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![Kees Cook](/assets/img/avatar_default.png)
Since the panic handlers may produce additional information (via printk) for the kernel log, it should be reported as part of the panic output saved by kmsg_dump(). Without this re-ordering, nothing that adds information to a panic will show up in pstore's view when kmsg_dump runs, and is therefore not visible to crash reporting tools that examine pstore output. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Colin Cross <ccross@android.com> Acked-by: Tony Luck <tony.luck@intel.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Vikram Mulukutla <markivx@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
482 lines
11 KiB
C
482 lines
11 KiB
C
/*
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* linux/kernel/panic.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* This function is used through-out the kernel (including mm and fs)
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* to indicate a major problem.
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*/
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#include <linux/debug_locks.h>
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#include <linux/interrupt.h>
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#include <linux/kmsg_dump.h>
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#include <linux/kallsyms.h>
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#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>
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#include <linux/kexec.h>
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#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
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#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;
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static int pause_on_oops_flag;
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static DEFINE_SPINLOCK(pause_on_oops_lock);
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int 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 */
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long (*panic_blink)(int state);
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EXPORT_SYMBOL(panic_blink);
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/*
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* Stop ourself in panic -- architecture code may override this
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*/
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void __weak panic_smp_self_stop(void)
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{
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while (1)
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cpu_relax();
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}
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/**
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* panic - halt the system
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* @fmt: The text string to print
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*
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* Display a message, then perform cleanups.
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*
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* This function never returns.
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*/
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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];
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va_list args;
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long i, i_next = 0;
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int state = 0;
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/*
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* Disable local interrupts. This will prevent panic_smp_self_stop
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* from deadlocking the first cpu that invokes the panic, since
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* there is nothing to prevent an interrupt handler (that runs
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* after the panic_lock is acquired) from invoking panic again.
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*/
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local_irq_disable();
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/*
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* It's possible to come here directly from a panic-assertion and
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* 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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*
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* Only one CPU is allowed to execute the panic code from here. For
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* multiple parallel invocations of panic, all other CPUs either
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* stop themself or will wait until they are stopped by the 1st CPU
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* with smp_send_stop().
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*/
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if (!spin_trylock(&panic_lock))
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panic_smp_self_stop();
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console_verbose();
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bust_spinlocks(1);
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va_start(args, fmt);
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vsnprintf(buf, sizeof(buf), fmt, args);
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va_end(args);
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printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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/*
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* Avoid nested stack-dumping if a panic occurs during oops processing
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*/
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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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/*
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* If we have crashed and we have a crash kernel loaded let it handle
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* everything else.
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* Do we want to call this before we try to display a message?
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*/
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crash_kexec(NULL);
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/*
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* Note smp_send_stop is the usual smp shutdown function, which
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* unfortunately means it may not be hardened to work in a panic
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* situation.
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*/
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smp_send_stop();
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/*
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* Run any panic handlers, including those that might need to
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* add information to the kmsg dump output.
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*/
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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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bust_spinlocks(0);
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if (!panic_blink)
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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.
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* We can't use the "normal" timers since we just panicked.
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*/
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printk(KERN_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) {
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i += panic_blink(state ^= 1);
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i_next = i + 3600 / PANIC_BLINK_SPD;
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}
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mdelay(PANIC_TIMER_STEP);
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}
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}
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if (panic_timeout != 0) {
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/*
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* This will not be a clean reboot, with everything
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* shutting down. But if there is a chance of
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* rebooting the system it will be rebooted.
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*/
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emergency_restart();
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}
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#ifdef __sparc__
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{
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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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printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
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}
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#endif
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#if defined(CONFIG_S390)
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{
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unsigned long caller;
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caller = (unsigned long)__builtin_return_address(0);
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disabled_wait(caller);
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}
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#endif
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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) {
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i += panic_blink(state ^= 1);
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i_next = i + 3600 / PANIC_BLINK_SPD;
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}
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mdelay(PANIC_TIMER_STEP);
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}
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}
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EXPORT_SYMBOL(panic);
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struct tnt {
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u8 bit;
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char true;
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char false;
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};
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static const struct tnt tnts[] = {
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{ TAINT_PROPRIETARY_MODULE, 'P', 'G' },
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{ TAINT_FORCED_MODULE, 'F', ' ' },
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{ TAINT_UNSAFE_SMP, 'S', ' ' },
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{ TAINT_FORCED_RMMOD, 'R', ' ' },
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{ TAINT_MACHINE_CHECK, 'M', ' ' },
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{ TAINT_BAD_PAGE, 'B', ' ' },
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{ TAINT_USER, 'U', ' ' },
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{ TAINT_DIE, 'D', ' ' },
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{ TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
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{ TAINT_WARN, 'W', ' ' },
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{ TAINT_CRAP, 'C', ' ' },
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{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
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{ TAINT_OOT_MODULE, 'O', ' ' },
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};
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/**
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* print_tainted - return a string to represent the kernel taint state.
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*
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* 'P' - Proprietary module has been loaded.
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* 'F' - Module has been forcibly loaded.
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* 'S' - SMP with CPUs not designed for SMP.
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* '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.
