sh: kgdb: Rework breakpoint handling on top of notifier chain.

This kills off kgdb's breakpoint handler and ties in to the notifier
chain instead.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 41 insertions, 5 deletions

diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
index 3e532d0d4a5c..70c69659b846 100644
--- a/arch/sh/kernel/kgdb.c
+++ b/arch/sh/kernel/kgdb.c
@@ -1,7 +1,7 @@
 /*
  * SuperH KGDB support
  *
- * Copyright (C) 2008  Paul Mundt
+ * Copyright (C) 2008 - 2009  Paul Mundt
  *
  * Single stepping taken from the old stub by Henry Bell and Jeremy Siegel.
  *
@@ -251,24 +251,60 @@ BUILD_TRAP_HANDLER(singlestep)
         local_irq_restore(flags);
 }
 
+static int __kgdb_notify(struct die_args *args, unsigned long cmd)
+{
+        int ret;
+
+        switch (cmd) {
+        case DIE_BREAKPOINT:
+                /*
+                 * This means a user thread is single stepping
+                 * a system call which should be ignored
+                 */
+                if (test_thread_flag(TIF_SINGLESTEP))
+                        return NOTIFY_DONE;
+
+                ret = kgdb_handle_exception(args->trapnr & 0xff, args->signr,
+                                            args->err, args->regs);
+                if (ret)
+                        return NOTIFY_DONE;
+
+                break;
+        }
 
-BUILD_TRAP_HANDLER(breakpoint)
+        return NOTIFY_STOP;
+}
+
+static int
+kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 {
         unsigned long flags;
-        TRAP_HANDLER_DECL;
+        int ret;
 
         local_irq_save(flags);
-        kgdb_handle_exception(vec >> 2, SIGTRAP, 0, regs);
+        ret = __kgdb_notify(ptr, cmd);
         local_irq_restore(flags);
+
+        return ret;
 }
 
+static struct notifier_block kgdb_notifier = {
+        .notifier_call  = kgdb_notify,
+
+        /*
+         * Lowest-prio notifier priority, we want to be notified last:
+         */
+        .priority       = -INT_MAX,
+};
+
 int kgdb_arch_init(void)
 {
-        return 0;
+        return register_die_notifier(&kgdb_notifier);
 }
 
 void kgdb_arch_exit(void)
 {
+        unregister_die_notifier(&kgdb_notifier);
 }
 
 struct kgdb_arch arch_kgdb_ops = {