| 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/debug_locks.h>
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| 12 | #include <linux/interrupt.h>
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| 13 | #include <linux/kmsg_dump.h>
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| 14 | #include <linux/kallsyms.h>
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| 15 | #include <linux/notifier.h>
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| 16 | #include <linux/module.h>
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| 17 | #include <linux/random.h>
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| 18 | #include <linux/reboot.h>
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| 19 | #include <linux/delay.h>
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| 20 | #include <linux/kexec.h>
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| 21 | #include <linux/sched.h>
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| 22 | #include <linux/sysrq.h>
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| 23 | #include <linux/init.h>
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| 24 | #include <linux/nmi.h>
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| 25 | #include <linux/dmi.h>
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| 26 |
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| 27 | int panic_on_oops;
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| 28 | static unsigned long tainted_mask;
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| 29 | static int pause_on_oops;
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| 30 | static int pause_on_oops_flag;
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| 31 | static DEFINE_SPINLOCK(pause_on_oops_lock);
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| 32 |
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| 33 | int panic_timeout;
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| 34 |
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| 35 | ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
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| 36 |
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| 37 | EXPORT_SYMBOL(panic_notifier_list);
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| 38 |
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| 39 |
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| 40 | long (*panic_blink)(long time);
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| 41 | EXPORT_SYMBOL(panic_blink);
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| 42 |
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| 43 | static void panic_blink_one_second(void)
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| 44 | {
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| 45 | static long i = 0, end;
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| 46 |
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| 47 | if (panic_blink) {
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| 48 | end = i + MSEC_PER_SEC;
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| 49 |
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| 50 | while (i < end) {
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| 51 | i += panic_blink(i);
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| 52 | mdelay(1);
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| 53 | i++;
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| 54 | }
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| 55 | } else {
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| 56 | |
| 57 | * When running under a hypervisor a small mdelay may get
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| 58 | * rounded up to the hypervisor timeslice. For example, with
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| 59 | * a 1ms in 10ms hypervisor timeslice we might inflate a
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| 60 | * mdelay(1) loop by 10x.
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| 61 | *
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| 62 | * If we have nothing to blink, spin on 1 second calls to
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| 63 | * mdelay to avoid this.
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| 64 |
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| 65 | mdelay(MSEC_PER_SEC);
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| 66 | }
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| 67 | }
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| 68 |
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| 69 | |
| 70 | * panic - halt the system
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| 71 | * @fmt: The text string to print
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| 72 | *
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| 73 | * Display a message, then perform cleanups.
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| 74 | *
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| 75 | * This function never returns.
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| 76 |
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| 77 | NORET_TYPE void panic(const char * fmt, ...)
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| 78 | {
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| 79 | static char buf[1024];
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| 80 | va_list args;
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| 81 | long i;
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| 82 |
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| 83 | |
| 84 | * It's possible to come here directly from a panic-assertion and
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| 85 | * not have preempt disabled. Some functions called from here want
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| 86 | * preempt to be disabled. No point enabling it later though...
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| 87 |
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| 88 | preempt_disable();
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| 89 |
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| 90 | bust_spinlocks(1);
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| 91 | va_start(args, fmt);
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| 92 | vsnprintf(buf, sizeof(buf), fmt, args);
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| 93 | va_end(args);
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| 94 | printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
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| 95 | #ifdef CONFIG_DEBUG_BUGVERBOSE
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| 96 | dump_stack();
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| 97 | #endif
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| 98 |
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| 99 | |
| 100 | * If we have crashed and we have a crash kernel loaded let it handle
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| 101 | * everything else.
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| 102 | * Do we want to call this before we try to display a message?
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| 103 |
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| 104 | crash_kexec(NULL);
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| 105 |
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| 106 | kmsg_dump(KMSG_DUMP_PANIC);
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| 107 |
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| 108 | |
| 109 | * Note smp_send_stop is the usual smp shutdown function, which
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| 110 | * unfortunately means it may not be hardened to work in a panic
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| 111 | * situation.
