[PATCH v4 0/2] ArmPkg/ArmMmuLib: rewrite and improve cache handling with MMU off

[PATCH v4 0/2] ArmPkg/ArmMmuLib: rewrite and improve cache handling with MMU off

[Ard Biesheuvel]

I finally got fed up with the state of the AArch64 MMU handling code, and
decided to rewrite it before rebasing the cache invalidation fix onto
it.

Changes since v3:
- move code for better diffing
- free allocated page tables on failure if it is safe to do so
- some minor style tweaks
- add Leif's ack to #2

Ard Biesheuvel (2):
  ArmPkg/ArmMmuLib AARCH64: rewrite page table code
  ArmPkg/ArmMmuLib AARCH64: invalidate page tables before populating
    them

 .../Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 405 +++++++-----------
 1 file changed, 162 insertions(+), 243 deletions(-)

-- 
2.17.1

[PATCH v4 1/2] ArmPkg/ArmMmuLib AARCH64: rewrite page table code

[Ard Biesheuvel]

Replace the slightly overcomplicated page table management code with
a simplified, recursive implementation that should be far easier to
reason about.

Note that, as a side effect, this extends the per-entry cache invalidation
that we do on page table entries to block and page entries, whereas the
previous change inadvertently only affected the creation of table entries.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 391 ++++++++------------
 1 file changed, 148 insertions(+), 243 deletions(-)

diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 204e33c75f95..00a38bc31d0a 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -1,7 +1,7 @@
 /** @file
 *  File managing the MMU for ARMv8 architecture
 *
-*  Copyright (c) 2011-2014, ARM Limited. All rights reserved.
+*  Copyright (c) 2011-2020, ARM Limited. All rights reserved.
 *  Copyright (c) 2016, Linaro Limited. All rights reserved.
 *  Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
 *
@@ -121,19 +121,150 @@ GetRootTranslationTableInfo (
 
 STATIC
 VOID
-ReplaceLiveEntry (
+ReplaceTableEntry (
   IN  UINT64  *Entry,
   IN  UINT64  Value,
-  IN  UINT64  RegionStart
+  IN  UINT64  RegionStart,
+  IN  BOOLEAN IsLiveBlockMapping
   )
 {
-  if (!ArmMmuEnabled ()) {
+  if (!ArmMmuEnabled () || !IsLiveBlockMapping) {
     *Entry = Value;
+    ArmUpdateTranslationTableEntry (Entry, (VOID *)(UINTN)RegionStart);
   } else {
     ArmReplaceLiveTranslationEntry (Entry, Value, RegionStart);
   }
 }
 
