[PATCH 2/6] ArmPkg/ArmMmuLib ARM: split ArmMmuLibCore.c into core and update code

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

Unlike the AArch64 implementation of ArmMmuLib, which combines the
initial page table population code with the code that runs at later
stages to manage permission attributes in the page tables, ARM uses
two completely separate sets of routines for this.

Since ArmMmuLib is a static library, we can prevent duplication of
this code between different users, which usually only need one or
the other. (Note that LTO should also achieve the same.)

This also makes it easier to reason about modifying the cache
maintenance handling, and replace the set/way ops with by-VA
ops, since the code that performs the set/way ops only executes
when the MMU is still off.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c |  32 ++
 ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c    | 434 -------------------
 ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c  | 435 ++++++++++++++++++++
 ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf      |   2 +
 4 files changed, 469 insertions(+), 434 deletions(-)

diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c
new file mode 100644
index 000000000000..e3b02a9fba57
--- /dev/null
+++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibConvert.c
@@ -0,0 +1,32 @@
+/** @file
+*  File managing the MMU for ARMv7 architecture
+*
+*  Copyright (c) 2011-2016, ARM Limited. All rights reserved.
+*
+*  SPDX-License-Identifier: BSD-2-Clause-Patent
+*
+**/
+
+#include <Uefi.h>
+
+#include <Library/ArmLib.h>
+
+#include <Chipset/ArmV7.h>
+
+UINT32
+ConvertSectionAttributesToPageAttributes (
+  IN UINT32   SectionAttributes,
+  IN BOOLEAN  IsLargePage
+  )
+{
+  UINT32 PageAttributes;
+
+  PageAttributes = 0;
+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_CACHE_POLICY (SectionAttributes, IsLargePage);
+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_AP (SectionAttributes);
+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_XN (SectionAttributes, IsLargePage);
+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_NG (SectionAttributes);
+  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_S (SectionAttributes);
+
+  return PageAttributes;
+}
diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
index a6601258bee0..aca7a37facac 100644
--- a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibCore.c
@@ -31,15 +31,6 @@
 #define ID_MMFR0_SHR_IMP_HW_COHERENT   1
 #define ID_MMFR0_SHR_IGNORED         0xf
 
-#define __EFI_MEMORY_RWX               0    // no restrictions
-
-#define CACHE_ATTRIBUTE_MASK   (EFI_MEMORY_UC | \
-                                EFI_MEMORY_WC | \
-                                EFI_MEMORY_WT | \
-                                EFI_MEMORY_WB | \
-                                EFI_MEMORY_UCE | \
-                                EFI_MEMORY_WP)
-
 UINTN
 EFIAPI
 ArmReadIdMmfr0 (
@@ -52,24 +43,6 @@ ArmHasMpExtensions (
   VOID
   );
 
-UINT32
-ConvertSectionAttributesToPageAttributes (
-  IN UINT32   SectionAttributes,
-  IN BOOLEAN  IsLargePage
-  )
-{
-  UINT32 PageAttributes;
-
-  PageAttributes = 0;
-  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_CACHE_POLICY (SectionAttributes, IsLargePage);
-  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_AP (SectionAttributes);
-  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_XN (SectionAttributes, IsLargePage);
-  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_NG (SectionAttributes);
-  PageAttributes |= TT_DESCRIPTOR_CONVERT_TO_PAGE_S (SectionAttributes);
-
-  return PageAttributes;
-}
-
 STATIC
 BOOLEAN
 PreferNonshareableMemory (
@@ -423,410 +396,3 @@ ArmConfigureMmu (
   ArmEnableMmu();
   return RETURN_SUCCESS;
 }
-
-STATIC
-EFI_STATUS
-ConvertSectionToPages (
-  IN EFI_PHYSICAL_ADDRESS  BaseAddress
-  )
-{
-  UINT32                  FirstLevelIdx;
-  UINT32                  SectionDescriptor;
-  UINT32                  PageTableDescriptor;
-  UINT32                  PageDescriptor;
-  UINT32                  Index;
-
-  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
-  volatile ARM_PAGE_TABLE_ENTRY         *PageTable;
-
-  DEBUG ((EFI_D_PAGE, "Converting section at 0x%x to pages\n", (UINTN)BaseAddress));
-
-  // Obtain page table base
-  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
-
