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9e3961a097
There have been several times where I have had to rebuild a kernel to cause a panic when hitting a WARN() in the code in order to get a crash dump from a system. Sometimes this is easy to do, other times (such as in the case of a remote admin) it is not trivial to send new images to the user. A much easier method would be a switch to change the WARN() over to a panic. This makes debugging easier in that I can now test the actual image the WARN() was seen on and I do not have to engage in remote debugging. This patch adds a panic_on_warn kernel parameter and /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() path. The function will still print out the location of the warning. An example of the panic_on_warn output: The first line below is from the WARN_ON() to output the WARN_ON()'s location. After that the panic() output is displayed. WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]() Kernel panic - not syncing: panic_on_warn set ... CPU: 30 PID: 11698 Comm: insmod Tainted: G W OE 3.17.0+ #57 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190 0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df Call Trace: [<ffffffff81665190>] dump_stack+0x46/0x58 [<ffffffff8165e2ec>] panic+0xd0/0x204 [<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module] [<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0 [<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module] [<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20 [<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module] [<ffffffff81002144>] do_one_initcall+0xd4/0x210 [<ffffffff811b52c2>] ? __vunmap+0xc2/0x110 [<ffffffff810f8889>] load_module+0x16a9/0x1b30 [<ffffffff810f3d30>] ? store_uevent+0x70/0x70 [<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180 [<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0 [<ffffffff8166cf29>] system_call_fastpath+0x12/0x17 Successfully tested by me. hpa said: There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Fabian Frederick <fabf@skynet.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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.. | ||
bpf | ||
configs | ||
debug | ||
events | ||
gcov | ||
irq | ||
locking | ||
power | ||
printk | ||
rcu | ||
sched | ||
time | ||
trace | ||
.gitignore | ||
acct.c | ||
async.c | ||
audit_tree.c | ||
audit_watch.c | ||
audit.c | ||
audit.h | ||
auditfilter.c | ||
auditsc.c | ||
backtracetest.c | ||
bounds.c | ||
capability.c | ||
cgroup_freezer.c | ||
cgroup.c | ||
compat.c | ||
configs.c | ||
context_tracking.c | ||
cpu_pm.c | ||
cpu.c | ||
cpuset.c | ||
crash_dump.c | ||
cred.c | ||
delayacct.c | ||
dma.c | ||
elfcore.c | ||
exec_domain.c | ||
exit.c | ||
extable.c | ||
fork.c | ||
freezer.c | ||
futex_compat.c | ||
futex.c | ||
groups.c | ||
hung_task.c | ||
irq_work.c | ||
jump_label.c | ||
kallsyms.c | ||
kcmp.c | ||
Kconfig.freezer | ||
Kconfig.hz | ||
Kconfig.locks | ||
Kconfig.preempt | ||
kexec.c | ||
kmod.c | ||
kprobes.c | ||
ksysfs.c | ||
kthread.c | ||
latencytop.c | ||
Makefile | ||
module_signing.c | ||
module-internal.h | ||
module.c | ||
notifier.c | ||
nsproxy.c | ||
padata.c | ||
panic.c | ||
params.c | ||
pid_namespace.c | ||
pid.c | ||
profile.c | ||
ptrace.c | ||
range.c | ||
reboot.c | ||
relay.c | ||
resource.c | ||
seccomp.c | ||
signal.c | ||
smp.c | ||
smpboot.c | ||
smpboot.h | ||
softirq.c | ||
stacktrace.c | ||
stop_machine.c | ||
sys_ni.c | ||
sys.c | ||
sysctl_binary.c | ||
sysctl.c | ||
system_certificates.S | ||
system_keyring.c | ||
task_work.c | ||
taskstats.c | ||
test_kprobes.c | ||
torture.c | ||
tracepoint.c | ||
tsacct.c | ||
uid16.c | ||
up.c | ||
user_namespace.c | ||
user-return-notifier.c | ||
user.c | ||
utsname_sysctl.c | ||
utsname.c | ||
watchdog.c | ||
workqueue_internal.h | ||
workqueue.c |