+STATIC
+VOID
+FreePageTablesRecursive (
+  IN  UINT64  *TranslationTable
+  )
+{
+  UINTN   Index;
+
+  for (Index = 0; Index < TT_ENTRY_COUNT; Index++) {
+    if ((TranslationTable[Index] & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY) {
+      FreePageTablesRecursive ((VOID *)(UINTN)(TranslationTable[Index] &
+                                               TT_ADDRESS_MASK_BLOCK_ENTRY));
+    }
+  }
+  FreePages (TranslationTable, 1);
+}
+
+STATIC
+EFI_STATUS
+UpdateRegionMappingRecursive (
+  IN  UINT64      RegionStart,
+  IN  UINT64      RegionEnd,
+  IN  UINT64      AttributeSetMask,
+  IN  UINT64      AttributeClearMask,
+  IN  UINT64      *PageTable,
+  IN  UINTN       Level
+  )
+{
+  UINTN           BlockShift;
+  UINT64          BlockMask;
+  UINT64          BlockEnd;
+  UINT64          *Entry;
+  UINT64          EntryValue;
+  VOID            *TranslationTable;
+  EFI_STATUS      Status;
+
+  ASSERT (((RegionStart | RegionEnd) & EFI_PAGE_MASK) == 0);
+
+  BlockShift = (Level + 1) * BITS_PER_LEVEL + MIN_T0SZ;
+  BlockMask = MAX_UINT64 >> BlockShift;
+
+  DEBUG ((DEBUG_VERBOSE, "%a(%d): %llx - %llx set %lx clr %lx\n", __FUNCTION__,
+    Level, RegionStart, RegionEnd, AttributeSetMask, AttributeClearMask));
+
+  for (; RegionStart < RegionEnd; RegionStart = BlockEnd) {
+    BlockEnd = MIN (RegionEnd, (RegionStart | BlockMask) + 1);
+    Entry = &PageTable[(RegionStart >> (64 - BlockShift)) & (TT_ENTRY_COUNT - 1)];
+
+    //
+    // If RegionStart or BlockEnd is not aligned to the block size at this
+    // level, we will have to create a table mapping in order to map less
+    // than a block, and recurse to create the block or page entries at
+    // the next level. No block mappings are allowed at all at level 0,
+    // so in that case, we have to recurse unconditionally.
+    //
+    if (Level == 0 || ((RegionStart | BlockEnd) & BlockMask) != 0) {
+      ASSERT (Level < 3);
+
+      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+        //
+        // No table entry exists yet, so we need to allocate a page table
+        // for the next level.
+        //
+        TranslationTable = AllocatePages (1);
+        if (TranslationTable == NULL) {
+          return EFI_OUT_OF_RESOURCES;
+        }
+
+        if ((*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
+          //
+          // We are splitting an existing block entry, so we have to populate
+          // the new table with the attributes of the block entry it replaces.
+          //
+          Status = UpdateRegionMappingRecursive (RegionStart & ~BlockMask,
+                     (RegionStart | BlockMask) + 1, *Entry & TT_ATTRIBUTES_MASK,
+                     0, TranslationTable, Level + 1);
+          if (EFI_ERROR (Status)) {
+            //
+            // The range we passed to UpdateRegionMappingRecursive () is block
+            // aligned, so it is guaranteed that no further pages were allocated
+            // by it, and so we only have to free the page we allocated here.
+            //
+            FreePages (TranslationTable, 1);
+            return Status;
+          }
+        } else {
+          ZeroMem (TranslationTable, EFI_PAGE_SIZE);
+        }
+      } else {
+        TranslationTable = (VOID *)(UINTN)(*Entry & TT_ADDRESS_MASK_BLOCK_ENTRY);
+      }
+
+      //
+      // Recurse to the next level
+      //
+      Status = UpdateRegionMappingRecursive (RegionStart, BlockEnd,
+                 AttributeSetMask, AttributeClearMask, TranslationTable,
+                 Level + 1);
+      if (EFI_ERROR (Status)) {
+        if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+          //
+          // We are creating a new table entry, so on failure, we can free all
+          // allocations we made recursively, given that the whole subhierarchy
+          // has not been wired into the live page tables yet. (This is not
+          // possible for existing table entries, since we cannot revert the
+          // modifications we made to the subhierarchy it represents.)
+          //
+          FreePageTablesRecursive (TranslationTable);
+        }
+        return Status;
+      }
+
+      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
+        EntryValue = (UINTN)TranslationTable | TT_TYPE_TABLE_ENTRY;
+        ReplaceTableEntry (Entry, EntryValue, RegionStart,
+                           (*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY);
+      }
+    } else {
+      EntryValue = (*Entry & AttributeClearMask) | AttributeSetMask;
+      EntryValue |= RegionStart;
+      EntryValue |= (Level == 3) ? TT_TYPE_BLOCK_ENTRY_LEVEL3
+                                 : TT_TYPE_BLOCK_ENTRY;
+
+      ReplaceTableEntry (Entry, EntryValue, RegionStart, FALSE);
+    }
+  }
+  return EFI_SUCCESS;
+}
+
 STATIC
 VOID
 LookupAddresstoRootTable (
@@ -164,230 +295,28 @@ LookupAddresstoRootTable (
   GetRootTranslationTableInfo (*T0SZ, NULL, TableEntryCount);
 }
 
