Commit de6da1e8 authored by Feng Tang's avatar Feng Tang Committed by Linus Torvalds

panic: add an option to replay all the printk message in buffer

Currently on panic, kernel will lower the loglevel and print out pending
printk msg only with console_flush_on_panic().

Add an option for users to configure the "panic_print" to replay all
dmesg in buffer, some of which they may have never seen due to the
loglevel setting, which will help panic debugging .

[feng.tang@intel.com: keep the original console_flush_on_panic() inside panic()]
  Link: http://lkml.kernel.org/r/1556199137-14163-1-git-send-email-feng.tang@intel.com
[feng.tang@intel.com: use logbuf lock to protect the console log index]
  Link: http://lkml.kernel.org/r/1556269868-22654-1-git-send-email-feng.tang@intel.com
Link: http://lkml.kernel.org/r/1556095872-36838-1-git-send-email-feng.tang@intel.comSigned-off-by: default avatarFeng Tang <feng.tang@intel.com>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5d59aa8f
...@@ -3212,6 +3212,7 @@ ...@@ -3212,6 +3212,7 @@
bit 2: print timer info bit 2: print timer info
bit 3: print locks info if CONFIG_LOCKDEP is on bit 3: print locks info if CONFIG_LOCKDEP is on
bit 4: print ftrace buffer bit 4: print ftrace buffer
bit 5: print all printk messages in buffer
panic_on_warn panic() instead of WARN(). Useful to cause kdump panic_on_warn panic() instead of WARN(). Useful to cause kdump
on a WARN(). on a WARN().
......
...@@ -179,7 +179,7 @@ extern void panic_flush_kmsg_end(void) ...@@ -179,7 +179,7 @@ extern void panic_flush_kmsg_end(void)
kmsg_dump(KMSG_DUMP_PANIC); kmsg_dump(KMSG_DUMP_PANIC);
bust_spinlocks(0); bust_spinlocks(0);
debug_locks_off(); debug_locks_off();
console_flush_on_panic(); console_flush_on_panic(CONSOLE_FLUSH_PENDING);
} }
static unsigned long oops_begin(struct pt_regs *regs) static unsigned long oops_begin(struct pt_regs *regs)
......
...@@ -166,6 +166,11 @@ struct console { ...@@ -166,6 +166,11 @@ struct console {
extern int console_set_on_cmdline; extern int console_set_on_cmdline;
extern struct console *early_console; extern struct console *early_console;
enum con_flush_mode {
CONSOLE_FLUSH_PENDING,
CONSOLE_REPLAY_ALL,
};
extern int add_preferred_console(char *name, int idx, char *options); extern int add_preferred_console(char *name, int idx, char *options);
extern void register_console(struct console *); extern void register_console(struct console *);
extern int unregister_console(struct console *); extern int unregister_console(struct console *);
...@@ -175,7 +180,7 @@ extern int console_trylock(void); ...@@ -175,7 +180,7 @@ extern int console_trylock(void);
extern void console_unlock(void); extern void console_unlock(void);
extern void console_conditional_schedule(void); extern void console_conditional_schedule(void);
extern void console_unblank(void); extern void console_unblank(void);
extern void console_flush_on_panic(void); extern void console_flush_on_panic(enum con_flush_mode mode);
extern struct tty_driver *console_device(int *); extern struct tty_driver *console_device(int *);
extern void console_stop(struct console *); extern void console_stop(struct console *);
extern void console_start(struct console *); extern void console_start(struct console *);
......
...@@ -51,6 +51,7 @@ EXPORT_SYMBOL_GPL(panic_timeout); ...@@ -51,6 +51,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
#define PANIC_PRINT_TIMER_INFO 0x00000004 #define PANIC_PRINT_TIMER_INFO 0x00000004
#define PANIC_PRINT_LOCK_INFO 0x00000008 #define PANIC_PRINT_LOCK_INFO 0x00000008
#define PANIC_PRINT_FTRACE_INFO 0x00000010 #define PANIC_PRINT_FTRACE_INFO 0x00000010
#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
unsigned long panic_print; unsigned long panic_print;
ATOMIC_NOTIFIER_HEAD(panic_notifier_list); ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
...@@ -134,6 +135,9 @@ EXPORT_SYMBOL(nmi_panic); ...@@ -134,6 +135,9 @@ EXPORT_SYMBOL(nmi_panic);
static void panic_print_sys_info(void) static void panic_print_sys_info(void)
{ {
if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
console_flush_on_panic(CONSOLE_REPLAY_ALL);
if (panic_print & PANIC_PRINT_TASK_INFO) if (panic_print & PANIC_PRINT_TASK_INFO)
show_state(); show_state();
...@@ -277,7 +281,7 @@ void panic(const char *fmt, ...) ...@@ -277,7 +281,7 @@ void panic(const char *fmt, ...)
* panic() is not being callled from OOPS. * panic() is not being callled from OOPS.
*/ */
debug_locks_off(); debug_locks_off();
console_flush_on_panic(); console_flush_on_panic(CONSOLE_FLUSH_PENDING);
panic_print_sys_info(); panic_print_sys_info();
......
...@@ -2535,10 +2535,11 @@ void console_unblank(void) ...@@ -2535,10 +2535,11 @@ void console_unblank(void)
/** /**
* console_flush_on_panic - flush console content on panic * console_flush_on_panic - flush console content on panic
* @mode: flush all messages in buffer or just the pending ones
* *
* Immediately output all pending messages no matter what. * Immediately output all pending messages no matter what.
*/ */
void console_flush_on_panic(void) void console_flush_on_panic(enum con_flush_mode mode)
{ {
/* /*
* If someone else is holding the console lock, trylock will fail * If someone else is holding the console lock, trylock will fail
...@@ -2549,6 +2550,15 @@ void console_flush_on_panic(void) ...@@ -2549,6 +2550,15 @@ void console_flush_on_panic(void)
*/ */
console_trylock(); console_trylock();
console_may_schedule = 0; console_may_schedule = 0;
if (mode == CONSOLE_REPLAY_ALL) {
unsigned long flags;
logbuf_lock_irqsave(flags);
console_seq = log_first_seq;
console_idx = log_first_idx;
logbuf_unlock_irqrestore(flags);
}
console_unlock(); console_unlock();
} }
......
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