17664c5a1SJeremy Fitzhardinge /* 27664c5a1SJeremy Fitzhardinge Generic support for BUG() 37664c5a1SJeremy Fitzhardinge 47664c5a1SJeremy Fitzhardinge This respects the following config options: 57664c5a1SJeremy Fitzhardinge 67664c5a1SJeremy Fitzhardinge CONFIG_BUG - emit BUG traps. Nothing happens without this. 77664c5a1SJeremy Fitzhardinge CONFIG_GENERIC_BUG - enable this code. 8b93a531eSJan Beulich CONFIG_GENERIC_BUG_RELATIVE_POINTERS - use 32-bit pointers relative to 9b93a531eSJan Beulich the containing struct bug_entry for bug_addr and file. 107664c5a1SJeremy Fitzhardinge CONFIG_DEBUG_BUGVERBOSE - emit full file+line information for each BUG 117664c5a1SJeremy Fitzhardinge 127664c5a1SJeremy Fitzhardinge CONFIG_BUG and CONFIG_DEBUG_BUGVERBOSE are potentially user-settable 137664c5a1SJeremy Fitzhardinge (though they're generally always on). 147664c5a1SJeremy Fitzhardinge 157664c5a1SJeremy Fitzhardinge CONFIG_GENERIC_BUG is set by each architecture using this code. 167664c5a1SJeremy Fitzhardinge 177664c5a1SJeremy Fitzhardinge To use this, your architecture must: 187664c5a1SJeremy Fitzhardinge 197664c5a1SJeremy Fitzhardinge 1. Set up the config options: 207664c5a1SJeremy Fitzhardinge - Enable CONFIG_GENERIC_BUG if CONFIG_BUG 217664c5a1SJeremy Fitzhardinge 227664c5a1SJeremy Fitzhardinge 2. Implement BUG (and optionally BUG_ON, WARN, WARN_ON) 237664c5a1SJeremy Fitzhardinge - Define HAVE_ARCH_BUG 247664c5a1SJeremy Fitzhardinge - Implement BUG() to generate a faulting instruction 257664c5a1SJeremy Fitzhardinge - NOTE: struct bug_entry does not have "file" or "line" entries 267664c5a1SJeremy Fitzhardinge when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate 277664c5a1SJeremy Fitzhardinge the values accordingly. 287664c5a1SJeremy Fitzhardinge 297664c5a1SJeremy Fitzhardinge 3. Implement the trap 307664c5a1SJeremy Fitzhardinge - In the illegal instruction trap handler (typically), verify 317664c5a1SJeremy Fitzhardinge that the fault was in kernel mode, and call report_bug() 327664c5a1SJeremy Fitzhardinge - report_bug() will return whether it was a false alarm, a warning, 337664c5a1SJeremy Fitzhardinge or an actual bug. 347664c5a1SJeremy Fitzhardinge - You must implement the is_valid_bugaddr(bugaddr) callback which 357664c5a1SJeremy Fitzhardinge returns true if the eip is a real kernel address, and it points 367664c5a1SJeremy Fitzhardinge to the expected BUG trap instruction. 377664c5a1SJeremy Fitzhardinge 387664c5a1SJeremy Fitzhardinge Jeremy Fitzhardinge <jeremy@goop.org> 2006 397664c5a1SJeremy Fitzhardinge */ 407664c5a1SJeremy Fitzhardinge #include <linux/list.h> 417664c5a1SJeremy Fitzhardinge #include <linux/module.h> 42da9eac89SPaul Mundt #include <linux/kernel.h> 437664c5a1SJeremy Fitzhardinge #include <linux/bug.h> 44608e2619SHeiko Carstens #include <linux/sched.h> 457664c5a1SJeremy Fitzhardinge 467664c5a1SJeremy Fitzhardinge extern const struct bug_entry __start___bug_table[], __stop___bug_table[]; 477664c5a1SJeremy Fitzhardinge 48b93a531eSJan Beulich static inline unsigned long bug_addr(const struct bug_entry *bug) 49b93a531eSJan Beulich { 50b93a531eSJan Beulich #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS 51b93a531eSJan Beulich return bug->bug_addr; 52b93a531eSJan Beulich #else 53b93a531eSJan Beulich return (unsigned long)bug + bug->bug_addr_disp; 54b93a531eSJan