-STATIC
-UINT64*
-GetBlockEntryListFromAddress (
-  IN  UINT64       *RootTable,
-  IN  UINT64        RegionStart,
-  OUT UINTN        *TableLevel,
-  IN OUT UINT64    *BlockEntrySize,
-  OUT UINT64      **LastBlockEntry
-  )
-{
-  UINTN   RootTableLevel;
-  UINTN   RootTableEntryCount;
-  UINT64 *TranslationTable;
-  UINT64 *BlockEntry;
-  UINT64 *SubTableBlockEntry;
-  UINT64  BlockEntryAddress;
-  UINTN   BaseAddressAlignment;
-  UINTN   PageLevel;
-  UINTN   Index;
-  UINTN   IndexLevel;
-  UINTN   T0SZ;
-  UINT64  Attributes;
-  UINT64  TableAttributes;
-
-  // Initialize variable
-  BlockEntry = NULL;
-
-  // Ensure the parameters are valid
-  if (!(TableLevel && BlockEntrySize && LastBlockEntry)) {
-    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
-    return NULL;
-  }
-
-  // Ensure the Region is aligned on 4KB boundary
-  if ((RegionStart & (SIZE_4KB - 1)) != 0) {
-    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
-    return NULL;
-  }
-
-  // Ensure the required size is aligned on 4KB boundary and not 0
-  if ((*BlockEntrySize & (SIZE_4KB - 1)) != 0 || *BlockEntrySize == 0) {
-    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
-    return NULL;
-  }
-
-  T0SZ = ArmGetTCR () & TCR_T0SZ_MASK;
-  // Get the Table info from T0SZ
-  GetRootTranslationTableInfo (T0SZ, &RootTableLevel, &RootTableEntryCount);
-
-  // If the start address is 0x0 then we use the size of the region to identify the alignment
-  if (RegionStart == 0) {
-    // Identify the highest possible alignment for the Region Size
-    BaseAddressAlignment = LowBitSet64 (*BlockEntrySize);
-  } else {
-    // Identify the highest possible alignment for the Base Address
-    BaseAddressAlignment = LowBitSet64 (RegionStart);
-  }
-
-  // Identify the Page Level the RegionStart must belong to. Note that PageLevel
-  // should be at least 1 since block translations are not supported at level 0
-  PageLevel = MAX (3 - ((BaseAddressAlignment - 12) / 9), 1);
-
-  // If the required size is smaller than the current block size then we need to go to the page below.
-  // The PageLevel was calculated on the Base Address alignment but did not take in account the alignment
-  // of the allocation size
-  while (*BlockEntrySize < TT_BLOCK_ENTRY_SIZE_AT_LEVEL (PageLevel)) {
-    // It does not fit so we need to go a page level above
-    PageLevel++;
-  }
-
-  //
-  // Get the Table Descriptor for the corresponding PageLevel. We need to decompose RegionStart to get appropriate entries
-  //
-
-  TranslationTable = RootTable;
-  for (IndexLevel = RootTableLevel; IndexLevel <= PageLevel; IndexLevel++) {
-    BlockEntry = (UINT64*)TT_GET_ENTRY_FOR_ADDRESS (TranslationTable, IndexLevel, RegionStart);
-
-    if ((IndexLevel != 3) && ((*BlockEntry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY)) {
-      // Go to the next table
-      TranslationTable = (UINT64*)(*BlockEntry & TT_ADDRESS_MASK_DESCRIPTION_TABLE);
-
-      // If we are at the last level then update the last level to next level
-      if (IndexLevel == PageLevel) {
-        // Enter the next level
-        PageLevel++;
-      }
-    } else if ((*BlockEntry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
-      // If we are not at the last level then we need to split this BlockEntry
