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Message-ID: <20070430105646.GA15919@infradead.org>
Date: Mon, 30 Apr 2007 11:56:46 +0100
From: Christoph Hellwig <hch@...radead.org>
To: Paul Mackerras <paulus@...ba.org>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>,
linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
Heiko Carstens <heiko.carstens@...ibm.com>
Subject: [PATCH] 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@....de>
Index: linux-2.6/arch/powerpc/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/fault.c 2007-03-23 20:07:28.000000000 +0100
+++ linux-2.6/arch/powerpc/mm/fault.c 2007-04-30 11:33:36.000000000 +0200
@@ -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)
+#ifdef CONFIG_KPROBES
+static inline int notify_page_fault(struct pt_regs *regs)
{
- return atomic_notifier_chain_register(¬ify_page_fault_chain, nb);
-}
+ int ret = 0;
-int unregister_page_fault_notifier(struct notifier_block *nb)
-{
- return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb);
-}
+ /* 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(¬ify_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_re
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) {
Index: linux-2.6/arch/powerpc/kernel/kprobes.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/kprobes.c 2007-04-02 20:18:18.000000000 +0200
+++ linux-2.6/arch/powerpc/kernel/kprobes.c 2007-04-30 11:33:36.000000000 +0200
@@ -376,7 +376,7 @@ 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();
@@ -461,14 +461,6 @@ int __kprobes kprobe_exceptions_notify(s
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;
}
Index: linux-2.6/include/asm-powerpc/kdebug.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/kdebug.h 2007-03-23 20:07:29.000000000 +0100
+++ linux-2.6/include/asm-powerpc/kdebug.h 2007-04-30 11:51:04.000000000 +0200
@@ -18,8 +18,20 @@ 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 powerpc_die_chain;
/* Grossly misnamed. */
@@ -29,7 +41,6 @@ enum die_val {
DIE_DABR_MATCH,
DIE_BPT,
DIE_SSTEP,
- DIE_PAGE_FAULT,
};
static inline int notify_die(enum die_val val,char *str,struct pt_regs *regs,long err,int trap, int sig)
Index: linux-2.6/include/asm-powerpc/kprobes.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/kprobes.h 2007-02-11 08:17:32.000000000 +0100
+++ linux-2.6/include/asm-powerpc/kprobes.h 2007-04-30 11:33:36.000000000 +0200
@@ -105,5 +105,6 @@ 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 /* __KERNEL__ */
#endif /* _ASM_POWERPC_KPROBES_H */
-
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