Beulich #endif 55b93a531eSJan Beulich } 56b93a531eSJan Beulich 577664c5a1SJeremy Fitzhardinge #ifdef CONFIG_MODULES 587664c5a1SJeremy Fitzhardinge static LIST_HEAD(module_bug_list); 597664c5a1SJeremy Fitzhardinge 607664c5a1SJeremy Fitzhardinge static const struct bug_entry *module_find_bug(unsigned long bugaddr) 617664c5a1SJeremy Fitzhardinge { 627664c5a1SJeremy Fitzhardinge struct module *mod; 637664c5a1SJeremy Fitzhardinge 647664c5a1SJeremy Fitzhardinge list_for_each_entry(mod, &module_bug_list, bug_list) { 657664c5a1SJeremy Fitzhardinge const struct bug_entry *bug = mod->bug_table; 667664c5a1SJeremy Fitzhardinge unsigned i; 677664c5a1SJeremy Fitzhardinge 687664c5a1SJeremy Fitzhardinge for (i = 0; i < mod->num_bugs; ++i, ++bug) 69b93a531eSJan Beulich if (bugaddr == bug_addr(bug)) 707664c5a1SJeremy Fitzhardinge return bug; 717664c5a1SJeremy Fitzhardinge } 727664c5a1SJeremy Fitzhardinge return NULL; 737664c5a1SJeremy Fitzhardinge } 747664c5a1SJeremy Fitzhardinge 757664c5a1SJeremy Fitzhardinge int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, 767664c5a1SJeremy Fitzhardinge struct module *mod) 777664c5a1SJeremy Fitzhardinge { 787664c5a1SJeremy Fitzhardinge char *secstrings; 797664c5a1SJeremy Fitzhardinge unsigned int i; 807664c5a1SJeremy Fitzhardinge 817664c5a1SJeremy Fitzhardinge mod->bug_table = NULL; 827664c5a1SJeremy Fitzhardinge mod->num_bugs = 0; 837664c5a1SJeremy Fitzhardinge 847664c5a1SJeremy Fitzhardinge /* Find the __bug_table section, if present */ 857664c5a1SJeremy Fitzhardinge secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 867664c5a1SJeremy Fitzhardinge for (i = 1; i < hdr->e_shnum; i++) { 877664c5a1SJeremy Fitzhardinge if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) 887664c5a1SJeremy Fitzhardinge continue; 897664c5a1SJeremy Fitzhardinge mod->bug_table = (void *) sechdrs[i].sh_addr; 907664c5a1SJeremy Fitzhardinge mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); 917664c5a1SJeremy Fitzhardinge break; 927664c5a1SJeremy Fitzhardinge } 937664c5a1SJeremy Fitzhardinge 947664c5a1SJeremy Fitzhardinge /* 957664c5a1SJeremy Fitzhardinge * Strictly speaking this should have a spinlock to protect against 967664c5a1SJeremy Fitzhardinge * traversals, but since we only traverse on BUG()s, a spinlock 977664c5a1SJeremy Fitzhardinge * could potentially lead to deadlock and thus be counter-productive. 987664c5a1SJeremy Fitzhardinge */ 997664c5a1SJeremy Fitzhardinge list_add(&mod->bug_list, &module_bug_list); 1007664c5a1SJeremy Fitzhardinge 1017664c5a1SJeremy Fitzhardinge return 0; 1027664c5a1SJeremy Fitzhardinge } 1037664c5a1SJeremy Fitzhardinge 1047664c5a1SJeremy Fitzhardinge void module_bug_cleanup(struct module *mod) 1057664c5a1SJeremy Fitzhardinge { 1067664c5a1SJeremy Fitzhardinge list_del(&mod->bug_list); 1077664c5a1SJeremy Fitzhardinge } 1087664c5a1SJeremy Fitzhardinge 1097664c5a1SJeremy Fitzhardinge #else 1107664c5a1SJeremy Fitzhardinge 1117664c5a1SJeremy Fitzhardinge static inline const struct bug_entry *module_find_bug(unsigned long bugaddr) 1127664c5a1SJeremy Fitzhardinge { 1137664c5a1SJeremy Fitzhardinge return NULL; 1147664c5a1SJeremy Fitzhardinge } 1157664c5a1SJeremy Fitzhardinge #endif 1167664c5a1SJeremy Fitzhardinge 1177664c5a1SJeremy Fitzhardinge const struct bug_entry *find_bug(unsigned long bugaddr) 1187664c5a1SJeremy Fitzhardinge { 