-  // Calculate index into first level translation table for start of modification
-  FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
-  ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
-
-  // Get section attributes and convert to page attributes
-  SectionDescriptor = FirstLevelTable[FirstLevelIdx];
-  PageDescriptor = TT_DESCRIPTOR_PAGE_TYPE_PAGE | ConvertSectionAttributesToPageAttributes (SectionDescriptor, FALSE);
-
-  // Allocate a page table for the 4KB entries (we use up a full page even though we only need 1KB)
-  PageTable = (volatile ARM_PAGE_TABLE_ENTRY *)AllocatePages (1);
-  if (PageTable == NULL) {
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  // Write the page table entries out
-  for (Index = 0; Index < TRANSLATION_TABLE_PAGE_COUNT; Index++) {
-    PageTable[Index] = TT_DESCRIPTOR_PAGE_BASE_ADDRESS(BaseAddress + (Index << 12)) | PageDescriptor;
-  }
-
-  // Formulate page table entry, Domain=0, NS=0
-  PageTableDescriptor = (((UINTN)PageTable) & TT_DESCRIPTOR_SECTION_PAGETABLE_ADDRESS_MASK) | TT_DESCRIPTOR_SECTION_TYPE_PAGE_TABLE;
-
-  // Write the page table entry out, replacing section entry
-  FirstLevelTable[FirstLevelIdx] = PageTableDescriptor;
-
-  return EFI_SUCCESS;
-}
-
-STATIC
-EFI_STATUS
-UpdatePageEntries (
-  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN  UINT64                    Length,
-  IN  UINT64                    Attributes,
-  OUT BOOLEAN                   *FlushTlbs OPTIONAL
-  )
-{
-  EFI_STATUS    Status;
-  UINT32        EntryValue;
-  UINT32        EntryMask;
-  UINT32        FirstLevelIdx;
-  UINT32        Offset;
-  UINT32        NumPageEntries;
-  UINT32        Descriptor;
-  UINT32        p;
-  UINT32        PageTableIndex;
-  UINT32        PageTableEntry;
-  UINT32        CurrentPageTableEntry;
-  VOID          *Mva;
-
-  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
-  volatile ARM_PAGE_TABLE_ENTRY         *PageTable;
-
-  Status = EFI_SUCCESS;
-
-  // 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;
-  if (Attributes & EFI_MEMORY_XP) {
-    EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE_XN;
-  } else {
-    EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE;
-  }
-
-  // Although the PI spec is unclear on this, the GCD guarantees that only
-  // one Attribute bit is set at a time, so the order of the conditionals below
-  // is irrelevant. If no memory attribute is specified, we preserve whatever
-  // memory type is set in the page tables, and update the permission attributes
-  // only.
-  if (Attributes & EFI_MEMORY_UC) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
-    // map to strongly ordered
-    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
-  } else if (Attributes & EFI_MEMORY_WC) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
-    // map to normal non-cachable
-    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
-  } else if (Attributes & EFI_MEMORY_WT) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
-    // write through with no-allocate
-    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
-  } else if (Attributes & EFI_MEMORY_WB) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
-    // write back (with allocate)
-    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
-  } else if (Attributes & CACHE_ATTRIBUTE_MASK) {
-    // catch unsupported memory type attributes
-    ASSERT (FALSE);
-    return EFI_UNSUPPORTED;
-  }
-
-  if (Attributes & EFI_MEMORY_RO) {
-    EntryValue |= TT_DESCRIPTOR_PAGE_AP_RO_RO;
-  } else {
-    EntryValue |= TT_DESCRIPTOR_PAGE_AP_RW_RW;
-  }
-
-  // Obtain page table base
-  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
-
-  // Calculate number of 4KB page table entries to change
-  NumPageEntries = Length / TT_DESCRIPTOR_PAGE_SIZE;
-
-  // Iterate for the number of 4KB pages to change
-  Offset = 0;
-  for(p = 0; p < NumPageEntries; p++) {
-    // Calculate index into first level translation table for page table value
-
-    FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress + Offset) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
-    ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
-
-    // Read the descriptor from the first level page table
-    Descriptor = FirstLevelTable[FirstLevelIdx];
-
-    // Does this descriptor need to be converted from section entry to 4K pages?
