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kernel/panic.c
12.5 KB
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/* * linux/kernel/panic.c * * Copyright (C) 1991, 1992 Linus Torvalds */ /* * This function is used through-out the kernel (including mm and fs) * to indicate a major problem. */ |
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#include <linux/debug_locks.h> #include <linux/interrupt.h> |
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#include <linux/kmsg_dump.h> |
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#include <linux/kallsyms.h> #include <linux/notifier.h> |
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#include <linux/module.h> |
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#include <linux/random.h> |
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#include <linux/ftrace.h> |
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#include <linux/reboot.h> |
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#include <linux/delay.h> #include <linux/kexec.h> #include <linux/sched.h> |
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#include <linux/sysrq.h> |
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#include <linux/init.h> |
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#include <linux/nmi.h> |
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#define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 |
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int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; |
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static unsigned long tainted_mask; |
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static int pause_on_oops; static int pause_on_oops_flag; static DEFINE_SPINLOCK(pause_on_oops_lock); |
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static bool crash_kexec_post_notifiers; |
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int panic_on_warn __read_mostly; |
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int panic_timeout = CONFIG_PANIC_TIMEOUT; |
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EXPORT_SYMBOL_GPL(panic_timeout); |
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ATOMIC_NOTIFIER_HEAD(panic_notifier_list); |
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EXPORT_SYMBOL(panic_notifier_list); |
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static long no_blink(int state) |
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{ |
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return 0; |
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} |
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/* Returns how long it waited in ms */ long (*panic_blink)(int state); EXPORT_SYMBOL(panic_blink); |
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/* * Stop ourself in panic -- architecture code may override this */ void __weak panic_smp_self_stop(void) { while (1) cpu_relax(); } |
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/** * panic - halt the system * @fmt: The text string to print * * Display a message, then perform cleanups. * * This function never returns. */ |
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void panic(const char *fmt, ...) |
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{ |
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static DEFINE_SPINLOCK(panic_lock); |
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static char buf[1024]; va_list args; |
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long i, i_next = 0; int state = 0; |
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/* |
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* Disable local interrupts. This will prevent panic_smp_self_stop * from deadlocking the first cpu that invokes the panic, since * there is nothing to prevent an interrupt handler (that runs * after the panic_lock is acquired) from invoking panic again. */ local_irq_disable(); /* |
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* It's possible to come here directly from a panic-assertion and * not have preempt disabled. Some functions called from here want |
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* preempt to be disabled. No point enabling it later though... |
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* * Only one CPU is allowed to execute the panic code from here. For * multiple parallel invocations of panic, all other CPUs either * stop themself or will wait until they are stopped by the 1st CPU * with smp_send_stop(). |
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*/ |
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if (!spin_trylock(&panic_lock)) panic_smp_self_stop(); |
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console_verbose(); |
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bust_spinlocks(1); va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); |
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pr_emerg("Kernel panic - not syncing: %s ", buf); |
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#ifdef CONFIG_DEBUG_BUGVERBOSE |
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/* * Avoid nested stack-dumping if a panic occurs during oops processing */ |
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if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) |
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dump_stack(); |
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#endif |
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/* * If we have crashed and we have a crash kernel loaded let it handle * everything else. |
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* If we want to run this after calling panic_notifiers, pass * the "crash_kexec_post_notifiers" option to the kernel. |
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*/ |
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if (!crash_kexec_post_notifiers) crash_kexec(NULL); |
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/* * Note smp_send_stop is the usual smp shutdown function, which * unfortunately means it may not be hardened to work in a panic * situation. */ |
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smp_send_stop(); |
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/* * Run any panic handlers, including those that might need to * add information to the kmsg dump output. */ |
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atomic_notifier_call_chain(&panic_notifier_list, 0, buf); |
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kmsg_dump(KMSG_DUMP_PANIC); |
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/* * If you doubt kdump always works fine in any situation, * "crash_kexec_post_notifiers" offers you a chance to run * panic_notifiers and dumping kmsg before kdump. * Note: since some panic_notifiers can make crashed kernel * more unstable, it can increase risks of the kdump failure too. */ crash_kexec(NULL); |
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bust_spinlocks(0); |
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if (!panic_blink) panic_blink = no_blink; |
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if (panic_timeout > 0) { |
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/* |
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* Delay timeout seconds before rebooting the machine. * We can't use the "normal" timers since we just panicked. */ |
