Re: [PATCH 2/2] ArmPlatformPkg/PrePeiCore: enable VFP at startup

[Leif Lindholm <leif.lindholm@linaro.org>]

On Tue, Jan 07, 2020 at 10:22:15 +0100, Ard Biesheuvel wrote:
> While the alternative PEI-less SEC implementation in PrePi already
> takes the EnableVFP PCD into account, the PrePeiCore code does not,
> and so we may end up triggering synchronous exception when code
> attempts to use FP or SIMD registers, which is permitted by the spec.

If you insert "on AARCH64" in an appropriate place in the above line:
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> 
> So enable the VFP as early as feasible.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf  | 1 +
>  ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf | 1 +
>  ArmPlatformPkg/PrePeiCore/PrePeiCore.c          | 5 +++++
>  3 files changed, 7 insertions(+)
> 
> diff --git a/ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf b/ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf
> index f2ac45d171bc..104c7da53317 100644
> --- a/ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf
> +++ b/ArmPlatformPkg/PrePeiCore/PrePeiCoreMPCore.inf
> @@ -62,6 +62,7 @@ [FeaturePcd]
>  [FixedPcd]
>    gArmTokenSpaceGuid.PcdFvBaseAddress
>    gArmTokenSpaceGuid.PcdFvSize
> +  gArmTokenSpaceGuid.PcdVFPEnabled
>  
>    gArmPlatformTokenSpaceGuid.PcdCPUCoresStackBase
>    gArmPlatformTokenSpaceGuid.PcdCPUCorePrimaryStackSize
> diff --git a/ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf b/ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf
> index 84c319c3679b..ceb173d34f5d 100644
> --- a/ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf
> +++ b/ArmPlatformPkg/PrePeiCore/PrePeiCoreUniCore.inf
> @@ -60,6 +60,7 @@ [FeaturePcd]
>  [FixedPcd]
>    gArmTokenSpaceGuid.PcdFvBaseAddress
>    gArmTokenSpaceGuid.PcdFvSize
> +  gArmTokenSpaceGuid.PcdVFPEnabled
>  
>    gArmPlatformTokenSpaceGuid.PcdCPUCoresStackBase
>    gArmPlatformTokenSpaceGuid.PcdCPUCorePrimaryStackSize
> diff --git a/ArmPlatformPkg/PrePeiCore/PrePeiCore.c b/ArmPlatformPkg/PrePeiCore/PrePeiCore.c
> index 4911f67577a2..4f691d62cf3b 100644
> --- a/ArmPlatformPkg/PrePeiCore/PrePeiCore.c
> +++ b/ArmPlatformPkg/PrePeiCore/PrePeiCore.c
> @@ -77,6 +77,11 @@ CEntryPoint (
>    ASSERT (((UINTN)PeiVectorTable & ARM_VECTOR_TABLE_ALIGNMENT) == 0);
>    ArmWriteVBar ((UINTN)PeiVectorTable);
>  
> +  // Enable Floating Point
> +  if (FixedPcdGet32 (PcdVFPEnabled)) {
> +    ArmEnableVFP ();
> +  }
> +
>    //Note: The MMU will be enabled by MemoryPeim. Only the primary core will have the MMU on.
>  
>    // If not primary Jump to Secondary Main
> -- 
> 2.20.1
>