-    if (!TT_DESCRIPTOR_SECTION_TYPE_IS_PAGE_TABLE(Descriptor)) {
-      Status = ConvertSectionToPages (FirstLevelIdx << TT_DESCRIPTOR_SECTION_BASE_SHIFT);
-      if (EFI_ERROR(Status)) {
-        // Exit for loop
-        break;
-      }
-
-      // Re-read descriptor
-      Descriptor = FirstLevelTable[FirstLevelIdx];
-      if (FlushTlbs != NULL) {
-        *FlushTlbs = TRUE;
-      }
-    }
-
-    // Obtain page table base address
-    PageTable = (ARM_PAGE_TABLE_ENTRY *)TT_DESCRIPTOR_PAGE_BASE_ADDRESS(Descriptor);
-
-    // Calculate index into the page table
-    PageTableIndex = ((BaseAddress + Offset) & TT_DESCRIPTOR_PAGE_INDEX_MASK) >> TT_DESCRIPTOR_PAGE_BASE_SHIFT;
-    ASSERT (PageTableIndex < TRANSLATION_TABLE_PAGE_COUNT);
-
-    // Get the entry
-    CurrentPageTableEntry = PageTable[PageTableIndex];
-
-    // Mask off appropriate fields
-    PageTableEntry = CurrentPageTableEntry & ~EntryMask;
-
-    // Mask in new attributes and/or permissions
-    PageTableEntry |= EntryValue;
-
-    if (CurrentPageTableEntry  != PageTableEntry) {
-      Mva = (VOID *)(UINTN)((((UINTN)FirstLevelIdx) << TT_DESCRIPTOR_SECTION_BASE_SHIFT) + (PageTableIndex << TT_DESCRIPTOR_PAGE_BASE_SHIFT));
-
-      // Only need to update if we are changing the entry
-      PageTable[PageTableIndex] = PageTableEntry;
-      ArmUpdateTranslationTableEntry ((VOID *)&PageTable[PageTableIndex], Mva);
-    }
-
-    Status = EFI_SUCCESS;
-    Offset += TT_DESCRIPTOR_PAGE_SIZE;
-
-  } // End first level translation table loop
-
-  return Status;
-}
-
-STATIC
-EFI_STATUS
-UpdateSectionEntries (
-  IN EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN UINT64                    Length,
-  IN UINT64                    Attributes
-  )
-{
-  EFI_STATUS    Status = EFI_SUCCESS;
-  UINT32        EntryMask;
-  UINT32        EntryValue;
-  UINT32        FirstLevelIdx;
-  UINT32        NumSections;
-  UINT32        i;
-  UINT32        CurrentDescriptor;
-  UINT32        Descriptor;
-  VOID          *Mva;
-  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
-
-  // EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)
-  // EntryValue: values at bit positions specified by EntryMask
-
-  // 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;
-  EntryValue = TT_DESCRIPTOR_SECTION_TYPE_SECTION;
-
-  // Although the PI spec is unclear on this, the GCD guarantees that only
-  // one Attribute bit is set at a time, so the order of the conditionals below
-  // is irrelevant. If no memory attribute is specified, we preserve whatever
-  // memory type is set in the page tables, and update the permission attributes
-  // only.
-  if (Attributes & EFI_MEMORY_UC) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
-    // map to strongly ordered
-    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
-  } else if (Attributes & EFI_MEMORY_WC) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
-    // map to normal non-cachable
-    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
-  } else if (Attributes & EFI_MEMORY_WT) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
-    // write through with no-allocate
-    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
-  } else if (Attributes & EFI_MEMORY_WB) {
-    // modify cacheability attributes
-    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
-    // write back (with allocate)
-    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
-  } else if (Attributes & CACHE_ATTRIBUTE_MASK) {
-    // catch unsupported memory type attributes
-    ASSERT (FALSE);
-    return EFI_UNSUPPORTED;
-  }
-
-  if (Attributes & EFI_MEMORY_RO) {
-    EntryValue |= TT_DESCRIPTOR_SECTION_AP_RO_RO;
-  } else {
-    EntryValue |= TT_DESCRIPTOR_SECTION_AP_RW_RW;
-  }
-
-  if (Attributes & EFI_MEMORY_XP) {
-    EntryValue |= TT_DESCRIPTOR_SECTION_XN_MASK;
-  }
-
-  // obtain page table base
-  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
-
-  // calculate index into first level translation table for start of modification
-  FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
-  ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
-
-  // calculate number of 1MB first level entries this applies to
-  NumSections = Length / TT_DESCRIPTOR_SECTION_SIZE;
-
-  // iterate through each descriptor
-  for(i=0; i<NumSections; i++) {
-    CurrentDescriptor = FirstLevelTable[FirstLevelIdx + i];
-
-    // has this descriptor already been converted to pages?
