From 5ab77c6630317f0ab2da1892e6d36a4b83e06a2f Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Thu, 8 Oct 2015 18:52:06 +0000
Subject: [PATCH] ArmPkg/AArch64Mmu: move page table traversal code to separate
 function

Move the page table traversal and splitting logic to a separate function
UpdateRegionMapping() and refactor it slightly so we can reuse it later to
implement non-executable regions, for the stack. This primarly involves
adding a value/mask pair to the function prototype that allows us to flip
arbitrary bits on each block entry as the page tables are traversed.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18586 6f19259b-4bc3-4df7-8a09-765794883524
---
 ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c | 50 ++++++++++++++--------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
index d82c82c202..60f5cf188d 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Mmu.c
@@ -408,35 +408,30 @@ GetBlockEntryListFromAddress (
 
 STATIC
 RETURN_STATUS
-FillTranslationTable (
-  IN  UINT64                        *RootTable,
-  IN  ARM_MEMORY_REGION_DESCRIPTOR  *MemoryRegion
+UpdateRegionMapping (
+  IN  UINT64  *RootTable,
+  IN  UINT64  RegionStart,
+  IN  UINT64  RegionLength,
+  IN  UINT64  Attributes,
+  IN  UINT64  BlockEntryMask
   )
 {
-  UINT64  Attributes;
   UINT32  Type;
-  UINT64  RegionStart;
-  UINT64  RemainingRegionLength;
-  UINT64 *BlockEntry;
-  UINT64 *LastBlockEntry;
+  UINT64  *BlockEntry;
+  UINT64  *LastBlockEntry;
   UINT64  BlockEntrySize;
   UINTN   TableLevel;
 
   // Ensure the Length is aligned on 4KB boundary
-  if ((MemoryRegion->Length == 0) || ((MemoryRegion->Length & (SIZE_4KB - 1)) != 0)) {
+  if ((RegionLength == 0) || ((RegionLength & (SIZE_4KB - 1)) != 0)) {
     ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
     return RETURN_INVALID_PARAMETER;
   }
 
-  // Variable initialization
-  Attributes = ArmMemoryAttributeToPageAttribute (MemoryRegion->Attributes) | TT_AF;
-  RemainingRegionLength = MemoryRegion->Length;
-  RegionStart = MemoryRegion->VirtualBase;
-
   do {
     // Get the first Block Entry that matches the Virtual Address and also the information on the Table Descriptor
     // such as the the size of the Block Entry and the address of the last BlockEntry of the Table Descriptor
-    BlockEntrySize = RemainingRegionLength;
+    BlockEntrySize = RegionLength;
     BlockEntry = GetBlockEntryListFromAddress (RootTable, RegionStart, &TableLevel, &BlockEntrySize, &LastBlockEntry);
     if (BlockEntry == NULL) {
       // GetBlockEntryListFromAddress() return NULL when it fails to allocate new pages from the Translation Tables
@@ -451,11 +446,12 @@ FillTranslationTable (
 
     do {
       // Fill the Block Entry with attribute and output block address
-      *BlockEntry = (RegionStart & TT_ADDRESS_MASK_BLOCK_ENTRY) | Attributes | Type;
+      *BlockEntry &= BlockEntryMask;
+      *BlockEntry |= (RegionStart & TT_ADDRESS_MASK_BLOCK_ENTRY) | Attributes | Type;
 
       // Go to the next BlockEntry
       RegionStart += BlockEntrySize;
-      RemainingRegionLength -= BlockEntrySize;
+      RegionLength -= BlockEntrySize;
       BlockEntry++;
 
       // Break the inner loop when next block is a table
@@ -464,12 +460,28 @@ FillTranslationTable (
           (*BlockEntry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY) {
             break;
       }
-    } while ((RemainingRegionLength >= BlockEntrySize) && (BlockEntry <= LastBlockEntry));
-  } while (RemainingRegionLength != 0);
+    } while ((RegionLength >= BlockEntrySize) && (BlockEntry <= LastBlockEntry));
+  } while (RegionLength != 0);
 
   return RETURN_SUCCESS;
 }
 
+STATIC
+RETURN_STATUS
+FillTranslationTable (
+  IN  UINT64                        *RootTable,
+  IN  ARM_MEMORY_REGION_DESCRIPTOR  *MemoryRegion
+  )
+{
+  return UpdateRegionMapping (
+           RootTable,
+           MemoryRegion->VirtualBase,
+           MemoryRegion->Length,
+           ArmMemoryAttributeToPageAttribute (MemoryRegion->Attributes) | TT_AF,
+           0
+           );
+}
+
 RETURN_STATUS
 SetMemoryAttributes (
   IN EFI_PHYSICAL_ADDRESS      BaseAddress,
-- 
2.39.5