From: Pan Xinhui xinhui.pan@linux.vnet.ibm.com
[ Upstream commit 3b5bf42b81d56085fd58692b5117f69aa77fdff7 ]
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 xinhui.pan@linux.vnet.ibm.com Signed-off-by: Guilherme G. Piccoli gpiccoli@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 760545519a0b..b975a256e606 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -74,6 +74,7 @@ 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; @@ -3244,6 +3245,8 @@ 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 = { @@ -3260,7 +3263,7 @@ 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) { @@ -3268,10 +3271,12 @@ 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 @@ -3283,10 +3288,8 @@ 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); }