| 1 | /* |
| 2 | * linux/kernel/panic.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * This function is used through-out the kernel (including mm and fs) |
| 9 | * to indicate a major problem. |
| 10 | */ |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/sched.h> |
| 13 | #include <linux/delay.h> |
| 14 | #include <linux/reboot.h> |
| 15 | #include <linux/notifier.h> |
| 16 | #include <linux/init.h> |
| 17 | #include <linux/sysrq.h> |
| 18 | #include <linux/interrupt.h> |
| 19 | #include <linux/nmi.h> |
| 20 | #include <linux/kexec.h> |
| 21 | #include <linux/debug_locks.h> |
| 22 | #include <linux/random.h> |
| 23 | #include <linux/kallsyms.h> |
| 24 | |
| 25 | int panic_on_oops; |
| 26 | int tainted; |
| 27 | static int pause_on_oops; |
| 28 | static int pause_on_oops_flag; |
| 29 | static DEFINE_SPINLOCK(pause_on_oops_lock); |
| 30 | |
| 31 | int panic_timeout; |
| 32 | |
| 33 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
| 34 | |
| 35 | EXPORT_SYMBOL(panic_notifier_list); |
| 36 | |
| 37 | static int __init panic_setup(char *str) |
| 38 | { |
| 39 | panic_timeout = simple_strtoul(str, NULL, 0); |
| 40 | return 1; |
| 41 | } |
| 42 | __setup("panic=", panic_setup); |
| 43 | |
| 44 | static long no_blink(long time) |
| 45 | { |
| 46 | return 0; |
| 47 | } |
| 48 | |
| 49 | /* Returns how long it waited in ms */ |
| 50 | long (*panic_blink)(long time); |
| 51 | EXPORT_SYMBOL(panic_blink); |
| 52 | |
| 53 | /** |
| 54 | * panic - halt the system |
| 55 | * @fmt: The text string to print |
| 56 | * |
| 57 | * Display a message, then perform cleanups. |
| 58 | * |
| 59 | * This function never returns. |
| 60 | */ |
| 61 | |
| 62 | NORET_TYPE void panic(const char * fmt, ...) |
| 63 | { |
| 64 | long i; |
| 65 | static char buf[1024]; |
| 66 | va_list args; |
| 67 | #if defined(CONFIG_S390) |
| 68 | unsigned long caller = (unsigned long) __builtin_return_address(0); |
| 69 | #endif |
| 70 | |
| 71 | /* |
| 72 | * It's possible to come here directly from a panic-assertion and not |
| 73 | * have preempt disabled. Some functions called from here want |
| 74 | * preempt to be disabled. No point enabling it later though... |
| 75 | */ |
| 76 | preempt_disable(); |
| 77 | |
| 78 | bust_spinlocks(1); |
| 79 | va_start(args, fmt); |
| 80 | vsnprintf(buf, sizeof(buf), fmt, args); |
| 81 | va_end(args); |
| 82 | printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); |
| 83 | bust_spinlocks(0); |
| 84 | |
| 85 | /* |
| 86 | * If we have crashed and we have a crash kernel loaded let it handle |
| 87 | * everything else. |
| 88 | * Do we want to call this before we try to display a message? |
| 89 | */ |
| 90 | crash_kexec(NULL); |
| 91 | |
| 92 | #ifdef CONFIG_SMP |
| 93 | /* |
| 94 | * Note smp_send_stop is the usual smp shutdown function, which |
| 95 | * unfortunately means it may not be hardened to work in a panic |
| 96 | * situation. |
| 97 | */ |
| 98 | smp_send_stop(); |
| 99 | #endif |
| 100 | |
| 101 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
| 102 | |
| 103 | if (!panic_blink) |
| 104 | panic_blink = no_blink; |
| 105 | |
| 106 | if (panic_timeout > 0) { |
| 107 | /* |
| 108 | * Delay timeout seconds before rebooting the machine. |
| 109 | * We can't use the "normal" timers since we just panicked.. |
| 110 | */ |
| 111 | printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout); |
| 112 | for (i = 0; i < panic_timeout*1000; ) { |
| 113 | touch_nmi_watchdog(); |
| 114 | i += panic_blink(i); |
| 115 | mdelay(1); |
| 116 | i++; |
| 117 | } |
| 118 | /* This will not be a clean reboot, with everything |
| 119 | * shutting down. But if there is a chance of |
| 120 | * rebooting the system it will be rebooted. |
| 121 | */ |
| 122 | emergency_restart(); |
| 123 | } |
| 124 | #ifdef __sparc__ |
| 125 | { |
| 126 | extern int stop_a_enabled; |
