[PATCH v2 2/2] efi/arm64: preserve FP/SIMD registers on UEFI runtime services calls

[catalin.marinas@arm.com (Catalin Marinas)]

On Fri, Jul 04, 2014 at 04:51:31PM +0100, Ard Biesheuvel wrote:
> On 4 July 2014 17:45, Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Thu, Jun 26, 2014 at 11:09:06AM +0100, Ard Biesheuvel wrote:
> >> According to the UEFI spec section 2.3.6.4, the use of FP/SIMD instructions is
> >> allowed, and should adhere to the AAPCS64 calling convention, which states that
> >> 'only the bottom 64 bits of each value stored in registers v8-v15 need to be
> >> preserved' (section 5.1.2).
> >>
> >> This applies equally to UEFI Runtime Services called by the kernel, so make sure
> >> the FP/SIMD register file is preserved in this case.
> >>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >
> > While the code looks fine, I think there is a mismatch between what the
> > subject says and what the patch does (enabling EFI_RUNTIME_WRAPPERS).
> >
> 
> Not entirely. In order to be able to insert calls to
> kernel_neon_begin()/end() into the runtime services calls, we need
> a) to supply definitions for efi_call_virt() and __efi_call_virt()
> that contain those calls to kernel_neon_begin()/end()
> b) to enable runtime wrappers (which is what uses those definitions)
> 
> Would you prefer those to be split in 2 patches?

No, that's fine. You could just add the above explanation to the commit
log. Otherwise:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>