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