netdev - Re: [PATCH net-next 01/13] ARM: net: bpf: enumerate the JIT scratch stack layout

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Date:   Tue, 10 Jul 2018 22:57:23 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH net-next 01/13] ARM: net: bpf: enumerate the JIT scratch
 stack layout

On Tue, Jul 10, 2018 at 08:30:04PM +0200, Daniel Borkmann wrote:
> Hi Russell,
> 
> thanks a lot for your work on the arm32 JIT!
> 
> On 07/10/2018 02:36 PM, Russell King wrote:
> > Enumerate the contents of the JIT scratch stack layout used for storing
> > some of the JITs 64-bit registers, tail call counter and AX register.
> > 
> > XXX: what about the skb_copy_bits buffer - this appears to overlap with
> > the first word of the JITs accessible stack.
> 
> Could you elaborate on that case? Unless I'm missing something there should
> be no use of the skb_copy_bits buffer anymore (aka former SKB_BUFFER at
> STACK_VAR(SCRATCH_SIZE) offset), but aside from that it's not supposed to
> overlap either.

Probably an old comment - these were originally developed back in
January timeframe when there was the SKB_BUFFER stuff, but that was
removed during the 4.18 merge window.  I'll kill the comment.

Thanks.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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