Re: [PATCH v3 2/3] ArmPkg/ArmMmuLib AARCH64: use helpers to determine table entry types

["Ashish Singhal" <ashishsingha@nvidia.com>]

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Reviewed-by: Ashish Singhal <ashishsingha@nvidia.com>
Tested-by: Ashish Singhal <ashishsingha@nvidia.com>

________________________________
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Sent: Wednesday, March 25, 2020 9:29 AM
To: devel@edk2.groups.io <devel@edk2.groups.io>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; Laszlo Ersek <lersek@redhat.com>; Leif Lindholm <leif@nuviainc.com>; Ashish Singhal <ashishsingha@nvidia.com>
Subject: [PATCH v3 2/3] ArmPkg/ArmMmuLib AARCH64: use helpers to determine table entry types

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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.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>
---
 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 d78918cf7ba8..0680ba36d907 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -162,6 +162,36 @@ 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 (
@@ -203,7 +233,7 @@ 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.
@@ -221,7 +251,7 @@ 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.
@@ -252,7 +282,7 @@ 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
@@ -265,10 +295,10 @@ 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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