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authorAnton Vorontsov <anton.vorontsov@linaro.org>2012-09-24 14:27:51 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-09-26 13:42:25 -0700
commitad394f66fa57ae66014cb74f337e2820bac4c417 (patch)
treea10670b8a9b695aec7fba79d2be2191bd405a12a /kernel
parent5a14fead07bcf4e0acc877a8d9e1d1f40a441153 (diff)
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: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/debug/kdb/kdb_main.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 31df1706b9a..1261dc7eaeb 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -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>",