panic: add 'panic_sys_info=' setup option for kernel cmdline

'panic_sys_info=' sysctl interface is already added for runtime setting. 
Add counterpart kernel cmdline option for boottime setting.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Feng Tang <[email protected]>
Suggested-by: Petr Mladek <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: "Paul E . McKenney" <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Feng Tang

Documentation/admin-guide/kernel-parameters.txt

@@ -4563,6 +4563,21 @@
 			Use this option carefully, maybe worth to setup a
 			bigger log buffer with "log_buf_len" along with this.
 
+	panic_sys_info= A comma separated list of extra information to be dumped
+                        on panic.
+                        Format: val[,val...]
+                        Where @val can be any of the following:
+
+                        tasks:          print all tasks info
+                        mem:            print system memory info
+			timers:         print timers info
+                        locks:          print locks info if CONFIG_LOCKDEP is on
+                        ftrace:         print ftrace buffer
+                        all_bt:         print all CPUs backtrace (if available in the arch)
+                        blocked_tasks:  print only tasks in uninterruptible (blocked) state
+
+                        This is a human readable alternative to the 'panic_print' option.
+
 	parkbd.port=	[HW] Parallel port number the keyboard adapter is
 			connected to, default is 0.
 			Format: <parport#>

kernel/panic.c

@@ -143,6 +143,15 @@ static __init int kernel_panic_sysctls_init(void)
 late_initcall(kernel_panic_sysctls_init);
 #endif
 
+/* The format is "panic_sys_info=tasks,mem,locks,ftrace,..." */
+static int __init setup_panic_sys_info(char *buf)
+{
+	/* There is no risk of race in kernel boot phase */
+	panic_print = sys_info_parse_param(buf);
+	return 1;
+}
+__setup("panic_sys_info=", setup_panic_sys_info);
+
 static atomic_t warn_count = ATOMIC_INIT(0);
 
 #ifdef CONFIG_SYSFS