Re: [PATCH 07/10] uprobes/x86: Introduce arch_uretprobe_is_alive()

From: Srikar Dronamraju
Date: Thu May 07 2015 - 07:09:09 EST


>
> diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
> index f011fd0..60777f3 100644
> --- a/arch/x86/include/asm/uprobes.h
> +++ b/arch/x86/include/asm/uprobes.h
> @@ -57,6 +57,7 @@ struct arch_uprobe {
> };
>
> struct arch_uretprobe {
> + unsigned long sp;

While this looks good, I was wondering if you did think of having the sp
in the return_instance structure itself. I mean can we use
user_stack_pointer() to populate the ri->sp?
In which case the weak function itself should suffice for most archs.

Something like this.
prepare_uretprobe() we can have
ri->sp = user_stack_pointer(regs)

and handle_trampoline() would call something like

arch_uretprobe_is_alive(next->sp, regs);

bool __weak arch_uretprobe_is_alive(unsigned long sp, struct pt_regs *regs)
{
return user_stack_pointer(regs) <= sp;
}

Am I missing something?

>
--
Thanks and Regards
Srikar Dronamraju

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