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

Hi Nick,

On Mon, Oct 1, 2018 at 7:27 AM Nicholas Piggin [off-list ref] wrote:

On Sat, 29 Sep 2018 23:25:20 -0700
Bin Meng [off-list ref] wrote:

quoted

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