[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>

4 files changed, 33 insertions, 44 deletions

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 993f35381496..23c61f6d965b 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 2b76a879a7b5..91f705adc3f9 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;
diff --git a/include/asm-s390/kdebug.h b/include/asm-s390/kdebug.h
index 1b50f89819a4..d2d7ad276148 100644
--- a/include/asm-s390/kdebug.h
+++ b/include/asm-s390/kdebug.h
@@ -22,8 +22,21 @@ struct die_args {
  */
 extern int register_die_notifier(struct notifier_block *);
 extern int unregister_die_notifier(struct notifier_block *);
-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 struct atomic_notifier_head s390die_chain;
 
 enum die_val {
@@ -39,7 +52,6 @@ enum die_val {
         DIE_GPF,
         DIE_CALL,
         DIE_NMI_IPI,
-        DIE_PAGE_FAULT,
 };
 
 static inline int notify_die(enum die_val val, const char *str,
diff --git a/include/asm-s390/kprobes.h b/include/asm-s390/kprobes.h
index b847ff0ec3fa..830fe4c4eea6 100644
--- a/include/asm-s390/kprobes.h
+++ b/include/asm-s390/kprobes.h
@@ -97,18 +97,10 @@ void kretprobe_trampoline(void);
 int  is_prohibited_opcode(kprobe_opcode_t *instruction);
 void get_instruction_type(struct arch_specific_insn *ainsn);
 
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
+int kprobe_exceptions_notify(struct notifier_block *self,
+        unsigned long val, void *data);
+
 #define flush_insn_slot(p)      do { } while (0)
 
 #endif  /* _ASM_S390_KPROBES_H */
-
-#ifdef CONFIG_KPROBES
-
-extern int kprobe_exceptions_notify(struct notifier_block *self,
-                                        unsigned long val, void *data);
-#else   /* !CONFIG_KPROBES */
-static inline int kprobe_exceptions_notify(struct notifier_block *self,
-                                                unsigned long val, void *data)
-{
-        return 0;
-}
-#endif