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 22 int panic_on_oops; 23 int tainted; 24 static int pause_on_oops; 25 static int pause_on_oops_flag; 26 static DEFINE_SPINLOCK(pause_on_oops_lock); 27 28 int panic_timeout; 29 30 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 31 32 EXPORT_SYMBOL(panic_notifier_list); 33 34 static int __init panic_setup(char *str) 35 { 36 panic_timeout = simple_strtoul(str, NULL, 0); 37 return 1; 38 } 39 __setup("panic=", panic_setup); 40 41 static long no_blink(long time) 42 { 43 return 0; 44 } 45 46 /* Returns how long it waited in ms */ 47 long (*panic_blink)(long time); 48 EXPORT_SYMBOL(panic_blink); 49 50 /** 51 * panic - halt the system 52 * @fmt: The text string to print 53 * 54 * Display a message, then perform cleanups. 55 * 56 * This function never returns. 57 */ 58 59 NORET_TYPE void panic(const char * fmt, ...) 60 { 61 long i; 62 static char buf[1024]; 63 va_list args; 64 #if defined(CONFIG_S390) 65 unsigned long caller = (unsigned long) __builtin_return_address(0); 66 #endif 67 68 /* 69 * It's possible to come here directly from a panic-assertion and not 70 * have preempt disabled. Some functions called from here want 71 * preempt to be disabled. No point enabling it later though... 72 */ 73 preempt_disable(); 74 75 bust_spinlocks(1); 76 va_start(args, fmt); 77 vsnprintf(buf, sizeof(buf), fmt, args); 78 va_end(args); 79 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 80 bust_spinlocks(0); 81 82 /* 83 * If we have crashed and we have a crash kernel loaded let it handle 84 * everything else. 85 * Do we want to call this before we try to display a message? 86 */ 87 crash_kexec(NULL); 88 89 #ifdef CONFIG_SMP 90 /* 91 * Note smp_send_stop is the usual smp shutdown function, which 92 * unfortunately means it may not be hardened to work in a panic 93 * situation. 94 */ 95 smp_send_stop(); 96 #endif 97 98 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 99 100 if (!panic_blink) 101 panic_blink = no_blink; 102 103 if (panic_timeout > 0) { 104 /* 105 * Delay timeout seconds before rebooting the machine. 106 * We can't use the "normal" timers since we just panicked.. 107 */ 108 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout); 109 for (i = 0; i < panic_timeout*1000; ) { 110 touch_nmi_watchdog(); 111 i += panic_blink(i); 112 mdelay(1); 113 i++; 114 } 115 /* This will not be a clean reboot, with everything 116 * shutting down. But if there is a chance of 117 * rebooting the system it will be rebooted. 118 */ 119 emergency_restart(); 120 } 121 #ifdef __sparc__ 122 { 123 extern int stop_a_enabled; 124 /* Make sure the user can actually press Stop-A (L1-A) */ 125 stop_a_enabled = 1; 126 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 127 } 128 #endif 129 #if defined(CONFIG_S390) 130 disabled_wait(caller); 131 #endif 132 local_irq_enable(); 133 for (i = 0;;) { 134 touch_softlockup_watchdog(); 135 i += panic_blink(i); 136 mdelay(1); 137 i++; 138 } 139 } 140 141 EXPORT_SYMBOL(panic); 142 143 /** 144 * print_tainted - return a string to represent the kernel taint state. 145 * 146 * 'P' - Proprietary module has been loaded. 147 * 'F' - Module has been forcibly loaded. 148 * 'S' - SMP with CPUs not designed for SMP. 149 * 'R' - User forced a module unload. 150 * 'M' - Machine had a machine check experience. 151 * 'B' - System has hit bad_page. 152 * 153 * The string is overwritten by the next call to print_taint(). 154 */ 155 156 const char *print_tainted(void) 157 { 158 static char buf[20]; 159 if (tainted) { 160 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c", 161 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', 162 tainted & TAINT_FORCED_MODULE ? 'F' : ' ', 163 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', 164 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', 165 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', 166 tainted & TAINT_BAD_PAGE ? 'B' : ' '); 167 } 168 else 169 snprintf(buf, sizeof(buf), "Not tainted"); 170 return(buf); 171 } 172 173 void add_taint(unsigned flag) 174 { 175 tainted |= flag; 176 } 177 EXPORT_SYMBOL(add_taint); 178 179 static int __init pause_on_oops_setup(char *str) 180 { 181 pause_on_oops = simple_strtoul(str, NULL, 0); 182 return 1; 183 } 184 __setup("pause_on_oops=", pause_on_oops_setup); 185 186 static void spin_msec(int msecs) 187 { 188 int i; 189 190 for (i = 0; i < msecs; i++) { 191 touch_nmi_watchdog(); 192 mdelay(1); 193 } 194 } 195 196 /* 197 * It just happens that oops_enter() and oops_exit() are identically 198 * implemented... 199 */ 200 static void do_oops_enter_exit(void) 201 { 202 unsigned long flags; 203 static int spin_counter; 204 205 if (!pause_on_oops) 206 return; 207 208 spin_lock_irqsave(&pause_on_oops_lock, flags); 209 if (pause_on_oops_flag == 0) { 210 /* This CPU may now print the oops message */ 211 pause_on_oops_flag = 1; 212 } else { 213 /* We need to stall this CPU */ 214 if (!spin_counter) { 215 /* This CPU gets to do the counting */ 216 spin_counter = pause_on_oops; 217 do { 218 spin_unlock(&pause_on_oops_lock); 219 spin_msec(MSEC_PER_SEC); 220 spin_lock(&pause_on_oops_lock); 221 } while (--spin_counter); 222 pause_on_oops_flag = 0; 223 } else { 224 /* This CPU waits for a different one */ 225 while (spin_counter) { 226 spin_unlock(&pause_on_oops_lock); 227 spin_msec(1); 228 spin_lock(&pause_on_oops_lock); 229 } 230 } 231 } 232 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 233 } 234 235 /* 236 * Return true if the calling CPU is allowed to print oops-related info. This 237 * is a bit racy.. 238 */ 239 int oops_may_print(void) 240 { 241 return pause_on_oops_flag == 0; 242 } 243 244 /* 245 * Called when the architecture enters its oops handler, before it prints 246 * anything. If this is the first CPU to oops, and it's oopsing the first time 247 * then let it proceed. 248 * 249 * This is all enabled by the pause_on_oops kernel boot option. We do all this 250 * to ensure that oopses don't scroll off the screen. It has the side-effect 251 * of preventing later-oopsing CPUs from mucking up the display, too. 252 * 253 * It turns out that the CPU which is allowed to print ends up pausing for the 254 * right duration, whereas all the other CPUs pause for twice as long: once in 255 * oops_enter(), once in oops_exit(). 256 */ 257 void oops_enter(void) 258 { 259 do_oops_enter_exit(); 260 } 261 262 /* 263 * Called when the architecture exits its oops handler, after printing 264 * everything. 265 */ 266 void oops_exit(void) 267 { 268 do_oops_enter_exit(); 269 } 270