| 127 | /* Make sure the user can actually press Stop-A (L1-A) */ |
| 128 | stop_a_enabled = 1; |
| 129 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); |
| 130 | } |
| 131 | #endif |
| 132 | #if defined(CONFIG_S390) |
| 133 | disabled_wait(caller); |
| 134 | #endif |
| 135 | local_irq_enable(); |
| 136 | for (i = 0;;) { |
| 137 | touch_softlockup_watchdog(); |
| 138 | i += panic_blink(i); |
| 139 | mdelay(1); |
| 140 | i++; |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | EXPORT_SYMBOL(panic); |
| 145 | |
| 146 | /** |
| 147 | * print_tainted - return a string to represent the kernel taint state. |
| 148 | * |
| 149 | * 'P' - Proprietary module has been loaded. |
| 150 | * 'F' - Module has been forcibly loaded. |
| 151 | * 'S' - SMP with CPUs not designed for SMP. |
| 152 | * 'R' - User forced a module unload. |
| 153 | * 'M' - System experienced a machine check exception. |
| 154 | * 'B' - System has hit bad_page. |
| 155 | * 'U' - Userspace-defined naughtiness. |
| 156 | * 'A' - ACPI table overridden. |
| 157 | * 'W' - Taint on warning. |
| 158 | * |
| 159 | * The string is overwritten by the next call to print_taint(). |
| 160 | */ |
| 161 | |
| 162 | const char *print_tainted(void) |
| 163 | { |
| 164 | static char buf[20]; |
| 165 | if (tainted) { |
| 166 | snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c%c%c", |
| 167 | tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', |
| 168 | tainted & TAINT_FORCED_MODULE ? 'F' : ' ', |
| 169 | tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', |
| 170 | tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', |
| 171 | tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', |
| 172 | tainted & TAINT_BAD_PAGE ? 'B' : ' ', |
| 173 | tainted & TAINT_USER ? 'U' : ' ', |
| 174 | tainted & TAINT_DIE ? 'D' : ' ', |
| 175 | tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' ', |
| 176 | tainted & TAINT_WARN ? 'W' : ' '); |
| 177 | } |
| 178 | else |
| 179 | snprintf(buf, sizeof(buf), "Not tainted"); |
| 180 | return(buf); |
| 181 | } |
| 182 | |
| 183 | void add_taint(unsigned flag) |
| 184 | { |
| 185 | debug_locks = 0; /* can't trust the integrity of the kernel anymore */ |
| 186 | tainted |= flag; |
| 187 | } |
| 188 | EXPORT_SYMBOL(add_taint); |
| 189 | |
| 190 | static int __init pause_on_oops_setup(char *str) |
| 191 | { |
| 192 | pause_on_oops = simple_strtoul(str, NULL, 0); |
| 193 | return 1; |
| 194 | } |
| 195 | __setup("pause_on_oops=", pause_on_oops_setup); |
| 196 | |
| 197 | static void spin_msec(int msecs) |
| 198 | { |
| 199 | int i; |
| 200 | |
| 201 | for (i = 0; i < msecs; i++) { |
| 202 | touch_nmi_watchdog(); |
| 203 | mdelay(1); |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * It just happens that oops_enter() and oops_exit() are identically |
| 209 | * implemented... |
| 210 | */ |
| 211 | static void do_oops_enter_exit(void) |
| 212 | { |
| 213 | unsigned long flags; |
| 214 | static int spin_counter; |
| 215 | |
| 216 | if (!pause_on_oops) |
| 217 | return; |
| 218 | |
| 219 | spin_lock_irqsave(&pause_on_oops_lock, flags); |
| 220 | if (pause_on_oops_flag == 0) { |
| 221 | /* This CPU may now print the oops message */ |
| 222 | pause_on_oops_flag = 1; |
| 223 | } else { |
| 224 | /* We need to stall this CPU */ |
| 225 | if (!spin_counter) { |
| 226 | /* This CPU gets to do the counting */ |
| 227 | spin_counter = pause_on_oops; |
| 228 | do { |
| 229 | spin_unlock(&pause_on_oops_lock); |
| 230 | spin_msec(MSEC_PER_SEC); |
| 231 | spin_lock(&pause_on_oops_lock); |
| 232 | } while (--spin_counter); |
| 233 | pause_on_oops_flag = 0; |
| 234 | } else { |
| 235 | /* This CPU waits for a different one */ |
| 236 | while (spin_counter) { |
| 237 | spin_unlock(&pause_on_oops_lock); |
| 238 | spin_msec(1); |
| 239 | spin_lock(&pause_on_oops_lock); |
| 240 | } |
| 241 | } |
