[S390] get rid of kprobes notifier call chain.

And here's a port of the powerpc patch to get rid of the notifier
chain completely to s390.  It's ontop of Martins patch as that one
is in mainline already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 14 insertions, 29 deletions

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 993f353..23c61f6 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -516,7 +516,7 @@ 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();
@@ -603,7 +603,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 			ret = NOTIFY_STOP;
 		break;
 	case DIE_TRAP:
-	case DIE_PAGE_FAULT:
 		/* kprobe_running() needs smp_processor_id() */
 		preempt_disable();
 		if (kprobe_running() &&
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 2b76a87..91f705a 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -52,38 +52,24 @@ extern int sysctl_userprocess_debug;
 extern void die(const char *,struct pt_regs *,long);
 
 #ifdef CONFIG_KPROBES
-static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
-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 int __kprobes __notify_page_fault(struct pt_regs *regs, long err)
-{
-	struct die_args args = { .str = "page fault",
-				 .trapnr = 14,
-				 .signr = SIGSEGV };
-	args.regs = regs;
-	args.err = err;
-	return atomic_notifier_call_chain(&notify_page_fault_chain,
-					  DIE_PAGE_FAULT, &args);
-}
-
 static inline int notify_page_fault(struct pt_regs *regs, long err)
 {
-	if (unlikely(kprobe_running()))
-		return __notify_page_fault(regs, err);
-	return NOTIFY_DONE;
+	int ret = 0;
+
+	/* kprobe_running() needs smp_processor_id() */
+	if (!user_mode(regs)) {
+		preempt_disable();
+		if (kprobe_running() && kprobe_fault_handler(regs, 14))
+			ret = 1;
+		preempt_enable();
+	}
+
+	return ret;
 }
 #else
 static inline int notify_page_fault(struct pt_regs *regs, long err)
 {
-	return NOTIFY_DONE;
+	return 0;
 }
 #endif
 
@@ -319,7 +305,7 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write)
 	int space;
 	int si_code;
 
-	if (notify_page_fault(regs, error_code) == NOTIFY_STOP)
+	if (notify_page_fault(regs, error_code))
 		return;
 
 	tsk = current;