcu_read_lock_sched(); list_for_each_entry_rcu(mod, &module_bug_list, bug_list) { unsigned i; bug = mod->bug_table; for (i = 0; i < mod->num_bugs; ++i, ++bug) if (bugaddr == bug_addr(bug)) goto out; } bug = NULL; out: rcu_read_unlock_sched(); return bug; }


jeremy fitzhardingejeremy fitzhardinge5763.33%125.00%
masami hiramatsumasami hiramatsu2831.11%125.00%
jan beulichjan beulich33.33%125.00%
peter zijlstrapeter zijlstra22.22%125.00%

void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod) { char *secstrings; unsigned int i; lockdep_assert_held(&module_mutex); 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. * Thus, this uses RCU to safely manipulate the bug list, since BUG * must run in non-interruptive state. */ list_add_rcu(&mod->bug_list, &module_bug_list); }


jeremy fitzhardingejeremy fitzhardinge13493.71%125.00%
peter zijlstrapeter zijlstra64.20%125.00%
masami hiramatsumasami hiramatsu21.40%125.00%
linus torvaldslinus torvalds10.70%125.00%

void module_bug_cleanup(struct module *mod) { lockdep_assert_held(&module_mutex); list_del_rcu(&mod->bug_list); }


jeremy fitzhardingejeremy fitzhardinge1770.83%133.33%
peter zijlstrapeter zijlstra625.00%133.33%
masami hiramatsumasami hiramatsu14.17%133.33%

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


jeremy fitzhardingejeremy fitzhardinge17100.00%1100.00%

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_addr(bug)) return bug; return module_find_bug(bugaddr); }


jeremy fitzhardingejeremy fitzhardinge4693.88%150.00%
jan beulichjan beulich36.12%150.00%

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); file = NULL; line = 0; warning = 0; if (bug) { #ifdef CONFIG_DEBUG_BUGVERBOSE #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS file = bug->file; #else file = (const char *)bug + bug->file_disp; #endif line = bug->line; #endif warning = (bug->flags & BUGFLAG_WARNING) != 0; } if (warning) { /* this is a WARN_ON rather than BUG/BUG_ON */ __warn(file, line, (void *)bugaddr, BUG_GET_TAINT(bug), regs, NULL); return BUG_TRAP_TYPE_WARN; } printk(KERN_DEFAULT "------------[ cut here ]------------\n"); if (file) pr_crit("kernel BUG at %s:%u!\n", file, line); else pr_crit("Kernel BUG at %p [verbose debug info unavailable]\n", (void *)bugaddr); return BUG_TRAP_TYPE_BUG; }


jeremy fitzhardingejeremy fitzhardinge13574.18%110.00%
jan beulichjan beulich2010.99%110.00%
anton blanchardanton blanchard63.30%110.00%
heiko carstensheiko carstens52.75%110.00%
josh poimboeufjosh poimboeuf52.75%110.00%
ben hutchingsben hutchings42.20%110.00%
fabian frederickfabian frederick31.65%110.00%
paul mundtpaul mundt21.10%110.00%
rusty russellrusty russell10.55%110.00%
prarit bhargavaprarit bhargava10.55%110.00%

Overall Contributors

jeremy fitzhardingejeremy fitzhardinge43874.36%17.14%
jan beulichjan beulich6410.87%17.14%
masami hiramatsumasami hiramatsu315.26%17.14%
peter zijlstrapeter zijlstra142.38%17.14%
fabian frederickfabian frederick101.70%17.14%
heiko carstensheiko carstens81.36%17.14%
anton blanchardanton blanchard61.02%17.14%
josh poimboeufjosh poimboeuf50.85%17.14%
paul mundtpaul mundt50.85%17.14%
ben hutchingsben hutchings40.68%17.14%
rusty russellrusty russell20.34%214.29%
linus torvaldslinus torvalds10.17%17.14%
prarit bhargavaprarit bhargava10.17%17.14%
Directory: lib