-    if (TT_DESCRIPTOR_SECTION_TYPE_IS_PAGE_TABLE(CurrentDescriptor)) {
-      // forward this 1MB range to page table function instead
-      Status = UpdatePageEntries (
-                 (FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT,
-                 TT_DESCRIPTOR_SECTION_SIZE,
-                 Attributes,
-                 NULL);
-    } else {
-      // still a section entry
-
-      if (CurrentDescriptor != 0) {
-        // mask off appropriate fields
-        Descriptor = CurrentDescriptor & ~EntryMask;
-      } else {
-        Descriptor = ((UINTN)FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT;
-      }
-
-      // mask in new attributes and/or permissions
-      Descriptor |= EntryValue;
-
-      if (CurrentDescriptor  != Descriptor) {
-        Mva = (VOID *)(UINTN)(((UINTN)FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT);
-
-        // Only need to update if we are changing the descriptor
-        FirstLevelTable[FirstLevelIdx + i] = Descriptor;
-        ArmUpdateTranslationTableEntry ((VOID *)&FirstLevelTable[FirstLevelIdx + i], Mva);
-      }
-
-      Status = EFI_SUCCESS;
-    }
-  }
-
-  return Status;
-}
-
-EFI_STATUS
-ArmSetMemoryAttributes (
-  IN EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN UINT64                    Length,
-  IN UINT64                    Attributes
-  )
-{
-  EFI_STATUS    Status;
-  UINT64        ChunkLength;
-  BOOLEAN       FlushTlbs;
-
-  if (BaseAddress > (UINT64)MAX_ADDRESS) {
-    return EFI_UNSUPPORTED;
-  }
-
-  Length = MIN (Length, (UINT64)MAX_ADDRESS - BaseAddress + 1);
-  if (Length == 0) {
-    return EFI_SUCCESS;
-  }
-
-  FlushTlbs = FALSE;
-  while (Length > 0) {
-    if ((BaseAddress % TT_DESCRIPTOR_SECTION_SIZE == 0) &&
-        Length >= TT_DESCRIPTOR_SECTION_SIZE) {
-
-      ChunkLength = Length - Length % TT_DESCRIPTOR_SECTION_SIZE;
-
-      DEBUG ((DEBUG_PAGE,
-        "SetMemoryAttributes(): MMU section 0x%lx length 0x%lx to %lx\n",
-        BaseAddress, ChunkLength, Attributes));
-
-      Status = UpdateSectionEntries (BaseAddress, ChunkLength, Attributes);
-
-      FlushTlbs = TRUE;
-    } else {
-
-      //
-      // Process page by page until the next section boundary, but only if
-      // we have more than a section's worth of area to deal with after that.
-      //
-      ChunkLength = TT_DESCRIPTOR_SECTION_SIZE -
-                    (BaseAddress % TT_DESCRIPTOR_SECTION_SIZE);
-      if (ChunkLength + TT_DESCRIPTOR_SECTION_SIZE > Length) {
-        ChunkLength = Length;
-      }
-
-      DEBUG ((DEBUG_PAGE,
-        "SetMemoryAttributes(): MMU page 0x%lx length 0x%lx to %lx\n",
-        BaseAddress, ChunkLength, Attributes));
-
-      Status = UpdatePageEntries (BaseAddress, ChunkLength, Attributes,
-                 &FlushTlbs);
-    }
-
-    if (EFI_ERROR (Status)) {
-      break;
-    }
-
-    BaseAddress += ChunkLength;
-    Length -= ChunkLength;
-  }
-
-  if (FlushTlbs) {
-    ArmInvalidateTlb ();
-  }
-  return Status;
-}
-
-EFI_STATUS
-ArmSetMemoryRegionNoExec (
-  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN  UINT64                    Length
-  )
-{
-  return ArmSetMemoryAttributes (BaseAddress, Length, EFI_MEMORY_XP);
-}
-
-EFI_STATUS
-ArmClearMemoryRegionNoExec (
-  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN  UINT64                    Length
-  )
-{
-  return ArmSetMemoryAttributes (BaseAddress, Length, __EFI_MEMORY_RWX);
-}
-
-EFI_STATUS
-ArmSetMemoryRegionReadOnly (
-  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN  UINT64                    Length
-  )
-{
-  return ArmSetMemoryAttributes (BaseAddress, Length, EFI_MEMORY_RO);
-}
-
-EFI_STATUS
-ArmClearMemoryRegionReadOnly (
-  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
-  IN  UINT64                    Length
-  )
-{
-  return ArmSetMemoryAttributes (BaseAddress, Length, __EFI_MEMORY_RWX);
-}
diff --git a/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
new file mode 100644
index 000000000000..3dafe1d964cd
--- /dev/null
+++ b/ArmPkg/Library/ArmMmuLib/Arm/ArmMmuLibUpdate.c
@@ -0,0 +1,435 @@
+/** @file
+*  File managing the MMU for ARMv7 architecture
+*
+*  Copyright (c) 2011-2016, ARM Limited. All rights reserved.
