Re: [PATCH 3/4] ArmPkg/ArmLib: AARCH64: allow the stack aligment (SA) bit to be managed

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

On Wed, Feb 22, 2017 at 09:38:20AM +0000, Ard Biesheuvel wrote:
> In preparation of enabling stack alignment checking, which is mandated
> by the UEFI spec for AARCH64, add the code to manage this bit to ArmLib.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
>  ArmPkg/Include/Chipset/AArch64.h               | 12 +++++++
>  ArmPkg/Library/ArmLib/AArch64/AArch64Support.S | 34 ++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/ArmPkg/Include/Chipset/AArch64.h b/ArmPkg/Include/Chipset/AArch64.h
> index 9aecb1df81e0..cebfc5da426a 100644
> --- a/ArmPkg/Include/Chipset/AArch64.h
> +++ b/ArmPkg/Include/Chipset/AArch64.h
> @@ -194,6 +194,18 @@ ArmEnableAlignmentCheck (
>  
>  VOID
>  EFIAPI
> +ArmDisableStackAlignmentCheck (
> +  VOID
> +  );
> +
> +VOID
> +EFIAPI
> +ArmEnableStackAlignmentCheck (
> +  VOID
> +  );
> +
> +VOID
> +EFIAPI
>  ArmDisableAllExceptions (
>    VOID
>    );
> diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
> index c35c05fdf681..e53b5fdc5986 100644
> --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
> +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S
> @@ -20,6 +20,7 @@
>  .set CTRL_M_BIT,      (1 << 0)
>  .set CTRL_A_BIT,      (1 << 1)
>  .set CTRL_C_BIT,      (1 << 2)
> +.set CTRL_SA_BIT,     (1 << 3)
>  .set CTRL_I_BIT,      (1 << 12)
>  .set CTRL_V_BIT,      (1 << 12)
>  .set CPACR_VFP_BITS,  (3 << 20)
> @@ -259,6 +260,39 @@ ASM_FUNC(ArmDisableAlignmentCheck)
>     isb
>     ret
>  
> +ASM_FUNC(ArmEnableStackAlignmentCheck)
> +   EL1_OR_EL2(x1)
> +1: mrs     x0, sctlr_el1        // Get control register EL1
> +   b       3f
> +2: mrs     x0, sctlr_el2        // Get control register EL2
> +3: orr     x0, x0, #CTRL_SA_BIT // Set SA (stack alignment check) bit
> +   EL1_OR_EL2(x1)
> +1: msr     sctlr_el1, x0        // Write back control register
> +   b       3f
> +2: msr     sctlr_el2, x0        // Write back control register
> +3: dsb     sy
> +   isb
> +   ret
> +
> +
> +ASM_FUNC(ArmDisableStackAlignmentCheck)
> +   EL1_OR_EL2_OR_EL3(x1)
> +1: mrs     x0, sctlr_el1        // Get control register EL1
> +   b       4f
> +2: mrs     x0, sctlr_el2        // Get control register EL2
> +   b       4f
> +3: mrs     x0, sctlr_el3        // Get control register EL3
> +4: bic     x0, x0, #CTRL_SA_BIT // Clear SA (stack alignment check) bit
> +   EL1_OR_EL2_OR_EL3(x1)
> +1: msr     sctlr_el1, x0        // Write back control register
> +   b       4f
> +2: msr     sctlr_el2, x0        // Write back control register
> +   b       4f
> +3: msr     sctlr_el3, x0        // Write back control register
> +4: dsb     sy
> +   isb
> +   ret
> +
>  
>  // Always turned on in AArch64. Else implementation specific. Leave in for C compatibility for now
>  ASM_FUNC(ArmEnableBranchPrediction)
> -- 
> 2.7.4
>