[IA64] optimize pagefaults a little

Get rid of the notifier list and call the kprobes code directly
if compiled in.  This mirrors the changes that recently went
into powerpc, s390 and sparc64.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>

4 files changed, 29 insertions, 38 deletions

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index be81fe42d80b..5bc46f151344 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -820,7 +820,7 @@ out:
         return 1;
 }
 
-static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
+int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
 {
         struct kprobe *cur = kprobe_running();
         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -904,13 +904,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
                         if (post_kprobes_handler(args->regs))
                                 ret = NOTIFY_STOP;
                 break;
-        case DIE_PAGE_FAULT:
-                /* kprobe_running() needs smp_processor_id() */
-                preempt_disable();
-                if (kprobe_running() &&
-                        kprobes_fault_handler(args->regs, args->trapnr))
-                        ret = NOTIFY_STOP;
-                preempt_enable();
         default:
                 break;
         }
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 21658e02116c..b87f785c2416 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -19,36 +19,24 @@
 extern void die (char *, struct pt_regs *, long);
 
 #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)
+static inline int notify_page_fault(struct pt_regs *regs, int trap)
 {
-        return atomic_notifier_chain_unregister(&notify_page_fault_chain, nb);
-}
+        int ret = 0;
+
+        if (!user_mode(regs)) {
+                /* kprobe_running() needs smp_processor_id() */
+                preempt_disable();
+                if (kprobe_running() && kprobes_fault_handler(regs, trap))
+                        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, int trap)
 {
-        return NOTIFY_DONE;
+        return 0;
 }
 #endif
 
@@ -117,8 +105,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
         /*
          * This is to handle the kprobes on user space access instructions
          */
-        if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, code, TRAP_BRKPT,
-                                        SIGSEGV) == NOTIFY_STOP)
+        if (notify_page_fault(regs, TRAP_BRKPT))
                 return;
 
         down_read(&mm->mmap_sem);
diff --git a/include/asm-ia64/kdebug.h b/include/asm-ia64/kdebug.h
index ba211e011a1d..320cd8e754ea 100644
--- a/include/asm-ia64/kdebug.h
+++ b/include/asm-ia64/kdebug.h
@@ -28,14 +28,24 @@
  */
 #include <linux/notifier.h>
 
-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;
+}
 
 enum die_val {
         DIE_BREAK = 1,
         DIE_FAULT,
         DIE_OOPS,
-        DIE_PAGE_FAULT,
         DIE_MACHINE_HALT,
         DIE_MACHINE_RESTART,
         DIE_MCA_MONARCH_ENTER,
diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h
index 2abc98b336f3..6382e52ec227 100644
--- a/include/asm-ia64/kprobes.h
+++ b/include/asm-ia64/kprobes.h
@@ -120,6 +120,7 @@ struct arch_specific_insn {
         unsigned short slot;
 };
 
+extern int kprobes_fault_handler(struct pt_regs *regs, int trapnr);
 extern int kprobe_exceptions_notify(struct notifier_block *self,
                                     unsigned long val, void *data);