-      if (IndexLevel != PageLevel) {
-        // Retrieve the attributes from the block entry
-        Attributes = *BlockEntry & TT_ATTRIBUTES_MASK;
-
-        // Convert the block entry attributes into Table descriptor attributes
-        TableAttributes = TT_TABLE_AP_NO_PERMISSION;
-        if (Attributes & TT_NS) {
-          TableAttributes = TT_TABLE_NS;
-        }
-
-        // Get the address corresponding at this entry
-        BlockEntryAddress = RegionStart;
-        BlockEntryAddress = BlockEntryAddress >> TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel);
-        // Shift back to right to set zero before the effective address
-        BlockEntryAddress = BlockEntryAddress << TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel);
-
-        // Set the correct entry type for the next page level
-        if ((IndexLevel + 1) == 3) {
-          Attributes |= TT_TYPE_BLOCK_ENTRY_LEVEL3;
-        } else {
-          Attributes |= TT_TYPE_BLOCK_ENTRY;
-        }
-
-        // Create a new translation table
-        TranslationTable = AllocatePages (1);
-        if (TranslationTable == NULL) {
-          return NULL;
-        }
-
-        // Populate the newly created lower level table
-        SubTableBlockEntry = TranslationTable;
-        for (Index = 0; Index < TT_ENTRY_COUNT; Index++) {
-          *SubTableBlockEntry = Attributes | (BlockEntryAddress + (Index << TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel + 1)));
-          SubTableBlockEntry++;
-        }
-
-        // Fill the BlockEntry with the new TranslationTable
-        ReplaceLiveEntry (BlockEntry,
-          (UINTN)TranslationTable | TableAttributes | TT_TYPE_TABLE_ENTRY,
-          RegionStart);
-      }
-    } else {
-      if (IndexLevel != PageLevel) {
-        //
-        // Case when we have an Invalid Entry and we are at a page level above of the one targetted.
-        //
-
-        // Create a new translation table
-        TranslationTable = AllocatePages (1);
-        if (TranslationTable == NULL) {
-          return NULL;
-        }
-
-        ZeroMem (TranslationTable, TT_ENTRY_COUNT * sizeof(UINT64));
-
-        // Fill the new BlockEntry with the TranslationTable
-        *BlockEntry = ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TT_TYPE_TABLE_ENTRY;
-      }
-    }
-  }
-
-  // Expose the found PageLevel to the caller
-  *TableLevel = PageLevel;
-
-  // Now, we have the Table Level we can get the Block Size associated to this table
-  *BlockEntrySize = TT_BLOCK_ENTRY_SIZE_AT_LEVEL (PageLevel);
-
-  // The last block of the root table depends on the number of entry in this table,
-  // otherwise it is always the (TT_ENTRY_COUNT - 1)th entry in the table.
-  *LastBlockEntry = TT_LAST_BLOCK_ADDRESS(TranslationTable,
-      (PageLevel == RootTableLevel) ? RootTableEntryCount : TT_ENTRY_COUNT);
-
-  return BlockEntry;
-}
-
 STATIC
 EFI_STATUS
 UpdateRegionMapping (
-  IN  UINT64  *RootTable,
   IN  UINT64  RegionStart,
   IN  UINT64  RegionLength,
-  IN  UINT64  Attributes,
-  IN  UINT64  BlockEntryMask
+  IN  UINT64  AttributeSetMask,
+  IN  UINT64  AttributeClearMask
   )
 {
-  UINT32  Type;
-  UINT64  *BlockEntry;
-  UINT64  *LastBlockEntry;
-  UINT64  BlockEntrySize;
-  UINTN   TableLevel;
+  UINTN     RootTableLevel;
+  UINTN     T0SZ;
 
