linux-kernel - Re: [PATCH v2 2/5] powerpc: kretprobes: override default function entry offset

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Date:   Fri, 24 Feb 2017 16:57:22 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2 2/5] powerpc: kretprobes: override default function
 entry offset

Em Wed, Feb 22, 2017 at 07:23:38PM +0530, Naveen N. Rao escreveu:
> With ABIv2, we offset 8 bytes into a function to get at the local entry
> point.

So, I think I can carry the first one via Ingo, etc, what about this
one?

Is it ok for me to process it?

Seems simple enough, has been thru a lot of discussion, but would be
better if it was Reviewed-by the PPC maintainers or else just processed
by them.

Please advise,

- Arnaldo
 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/kprobes.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
> index 735ff3d3f77d..e37b76b8b6b2 100644
> --- a/arch/powerpc/kernel/kprobes.c
> +++ b/arch/powerpc/kernel/kprobes.c
> @@ -131,6 +131,15 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
>  	kcb->kprobe_saved_msr = regs->msr;
>  }
>  
> +bool arch_function_offset_within_entry(unsigned long offset)
> +{
> +#ifdef PPC64_ELF_ABI_v2
> +	return offset <= 8;
> +#else
> +	return !offset;
> +#endif
> +}
> +
>  void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
>  				      struct pt_regs *regs)
>  {
> -- 
> 2.11.0