1197664c5a1SJeremy Fitzhardinge const struct bug_entry *bug; 1207664c5a1SJeremy Fitzhardinge 1217664c5a1SJeremy Fitzhardinge for (bug = __start___bug_table; bug < __stop___bug_table; ++bug) 122b93a531eSJan Beulich if (bugaddr == bug_addr(bug)) 1237664c5a1SJeremy Fitzhardinge return bug; 1247664c5a1SJeremy Fitzhardinge 1257664c5a1SJeremy Fitzhardinge return module_find_bug(bugaddr); 1267664c5a1SJeremy Fitzhardinge } 1277664c5a1SJeremy Fitzhardinge 128608e2619SHeiko Carstens enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) 1297664c5a1SJeremy Fitzhardinge { 1307664c5a1SJeremy Fitzhardinge const struct bug_entry *bug; 1317664c5a1SJeremy Fitzhardinge const char *file; 1327664c5a1SJeremy Fitzhardinge unsigned line, warning; 1337664c5a1SJeremy Fitzhardinge 1347664c5a1SJeremy Fitzhardinge if (!is_valid_bugaddr(bugaddr)) 1357664c5a1SJeremy Fitzhardinge return BUG_TRAP_TYPE_NONE; 1367664c5a1SJeremy Fitzhardinge 1377664c5a1SJeremy Fitzhardinge bug = find_bug(bugaddr); 1387664c5a1SJeremy Fitzhardinge 1397664c5a1SJeremy Fitzhardinge file = NULL; 1407664c5a1SJeremy Fitzhardinge line = 0; 1417664c5a1SJeremy Fitzhardinge warning = 0; 1427664c5a1SJeremy Fitzhardinge 1437664c5a1SJeremy Fitzhardinge if (bug) { 1447664c5a1SJeremy Fitzhardinge #ifdef CONFIG_DEBUG_BUGVERBOSE 145b93a531eSJan Beulich #ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS 1467664c5a1SJeremy Fitzhardinge file = bug->file; 147b93a531eSJan Beulich #else 148b93a531eSJan Beulich file = (const char *)bug + bug->file_disp; 149b93a531eSJan Beulich #endif 1507664c5a1SJeremy Fitzhardinge line = bug->line; 1517664c5a1SJeremy Fitzhardinge #endif 1527664c5a1SJeremy Fitzhardinge warning = (bug->flags & BUGFLAG_WARNING) != 0; 1537664c5a1SJeremy Fitzhardinge } 1547664c5a1SJeremy Fitzhardinge 1557664c5a1SJeremy Fitzhardinge if (warning) { 1567664c5a1SJeremy Fitzhardinge /* this is a WARN_ON rather than BUG/BUG_ON */ 157*e2e7e093SAnton Blanchard printk(KERN_WARNING "------------[ cut here ]------------\n"); 158*e2e7e093SAnton Blanchard 1597664c5a1SJeremy Fitzhardinge if (file) 160*e2e7e093SAnton Blanchard printk(KERN_WARNING "WARNING: at %s:%u\n", 1617664c5a1SJeremy Fitzhardinge file, line); 1627664c5a1SJeremy Fitzhardinge else 163*e2e7e093SAnton Blanchard printk(KERN_WARNING "WARNING: at %p " 1647664c5a1SJeremy Fitzhardinge "[verbose debug info unavailable]\n", 1657664c5a1SJeremy Fitzhardinge (void *)bugaddr); 1667664c5a1SJeremy Fitzhardinge 167*e2e7e093SAnton Blanchard print_modules(); 168608e2619SHeiko Carstens show_regs(regs); 169b2be0527SBen Hutchings add_taint(BUG_GET_TAINT(bug)); 1707664c5a1SJeremy Fitzhardinge return BUG_TRAP_TYPE_WARN; 1717664c5a1SJeremy Fitzhardinge } 1727664c5a1SJeremy Fitzhardinge 173*e2e7e093SAnton Blanchard printk(KERN_EMERG "------------[ cut here ]------------\n"); 174*e2e7e093SAnton Blanchard 1757664c5a1SJeremy Fitzhardinge if (file) 1767664c5a1SJeremy Fitzhardinge printk(KERN_CRIT "kernel BUG at %s:%u!\n", 1777664c5a1SJeremy Fitzhardinge file, line); 1787664c5a1SJeremy Fitzhardinge else 1797664c5a1SJeremy Fitzhardinge printk(KERN_CRIT "Kernel BUG at %p " 1807664c5a1SJeremy Fitzhardinge "[verbose debug info unavailable]\n", 1817664c5a1SJeremy Fitzhardinge (void *)bugaddr); 1827664c5a1SJeremy Fitzhardinge 1837664c5a1SJeremy Fitzhardinge return BUG_TRAP_TYPE_BUG; 1847664c5a1SJeremy Fitzhardinge } 185