-  // Ensure the Length is aligned on 4KB boundary
-  if ((RegionLength == 0) || ((RegionLength & (SIZE_4KB - 1)) != 0)) {
-    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
+  if (((RegionStart | RegionLength) & EFI_PAGE_MASK)) {
     return EFI_INVALID_PARAMETER;
   }
 
-  do {
-    // Get the first Block Entry that matches the Virtual Address and also the information on the Table Descriptor
-    // such as the size of the Block Entry and the address of the last BlockEntry of the Table Descriptor
-    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
-      return EFI_OUT_OF_RESOURCES;
-    }
+  T0SZ = ArmGetTCR () & TCR_T0SZ_MASK;
+  GetRootTranslationTableInfo (T0SZ, &RootTableLevel, NULL);
 
-    if (TableLevel != 3) {
-      Type = TT_TYPE_BLOCK_ENTRY;
-    } else {
-      Type = TT_TYPE_BLOCK_ENTRY_LEVEL3;
-    }
-
-    do {
-      // Fill the Block Entry with attribute and output block address
-      *BlockEntry &= BlockEntryMask;
-      *BlockEntry |= (RegionStart & TT_ADDRESS_MASK_BLOCK_ENTRY) | Attributes | Type;
-
-      ArmUpdateTranslationTableEntry (BlockEntry, (VOID *)RegionStart);
-
-      // Go to the next BlockEntry
-      RegionStart += BlockEntrySize;
-      RegionLength -= BlockEntrySize;
-      BlockEntry++;
-
-      // Break the inner loop when next block is a table
-      // Rerun GetBlockEntryListFromAddress to avoid page table memory leak
-      if (TableLevel != 3 && BlockEntry <= LastBlockEntry &&
-          (*BlockEntry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY) {
-            break;
-      }
-    } while ((RegionLength >= BlockEntrySize) && (BlockEntry <= LastBlockEntry));
-  } while (RegionLength != 0);
-
-  return EFI_SUCCESS;
+  return UpdateRegionMappingRecursive (RegionStart, RegionStart + RegionLength,
+           AttributeSetMask, AttributeClearMask, ArmGetTTBR0BaseAddress (),
+           RootTableLevel);
 }
 
 STATIC
@@ -398,7 +327,6 @@ FillTranslationTable (
   )
 {
   return UpdateRegionMapping (
-           RootTable,
            MemoryRegion->VirtualBase,
            MemoryRegion->Length,
            ArmMemoryAttributeToPageAttribute (MemoryRegion->Attributes) | TT_AF,
@@ -455,8 +383,6 @@ ArmSetMemoryAttributes (
   IN UINT64                    Attributes
   )
 {
-  EFI_STATUS                   Status;
-  UINT64                      *TranslationTable;
   UINT64                       PageAttributes;
   UINT64                       PageAttributeMask;
 
@@ -473,19 +399,8 @@ ArmSetMemoryAttributes (
                           TT_PXN_MASK | TT_XN_MASK);
   }
 
-  TranslationTable = ArmGetTTBR0BaseAddress ();
-
-  Status = UpdateRegionMapping (
-             TranslationTable,
-             BaseAddress,
-             Length,
-             PageAttributes,
-             PageAttributeMask);
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  return EFI_SUCCESS;
+  return UpdateRegionMapping (BaseAddress, Length, PageAttributes,
+           PageAttributeMask);
 }
 
 STATIC
@@ -497,17 +412,7 @@ SetMemoryRegionAttribute (
   IN  UINT64                    BlockEntryMask
   )
 {
-  EFI_STATUS                   Status;
-  UINT64                       *RootTable;
-
-  RootTable = ArmGetTTBR0BaseAddress ();
-
-  Status = UpdateRegionMapping (RootTable, BaseAddress, Length, Attributes, BlockEntryMask);
-  if (EFI_ERROR (Status)) {
-    return Status;
-  }
-
-  return EFI_SUCCESS;
+  return UpdateRegionMapping (BaseAddress, Length, Attributes, BlockEntryMask);
 }
 
 EFI_STATUS
-- 
2.17.1

Re: [PATCH v4 1/2] ArmPkg/ArmMmuLib AARCH64: rewrite page table code

[Leif Lindholm]

On Sat, Mar 07, 2020 at 09:38:48 +0100, Ard Biesheuvel wrote:
> Replace the slightly overcomplicated page table management code with
> a simplified, recursive implementation that should be far easier to
> reason about.
> 
> Note that, as a side effect, this extends the per-entry cache invalidation
> that we do on page table entries to block and page entries, whereas the
> previous change inadvertently only affected the creation of table entries.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Leif Lindholm <leif@nuviainc.com>

Thanks!

