linux-kernel - Re: [tip:x86/mm] x86, mm, kprobes: fault.c, simplify notify_page

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Date:	Fri, 20 Feb 2009 18:09:47 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	hpa@...or.com, mingo@...hat.com, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, tglx@...utronix.de, mhiramat@...hat.com,
	mingo@...e.hu, linux-kernel@...r.kernel.org
CC:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/mm] x86, mm, kprobes: fault.c, simplify notify_page_fault()

Ingo Molnar wrote:
> Author:     Ingo Molnar <mingo@...e.hu>
> AuthorDate: Fri, 20 Feb 2009 22:42:57 +0100
> Commit:     Ingo Molnar <mingo@...e.hu>
> CommitDate: Sat, 21 Feb 2009 00:09:42 +0100
> 
> x86, mm, kprobes: fault.c, simplify notify_page_fault()
> 
> Impact: cleanup
> 
> Remove an #ifdef from notify_page_fault(). The function still
> compiles to nothing in the !CONFIG_KPROBES case.
> 
> Introduce kprobes_built_in() and kprobe_fault_handler() helpers
> to allow this - they returns 0 if !CONFIG_KPROBES.
> 
> No code changed:
> 
>    text	   data	    bss	    dec	    hex	filename
>    4618	     32	     24	   4674	   1242	fault.o.before
>    4618	     32	     24	   4674	   1242	fault.o.after

It seems good for me. Thank you for cleanup!

Acked-by: Masami Hiramatsu <mhiramat@...hat.com>

> 
> Cc: Masami Hiramatsu <mhiramat@...hat.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> 
> 
> ---
>  arch/x86/mm/fault.c     |    6 +-----
>  include/linux/kprobes.h |   22 +++++++++++++++++++---
>  2 files changed, 20 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index fe99af4..379beae 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -68,11 +68,10 @@ static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
>  
>  static inline int notify_page_fault(struct pt_regs *regs)
>  {
> -#ifdef CONFIG_KPROBES
>  	int ret = 0;
>  
>  	/* kprobe_running() needs smp_processor_id() */
> -	if (!user_mode_vm(regs)) {
> +	if (kprobes_built_in() && !user_mode_vm(regs)) {
>  		preempt_disable();
>  		if (kprobe_running() && kprobe_fault_handler(regs, 14))
>  			ret = 1;
> @@ -80,9 +79,6 @@ static inline int notify_page_fault(struct pt_regs *regs)
>  	}
>  
>  	return ret;
> -#else
> -	return 0;
> -#endif
>  }
>  
>  /*
> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
> index 32851ee..2ec6cc1 100644
> --- a/include/linux/kprobes.h
> +++ b/include/linux/kprobes.h
> @@ -182,6 +182,14 @@ struct kprobe_blackpoint {
>  DECLARE_PER_CPU(struct kprobe *, current_kprobe);
>  DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
>  
> +/*
> + * For #ifdef avoidance:
> + */
> +static inline int kprobes_built_in(void)
> +{
> +	return 1;
> +}
> +
>  #ifdef CONFIG_KRETPROBES
>  extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
>  				   struct pt_regs *regs);
> @@ -271,8 +279,16 @@ void unregister_kretprobes(struct kretprobe **rps, int num);
>  void kprobe_flush_task(struct task_struct *tk);
>  void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
>  
> -#else /* CONFIG_KPROBES */
> +#else /* !CONFIG_KPROBES: */
>  
> +static inline int kprobes_built_in(void)
> +{
> +	return 0;
> +}
> +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
> +{
> +	return 0;
> +}
>  static inline struct kprobe *get_kprobe(void *addr)
>  {
>  	return NULL;
> @@ -329,5 +345,5 @@ static inline void unregister_kretprobes(struct kretprobe **rps, int num)
>  static inline void kprobe_flush_task(struct task_struct *tk)
>  {
>  }
> -#endif				/* CONFIG_KPROBES */
> -#endif				/* _LINUX_KPROBES_H */
> +#endif /* CONFIG_KPROBES */
> +#endif /* _LINUX_KPROBES_H */

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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