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| 112 |
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| 113 | smp_send_stop();
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| 114 |
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| 115 | atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
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| 116 |
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| 117 | bust_spinlocks(0);
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| 118 |
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| 119 | if (panic_timeout > 0) {
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| 120 | |
| 121 | * Delay timeout seconds before rebooting the machine.
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| 122 | * We can't use the "normal" timers since we just panicked.
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| 123 |
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| 124 | printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
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| 125 |
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| 126 | for (i = 0; i < panic_timeout; i++) {
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| 127 | touch_nmi_watchdog();
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| 128 | panic_blink_one_second();
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| 129 | }
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| 130 | |
| 131 | * This will not be a clean reboot, with everything
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| 132 | * shutting down. But if there is a chance of
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| 133 | * rebooting the system it will be rebooted.
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| 134 |
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| 135 | emergency_restart();
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| 136 | }
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| 137 | #ifdef __sparc__
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| 138 | {
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| 139 | extern int stop_a_enabled;
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| 140 |
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| 141 | stop_a_enabled = 1;
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| 142 | printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
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| 143 | }
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| 144 | #endif
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| 145 | #if defined(CONFIG_S390)
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| 146 | {
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| 147 | unsigned long caller;
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| 148 |
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| 149 | caller = (unsigned long)__builtin_return_address(0);
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| 150 | disabled_wait(caller);
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| 151 | }
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| 152 | #endif
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| 153 | local_irq_enable();
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| 154 | while (1) {
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| 155 | touch_softlockup_watchdog();
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| 156 | panic_blink_one_second();
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| 157 | }
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| 158 | }
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| 159 |
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| 160 | EXPORT_SYMBOL(panic);
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| 161 |
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| 162 |
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| 163 | struct tnt {
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| 164 | u8 bit;
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| 165 | char true;
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| 166 | char false;
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| 167 | };
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| 168 |
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| 169 | static const struct tnt tnts[] = {
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| 170 | { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
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| 171 | { TAINT_FORCED_MODULE, 'F', ' ' },
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| 172 | { TAINT_UNSAFE_SMP, 'S', ' ' },
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| 173 | { TAINT_FORCED_RMMOD, 'R', ' ' },
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| 174 | { TAINT_MACHINE_CHECK, 'M', ' ' },
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| 175 | { TAINT_BAD_PAGE, 'B', ' ' },
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| 176 | { TAINT_USER, 'U', ' ' },
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| 177 | { TAINT_DIE, 'D', ' ' },
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| 178 | { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
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| 179 | { TAINT_WARN, 'W', ' ' },
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| 180 | { TAINT_CRAP, 'C', ' ' },
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| 181 | };
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| 182 |
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| 183 | |
| 184 | * print_tainted - return a string to represent the kernel taint state.
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| 185 | *
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| 186 | * 'P' - Proprietary module has been loaded.
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| 187 | * 'F' - Module has been forcibly loaded.
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| 188 | * 'S' - SMP with CPUs not designed for SMP.
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| 189 | * 'R' - User forced a module unload.
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| 190 | * 'M' - System experienced a machine check exception.
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| 191 | * 'B' - System has hit bad_page.
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| 192 | * 'U' - Userspace-defined naughtiness.
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| 193 | * 'D' - Kernel has oopsed before
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| 194 | * 'A' - ACPI table overridden.
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| 195 | * 'W' - Taint on warning.
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| 196 | * 'C' - modules from drivers/staging are loaded.
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| 197 | *
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| 198 | * The string is overwritten by the next call to print_tainted().
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| 199 |
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| 200 | const char *print_tainted(void)
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| 201 | {
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| 202 | static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
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| 203 |
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| 204 | if (tainted_mask) {
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| 205 | char *s;
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| 206 | int i;
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| 207 |
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| 208 | s = buf + sprintf(buf, "Tainted: ");
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| 209 | for (i = 0; i < ARRAY_SIZE(tnts); i++) {
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| 210 | const struct tnt *t = &tnts[i];
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| 211 | *s++ = test_bit(t->bit, &tainted_mask) ?
