diff options
Diffstat (limited to 'kernel/panic.c')
| -rw-r--r-- | kernel/panic.c | 106 |
1 files changed, 86 insertions, 20 deletions
diff --git a/kernel/panic.c b/kernel/panic.c index 04e91ff7560b..535c96510a44 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -23,6 +23,8 @@ #include <linux/sysrq.h> #include <linux/init.h> #include <linux/nmi.h> +#include <linux/console.h> +#include <linux/bug.h> #define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 @@ -60,6 +62,37 @@ void __weak panic_smp_self_stop(void) cpu_relax(); } +/* + * Stop ourselves in NMI context if another CPU has already panicked. Arch code + * may override this to prepare for crash dumping, e.g. save regs info. + */ +void __weak nmi_panic_self_stop(struct pt_regs *regs) +{ + panic_smp_self_stop(); +} + +atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); + +/* + * A variant of panic() called from NMI context. We return if we've already + * panicked on this CPU. If another CPU already panicked, loop in + * nmi_panic_self_stop() which can provide architecture dependent code such + * as saving register state for crash dump. + */ +void nmi_panic(struct pt_regs *regs, const char *msg) +{ + int old_cpu, cpu; + + cpu = raw_smp_processor_id(); + old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu); + + if (old_cpu == PANIC_CPU_INVALID) + panic("%s", msg); + else if (old_cpu != cpu) + nmi_panic_self_stop(regs); +} +EXPORT_SYMBOL(nmi_panic); + /** * panic - halt the system * @fmt: The text string to print @@ -70,17 +103,17 @@ void __weak panic_smp_self_stop(void) */ void panic(const char *fmt, ...) { - static DEFINE_SPINLOCK(panic_lock); static char buf[1024]; va_list args; long i, i_next = 0; int state = 0; + int old_cpu, this_cpu; /* * 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. + * after setting panic_cpu) from invoking panic() again. */ local_irq_disable(); @@ -93,8 +126,16 @@ void panic(const char *fmt, ...) * 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(). + * + * `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which + * comes here, so go ahead. + * `old_cpu == this_cpu' means we came from nmi_panic() which sets + * panic_cpu to this CPU. In this case, this is also the 1st CPU. */ - if (!spin_trylock(&panic_lock)) + this_cpu = raw_smp_processor_id(); + old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); + + if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu) panic_smp_self_stop(); console_verbose(); @@ -116,9 +157,11 @@ void panic(const char *fmt, ...) * everything else. * If we want to run this after calling panic_notifiers, pass * the "crash_kexec_post_notifiers" option to the kernel. + * + * Bypass the panic_cpu check and call __crash_kexec directly. */ if (!crash_kexec_post_notifiers) - crash_kexec(NULL); + __crash_kexec(NULL); /* * Note smp_send_stop is the usual smp shutdown function, which @@ -141,12 +184,25 @@ void panic(const char *fmt, ...) * 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. + * + * Bypass the panic_cpu check and call __crash_kexec directly. */ if (crash_kexec_post_notifiers) - crash_kexec(NULL); + __crash_kexec(NULL); bust_spinlocks(0); + /* + * We may have ended up stopping the CPU holding the lock (in + * smp_send_stop()) while still having some valuable data in the console + * buffer. Try to acquire the lock then release it regardless of the + * result. The release will also print the buffers out. Locks debug + * should be disabled to avoid reporting bad unlock balance when + * panic() is not being callled from OOPS. + */ + debug_locks_off(); + console_flush_on_panic(); + if (!panic_blink) panic_blink = no_blink; @@ -414,20 +470,25 @@ void oops_exit(void) kmsg_dump(KMSG_DUMP_OOPS); } -#ifdef WANT_WARN_ON_SLOWPATH -struct slowpath_args { +struct warn_args { const char *fmt; va_list args; }; -static void warn_slowpath_common(const char *file, int line, void *caller, - unsigned taint, struct slowpath_args *args) +void __warn(const char *file, int line, void *caller, unsigned taint, + struct pt_regs *regs, struct warn_args *args) { disable_trace_on_warning(); pr_warn("------------[ cut here ]------------\n"); - pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", - raw_smp_processor_id(), current->pid, file, line, caller); + + if (file) + pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", + raw_smp_processor_id(), current->pid, file, line, + caller); + else + pr_warn("WARNING: CPU: %d PID: %d at %pS\n", + raw_smp_processor_id(), current->pid, caller); if (args) vprintk(args->fmt, args->args); @@ -444,20 +505,27 @@ static void warn_slowpath_common(const char *file, int line, void *caller, } print_modules(); - dump_stack(); + + if (regs) + show_regs(regs); + else + dump_stack(); + print_oops_end_marker(); + /* Just a warning, don't kill lockdep. */ add_taint(taint, LOCKDEP_STILL_OK); } +#ifdef WANT_WARN_ON_SLOWPATH void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) { - struct slowpath_args args; + struct warn_args args; args.fmt = fmt; va_start(args.args, fmt); - warn_slowpath_common(file, line, __builtin_return_address(0), - TAINT_WARN, &args); + __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, + &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt); @@ -465,20 +533,18 @@ EXPORT_SYMBOL(warn_slowpath_fmt); void warn_slowpath_fmt_taint(const char *file, int line, unsigned taint, const char *fmt, ...) { - struct slowpath_args args; + struct warn_args args; args.fmt = fmt; va_start(args.args, fmt); - warn_slowpath_common(file, line, __builtin_return_address(0), - taint, &args); + __warn(file, line, __builtin_return_address(0), taint, NULL, &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt_taint); void warn_slowpath_null(const char *file, int line) { - warn_slowpath_common(file, line, __builtin_return_address(0), - TAINT_WARN, NULL); + __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL); } EXPORT_SYMBOL(warn_slowpath_null); #endif |