Subject: Re: [PATCH 2/2] kprobes: compile out IPMODIFY support if ftrace doesn't support it

From: Masami Hiramatsu <[email-masked]>
Date: Thu, 15 Jan 2015 12:04:13 +0900

(2015/01/14 17:48), Jiri Kosina wrote:
> If ftrace doesn't claim to support IPMODIFY support, there is no need to 
> compile IPMODIFY support in kprobes either.
> 

This looks good to me :)

Acked-by: Masami Hiramatsu <[email-masked]>

Thanks!

> Signed-off-by: Jiri Kosina <[email-masked]>
> ---
>  kernel/kprobes.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 06f5830..49a69d7 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -912,7 +912,7 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
>  }
>  #endif /* CONFIG_OPTPROBES */
>  
> -#ifdef CONFIG_KPROBES_ON_FTRACE
> +#if defined(CONFIG_KPROBES_ON_FTRACE) && (ftrace_ipmodify_supported == 1)
>  static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
>  	.func = kprobe_ftrace_handler,
>  	.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
> @@ -957,7 +957,7 @@ static void disarm_kprobe_ftrace(struct kprobe *p)
>  			   (unsigned long)p->addr, 1, 0);
>  	WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
>  }
> -#else	/* !CONFIG_KPROBES_ON_FTRACE */
> +#else	/* !CONFIG_KPROBES_ON_FTRACE || ftrace_ipmodify_supported == 0 */
>  #define prepare_kprobe(p)	arch_prepare_kprobe(p)
>  #define arm_kprobe_ftrace(p)	do {} while (0)
>  #define disarm_kprobe_ftrace(p)	do {} while (0)
> @@ -1416,12 +1416,12 @@ int __weak arch_check_ftrace_location(struct kprobe *p)
>  
>  	ftrace_addr = ftrace_location((unsigned long)p->addr);
>  	if (ftrace_addr) {
> -#ifdef CONFIG_KPROBES_ON_FTRACE
> +#if defined(CONFIG_KPROBES_ON_FTRACE) && (ftrace_ipmodify_supported == 1)
>  		/* Given address is not on the instruction boundary */
>  		if ((unsigned long)p->addr != ftrace_addr)
>  			return -EILSEQ;
>  		p->flags |= KPROBE_FLAG_FTRACE;
> -#else	/* !CONFIG_KPROBES_ON_FTRACE */
> +#else	/* !CONFIG_KPROBES_ON_FTRACE || ftrace_ipmodify_supported == 0 */
>  		return -EINVAL;
>  #endif
>  	}
> 

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email-masked]