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 * 157 * The string is overwritten by the next call to print_taint(). 158 */ 159 160 const char *print_tainted(void) 161 { 162 static char buf[20]; 163 if (tainted) { 164 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c%c", 165 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', 166 tainted & TAINT_FORCED_MODULE ? 'F' : ' ', 167 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', 168 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', 169 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', 170 tainted & TAINT_BAD_PAGE ? 'B' : ' ', 171 tainted & TAINT_USER ? 'U' : ' ', 172 tainted & TAINT_DIE ? 'D' : ' ', 173 tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' '); 174 } 175 else 176 snprintf(buf, sizeof(buf), "Not tainted"); 177 return(buf); 178 } 179 180 void add_taint(unsigned flag) 181 { 182 debug_locks = 0; /* can't trust the integrity of the kernel anymore */ 183 tainted |= flag; 184 } 185 EXPORT_SYMBOL(add_taint); 186 187 static int __init pause_on_oops_setup(char *str) 188 { 189 pause_on_oops = simple_strtoul(str, NULL, 0); 190 return 1; 191 } 192 __setup("pause_on_oops=", pause_on_oops_setup); 193 194 static void spin_msec(int msecs) 195 { 196 int i; 197 198 for (i = 0; i < msecs; i++) { 199 touch_nmi_watchdog(); 200 mdelay(1); 201 } 202 } 203 204 /* 205 * It just happens that oops_enter() and oops_exit() are identically 206 * implemented... 207 */ 208 static void do_oops_enter_exit(void) 209 { 210 unsigned long flags; 211 static int spin_counter; 212 213 if (!pause_on_oops) 214 return; 215 216 spin_lock_irqsave(&pause_on_oops_lock, flags); 217 if (pause_on_oops_flag == 0) { 218 /* This CPU may now print the oops message */ 219 pause_on_oops_flag = 1; 220 } else { 221 /* We need to stall this CPU */ 222 if (!spin_counter) { 223 /* This CPU gets to do the counting */ 224 spin_counter = pause_on_oops; 225 do { 226 spin_unlock(&pause_on_oops_lock); 227 spin_msec(MSEC_PER_SEC); 228 spin_lock(&pause_on_oops_lock); 229 } while (--spin_counter); 230 pause_on_oops_flag = 0; 231 } else { 232 /* This CPU waits for a different one */ 233 while (spin_counter) { 234 spin_unlock(&pause_on_oops_lock); 235 spin_msec(1); 236 spin_lock(&pause_on_oops_lock); 237 } 238 } 239 } 240 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 241 } 242 243 /* 244 * Return true if the calling CPU is allowed to print oops-related info. This 245 * is a bit racy.. 246 */ 247 int oops_may_print(void) 248 { 249 return pause_on_oops_flag == 0; 250 } 251 252 /* 253 * Called when the architecture enters its oops handler, before it prints 254 * anything. If this is the first CPU to oops, and it's oopsing the first time 255 * then let it proceed. 256 * 257 * This is all enabled by the pause_on_oops kernel boot option. We do all this 258 * to ensure that oopses don't scroll off the screen. It has the side-effect 259 * of preventing later-oopsing CPUs from mucking up the display, too. 260 * 261 * It turns out that the CPU which is allowed to print ends up pausing for the 262 * right duration, whereas all the other CPUs pause for twice as long: once in 263 * oops_enter(), once in oops_exit(). 264 */ 265 void oops_enter(void) 266 { 267 debug_locks_off(); /* can't trust the integrity of the kernel anymore */ 268 do_oops_enter_exit(); 269 } 270 271 /* 272 * 64-bit random ID for oopses: 273 */ 274 static u64 oops_id; 275 276 static int init_oops_id(void) 277 { 278 if (!oops_id) 279 get_random_bytes(&oops_id, sizeof(oops_id)); 280 281 return 0; 282 } 283 late_initcall(init_oops_id); 284 285 static void print_oops_end_marker(void) 286 { 287 init_oops_id(); 288 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 289 (unsigned long long)oops_id); 290 } 291 292 /* 293 * Called when the architecture exits its oops handler, after printing 294 * everything. 295 */ 296 void oops_exit(void) 297 { 298 do_oops_enter_exit(); 299 print_oops_end_marker(); 300 } 301 302 #ifdef WANT_WARN_ON_SLOWPATH 303 void warn_on_slowpath(const char *file, int line) 304 { 305 char function[KSYM_SYMBOL_LEN]; 306 unsigned long caller = (unsigned long) __builtin_return_address(0); 307 sprint_symbol(function, caller); 308 309 printk(KERN_WARNING "------------[ cut here ]------------\n"); 310 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, 311 line, function); 312 print_modules(); 313 dump_stack(); 314 print_oops_end_marker(); 315 } 316 EXPORT_SYMBOL(warn_on_slowpath); 317 #endif 318 319 #ifdef CONFIG_CC_STACKPROTECTOR 320 /* 321 * Called when gcc's -fstack-protector feature is used, and 322 * gcc detects corruption of the on-stack canary value 323 */ 324 void __stack_chk_fail(void) 325 { 326 panic("stack-protector: Kernel stack is corrupted"); 327 } 328 EXPORT_SYMBOL(__stack_chk_fail); 329 #endif 330