Re: [PATCH v3 35/75] x86/head/64: Build k/head64.c with -fno-stack-protector

Borislav Petkov
2020-05-19T09:15:37Z

On Tue, Apr 28, 2020 at 05:16:45PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
>
> The code inserted by the stack protector does not work in the early
> boot environment because it uses the GS segment, at least with memory
> encryption enabled.

Can you elaborate on why is that a problem?

The stack cookie is not generated that early yet so it should be
comparing %gs:40 to 0.

Also, it generates the checking code here only with

CONFIG_STACKPROTECTOR_STRONG=y

> Make sure the early code is compiled without this feature enabled.

If so, then this should be with CONFIG_AMD_MEM_ENCRYPT ifdeffery around
it.

--
Regards/Gruss,
Boris.