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| 212 | t->true : t->false;
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| 213 | }
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| 214 | *s = 0;
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| 215 | } else
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| 216 | snprintf(buf, sizeof(buf), "Not tainted");
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| 217 |
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| 218 | return buf;
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| 219 | }
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| 220 |
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| 221 | int test_taint(unsigned flag)
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| 222 | {
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| 223 | return test_bit(flag, &tainted_mask);
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| 224 | }
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| 225 | EXPORT_SYMBOL(test_taint);
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| 226 |
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| 227 | unsigned long get_taint(void)
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| 228 | {
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| 229 | return tainted_mask;
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| 230 | }
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| 231 |
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| 232 | void add_taint(unsigned flag)
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| 233 | {
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| 234 | |
| 235 | * Can't trust the integrity of the kernel anymore.
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| 236 | * We don't call directly debug_locks_off() because the issue
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| 237 | * is not necessarily serious enough to set oops_in_progress to 1
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| 238 | * Also we want to keep up lockdep for staging development and
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| 239 | * post-warning case.
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| 240 |
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| 241 | if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
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| 242 | printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
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| 243 |
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| 244 | set_bit(flag, &tainted_mask);
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| 245 | }
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| 246 | EXPORT_SYMBOL(add_taint);
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| 247 |
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| 248 | static void spin_msec(int msecs)
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| 249 | {
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| 250 | int i;
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| 251 |
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| 252 | for (i = 0; i < msecs; i++) {
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| 253 | touch_nmi_watchdog();
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| 254 | mdelay(1);
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| 255 | }
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| 256 | }
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| 257 |
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| 258 | |
| 259 | * It just happens that oops_enter() and oops_exit() are identically
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| 260 | * implemented...
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| 261 |
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| 262 | static void do_oops_enter_exit(void)
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| 263 | {
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| 264 | unsigned long flags;
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| 265 | static int spin_counter;
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| 266 |
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| 267 | if (!pause_on_oops)
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| 268 | return;
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| 269 |
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| 270 | spin_lock_irqsave(&pause_on_oops_lock, flags);
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| 271 | if (pause_on_oops_flag == 0) {
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| 272 |
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| 273 | pause_on_oops_flag = 1;
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| 274 | } else {
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| 275 |
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| 276 | if (!spin_counter) {
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| 277 |
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| 278 | spin_counter = pause_on_oops;
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| 279 | do {
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| 280 | spin_unlock(&pause_on_oops_lock);
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| 281 | spin_msec(MSEC_PER_SEC);
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| 282 | spin_lock(&pause_on_oops_lock);
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| 283 | } while (--spin_counter);
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| 284 | pause_on_oops_flag = 0;
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| 285 | } else {
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| 286 |
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| 287 | while (spin_counter) {
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| 288 | spin_unlock(&pause_on_oops_lock);
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| 289 | spin_msec(1);
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| 290 | spin_lock(&pause_on_oops_lock);
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| 291 | }
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| 292 | }
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| 293 | }
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| 294 | spin_unlock_irqrestore(&pause_on_oops_lock, flags);
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| 295 | }
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| 296 |
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| 297 | |
| 298 | * Return true if the calling CPU is allowed to print oops-related info.
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| 299 | * This is a bit racy..
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| 300 |
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| 301 | int oops_may_print(void)
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| 302 | {
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| 303 | return pause_on_oops_flag == 0;
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| 304 | }
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| 305 |
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| 306 | |
| 307 | * Called when the architecture enters its oops handler, before it prints
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| 308 | * anything. If this is the first CPU to oops, and it's oopsing the first
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| 309 | * time then let it proceed.
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| 310 | *
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| 311 | * This is all enabled by the pause_on_oops kernel boot option. We do all
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| 312 | * this to ensure that oopses don't scroll off the screen. It has the
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| 313 | * side-effect of preventing later-oopsing CPUs from mucking up the display,
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| 314 | * too.
