[PATCH 2/2] powerpc/64: Increase stack redzone for 64-bit kernel to 512 bytes

[Bin Meng]

Hi Nick,

On Mon, Oct 1, 2018 at 7:27 AM Nicholas Piggin <npiggin at gmail.com> wrote:
>
> On Sat, 29 Sep 2018 23:25:20 -0700
> Bin Meng <bmeng.cn at gmail.com> wrote:
>
> > commit 573ebfa6601f ("powerpc: Increase stack redzone for 64-bit
> > userspace to 512 bytes") only changes stack userspace redzone size.
> > We need increase the kernel one to 512 bytes too per ABIv2 spec.
>
> You're right we need 512 to be compatible with ABIv2, but as the
> comment says, gcc limits this to 288 bytes so that's what is used
> to save stack space. We can use a compiler version test to change
> this if llvm or a new version of gcc does something different.
>

I believe what the comment says is for ABIv1. At the time when commit
573ebfa6601f was submitted, kernel had not switched to ABIv2 build
yet.

Regards,
Bin