From 3b5bf42b81d56085fd58692b5117f69aa77fdff7 Mon Sep 17 00:00:00 2001 From: Pan Xinhui Date: Wed, 22 Mar 2017 16:27:49 -0300 Subject: [PATCH] powerpc/xmon: Fix an unexpected xmon on/off state change Once xmon is triggered by sysrq-x, it is enabled always afterwards even if it is disabled during boot. This will cause a system reset interrupt fail to dump. So keep xmon in its original state after exit. We have several ways to set xmon on or off. 1) by a build config CONFIG_XMON_DEFAULT. 2) by a boot cmdline with xmon or xmon=early or xmon=on to enable xmon and xmon=off to disable xmon. This value will override that in step 1. 3) by a debugfs interface, as proposed in this patchset. And this value can override those in step 1 and 2. Signed-off-by: Pan Xinhui Signed-off-by: Guilherme G. Piccoli Signed-off-by: Michael Ellerman --- arch/powerpc/xmon/xmon.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 16321ad9e70c..a89db1b3f66d 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -76,6 +76,7 @@ static int xmon_gate; #endif /* CONFIG_SMP */ static unsigned long in_xmon __read_mostly = 0; +static int xmon_on = IS_ENABLED(CONFIG_XMON_DEFAULT); static unsigned long adrs; static int size = 1; @@ -3302,6 +3303,8 @@ static void sysrq_handle_xmon(int key) /* ensure xmon is enabled */ xmon_init(1); debugger(get_irq_regs()); + if (!xmon_on) + xmon_init(0); } static struct sysrq_key_op sysrq_xmon_op = { @@ -3318,7 +3321,7 @@ static int __init setup_xmon_sysrq(void) __initcall(setup_xmon_sysrq); #endif /* CONFIG_MAGIC_SYSRQ */ -static int __initdata xmon_early, xmon_off; +static int __initdata xmon_early; static int __init early_parse_xmon(char *p) { @@ -3326,10 +3329,12 @@ static int __init early_parse_xmon(char *p) /* just "xmon" is equivalent to "xmon=early" */ xmon_init(1); xmon_early = 1; - } else if (strncmp(p, "on", 2) == 0) + xmon_on = 1; + } else if (strncmp(p, "on", 2) == 0) { xmon_init(1); - else if (strncmp(p, "off", 3) == 0) - xmon_off = 1; + xmon_on = 1; + } else if (strncmp(p, "off", 3) == 0) + xmon_on = 0; else if (strncmp(p, "nobt", 4) == 0) xmon_no_auto_backtrace = 1; else @@ -3341,10 +3346,8 @@ early_param("xmon", early_parse_xmon); void __init xmon_setup(void) { -#ifdef CONFIG_XMON_DEFAULT - if (!xmon_off) + if (xmon_on) xmon_init(1); -#endif if (xmon_early) debugger(NULL); } -- 2.11.0