+*
+*  SPDX-License-Identifier: BSD-2-Clause-Patent
+*
+**/
+
+#include <Uefi.h>
+
+#include <Library/ArmLib.h>
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/CacheMaintenanceLib.h>
+#include <Library/MemoryAllocationLib.h>
+
+#include <Chipset/ArmV7.h>
+
+#define __EFI_MEMORY_RWX               0    // no restrictions
+
+#define CACHE_ATTRIBUTE_MASK   (EFI_MEMORY_UC | \
+                                EFI_MEMORY_WC | \
+                                EFI_MEMORY_WT | \
+                                EFI_MEMORY_WB | \
+                                EFI_MEMORY_UCE | \
+                                EFI_MEMORY_WP)
+
+STATIC
+EFI_STATUS
+ConvertSectionToPages (
+  IN EFI_PHYSICAL_ADDRESS  BaseAddress
+  )
+{
+  UINT32                  FirstLevelIdx;
+  UINT32                  SectionDescriptor;
+  UINT32                  PageTableDescriptor;
+  UINT32                  PageDescriptor;
+  UINT32                  Index;
+
+  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
+  volatile ARM_PAGE_TABLE_ENTRY         *PageTable;
+
+  DEBUG ((EFI_D_PAGE, "Converting section at 0x%x to pages\n", (UINTN)BaseAddress));
+
+  // Obtain page table base
+  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
+
+  // Calculate index into first level translation table for start of modification
+  FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
+  ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
+
+  // Get section attributes and convert to page attributes
+  SectionDescriptor = FirstLevelTable[FirstLevelIdx];
+  PageDescriptor = TT_DESCRIPTOR_PAGE_TYPE_PAGE | ConvertSectionAttributesToPageAttributes (SectionDescriptor, FALSE);
+
+  // Allocate a page table for the 4KB entries (we use up a full page even though we only need 1KB)
+  PageTable = (volatile ARM_PAGE_TABLE_ENTRY *)AllocatePages (1);
+  if (PageTable == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  // Write the page table entries out
+  for (Index = 0; Index < TRANSLATION_TABLE_PAGE_COUNT; Index++) {
+    PageTable[Index] = TT_DESCRIPTOR_PAGE_BASE_ADDRESS(BaseAddress + (Index << 12)) | PageDescriptor;
+  }
+
+  // Formulate page table entry, Domain=0, NS=0
+  PageTableDescriptor = (((UINTN)PageTable) & TT_DESCRIPTOR_SECTION_PAGETABLE_ADDRESS_MASK) | TT_DESCRIPTOR_SECTION_TYPE_PAGE_TABLE;
+
+  // Write the page table entry out, replacing section entry
+  FirstLevelTable[FirstLevelIdx] = PageTableDescriptor;
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+UpdatePageEntries (
+  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN  UINT64                    Length,
+  IN  UINT64                    Attributes,
+  OUT BOOLEAN                   *FlushTlbs OPTIONAL
+  )
+{
+  EFI_STATUS    Status;
+  UINT32        EntryValue;
+  UINT32        EntryMask;
+  UINT32        FirstLevelIdx;
+  UINT32        Offset;
+  UINT32        NumPageEntries;
+  UINT32        Descriptor;
+  UINT32        p;
+  UINT32        PageTableIndex;
+  UINT32        PageTableEntry;
+  UINT32        CurrentPageTableEntry;
+  VOID          *Mva;
+
+  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
+  volatile ARM_PAGE_TABLE_ENTRY         *PageTable;
+
+  Status = EFI_SUCCESS;
+
+  // 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;
+  if (Attributes & EFI_MEMORY_XP) {
+    EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE_XN;
+  } else {
+    EntryValue = TT_DESCRIPTOR_PAGE_TYPE_PAGE;
+  }
+
+  // Although the PI spec is unclear on this, the GCD guarantees that only
+  // one Attribute bit is set at a time, so the order of the conditionals below
+  // is irrelevant. If no memory attribute is specified, we preserve whatever
+  // memory type is set in the page tables, and update the permission attributes
+  // only.
