efi/arm64: Preserve FP/SIMD registers on UEFI runtime services calls

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. We do this
by enabling the wrappers for UEFI Runtime Services (CONFIG_EFI_RUNTIME_WRAPPERS)
and inserting calls to kernel_neon_begin()and kernel_neon_end() into
these wrappers.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7295419165e1..2cc14cef01bd 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -298,6 +298,7 @@ config EFI
         select LIBFDT
         select UCS2_STRING
         select EFI_PARAMS_FROM_FDT
+        select EFI_RUNTIME_WRAPPERS
         default y
         help
           This option provides support for runtime services provided