From a71d64b4dc4067808549935583d984c7fc9ea647 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@samba.org>
Date: Tue, 5 Aug 2014 14:55:00 +1000
Subject: [PATCH] powerpc: Hard disable interrupts in xmon

xmon only soft disables interrupts. This seems like a bad idea - we
certainly don't want decrementer and PMU exceptions going off when
we are debugging something inside xmon.

This issue was uncovered when the hard lockup detector went off
inside xmon. To ensure we wont get a spurious hard lockup warning,
I also call touch_nmi_watchdog() when exiting xmon.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/xmon/xmon.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 8d198b5e9e0a..b988b5addf86 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -24,6 +24,7 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/bug.h>
+#include <linux/nmi.h>
 
 #include <asm/ptrace.h>
 #include <asm/string.h>
@@ -374,6 +375,7 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
 #endif
 
 	local_irq_save(flags);
+	hard_irq_disable();
 
 	bp = in_breakpoint_table(regs->nip, &offset);
 	if (bp != NULL) {
@@ -558,6 +560,7 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
 #endif
 	insert_cpu_bpts();
 
+	touch_nmi_watchdog();
 	local_irq_restore(flags);
 
 	return cmd != 'X' && cmd != EOF;