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: Feng Tang <feng.tang@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 408781e..e7b5c49 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -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().
 

diff --git a/kernel/panic.c b/kernel/panic.c
index d10c340..855f667 100644 (file)
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -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);