+  if (Attributes & EFI_MEMORY_UC) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
+    // map to strongly ordered
+    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
+  } else if (Attributes & EFI_MEMORY_WC) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
+    // map to normal non-cachable
+    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
+  } else if (Attributes & EFI_MEMORY_WT) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
+    // write through with no-allocate
+    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
+  } else if (Attributes & EFI_MEMORY_WB) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_MASK;
+    // write back (with allocate)
+    EntryValue |= TT_DESCRIPTOR_PAGE_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
+  } else if (Attributes & CACHE_ATTRIBUTE_MASK) {
+    // catch unsupported memory type attributes
+    ASSERT (FALSE);
+    return EFI_UNSUPPORTED;
+  }
+
+  if (Attributes & EFI_MEMORY_RO) {
+    EntryValue |= TT_DESCRIPTOR_PAGE_AP_RO_RO;
+  } else {
+    EntryValue |= TT_DESCRIPTOR_PAGE_AP_RW_RW;
+  }
+
+  // Obtain page table base
+  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
+
+  // Calculate number of 4KB page table entries to change
+  NumPageEntries = Length / TT_DESCRIPTOR_PAGE_SIZE;
+
+  // Iterate for the number of 4KB pages to change
+  Offset = 0;
+  for(p = 0; p < NumPageEntries; p++) {
+    // Calculate index into first level translation table for page table value
+
+    FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress + Offset) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
+    ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
+
+    // Read the descriptor from the first level page table
+    Descriptor = FirstLevelTable[FirstLevelIdx];
+
+    // Does this descriptor need to be converted from section entry to 4K pages?
+    if (!TT_DESCRIPTOR_SECTION_TYPE_IS_PAGE_TABLE(Descriptor)) {
+      Status = ConvertSectionToPages (FirstLevelIdx << TT_DESCRIPTOR_SECTION_BASE_SHIFT);
+      if (EFI_ERROR(Status)) {
+        // Exit for loop
+        break;
+      }
+
+      // Re-read descriptor
+      Descriptor = FirstLevelTable[FirstLevelIdx];
+      if (FlushTlbs != NULL) {
+        *FlushTlbs = TRUE;
+      }
+    }
+
+    // Obtain page table base address
+    PageTable = (ARM_PAGE_TABLE_ENTRY *)TT_DESCRIPTOR_PAGE_BASE_ADDRESS(Descriptor);
+
+    // Calculate index into the page table
+    PageTableIndex = ((BaseAddress + Offset) & TT_DESCRIPTOR_PAGE_INDEX_MASK) >> TT_DESCRIPTOR_PAGE_BASE_SHIFT;
+    ASSERT (PageTableIndex < TRANSLATION_TABLE_PAGE_COUNT);
+
+    // Get the entry
+    CurrentPageTableEntry = PageTable[PageTableIndex];
+
+    // Mask off appropriate fields
+    PageTableEntry = CurrentPageTableEntry & ~EntryMask;
+
+    // Mask in new attributes and/or permissions
+    PageTableEntry |= EntryValue;
+
+    if (CurrentPageTableEntry  != PageTableEntry) {
+      Mva = (VOID *)(UINTN)((((UINTN)FirstLevelIdx) << TT_DESCRIPTOR_SECTION_BASE_SHIFT) + (PageTableIndex << TT_DESCRIPTOR_PAGE_BASE_SHIFT));
+
+      // Only need to update if we are changing the entry
+      PageTable[PageTableIndex] = PageTableEntry;
+      ArmUpdateTranslationTableEntry ((VOID *)&PageTable[PageTableIndex], Mva);
+    }
+
+    Status = EFI_SUCCESS;
+    Offset += TT_DESCRIPTOR_PAGE_SIZE;
+
+  } // End first level translation table loop
+
+  return Status;
+}
+
+STATIC
+EFI_STATUS
+UpdateSectionEntries (
+  IN EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN UINT64                    Length,
+  IN UINT64                    Attributes
+  )
+{
+  EFI_STATUS    Status = EFI_SUCCESS;
+  UINT32        EntryMask;
+  UINT32        EntryValue;
+  UINT32        FirstLevelIdx;
+  UINT32        NumSections;
+  UINT32        i;
+  UINT32        CurrentDescriptor;
+  UINT32        Descriptor;
+  VOID          *Mva;
+  volatile ARM_FIRST_LEVEL_DESCRIPTOR   *FirstLevelTable;
+
+  // EntryMask: bitmask of values to change (1 = change this value, 0 = leave alone)
+  // EntryValue: values at bit positions specified by EntryMask
+
+  // 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;
+  EntryValue = TT_DESCRIPTOR_SECTION_TYPE_SECTION;
+
+  // Although the PI spec is unclear on this, the GCD guarantees that only
+  // one Attribute bit is set at a time, so the order of the conditionals below
+  // is irrelevant. If no memory attribute is specified, we preserve whatever
+  // memory type is set in the page tables, and update the permission attributes
+  // only.