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pr_emerg("Rebooting in %d seconds..", panic_timeout); |
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for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { |
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touch_nmi_watchdog(); |
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if (i >= i_next) { i += panic_blink(state ^= 1); i_next = i + 3600 / PANIC_BLINK_SPD; } mdelay(PANIC_TIMER_STEP); |
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} |
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} if (panic_timeout != 0) { |
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/* * This will not be a clean reboot, with everything * shutting down. But if there is a chance of * rebooting the system it will be rebooted. |
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*/ |
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emergency_restart(); |
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} #ifdef __sparc__ { extern int stop_a_enabled; |
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/* Make sure the user can actually press Stop-A (L1-A) */ |
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stop_a_enabled = 1; |
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pr_emerg("Press Stop-A (L1-A) to return to the boot prom "); |
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} #endif |
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#if defined(CONFIG_S390) |
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{ unsigned long caller; caller = (unsigned long)__builtin_return_address(0); disabled_wait(caller); } |
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#endif |
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pr_emerg("---[ end Kernel panic - not syncing: %s ", buf); |
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local_irq_enable(); |
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for (i = 0; ; i += PANIC_TIMER_STEP) { |
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touch_softlockup_watchdog(); |
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if (i >= i_next) { i += panic_blink(state ^= 1); i_next = i + 3600 / PANIC_BLINK_SPD; } mdelay(PANIC_TIMER_STEP); |
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} } EXPORT_SYMBOL(panic); |
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struct tnt { |
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u8 bit; char true; char false; |
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}; static const struct tnt tnts[] = { |
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{ TAINT_PROPRIETARY_MODULE, 'P', 'G' }, { TAINT_FORCED_MODULE, 'F', ' ' }, |
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{ TAINT_CPU_OUT_OF_SPEC, 'S', ' ' }, |
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{ TAINT_FORCED_RMMOD, 'R', ' ' }, { TAINT_MACHINE_CHECK, 'M', ' ' }, { TAINT_BAD_PAGE, 'B', ' ' }, { TAINT_USER, 'U', ' ' }, { TAINT_DIE, 'D', ' ' }, { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, { TAINT_WARN, 'W', ' ' }, { TAINT_CRAP, 'C', ' ' }, |
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{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, |
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{ TAINT_OOT_MODULE, 'O', ' ' }, |
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{ TAINT_UNSIGNED_MODULE, 'E', ' ' }, |
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{ TAINT_SOFTLOCKUP, 'L', ' ' }, |
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}; |
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/** * print_tainted - return a string to represent the kernel taint state. * * 'P' - Proprietary module has been loaded. * 'F' - Module has been forcibly loaded. * 'S' - SMP with CPUs not designed for SMP. * 'R' - User forced a module unload. |
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* 'M' - System experienced a machine check exception. |
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* 'B' - System has hit bad_page. |
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* 'U' - Userspace-defined naughtiness. |
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* 'D' - Kernel has oopsed before |
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* 'A' - ACPI table overridden. * 'W' - Taint on warning. |
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* 'C' - modules from drivers/staging are loaded. |
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* 'I' - Working around severe firmware bug. |
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* 'O' - Out-of-tree module has been loaded. |
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* 'E' - Unsigned module has been loaded. |
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* 'L' - A soft lockup has previously occurred. |
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* |
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* The string is overwritten by the next call to print_tainted(). |
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*/ |
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const char *print_tainted(void) { |
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static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")]; |
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if (tainted_mask) { char *s; int i; s = buf + sprintf(buf, "Tainted: "); for (i = 0; i < ARRAY_SIZE(tnts); i++) { const struct tnt *t = &tnts[i]; *s++ = test_bit(t->bit, &tainted_mask) ? t->true : t->false; } *s = 0; } else |
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snprintf(buf, sizeof(buf), "Not tainted"); |
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return buf; |
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} |
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int test_taint(unsigned flag) |
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{ |
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return test_bit(flag, &tainted_mask); } EXPORT_SYMBOL(test_taint); unsigned long get_taint(void) { return tainted_mask; |
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} |
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/** * add_taint: add a taint flag if not already set. * @flag: one of the TAINT_* constants. * @lockdep_ok: whether lock debugging is still OK. * * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for * some notewortht-but-not-corrupting cases, it can be set to true. */ void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) |
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{ |
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if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) |
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pr_warn("Disabling lock debugging due to kernel taint "); |
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set_bit(flag, &tainted_mask); |
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} |
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EXPORT_SYMBOL(add_taint); |
