[SPARC64]: Optimize fault kprobe handling just like powerpc.

And eliminate DIE_GPF while we're at it.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/kernel/kprobes.c

@@ -313,7 +313,7 @@ out:
 	return 1;
 }
 
-static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -403,15 +403,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 		if (post_kprobe_handler(args->regs))
 			ret = NOTIFY_STOP;
 		break;
-	case DIE_GPF:
-	case DIE_PAGE_FAULT:
-		/* kprobe_running() needs smp_processor_id() */
-		preempt_disable();
-		if (kprobe_running() &&
-		    kprobe_fault_handler(args->regs, args->trapnr))
-			ret = NOTIFY_STOP;
-		preempt_enable();
-		break;
 	default:
 		break;
 	}

arch/sparc64/mm/fault.c

@@ -32,36 +32,23 @@
 #include <asm/mmu_context.h>
 
 #ifdef CONFIG_KPROBES
-ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
-
-/* Hook to register for page fault notifications */
-int register_page_fault_notifier(struct notifier_block *nb)
-{
-	return atomic_notifier_chain_register(&notify_page_fault_chain, nb);
-}
-
-int unregister_page_fault_notifier(struct notifier_block *nb)
-{
-	return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
-}
-
-static inline int notify_page_fault(enum die_val val, const char *str,
-			struct pt_regs *regs, long err, int trap, int sig)
+static inline int notify_page_fault(struct pt_regs *regs)
 {
-	struct die_args args = {
-		.regs = regs,
-		.str = str,
-		.err = err,
-		.trapnr = trap,
-		.signr = sig
-	};
-	return atomic_notifier_call_chain(&notify_page_fault_chain, val, &args);
+	int ret = 0;
+
+	/* kprobe_running() needs smp_processor_id() */
+	if (!user_mode(regs)) {
+		preempt_disable();
+		if (kprobe_running() && kprobe_fault_handler(regs, 0))
+			ret = 1;
+		preempt_enable();
+	}
+	return ret;
 }
 #else
-static inline int notify_page_fault(enum die_val val, const char *str,
-			struct pt_regs *regs, long err, int trap, int sig)
+static inline int notify_page_fault(struct pt_regs *regs)
 {
-	return NOTIFY_DONE;
+	return 0;
 }
 #endif
 
@@ -120,9 +107,6 @@ static void __kprobes unhandled_fault(unsigned long address,
 	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
 	       (tsk->mm ? (unsigned long) tsk->mm->pgd :
 		          (unsigned long) tsk->active_mm->pgd));
-	if (notify_die(DIE_GPF, "general protection fault", regs,
-		       0, 0, SIGSEGV) == NOTIFY_STOP)
-		return;
 	die_if_kernel("Oops", regs);
 }
 
@@ -299,8 +283,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 
 	fault_code = get_thread_fault_code();
 
-	if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs,
-		       fault_code, 0, SIGSEGV) == NOTIFY_STOP)
+	if (notify_page_fault(regs))
 		return;
 
 	si_code = SEGV_MAPERR;

include/asm-sparc64/kdebug.h

@@ -7,8 +7,19 @@
 
 struct pt_regs;
 
-extern int register_page_fault_notifier(struct notifier_block *);
-extern int unregister_page_fault_notifier(struct notifier_block *);
+/*
+ * These are only here because kprobes.c wants them to implement a
+ * blatant layering violation.  Will hopefully go away soon once all
+ * architectures are updated.
+ */
+static inline int register_page_fault_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+static inline int unregister_page_fault_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
 
 extern void bad_trap(struct pt_regs *, long);
 
@@ -20,7 +31,6 @@ enum die_val {
 	DIE_DIE,
 	DIE_TRAP,
 	DIE_TRAP_TL1,
-	DIE_GPF,
 	DIE_CALL,
 	DIE_PAGE_FAULT,
 };

include/asm-sparc64/kprobes.h

@@ -43,4 +43,5 @@ struct kprobe_ctlblk {
 
 extern int kprobe_exceptions_notify(struct notifier_block *self,
 				    unsigned long val, void *data);
+extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 #endif /* _SPARC64_KPROBES_H */