+  if (Attributes & EFI_MEMORY_UC) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
+    // map to strongly ordered
+    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_STRONGLY_ORDERED; // TEX[2:0] = 0, C=0, B=0
+  } else if (Attributes & EFI_MEMORY_WC) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
+    // map to normal non-cachable
+    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_NON_CACHEABLE; // TEX [2:0]= 001 = 0x2, B=0, C=0
+  } else if (Attributes & EFI_MEMORY_WT) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
+    // write through with no-allocate
+    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_THROUGH_NO_ALLOC; // TEX [2:0] = 0, C=1, B=0
+  } else if (Attributes & EFI_MEMORY_WB) {
+    // modify cacheability attributes
+    EntryMask |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_MASK;
+    // write back (with allocate)
+    EntryValue |= TT_DESCRIPTOR_SECTION_CACHE_POLICY_WRITE_BACK_ALLOC; // TEX [2:0] = 001, C=1, B=1
+  } else if (Attributes & CACHE_ATTRIBUTE_MASK) {
+    // catch unsupported memory type attributes
+    ASSERT (FALSE);
+    return EFI_UNSUPPORTED;
+  }
+
+  if (Attributes & EFI_MEMORY_RO) {
+    EntryValue |= TT_DESCRIPTOR_SECTION_AP_RO_RO;
+  } else {
+    EntryValue |= TT_DESCRIPTOR_SECTION_AP_RW_RW;
+  }
+
+  if (Attributes & EFI_MEMORY_XP) {
+    EntryValue |= TT_DESCRIPTOR_SECTION_XN_MASK;
+  }
+
+  // obtain page table base
+  FirstLevelTable = (ARM_FIRST_LEVEL_DESCRIPTOR *)ArmGetTTBR0BaseAddress ();
+
+  // calculate index into first level translation table for start of modification
+  FirstLevelIdx = TT_DESCRIPTOR_SECTION_BASE_ADDRESS(BaseAddress) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;
+  ASSERT (FirstLevelIdx < TRANSLATION_TABLE_SECTION_COUNT);
+
+  // calculate number of 1MB first level entries this applies to
+  NumSections = Length / TT_DESCRIPTOR_SECTION_SIZE;
+
+  // iterate through each descriptor
+  for(i=0; i<NumSections; i++) {
+    CurrentDescriptor = FirstLevelTable[FirstLevelIdx + i];
+
+    // has this descriptor already been converted to pages?
