Messages in this thread | | | Date | Thu, 7 May 2015 19:11:19 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 07/10] uprobes/x86: Introduce arch_uretprobe_is_alive() |
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On 05/07, Srikar Dronamraju wrote: > > > > > 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?
Yes, yes, I considered this option. And note that we can cleanup the (a bit ugly) arch_uretprobe_hijack_return_addr() if we export "struct return_instance" and pass it to arch_ helper.
> 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)
Yes, and we can do this without changing arch_uretprobe_hijack_return_addr() interface (which imo should be changed anyway, but this is off-topic).
> 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; > }
The problem is, I simply do not know if this is right on !x86.
And. I wanted to ensure that if (say) arch/ppc needs something else to save/check in hijack/alive, then this architecture can just add the new members in arch_uretprobe and change the arch_ helpers.
> Am I missing something?
I do not know. Lets wait for the comments from arch/ maintainers?
Oleg.
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