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| 315 | *
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| 316 | * It turns out that the CPU which is allowed to print ends up pausing for
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| 317 | * the right duration, whereas all the other CPUs pause for twice as long:
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| 318 | * once in oops_enter(), once in oops_exit().
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| 319 |
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| 320 | void oops_enter(void)
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| 321 | {
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| 322 | tracing_off();
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| 323 |
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| 324 | debug_locks_off();
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| 325 | do_oops_enter_exit();
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| 326 | }
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| 327 |
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| 328 | |
| 329 | * 64-bit random ID for oopses:
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| 330 |
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| 331 | static u64 oops_id;
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| 332 |
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| 333 | static int init_oops_id(void)
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| 334 | {
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| 335 | if (!oops_id)
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| 336 | get_random_bytes(&oops_id, sizeof(oops_id));
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| 337 | else
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| 338 | oops_id++;
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| 339 |
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| 340 | return 0;
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| 341 | }
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| 342 | late_initcall(init_oops_id);
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| 343 |
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| 344 | static void print_oops_end_marker(void)
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| 345 | {
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| 346 | init_oops_id();
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| 347 | printk(KERN_WARNING "---[ end trace %016llx ]---\n",
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| 348 | (unsigned long long)oops_id);
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| 349 | }
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| 350 |
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| 351 | |
| 352 | * Called when the architecture exits its oops handler, after printing
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| 353 | * everything.
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| 354 |
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| 355 | void oops_exit(void)
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| 356 | {
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| 357 | do_oops_enter_exit();
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| 358 | print_oops_end_marker();
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| 359 | kmsg_dump(KMSG_DUMP_OOPS);
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| 360 | }
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| 361 |
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| 362 | #ifdef WANT_WARN_ON_SLOWPATH
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| 363 | struct slowpath_args {
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| 364 | const char *fmt;
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| 365 | va_list args;
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| 366 | };
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| 367 |
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| 368 | static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args)
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| 369 | {
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| 370 | const char *board;
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| 371 |
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| 372 | printk(KERN_WARNING "------------[ cut here ]------------\n");
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| 373 | printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
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| 374 | board = dmi_get_system_info(DMI_PRODUCT_NAME);
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| 375 | if (board)
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| 376 | printk(KERN_WARNING "Hardware name: %s\n", board);
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| 377 |
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| 378 | if (args)
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| 379 | vprintk(args->fmt, args->args);
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| 380 |
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| 381 | print_modules();
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| 382 | dump_stack();
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| 383 | print_oops_end_marker();
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| 384 | add_taint(TAINT_WARN);
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| 385 | }
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| 386 |
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| 387 | void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
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| 388 | {
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| 389 | struct slowpath_args args;
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| 390 |
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| 391 | args.fmt = fmt;
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| 392 | va_start(args.args, fmt);
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| 393 | warn_slowpath_common(file, line, __builtin_return_address(0), &args);
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| 394 | va_end(args.args);
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| 395 | }
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| 396 | EXPORT_SYMBOL(warn_slowpath_fmt);
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| 397 |
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| 398 | void warn_slowpath_null(const char *file, int line)
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| 399 | {
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| 400 | warn_slowpath_common(file, line, __builtin_return_address(0), NULL);
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| 401 | }
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| 402 | EXPORT_SYMBOL(warn_slowpath_null);
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| 403 | #endif
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| 404 |
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| 405 | #ifdef CONFIG_CC_STACKPROTECTOR
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| 406 |
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| 407 | |
| 408 | * Called when gcc's -fstack-protector feature is used, and
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| 409 | * gcc detects corruption of the on-stack canary value
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| 410 |
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| 411 | void __stack_chk_fail(void)
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| 412 | {
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| 413 | panic("stack-protector: Kernel stack is corrupted in: %p\n",
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| 414 | __builtin_return_address(0));
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| 415 | }
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| 416 | EXPORT_SYMBOL(__stack_chk_fail);
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| 417 |
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| 418 | #endif
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| 419 |
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| 420 | core_param(panic, panic_timeout, int, 0644);
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| 421 | core_param(pause_on_oops, pause_on_oops, int, 0644);
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