Commit d999bd93 authored by Feng Tang's avatar Feng Tang Committed by Linus Torvalds
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panic: add options to print system info when panic happens 

Kernel panic issues are always painful to debug, partially because it's
not easy to get enough information of the context when panic happens.

And we have ramoops and kdump for that, while this commit tries to
provide a easier way to show the system info by adding a cmdline
parameter, referring some idea from sysrq handler.

Link: http://lkml.kernel.org/r/1543398842-19295-2-git-send-email-feng.tang@intel.com


Signed-off-by: default avatarFeng Tang <feng.tang@intel.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d1877155

Documentation/admin-guide/kernel-parameters.txt

+8 −0
Original line number Diff line number Diff line
@@ -3092,6 +3092,14 @@ 
			timeout < 0: reboot immediately

			Format: <timeout>



	panic_print=	Bitmask for printing system info when panic happens.

			User can chose combination of the following bits:

			bit 0: print all tasks info

			bit 1: print system memory info

			bit 2: print timer info

			bit 3: print locks info if CONFIG_LOCKDEP is on

			bit 4: print ftrace buffer



	panic_on_warn	panic() instead of WARN().  Useful to cause kdump

			on a WARN().

kernel/panic.c

+28 −0
Original line number Diff line number Diff line
@@ -46,6 +46,13 @@ int panic_on_warn __read_mostly; 
int panic_timeout = CONFIG_PANIC_TIMEOUT;

EXPORT_SYMBOL_GPL(panic_timeout);



#define PANIC_PRINT_TASK_INFO		0x00000001

#define PANIC_PRINT_MEM_INFO		0x00000002

#define PANIC_PRINT_TIMER_INFO		0x00000004

#define PANIC_PRINT_LOCK_INFO		0x00000008

#define PANIC_PRINT_FTRACE_INFO		0x00000010

static unsigned long panic_print;



ATOMIC_NOTIFIER_HEAD(panic_notifier_list);



EXPORT_SYMBOL(panic_notifier_list);
@@ -125,6 +132,24 @@ void nmi_panic(struct pt_regs *regs, const char *msg) 
}

EXPORT_SYMBOL(nmi_panic);



static void panic_print_sys_info(void)

{

	if (panic_print & PANIC_PRINT_TASK_INFO)

		show_state();



	if (panic_print & PANIC_PRINT_MEM_INFO)

		show_mem(0, NULL);



	if (panic_print & PANIC_PRINT_TIMER_INFO)

		sysrq_timer_list_show();



	if (panic_print & PANIC_PRINT_LOCK_INFO)

		debug_show_all_locks();



	if (panic_print & PANIC_PRINT_FTRACE_INFO)

		ftrace_dump(DUMP_ALL);

}



/**

 *	panic - halt the system

 *	@fmt: The text string to print
@@ -254,6 +279,8 @@ void panic(const char *fmt, ...) 
	debug_locks_off();

	console_flush_on_panic();



	panic_print_sys_info();



	if (!panic_blink)

		panic_blink = no_blink;
@@ -658,6 +685,7 @@ void refcount_error_report(struct pt_regs *regs, const char *err) 
#endif



core_param(panic, panic_timeout, int, 0644);

core_param(panic_print, panic_print, ulong, 0644);

core_param(pause_on_oops, pause_on_oops, int, 0644);

core_param(panic_on_warn, panic_on_warn, int, 0644);

core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);

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