| 242 | } |
| 243 | spin_unlock_irqrestore(&pause_on_oops_lock, flags); |
| 244 | } |
| 245 | |
| 246 | /* |
| 247 | * Return true if the calling CPU is allowed to print oops-related info. This |
| 248 | * is a bit racy.. |
| 249 | */ |
| 250 | int oops_may_print(void) |
| 251 | { |
| 252 | return pause_on_oops_flag == 0; |
| 253 | } |
| 254 | |
| 255 | /* |
| 256 | * Called when the architecture enters its oops handler, before it prints |
| 257 | * anything. If this is the first CPU to oops, and it's oopsing the first time |
| 258 | * then let it proceed. |
| 259 | * |
| 260 | * This is all enabled by the pause_on_oops kernel boot option. We do all this |
| 261 | * to ensure that oopses don't scroll off the screen. It has the side-effect |
| 262 | * of preventing later-oopsing CPUs from mucking up the display, too. |
| 263 | * |
| 264 | * It turns out that the CPU which is allowed to print ends up pausing for the |
| 265 | * right duration, whereas all the other CPUs pause for twice as long: once in |
| 266 | * oops_enter(), once in oops_exit(). |
| 267 | */ |
| 268 | void oops_enter(void) |
| 269 | { |
| 270 | debug_locks_off(); /* can't trust the integrity of the kernel anymore */ |
| 271 | do_oops_enter_exit(); |
| 272 | } |
| 273 | |
| 274 | /* |
| 275 | * 64-bit random ID for oopses: |
| 276 | */ |
| 277 | static u64 oops_id; |
| 278 | |
| 279 | static int init_oops_id(void) |
| 280 | { |
| 281 | if (!oops_id) |
| 282 | get_random_bytes(&oops_id, sizeof(oops_id)); |
| 283 | |
| 284 | return 0; |
| 285 | } |
| 286 | late_initcall(init_oops_id); |
| 287 | |
| 288 | static void print_oops_end_marker(void) |
| 289 | { |
| 290 | init_oops_id(); |
| 291 | printk(KERN_WARNING "---[ end trace %016llx ]---\n", |
| 292 | (unsigned long long)oops_id); |
| 293 | } |
| 294 | |
| 295 | /* |
| 296 | * Called when the architecture exits its oops handler, after printing |
| 297 | * everything. |
| 298 | */ |
| 299 | void oops_exit(void) |
| 300 | { |
| 301 | do_oops_enter_exit(); |
| 302 | print_oops_end_marker(); |
| 303 | } |
| 304 | |
| 305 | #ifdef WANT_WARN_ON_SLOWPATH |
| 306 | void warn_on_slowpath(const char *file, int line) |
| 307 | { |
| 308 | char function[KSYM_SYMBOL_LEN]; |
| 309 | unsigned long caller = (unsigned long) __builtin_return_address(0); |
| 310 | sprint_symbol(function, caller); |
| 311 | |
| 312 | printk(KERN_WARNING "------------[ cut here ]------------\n"); |
| 313 | printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, |
| 314 | line, function); |
| 315 | print_modules(); |
| 316 | dump_stack(); |
| 317 | print_oops_end_marker(); |
| 318 | add_taint(TAINT_WARN); |
| 319 | } |
| 320 | EXPORT_SYMBOL(warn_on_slowpath); |
| 321 | |
| 322 | |
| 323 | void warn_slowpath(const char *file, int line, const char *fmt, ...) |
| 324 | { |
| 325 | va_list args; |
| 326 | char function[KSYM_SYMBOL_LEN]; |
| 327 | unsigned long caller = (unsigned long)__builtin_return_address(0); |
| 328 | sprint_symbol(function, caller); |
| 329 | |
| 330 | printk(KERN_WARNING "------------[ cut here ]------------\n"); |
| 331 | printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, |
| 332 | line, function); |
| 333 | va_start(args, fmt); |
| 334 | vprintk(fmt, args); |
| 335 | va_end(args); |
| 336 | |
| 337 | print_modules(); |
| 338 | dump_stack(); |
| 339 | print_oops_end_marker(); |
| 340 | add_taint(TAINT_WARN); |
| 341 | } |
| 342 | EXPORT_SYMBOL(warn_slowpath); |
| 343 | #endif |
| 344 | |
| 345 | #ifdef CONFIG_CC_STACKPROTECTOR |
| 346 | /* |
| 347 | * Called when gcc's -fstack-protector feature is used, and |
| 348 | * gcc detects corruption of the on-stack canary value |
| 349 | */ |
| 350 | void __stack_chk_fail(void) |
| 351 | { |
| 352 | panic("stack-protector: Kernel stack is corrupted"); |
| 353 | } |
| 354 | EXPORT_SYMBOL(__stack_chk_fail); |
| 355 | #endif |