From: Vincent Whitchurch <vincent.whitchurch@axis.com>
Date: Tue, 21 Aug 2018 17:25:07 +0200
Subject: watchdog: Mark watchdog touch functions as notrace
Git-commit: cb9d7fd51d9fbb329d182423bd7b92d0f8cb0e01
Patch-mainline: v4.19-rc2
References: git-fixes

Some architectures need to use stop_machine() to patch functions for
ftrace, and the assumption is that the stopped CPUs do not make function
calls to traceable functions when they are in the stopped state.

Commit ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after
MULTI_STOP_PREPARE") added calls to the watchdog touch functions from
the stopped CPUs and those functions lack notrace annotations.  This
leads to crashes when enabling/disabling ftrace on ARM kernels built
with the Thumb-2 instruction set.

Fix it by adding the necessary notrace annotations.

Fixes: ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: tj@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 kernel/watchdog.c     |    4 ++--
 kernel/watchdog_hld.c |    2 +-
 kernel/workqueue.c    |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -178,7 +178,7 @@ static void __touch_watchdog(void)
  * entering idle state.  This should only be used for scheduler events.
  * Use touch_softlockup_watchdog() for everything else.
  */
-void touch_softlockup_watchdog_sched(void)
+notrace void touch_softlockup_watchdog_sched(void)
 {
 	/*
 	 * Preemption can be enabled.  It doesn't matter which CPU's timestamp
@@ -187,7 +187,7 @@ void touch_softlockup_watchdog_sched(voi
 	raw_cpu_write(watchdog_touch_ts, 0);
 }
 
-void touch_softlockup_watchdog(void)
+notrace void touch_softlockup_watchdog(void)
 {
 	touch_softlockup_watchdog_sched();
 	wq_watchdog_touch(raw_smp_processor_id());
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -56,7 +56,7 @@ static int __init hardlockup_panic_setup
 }
 __setup("nmi_watchdog=", hardlockup_panic_setup);
 
-void touch_nmi_watchdog(void)
+notrace void touch_nmi_watchdog(void)
 {
 	/*
 	 * Using __raw here because some code paths have
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5451,7 +5451,7 @@ static void wq_watchdog_timer_fn(unsigne
 	mod_timer(&wq_watchdog_timer, jiffies + thresh);
 }
 
-void wq_watchdog_touch(int cpu)
+notrace void wq_watchdog_touch(int cpu)
 {
 	if (cpu >= 0)
 		per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;