[POWERPC] Minor fault path optimization

Call the kprobes pagefault handler directly instead of going through
the complex notifier chain.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 16 insertions, 36 deletions

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index ef647e7a9dc3..c27f41870c8f 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -410,7 +410,7 @@ 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();
@@ -495,14 +495,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
                 if (post_kprobe_handler(args->regs))
                         ret = NOTIFY_STOP;
                 break;
-        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;
         }
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 03aeb3a46077..a0f88026e464 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -39,37 +39,26 @@
 #include <asm/kdebug.h>
 #include <asm/siginfo.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)
+#ifdef CONFIG_KPROBES
+static inline int notify_page_fault(struct pt_regs *regs)
 {
-        return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
-}
+        int ret = 0;
+
+        /* kprobe_running() needs smp_processor_id() */
+        if (!user_mode(regs)) {
+                preempt_disable();
+                if (kprobe_running() && kprobe_fault_handler(regs, 11))
+                        ret = 1;
+                preempt_enable();
+        }
 
-static inline int notify_page_fault(enum die_val val, const char *str,
-                        struct pt_regs *regs, long err, int trap, int sig)
-{
-        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);
+        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
 
@@ -175,8 +164,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
         is_write = error_code & ESR_DST;
 #endif /* CONFIG_4xx || CONFIG_BOOKE */
 
-        if (notify_page_fault(DIE_PAGE_FAULT, "page_fault", regs, error_code,
-                                11, SIGSEGV) == NOTIFY_STOP)
+        if (notify_page_fault(regs))
                 return 0;
 
         if (trap == 0x300) {