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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314// 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 <jeremy@goop.org> 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>#include <linux/rculist.h>#include <linux/ftrace.h>#include <linux/context_tracking.h>#include <kunit/test-bug.h>
extern struct bug_entry __start___bug_table[], __stop___bug_table[];
static inline unsigned long bug_addr(const struct bug_entry *bug){#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS return (unsigned long)&bug->bug_addr_disp + bug->bug_addr_disp;#else return bug->bug_addr;#endif}
#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){ struct bug_entry *bug; struct module *mod;
guard(rcu)(); list_for_each_entry_rcu(mod, &module_bug_list, bug_list) { unsigned int i;
bug = mod->bug_table; for (i = 0; i < mod->num_bugs; ++i, ++bug) if (bugaddr == bug_addr(bug)) return bug; } return NULL;}
void 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. * 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);}
void module_bug_cleanup(struct module *mod){ list_del_rcu(&mod->bug_list);}
#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){#ifdef CONFIG_DEBUG_BUGVERBOSE#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS *file = (const char *)&bug->file_disp + bug->file_disp;#else *file = bug->file;#endif *line = bug->line;#else *file = NULL; *line = 0;#endif}
static const char *bug_get_format(struct bug_entry *bug){ const char *format = NULL;#ifdef HAVE_ARCH_BUG_FORMAT#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS /* * Allow an architecture to: * - relative encode NULL (difficult vs KASLR); * - use a literal 0 (there are no valid objects inside * the __bug_table itself to refer to after all); * - use an empty string. */ if (bug->format_disp) format = (const char *)&bug->format_disp + bug->format_disp; if (format && format[0] == '\0') format = NULL;#else format = bug->format;#endif#endif return format;}
struct bug_entry *find_bug(unsigned long bugaddr){ 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);}
static __printf(1, 0)void __warn_printf(const char *fmt, struct pt_regs *regs){ if (!fmt) return;
#ifdef HAVE_ARCH_BUG_FORMAT_ARGS if (regs) { struct arch_va_list _args; va_list *args = __warn_args(&_args, regs);
if (args) { vprintk(fmt, *args); return; } }#endif
pr_warn("%s", fmt);}
static enum bug_trap_type __report_bug(struct bug_entry *bug, unsigned long bugaddr, struct pt_regs *regs){ bool warning, once, done, no_cut, has_args; const char *file, *fmt; unsigned int line;
if (!bug) { if (!is_valid_bugaddr(bugaddr)) return BUG_TRAP_TYPE_NONE;
bug = find_bug(bugaddr); if (!bug) return BUG_TRAP_TYPE_NONE; }
bug_get_file_line(bug, &file, &line); fmt = bug_get_format(bug);
warning = bug->flags & BUGFLAG_WARNING; once = bug->flags & BUGFLAG_ONCE; done = bug->flags & BUGFLAG_DONE; no_cut = bug->flags & BUGFLAG_NO_CUT_HERE; has_args = bug->flags & BUGFLAG_ARGS;
/* * Before the once logic so suppressed warnings do not consume * the single-fire budget of WARN_ON_ONCE(). */ if (warning && kunit_is_suppressed_warning(true)) return BUG_TRAP_TYPE_WARN;
disable_trace_on_warning();
if (warning && once) { if (done) return BUG_TRAP_TYPE_WARN;
/* * Since this is the only store, concurrency is not an issue. */ bug->flags |= BUGFLAG_DONE; }
/* * BUG() and WARN_ON() families don't print a custom debug message * before triggering the exception handler, so we must add the * "cut here" line now. WARN() issues its own "cut here" before the * extra debugging message it writes before triggering the handler. */ if (!no_cut) { pr_info(CUT_HERE); __warn_printf(fmt, has_args ? regs : NULL); }
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; }
if (file) pr_crit("kernel BUG at %s:%u!\n", file, line); else pr_crit("kernel BUG at %pB [verbose debug info unavailable]\n", (void *)bugaddr);
return BUG_TRAP_TYPE_BUG;}
enum bug_trap_type report_bug_entry(struct bug_entry *bug, struct pt_regs *regs){ enum bug_trap_type ret; bool rcu;
rcu = warn_rcu_enter(); ret = __report_bug(bug, bug_addr(bug), regs); warn_rcu_exit(rcu);
return ret;}
enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs){ enum bug_trap_type ret; bool rcu;
rcu = warn_rcu_enter(); ret = __report_bug(NULL, bugaddr, regs); warn_rcu_exit(rcu);
return ret;}
static void clear_once_table(struct bug_entry *start, struct bug_entry *end){ struct bug_entry *bug;
for (bug = start; bug < end; bug++) bug->flags &= ~BUGFLAG_DONE;}
void generic_bug_clear_once(void){#ifdef CONFIG_MODULES struct module *mod;
scoped_guard(rcu) { list_for_each_entry_rcu(mod, &module_bug_list, bug_list) clear_once_table(mod->bug_table, mod->bug_table + mod->num_bugs); }#endif
clear_once_table(__start___bug_table, __stop___bug_table);}