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static void spin_msec(int msecs) { int i; for (i = 0; i < msecs; i++) { touch_nmi_watchdog(); mdelay(1); } } /* * It just happens that oops_enter() and oops_exit() are identically * implemented... */ static void do_oops_enter_exit(void) { unsigned long flags; static int spin_counter; if (!pause_on_oops) return; spin_lock_irqsave(&pause_on_oops_lock, flags); if (pause_on_oops_flag == 0) { /* This CPU may now print the oops message */ pause_on_oops_flag = 1; } else { /* We need to stall this CPU */ if (!spin_counter) { /* This CPU gets to do the counting */ spin_counter = pause_on_oops; do { spin_unlock(&pause_on_oops_lock); spin_msec(MSEC_PER_SEC); spin_lock(&pause_on_oops_lock); } while (--spin_counter); pause_on_oops_flag = 0; } else { /* This CPU waits for a different one */ while (spin_counter) { spin_unlock(&pause_on_oops_lock); spin_msec(1); spin_lock(&pause_on_oops_lock); } } } spin_unlock_irqrestore(&pause_on_oops_lock, flags); } /* |
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* Return true if the calling CPU is allowed to print oops-related info. * This is a bit racy.. |
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*/ int oops_may_print(void) { return pause_on_oops_flag == 0; } /* * Called when the architecture enters its oops handler, before it prints |
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* anything. If this is the first CPU to oops, and it's oopsing the first * time then let it proceed. |
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* |
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* This is all enabled by the pause_on_oops kernel boot option. We do all * this to ensure that oopses don't scroll off the screen. It has the * side-effect of preventing later-oopsing CPUs from mucking up the display, * too. |
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* |
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* It turns out that the CPU which is allowed to print ends up pausing for * the right duration, whereas all the other CPUs pause for twice as long: * once in oops_enter(), once in oops_exit(). |
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*/ void oops_enter(void) { |
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tracing_off(); |
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/* can't trust the integrity of the kernel anymore: */ debug_locks_off(); |
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do_oops_enter_exit(); } /* |
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* 64-bit random ID for oopses: */ static u64 oops_id; static int init_oops_id(void) { if (!oops_id) get_random_bytes(&oops_id, sizeof(oops_id)); |
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else oops_id++; |
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return 0; } late_initcall(init_oops_id); |
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void print_oops_end_marker(void) |
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{ init_oops_id(); |
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pr_warn("---[ end trace %016llx ]--- ", (unsigned long long)oops_id); |
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} |
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/* |
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* Called when the architecture exits its oops handler, after printing * everything. */ void oops_exit(void) { do_oops_enter_exit(); |
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print_oops_end_marker(); |
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kmsg_dump(KMSG_DUMP_OOPS); |
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} |
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#ifdef WANT_WARN_ON_SLOWPATH |
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struct slowpath_args { const char *fmt; |
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va_list args; |
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}; |
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static void warn_slowpath_common(const char *file, int line, void *caller, unsigned taint, struct slowpath_args *args) |
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{ |
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disable_trace_on_warning(); |
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pr_warn("------------[ cut here ]------------ "); pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS() ", raw_smp_processor_id(), current->pid, file, line, caller); |
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if (args) vprintk(args->fmt, args->args); |
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if (panic_on_warn) { /* * This thread may hit another WARN() in the panic path. * Resetting this prevents additional WARN() from panicking the * system on this thread. Other threads are blocked by the * panic_mutex in panic(). */ panic_on_warn = 0; panic("panic_on_warn set ... "); } |
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print_modules(); dump_stack(); print_oops_end_marker(); |
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/* Just a warning, don't kill lockdep. */ add_taint(taint, LOCKDEP_STILL_OK); |
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} |
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void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) { struct slowpath_args args; args.fmt = fmt; va_start(args.args, fmt); |
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warn_slowpath_common(file, line, __builtin_return_address(0), TAINT_WARN, &args); |
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va_end(args.args); } |
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EXPORT_SYMBOL(warn_slowpath_fmt); |
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void warn_slowpath_fmt_taint(const char *file, int line, unsigned taint, const char *fmt, ...) { struct slowpath_args args; args.fmt = fmt; va_start(args.args, fmt); warn_slowpath_common(file, line, __builtin_return_address(0), taint, &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt_taint); |
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void warn_slowpath_null(const char *file, int line) { |
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warn_slowpath_common(file, line, __builtin_return_address(0), TAINT_WARN, NULL); |
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} EXPORT_SYMBOL(warn_slowpath_null); |
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#endif |
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#ifdef CONFIG_CC_STACKPROTECTOR |
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/* * Called when gcc's -fstack-protector feature is used, and * gcc detects corruption of the on-stack canary value */ |
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__visible void __stack_chk_fail(void) |
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{ |
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panic("stack-protector: Kernel stack is corrupted in: %p ", __builtin_return_address(0)); |
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} EXPORT_SYMBOL(__stack_chk_fail); |
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#endif |
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core_param(panic, panic_timeout, int, 0644); core_param(pause_on_oops, pause_on_oops, int, 0644); |
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core_param(panic_on_warn, panic_on_warn, int, 0644); |
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static int __init setup_crash_kexec_post_notifiers(char *s) { crash_kexec_post_notifiers = true; return 0; } early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers); |
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static int __init oops_setup(char *s) { if (!s) return -EINVAL; if (!strcmp(s, "panic")) panic_on_oops = 1; return 0; } early_param("oops", oops_setup); |