ArmPkg: Update GetMemoryRegion() to Handle No mapping

This patch updates the GetMemoryRegion() function to handle the case
where there is no mapping for the requested address.

The original logic for the ARM would hit an ASSERT after
GetMemoryRegionPage() returned EFI_SUCCESS but did not update The
RegionLength parameter.

The original logic for the AARCH64 would never initialize the
RegionLength parameter to zero and return EFI_SUCCESS after
traversing an unknown number of pages.

To fix this, update the logic for both architecture to return
EFI_NO_MAPPING if the BaseAddress being checked is unmapped.

Signed-off-by: Taylor Beebe <t@taylorbeebe.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 42 insertions, 23 deletions

diff --git a/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c b/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c
index afd6aab602..268c0bf3f9 100644
--- a/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c
+++ b/ArmPkg/Drivers/CpuDxe/Arm/Mmu.c
@@ -427,17 +427,20 @@ EfiAttributeToArmAttribute (
 EFI_STATUS

 GetMemoryRegionPage (

   IN     UINT32  *PageTable,

-  IN OUT UINTN   *BaseAddress,

-  OUT    UINTN   *RegionLength,

-  OUT    UINTN   *RegionAttributes

+  IN     UINTN   *BaseAddress,

+  IN     UINTN   *RegionAttributes,

+  OUT    UINTN   *RegionLength

   )

 {

-  UINT32  PageAttributes;

-  UINT32  TableIndex;

-  UINT32  PageDescriptor;

+  UINT32      PageAttributes;

+  UINT32      TableIndex;

+  UINT32      PageDescriptor;

+  EFI_STATUS  Status;

 

   // Convert the section attributes into page attributes

   PageAttributes = ConvertSectionAttributesToPageAttributes (*RegionAttributes);

+  Status         = EFI_NOT_FOUND;

+  *RegionLength  = 0;

 

   // Calculate index into first level translation table for start of modification

   TableIndex = ((*BaseAddress) & TT_DESCRIPTOR_PAGE_INDEX_MASK)  >> TT_DESCRIPTOR_PAGE_BASE_SHIFT;

@@ -449,23 +452,24 @@ GetMemoryRegionPage (
     PageDescriptor = PageTable[TableIndex];

 

     if ((PageDescriptor & TT_DESCRIPTOR_PAGE_TYPE_MASK) == TT_DESCRIPTOR_PAGE_TYPE_FAULT) {

-      // Case: End of the boundary of the region

-      return EFI_SUCCESS;

+      Status = (*RegionLength > 0) ? EFI_SUCCESS : EFI_NO_MAPPING;

+      break;

     } else if ((PageDescriptor & TT_DESCRIPTOR_PAGE_TYPE_PAGE) == TT_DESCRIPTOR_PAGE_TYPE_PAGE) {

-      if ((PageDescriptor & TT_DESCRIPTOR_PAGE_ATTRIBUTE_MASK) == PageAttributes) {

-        *RegionLength = *RegionLength + TT_DESCRIPTOR_PAGE_SIZE;

-      } else {

-        // Case: End of the boundary of the region

-        return EFI_SUCCESS;

+      if ((PageDescriptor & TT_DESCRIPTOR_PAGE_ATTRIBUTE_MASK) != PageAttributes) {

+        Status = EFI_SUCCESS;

+        break;

       }

+

+      *RegionLength += TT_DESCRIPTOR_PAGE_SIZE;

     } else {

-      // We do not support Large Page yet. We return EFI_SUCCESS that means end of the region.

+      // Large pages are unsupported.

+      Status = EFI_UNSUPPORTED;

       ASSERT (0);

-      return EFI_SUCCESS;

+      break;

     }

   }

 

-  return EFI_NOT_FOUND;

+  return Status;

 }

 

 EFI_STATUS

@@ -482,6 +486,7 @@ GetMemoryRegion (
   UINT32                      SectionDescriptor;

   ARM_FIRST_LEVEL_DESCRIPTOR  *FirstLevelTable;

   UINT32                      *PageTable;

+  UINTN                       Length;

 

   // Initialize the arguments

   *RegionLength = 0;

@@ -491,7 +496,11 @@ GetMemoryRegion (
 

   // Calculate index into first level translation table for start of modification

   TableIndex = TT_DESCRIPTOR_SECTION_BASE_ADDRESS (*BaseAddress) >> TT_DESCRIPTOR_SECTION_BASE_SHIFT;

-  ASSERT (TableIndex < TRANSLATION_TABLE_SECTION_COUNT);

+

+  if (TableIndex >= TRANSLATION_TABLE_SECTION_COUNT) {

+    ASSERT (TableIndex < TRANSLATION_TABLE_SECTION_COUNT);

+    return EFI_INVALID_PARAMETER;

+  }

 

   // Get the section at the given index

   SectionDescriptor = FirstLevelTable[TableIndex];

@@ -524,6 +533,8 @@ GetMemoryRegion (
                         TT_DESCRIPTOR_CONVERT_TO_SECTION_AP (PageAttributes);

   }

 

+  Status = EFI_NOT_FOUND;

+

   for ( ; TableIndex < TRANSLATION_TABLE_SECTION_COUNT; TableIndex++) {

     // Get the section at the given index

     SectionDescriptor = FirstLevelTable[TableIndex];

@@ -532,15 +543,18 @@ GetMemoryRegion (
     if (TT_DESCRIPTOR_SECTION_TYPE_IS_PAGE_TABLE (SectionDescriptor)) {

       // Extract the page table location from the descriptor

       PageTable = (UINT32 *)(SectionDescriptor & TT_DESCRIPTOR_SECTION_PAGETABLE_ADDRESS_MASK);

+      Length    = 0;

 

       // Scan the page table to find the end of the region.

-      Status = GetMemoryRegionPage (PageTable, BaseAddress, RegionLength, RegionAttributes);

-      ASSERT (*RegionLength > 0);

+      Status         = GetMemoryRegionPage (PageTable, BaseAddress, RegionAttributes, &Length);

+      *RegionLength += Length;

 

-      // If we have found the end of the region (Status == EFI_SUCCESS) then we exit the for-loop

-      if (Status == EFI_SUCCESS) {

-        break;

+      // Status == EFI_NOT_FOUND implies we have not reached the end of the region.

+      if ((Status == EFI_NOT_FOUND) && (Length > 0)) {

+        continue;

       }

+

+      break;

     } else if (((SectionDescriptor & TT_DESCRIPTOR_SECTION_TYPE_MASK) == TT_DESCRIPTOR_SECTION_TYPE_SECTION) ||

                ((SectionDescriptor & TT_DESCRIPTOR_SECTION_TYPE_MASK) == TT_DESCRIPTOR_SECTION_TYPE_SUPERSECTION))

     {

@@ -556,5 +570,10 @@ GetMemoryRegion (
     }

   }

 

-  return EFI_SUCCESS;

+  // Check if the region length was updated.

+  if (*RegionLength > 0) {

+    Status = EFI_SUCCESS;

+  }

+

+  return Status;

 }