[edk2-devel] [PATCH 1/2] ArmPkg/ArmMmuLib AARCH64: use helpers to determine table entry types

[Ard Biesheuvel]

Given how the meaning of the attribute bits for page table entry types
is slightly awkward, and changes between levels, add some helpers to
abstract from this.

Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 40 +++++++++++++++++---
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c 
b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index a43d468b73ca..6f6ef5b05fbc 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -156,6 +156,36 @@ FreePageTablesRecursive (
   FreePages (TranslationTable, 1);
 }
 
+STATIC
+BOOLEAN
+IsBlockEntry (
+  IN  UINT64  Entry,
+  IN  UINTN   Level
+  )
+{
+  if (Level == 3) {
+    return (Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY_LEVEL3;
+  }
+  return (Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY;
+}
+
+STATIC
+BOOLEAN
+IsTableEntry (
+  IN  UINT64  Entry,
+  IN  UINTN   Level
+  )
+{
+  if (Level == 3) {
+    //
+    // TT_TYPE_TABLE_ENTRY aliases TT_TYPE_BLOCK_ENTRY_LEVEL3
+    // so we need to take the level into account as well.
+    //
+    return FALSE;
+  }
+  return (Entry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY;
+}
+
 STATIC
 EFI_STATUS
 UpdateRegionMappingRecursive (
@@ -197,7 +227,7 @@ UpdateRegionMappingRecursive (
     if (Level == 0 || ((RegionStart | BlockEnd) & BlockMask) != 0) {
       ASSERT (Level < 3);
 
-      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+      if (!IsTableEntry (*Entry, Level)) {
         //
         // No table entry exists yet, so we need to allocate a page table
         // for the next level.
@@ -215,7 +245,7 @@ UpdateRegionMappingRecursive (
           InvalidateDataCacheRange (TranslationTable, EFI_PAGE_SIZE);
         }
 
-        if ((*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
+        if (IsBlockEntry (*Entry, Level)) {
           //
           // We are splitting an existing block entry, so we have to populate
           // the new table with the attributes of the block entry it replaces.
@@ -246,7 +276,7 @@ UpdateRegionMappingRecursive (
                  AttributeSetMask, AttributeClearMask, TranslationTable,
                  Level + 1);
       if (EFI_ERROR (Status)) {
-        if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+        if (!IsTableEntry (*Entry, Level)) {
           //
           // We are creating a new table entry, so on failure, we can free all
           // allocations we made recursively, given that the whole subhierarchy
@@ -259,10 +289,10 @@ UpdateRegionMappingRecursive (
         return Status;
       }
 
-      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+      if (!IsTableEntry (*Entry, Level)) {
         EntryValue = (UINTN)TranslationTable | TT_TYPE_TABLE_ENTRY;
         ReplaceTableEntry (Entry, EntryValue, RegionStart,
-                           (*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY);
+          IsBlockEntry (*Entry, Level));
       }
     } else {
       EntryValue = (*Entry & AttributeClearMask) | AttributeSetMask;
-- 
2.17.1


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