| Message ID | 1347548615-18227-2-git-send-email-anton.vorontsov@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 09/13/2012 10:03 AM, Anton Vorontsov wrote: > 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> > --- > kernel/debug/kdb/kdb_main.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c > index 31df170..9fadff1 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); > + kgdb_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; > + kgdb_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 +2878,8 @@ static void __init kdb_inittab(void) > kdb_register_repeat("dmesg", kdb_dmesg, "[lines]", > "Display syslog buffer", 0, KDB_REPEAT_NONE); > #endif Based on what I commented in the 01/11 patch, we don't want to register a command if the architecture doesn't actually have it, because it just leads to confusion. It needs to have an "if" 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>", >
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 31df170..9fadff1 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); + kgdb_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; + kgdb_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 +2878,8 @@ static void __init kdb_inittab(void) kdb_register_repeat("dmesg", kdb_dmesg, "[lines]", "Display syslog buffer", 0, KDB_REPEAT_NONE); #endif + 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>",
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> --- kernel/debug/kdb/kdb_main.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)