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Commit ad394f66 authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Greg Kroah-Hartman
Browse files

kdb: Implement disable_nmi command 



This command disables NMI-entry. If NMI source has been previously shared
with a serial console ("debug port"), this effectively releases the port
from KDB exclusive use, and makes the console available for normal use.

Of course, NMI can be reenabled, enable_nmi modparam is used for that:

	echo 1 > /sys/module/kdb/parameters/enable_nmi

Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: default avatarJason Wessel <jason.wessel@windriver.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5a14fead

kernel/debug/kdb/kdb_main.c

+31 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/smp.h>

#include <linux/utsname.h>

#include <linux/vmalloc.h>

#include <linux/atomic.h>

#include <linux/module.h>

#include <linux/mm.h>

#include <linux/init.h>
@@ -2107,6 +2108,32 @@ static int kdb_dmesg(int argc, const char **argv) 
	return 0;

}

#endif /* CONFIG_PRINTK */



/* Make sure we balance enable/disable calls, must disable first. */

static atomic_t kdb_nmi_disabled;



static int kdb_disable_nmi(int argc, const char *argv[])

{

	if (atomic_read(&kdb_nmi_disabled))

		return 0;

	atomic_set(&kdb_nmi_disabled, 1);

	arch_kgdb_ops.enable_nmi(0);

	return 0;

}



static int kdb_param_enable_nmi(const char *val, const struct kernel_param *kp)

{

	if (!atomic_add_unless(&kdb_nmi_disabled, -1, 0))

		return -EINVAL;

	arch_kgdb_ops.enable_nmi(1);

	return 0;

}



static const struct kernel_param_ops kdb_param_ops_enable_nmi = {

	.set = kdb_param_enable_nmi,

};

module_param_cb(enable_nmi, &kdb_param_ops_enable_nmi, NULL, 0600);



/*

 * kdb_cpu - This function implements the 'cpu' command.

 *	cpu	[<cpunum>]
@@ -2851,6 +2878,10 @@ static void __init kdb_inittab(void) 
	kdb_register_repeat("dmesg", kdb_dmesg, "[lines]",

	  "Display syslog buffer", 0, KDB_REPEAT_NONE);

#endif

	if (arch_kgdb_ops.enable_nmi) {

		kdb_register_repeat("disable_nmi", kdb_disable_nmi, "",

		  "Disable NMI entry to KDB", 0, KDB_REPEAT_NONE);

	}

	kdb_register_repeat("defcmd", kdb_defcmd, "name \"usage\" \"help\"",

	  "Define a set of commands, down to endefcmd", 0, KDB_REPEAT_NONE);

	kdb_register_repeat("kill", kdb_kill, "<-signal> <pid>",