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* '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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*
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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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{
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static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
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if (tainted_mask) {
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char *s;
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int i;
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s = buf + sprintf(buf, "Tainted: ");
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for (i = 0; i < ARRAY_SIZE(tnts); i++) {
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const struct tnt *t = &tnts[i];
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*s++ = test_bit(t->bit, &tainted_mask) ?
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t->true : t->false;
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}
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*s = 0;
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} 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);
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}
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EXPORT_SYMBOL(test_taint);
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unsigned long get_taint(void)
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{
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return tainted_mask;
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}
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/**
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* add_taint: add a taint flag if not already set.
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* @flag: one of the TAINT_* constants.
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* @lockdep_ok: whether lock debugging is still OK.
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*
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* If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
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* some notewortht-but-not-corrupting cases, it can be set to true.
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*/
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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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printk(KERN_WARNING
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"Disabling lock debugging due to kernel taint\n");
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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)
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{
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int i;
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for (i = 0; i < msecs; i++) {
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touch_nmi_watchdog();
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mdelay(1);
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}
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}
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/*
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* It just happens that oops_enter() and oops_exit() are identically
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* implemented...
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*/
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static void do_oops_enter_exit(void)
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{
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unsigned long flags;
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static int spin_counter;
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if (!pause_on_oops)
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return;
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spin_lock_irqsave(&pause_on_oops_lock, flags);
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if (pause_on_oops_flag == 0) {
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/* This CPU may now print the oops message */
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pause_on_oops_flag = 1;
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} else {
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/* We need to stall this CPU */
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if (!spin_counter) {
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/* This CPU gets to do the counting */
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spin_counter = pause_on_oops;
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do {
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spin_unlock(&pause_on_oops_lock);
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spin_msec(MSEC_PER_SEC);
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spin_lock(&pause_on_oops_lock);
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} while (--spin_counter);
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pause_on_oops_flag = 0;
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} else {
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/* This CPU waits for a different one */
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while (spin_counter) {
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spin_unlock(&pause_on_oops_lock);
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spin_msec(1);
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spin_lock(&pause_on_oops_lock);
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}
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}
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}
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spin_unlock_irqrestore(&pause_on_oops_lock, flags);
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}
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/*
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* Return true if the calling CPU is allowed to print oops-related info.
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* This is a bit racy..
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*/
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int oops_may_print(void)
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{
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return pause_on_oops_flag == 0;
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}
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/*
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* 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
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* 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
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* this to ensure that oopses don't scroll off the screen. It has the
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* side-effect of preventing later-oopsing CPUs from mucking up the display,
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* too.
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*
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* It turns out that the CPU which is allowed to print ends up pausing for
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* the right duration, whereas all the other CPUs pause for twice as long:
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* once in oops_enter(), once in oops_exit().
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*/
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void oops_enter(void)
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{
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tracing_off();
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/* can't trust the integrity of the kernel anymore: */
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debug_locks_off();
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do_oops_enter_exit();
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}
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/*
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* 64-bit random ID for oopses:
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*/
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static u64 oops_id;
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static int init_oops_id(void)
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{
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if (!oops_id)
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get_random_bytes(&oops_id, sizeof(oops_id));
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else
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oops_id++;
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return 0;
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}
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late_initcall(init_oops_id);
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void print_oops_end_marker(void)
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{
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init_oops_id();
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printk(KERN_WARNING "---[ end trace %016llx ]---\n",
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(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
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* everything.
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*/
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void oops_exit(void)
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{
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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 {
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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,
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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 ]------------\n");
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pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
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raw_smp_processor_id(), current->pid, file, line, caller);
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if (args)
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vprintk(args->fmt, args->args);
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print_modules();
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dump_stack();
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print_oops_end_marker();
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/* Just a warning, don't kill lockdep. */
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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, ...)
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{
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struct slowpath_args args;
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args.fmt = fmt;
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va_start(args.args, fmt);
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warn_slowpath_common(file, line, __builtin_return_address(0),
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TAINT_WARN, &args);
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va_end(args.args);
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}
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EXPORT_SYMBOL(warn_slowpath_fmt);
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void warn_slowpath_fmt_taint(const char *file, int line,
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unsigned taint, const char *fmt, ...)
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{
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struct slowpath_args args;
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args.fmt = fmt;
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va_start(args.args, fmt);
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warn_slowpath_common(file, line, __builtin_return_address(0),
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taint, &args);
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va_end(args.args);
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}
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EXPORT_SYMBOL(warn_slowpath_fmt_taint);
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void warn_slowpath_null(const char *file, int line)
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{
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warn_slowpath_common(file, line, __builtin_return_address(0),
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TAINT_WARN, NULL);
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}
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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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/*
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* Called when gcc's -fstack-protector feature is used, and
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* gcc detects corruption of the on-stack canary value
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*/
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void __stack_chk_fail(void)
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{
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panic("stack-protector: Kernel stack is corrupted in: %p\n",
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__builtin_return_address(0));
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}
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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);
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core_param(pause_on_oops, pause_on_oops, int, 0644);
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static int __init oops_setup(char *s)
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{
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if (!s)
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return -EINVAL;
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if (!strcmp(s, "panic"))
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panic_on_oops = 1;
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return 0;
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}
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early_param("oops", oops_setup);
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