| Date | Fri, 13 Nov 2009 16:08:27 +0100 | | From | Martin Schwidefsky <> | | Subject | [patch 03/52] [PATCH] Improve notify_page_fault implementation. |
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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
notify_page_fault does a preempt_disable/preempt_enable for each fault generated by a kernel access to user space. If kprobes is not active that is unnecessary since the interrupts are not reenabled yet. To play safe repeat the kprobe_running check after preempt_disable().
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> ---
arch/s390/mm/fault.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-)
Index: quilt-2.6/arch/s390/mm/fault.c =================================================================== --- quilt-2.6.orig/arch/s390/mm/fault.c 2009-11-13 16:08:12.000000000 +0100 +++ quilt-2.6/arch/s390/mm/fault.c 2009-11-13 16:08:12.000000000 +0100 @@ -52,11 +52,11 @@ extern int sysctl_userprocess_debug; #endif -#ifdef CONFIG_KPROBES -static inline int notify_page_fault(struct pt_regs *regs, long err) +static inline int notify_page_fault(struct pt_regs *regs) { int ret = 0; +#ifdef CONFIG_KPROBES /* kprobe_running() needs smp_processor_id() */ if (!user_mode(regs)) { preempt_disable(); @@ -64,15 +64,9 @@ ret = 1; preempt_enable(); } - +#endif return ret; } -#else -static inline int notify_page_fault(struct pt_regs *regs, long err) -{ - return 0; -} -#endif /* @@ -274,7 +268,7 @@ int si_code; int fault; - if (notify_page_fault(regs, error_code)) + if (notify_page_fault(regs)) return; tsk = current;
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