Re: [PATCH] arm64: bpf: fix JIT stack setup

From: Shi, Yang
Date: Tue Nov 10 2015 - 14:46:51 EST

On 11/9/2015 12:00 PM, Z Lim wrote:
On Mon, Nov 9, 2015 at 10:08 AM, Shi, Yang <yang.shi@xxxxxxxxxx> wrote:
I added it to stay align with ARMv8 AAPCS to maintain the correct FP during
function call. It makes us get correct stack backtrace.

I think we'd better to keep compliant with ARMv8 AAPCS in BPF JIT prologue

If nobody thinks it is necessary, we definitely could remove that change.

Oh no, I don't think anyone will say it's unnecessary!
I agree the A64_FP-related change is a good idea, so stack unwinding works.

How about splitting this into two patches? One for the BPF-related
bug, and another for A64 FP-handling.

I'm not sure if this is a good approach or not. IMHO, they are kind of atomic. Without A64 FP-handling, that fix looks incomplete and introduces another problem (stack backtrace).


Thanks again for tracking this down and improving things overall for arm64 :)


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