+    if (TT_DESCRIPTOR_SECTION_TYPE_IS_PAGE_TABLE(CurrentDescriptor)) {
+      // forward this 1MB range to page table function instead
+      Status = UpdatePageEntries (
+                 (FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT,
+                 TT_DESCRIPTOR_SECTION_SIZE,
+                 Attributes,
+                 NULL);
+    } else {
+      // still a section entry
+
+      if (CurrentDescriptor != 0) {
+        // mask off appropriate fields
+        Descriptor = CurrentDescriptor & ~EntryMask;
+      } else {
+        Descriptor = ((UINTN)FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT;
+      }
+
+      // mask in new attributes and/or permissions
+      Descriptor |= EntryValue;
+
+      if (CurrentDescriptor  != Descriptor) {
+        Mva = (VOID *)(UINTN)(((UINTN)FirstLevelIdx + i) << TT_DESCRIPTOR_SECTION_BASE_SHIFT);
+
+        // Only need to update if we are changing the descriptor
+        FirstLevelTable[FirstLevelIdx + i] = Descriptor;
+        ArmUpdateTranslationTableEntry ((VOID *)&FirstLevelTable[FirstLevelIdx + i], Mva);
+      }
+
+      Status = EFI_SUCCESS;
+    }
+  }
+
+  return Status;
+}
+
+EFI_STATUS
+ArmSetMemoryAttributes (
+  IN EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN UINT64                    Length,
+  IN UINT64                    Attributes
+  )
+{
+  EFI_STATUS    Status;
+  UINT64        ChunkLength;
+  BOOLEAN       FlushTlbs;
+
+  if (BaseAddress > (UINT64)MAX_ADDRESS) {
+    return EFI_UNSUPPORTED;
+  }
+
+  Length = MIN (Length, (UINT64)MAX_ADDRESS - BaseAddress + 1);
+  if (Length == 0) {
+    return EFI_SUCCESS;
+  }
+
+  FlushTlbs = FALSE;
+  while (Length > 0) {
+    if ((BaseAddress % TT_DESCRIPTOR_SECTION_SIZE == 0) &&
+        Length >= TT_DESCRIPTOR_SECTION_SIZE) {
+
+      ChunkLength = Length - Length % TT_DESCRIPTOR_SECTION_SIZE;
+
+      DEBUG ((DEBUG_PAGE,
+        "SetMemoryAttributes(): MMU section 0x%lx length 0x%lx to %lx\n",
+        BaseAddress, ChunkLength, Attributes));
+
+      Status = UpdateSectionEntries (BaseAddress, ChunkLength, Attributes);
+
+      FlushTlbs = TRUE;
+    } else {
+
+      //
+      // Process page by page until the next section boundary, but only if
+      // we have more than a section's worth of area to deal with after that.
+      //
+      ChunkLength = TT_DESCRIPTOR_SECTION_SIZE -
+                    (BaseAddress % TT_DESCRIPTOR_SECTION_SIZE);
+      if (ChunkLength + TT_DESCRIPTOR_SECTION_SIZE > Length) {
+        ChunkLength = Length;
+      }
+
+      DEBUG ((DEBUG_PAGE,
+        "SetMemoryAttributes(): MMU page 0x%lx length 0x%lx to %lx\n",
+        BaseAddress, ChunkLength, Attributes));
+
+      Status = UpdatePageEntries (BaseAddress, ChunkLength, Attributes,
+                 &FlushTlbs);
+    }
+
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+
+    BaseAddress += ChunkLength;
+    Length -= ChunkLength;
+  }
+
+  if (FlushTlbs) {
+    ArmInvalidateTlb ();
+  }
+  return Status;
+}
+
+EFI_STATUS
+ArmSetMemoryRegionNoExec (
+  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN  UINT64                    Length
+  )
+{
+  return ArmSetMemoryAttributes (BaseAddress, Length, EFI_MEMORY_XP);
+}
+
+EFI_STATUS
+ArmClearMemoryRegionNoExec (
+  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN  UINT64                    Length
+  )
+{
+  return ArmSetMemoryAttributes (BaseAddress, Length, __EFI_MEMORY_RWX);
+}
+
+EFI_STATUS
+ArmSetMemoryRegionReadOnly (
+  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN  UINT64                    Length
+  )
+{
+  return ArmSetMemoryAttributes (BaseAddress, Length, EFI_MEMORY_RO);
+}
+
+EFI_STATUS
+ArmClearMemoryRegionReadOnly (
+  IN  EFI_PHYSICAL_ADDRESS      BaseAddress,
+  IN  UINT64                    Length
+  )
+{
+  return ArmSetMemoryAttributes (BaseAddress, Length, __EFI_MEMORY_RWX);
+}
diff --git a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
index 3dfe68ba48a6..2a7e7147958c 100644
--- a/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
+++ b/ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
@@ -23,7 +23,9 @@ [Sources.AARCH64]
   AArch64/ArmMmuLibReplaceEntry.S
 
 [Sources.ARM]
+  Arm/ArmMmuLibConvert.c
   Arm/ArmMmuLibCore.c
+  Arm/ArmMmuLibUpdate.c
   Arm/ArmMmuLibV7Support.S   |GCC
   Arm/ArmMmuLibV7Support.asm |RVCT
 
-- 
2.17.1