Commit 3b5bf42b authored by Pan Xinhui's avatar Pan Xinhui Committed by Michael Ellerman
Browse files

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: default avatarPan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: default avatarGuilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c7e790c5

arch/powerpc/xmon/xmon.c

+10 −7
Original line number Diff line number Diff line
@@ -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);

}

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