ArmPkg/ArmMmuLib ARM: Isolate the access flag from AP mask

Split the ARM permission fields in the short descriptors into an access
flag and AP[2:1] as per the recommendation in the ARM ARM. This makes
the access flag available separately, which allows us to implement
EFI_MEMORY_RP memory analogous to how it will be implemented for
AArch64.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c
index 6e2f08a7ce..52dbfd7140 100644
--- a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c
+++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c
@@ -23,6 +23,7 @@ ConvertSectionAttributesToPageAttributes (
   PageAttributes  = 0;

   PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_CACHE_POLICY (SectionAttributes);

   PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_AP (SectionAttributes);

+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_AF (SectionAttributes);

   PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_XN (SectionAttributes);

   PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_NG (SectionAttributes);

   PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_S (SectionAttributes);

diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
index 12d0f4c30f..484c674766 100644
--- a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
+++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
@@ -104,7 +104,7 @@ UpdatePageEntries (
 

   // EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)

   // EntryValue: values at bit positions specified by EntryMask

-  EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK | TT_DESCRIPTOR_PAGE_XN_MASK;

+  EntryMask = TT_DESCRIPTOR_PAGE_TYPE_MASK | TT_DESCRIPTOR_PAGE_AP_MASK | TT_DESCRIPTOR_PAGE_XN_MASK | TT_DESCRIPTOR_PAGE_AF;

   EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE;

 

   // Although the PI spec is unclear on this, the GCD guarantees that only

@@ -138,6 +138,10 @@ UpdatePageEntries (
     return EFI_UNSUPPORTED;

   }

 

+  if ((Attributes & EFI_MEMORY_RP) == 0) {

+    EntryValue |= TT_DESCRIPTOR_PAGE_AF;

+  }

+

   if ((Attributes & EFI_MEMORY_RO) != 0) {

     EntryValue |= TT_DESCRIPTOR_PAGE_AP_RO_RO;

   } else {

@@ -237,7 +241,7 @@ UpdateSectionEntries (
 

   // Make sure we handle a section range that is unmapped

   EntryMask = TT_DESCRIPTOR_SECTION_TYPE_MASK | TT_DESCRIPTOR_SECTION_XN_MASK |

-              TT_DESCRIPTOR_SECTION_AP_MASK;

+              TT_DESCRIPTOR_SECTION_AP_MASK | TT_DESCRIPTOR_SECTION_AF;

   EntryValue = TT_DESCRIPTOR_SECTION_TYPE_SECTION;

 

   // Although the PI spec is unclear on this, the GCD guarantees that only

@@ -281,6 +285,10 @@ UpdateSectionEntries (
     EntryValue |= TT_DESCRIPTOR_SECTION_XN_MASK;

   }

 

+  if ((Attributes & EFI_MEMORY_RP) == 0) {

+    EntryValue |= TT_DESCRIPTOR_SECTION_AF;

+  }

+

   // obtain page table base

   FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();