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authorGuilherme G. Piccoli <gpiccoli@igalia.com>2022-03-23 16:07:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 19:00:35 -0700
commit8d470a45d1a65e6a308aeee5da7f5b37d3303c04 (patch)
tree868c5db3a56bc8636621215a20ac3b310cb0f611 /kernel/panic.c
parenta1ff1de00db21ecb956213f046b79741b64c6b65 (diff)
panic: add option to dump all CPUs backtraces in panic_print
Currently the "panic_print" parameter/sysctl allows some interesting debug information to be printed during a panic event. This is useful for example in cases the user cannot kdump due to resource limits, or if the user collects panic logs in a serial output (or pstore) and prefers a fast reboot instead of a kdump. Happens that currently there's no way to see all CPUs backtraces in a panic using "panic_print" on architectures that support that. We do have "oops_all_cpu_backtrace" sysctl, but although partially overlapping in the functionality, they are orthogonal in nature: "panic_print" is a panic tuning (and we have panics without oopses, like direct calls to panic() or maybe other paths that don't go through oops_enter() function), and the original purpose of "oops_all_cpu_backtrace" is to provide more information on oopses for cases in which the users desire to continue running the kernel even after an oops, i.e., used in non-panic scenarios. So, we hereby introduce an additional bit for "panic_print" to allow dumping the CPUs backtraces during a panic event. Link: https://lkml.kernel.org/r/20211109202848.610874-3-gpiccoli@igalia.com Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Reviewed-by: Feng Tang <feng.tang@intel.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/panic.c')
-rw-r--r--kernel/panic.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index 95ba825522dd..3c3fb36d8d41 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -66,6 +66,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
#define PANIC_PRINT_LOCK_INFO 0x00000008
#define PANIC_PRINT_FTRACE_INFO 0x00000010
#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
+#define PANIC_PRINT_ALL_CPU_BT 0x00000040
unsigned long panic_print;
ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
@@ -152,6 +153,9 @@ 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_ALL_CPU_BT)
+ trigger_all_cpu_backtrace();
+
if (panic_print & PANIC_PRINT_TASK_INFO)
show_state();