Merge tag 'for_linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull KGDB/KDB updates from Jason Wessel:
 "Fixes:
   - Fix KDB keyboard repeat scan codes and leaked keyboard events
   - Fix kernel crash with kdb_printf() for users who compile new
     kdb_printf()'s in early code
   - Return all segment registers to gdb on x86_64

  Features:
   - KDB/KGDB hook the reboot notifier and end user can control if it
     stops, detaches or does nothing (updated docs as well)
   - Notify users who use CONFIG_DEBUG_RODATA to use hw breakpoints"

* tag 'for_linus-3.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  kdb: Add message about CONFIG_DEBUG_RODATA on failure to install breakpoint
  kdb: Avoid using dbg_io_ops until it is initialized
  kgdb,debug_core: add the ability to control the reboot notifier
  KDB: Fix usability issues relating to the 'enter' key.
  kgdb,debug-core,gdbstub: Hook the reboot notifier for debugger detach
  kgdb: Respect that flush op is optional
  kgdb: x86: Return all segment registers also in 64-bit mode

1 files changed, 33 insertions, 0 deletions

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0d7c08784efb..3f88a45e6f0a 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -41,6 +41,7 @@
 #include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/sysrq.h>
+#include <linux/reboot.h>
 #include <linux/init.h>
 #include <linux/kgdb.h>
 #include <linux/kdb.h>
@@ -75,6 +76,8 @@ static int			exception_level;
 struct kgdb_io		*dbg_io_ops;
 static DEFINE_SPINLOCK(kgdb_registration_lock);
 
+/* Action for the reboot notifiter, a global allow kdb to change it */
+static int kgdbreboot;
 /* kgdb console driver is loaded */
 static int kgdb_con_registered;
 /* determine if kgdb console output should be used */
@@ -96,6 +99,7 @@ static int __init opt_kgdb_con(char *str)
 early_param("kgdbcon", opt_kgdb_con);
 
 module_param(kgdb_use_con, int, 0644);
+module_param(kgdbreboot, int, 0644);
 
 /*
  * Holds information about breakpoints in a kernel. These breakpoints are
@@ -784,6 +788,33 @@ void __init dbg_late_init(void)
 	kdb_init(KDB_INIT_FULL);
 }
 
+static int
+dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x)
+{
+	/*
+	 * Take the following action on reboot notify depending on value:
+	 *    1 == Enter debugger
+	 *    0 == [the default] detatch debug client
+	 *   -1 == Do nothing... and use this until the board resets
+	 */
+	switch (kgdbreboot) {
+	case 1:
+		kgdb_breakpoint();
+	case -1:
+		goto done;
+	}
+	if (!dbg_kdb_mode)
+		gdbstub_exit(code);
+done:
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block dbg_reboot_notifier = {
+	.notifier_call		= dbg_notify_reboot,
+	.next			= NULL,
+	.priority		= INT_MAX,
+};
+
 static void kgdb_register_callbacks(void)
 {
 	if (!kgdb_io_module_registered) {
@@ -791,6 +822,7 @@ static void kgdb_register_callbacks(void)
 		kgdb_arch_init();
 		if (!dbg_is_early)
 			kgdb_arch_late();
+		register_reboot_notifier(&dbg_reboot_notifier);
 		atomic_notifier_chain_register(&panic_notifier_list,
 					       &kgdb_panic_event_nb);
 #ifdef CONFIG_MAGIC_SYSRQ
@@ -812,6 +844,7 @@ static void kgdb_unregister_callbacks(void)
 	 */
 	if (kgdb_io_module_registered) {
 		kgdb_io_module_registered = 0;
+		unregister_reboot_notifier(&dbg_reboot_notifier);
 		atomic_notifier_chain_unregister(&panic_notifier_list,
 					       &kgdb_panic_event_nb);
 		kgdb_arch_exit();