[PATCH] ArmPkg/CpuDxe: handle implied attributes in EfiAttributeToArmAttribute

[PATCH] ArmPkg/CpuDxe: handle implied attributes in EfiAttributeToArmAttribute

[Ard Biesheuvel]

Some memory attributes are implied by the memory type, e.g., device memory
is always mapped non-executable and cached memory should have the inner
shareable attribute.

In order to prevent unnecessary memory attribute updates of mappings
created early on, make EfiAttributeToArmAttribute() return these implied
attributes in the same way as ArmMmuLib does already. This avoids false
positives when looking for differences between current and desired mapping
attributes.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
index 7688846e70cb..3e216c7cb235 100644
--- a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
+++ b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
@@ -204,16 +204,20 @@ EfiAttributeToArmAttribute (
 
   switch (EfiAttributes & EFI_MEMORY_CACHETYPE_MASK) {
   case EFI_MEMORY_UC:
-    ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY;
+    if (ArmReadCurrentEL () == AARCH64_EL2) {
+      ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY | TT_XN_MASK;
+    } else {
+      ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY | TT_UXN_MASK | TT_PXN_MASK;
+    }
     break;
   case EFI_MEMORY_WC:
     ArmAttributes = TT_ATTR_INDX_MEMORY_NON_CACHEABLE;
     break;
   case EFI_MEMORY_WT:
-    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_THROUGH;
+    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_THROUGH | TT_SH_INNER_SHAREABLE;
     break;
   case EFI_MEMORY_WB:
-    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_BACK;
+    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_BACK | TT_SH_INNER_SHAREABLE;
     break;
   default:
     ArmAttributes = TT_ATTR_INDX_MASK;
-- 
2.7.4

Re: [PATCH] ArmPkg/CpuDxe: handle implied attributes in EfiAttributeToArmAttribute

[Leif Lindholm]

On Wed, Mar 08, 2017 at 12:51:44PM +0100, Ard Biesheuvel wrote:
> Some memory attributes are implied by the memory type, e.g., device memory
> is always mapped non-executable and cached memory should have the inner
> shareable attribute.
> 
> In order to prevent unnecessary memory attribute updates of mappings
> created early on, make EfiAttributeToArmAttribute() return these implied
> attributes in the same way as ArmMmuLib does already. This avoids false
> positives when looking for differences between current and desired mapping
> attributes.
> 
> 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/Drivers/CpuDxe/AArch64/Mmu.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
> index 7688846e70cb..3e216c7cb235 100644
> --- a/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
> +++ b/ArmPkg/Drivers/CpuDxe/AArch64/Mmu.c
> @@ -204,16 +204,20 @@ EfiAttributeToArmAttribute (
>  
>    switch (EfiAttributes & EFI_MEMORY_CACHETYPE_MASK) {
>    case EFI_MEMORY_UC:
> -    ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY;
> +    if (ArmReadCurrentEL () == AARCH64_EL2) {
> +      ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY | TT_XN_MASK;
> +    } else {
> +      ArmAttributes = TT_ATTR_INDX_DEVICE_MEMORY | TT_UXN_MASK | TT_PXN_MASK;
> +    }
>      break;
>    case EFI_MEMORY_WC:
>      ArmAttributes = TT_ATTR_INDX_MEMORY_NON_CACHEABLE;
>      break;
>    case EFI_MEMORY_WT:
> -    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_THROUGH;
> +    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_THROUGH | TT_SH_INNER_SHAREABLE;
>      break;
>    case EFI_MEMORY_WB:
> -    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_BACK;
> +    ArmAttributes = TT_ATTR_INDX_MEMORY_WRITE_BACK | TT_SH_INNER_SHAREABLE;
>      break;
>    default:
>      ArmAttributes = TT_ATTR_INDX_MASK;
> -- 
> 2.7.4
>