> ---
>  ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 391 ++++++++------------
>  1 file changed, 148 insertions(+), 243 deletions(-)
> 
> diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> index 204e33c75f95..00a38bc31d0a 100644
> --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
> @@ -1,7 +1,7 @@
>  /** @file
>  *  File managing the MMU for ARMv8 architecture
>  *
> -*  Copyright (c) 2011-2014, ARM Limited. All rights reserved.
> +*  Copyright (c) 2011-2020, ARM Limited. All rights reserved.
>  *  Copyright (c) 2016, Linaro Limited. All rights reserved.
>  *  Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
>  *
> @@ -121,19 +121,150 @@ GetRootTranslationTableInfo (
>  
>  STATIC
>  VOID
> -ReplaceLiveEntry (
> +ReplaceTableEntry (
>    IN  UINT64  *Entry,
>    IN  UINT64  Value,
> -  IN  UINT64  RegionStart
> +  IN  UINT64  RegionStart,
> +  IN  BOOLEAN IsLiveBlockMapping
>    )
>  {
> -  if (!ArmMmuEnabled ()) {
> +  if (!ArmMmuEnabled () || !IsLiveBlockMapping) {
>      *Entry = Value;
> +    ArmUpdateTranslationTableEntry (Entry, (VOID *)(UINTN)RegionStart);
>    } else {
>      ArmReplaceLiveTranslationEntry (Entry, Value, RegionStart);
>    }
>  }
>  
> +STATIC
> +VOID
> +FreePageTablesRecursive (
> +  IN  UINT64  *TranslationTable
> +  )
> +{
> +  UINTN   Index;
> +
> +  for (Index = 0; Index < TT_ENTRY_COUNT; Index++) {
> +    if ((TranslationTable[Index] & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY) {
> +      FreePageTablesRecursive ((VOID *)(UINTN)(TranslationTable[Index] &
> +                                               TT_ADDRESS_MASK_BLOCK_ENTRY));
> +    }
> +  }
> +  FreePages (TranslationTable, 1);
> +}
> +
> +STATIC
> +EFI_STATUS
> +UpdateRegionMappingRecursive (
> +  IN  UINT64      RegionStart,
> +  IN  UINT64      RegionEnd,
> +  IN  UINT64      AttributeSetMask,
> +  IN  UINT64      AttributeClearMask,
> +  IN  UINT64      *PageTable,
> +  IN  UINTN       Level
> +  )
> +{
> +  UINTN           BlockShift;
> +  UINT64          BlockMask;
> +  UINT64          BlockEnd;
> +  UINT64          *Entry;
> +  UINT64          EntryValue;
> +  VOID            *TranslationTable;
> +  EFI_STATUS      Status;
> +
> +  ASSERT (((RegionStart | RegionEnd) & EFI_PAGE_MASK) == 0);
> +
> +  BlockShift = (Level + 1) * BITS_PER_LEVEL + MIN_T0SZ;
> +  BlockMask = MAX_UINT64 >> BlockShift;
> +
> +  DEBUG ((DEBUG_VERBOSE, "%a(%d): %llx - %llx set %lx clr %lx\n", __FUNCTION__,
> +    Level, RegionStart, RegionEnd, AttributeSetMask, AttributeClearMask));
> +
> +  for (; RegionStart < RegionEnd; RegionStart = BlockEnd) {
> +    BlockEnd = MIN (RegionEnd, (RegionStart | BlockMask) + 1);
> +    Entry = &PageTable[(RegionStart >> (64 - BlockShift)) & (TT_ENTRY_COUNT - 1)];
> +
> +    //
> +    // If RegionStart or BlockEnd is not aligned to the block size at this
> +    // level, we will have to create a table mapping in order to map less
> +    // than a block, and recurse to create the block or page entries at
> +    // the next level. No block mappings are allowed at all at level 0,
> +    // so in that case, we have to recurse unconditionally.
> +    //
> +    if (Level == 0 || ((RegionStart | BlockEnd) & BlockMask) != 0) {
> +      ASSERT (Level < 3);
> +
> +      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
> +        //
> +        // No table entry exists yet, so we need to allocate a page table
> +        // for the next level.
> +        //
> +        TranslationTable = AllocatePages (1);
> +        if (TranslationTable == NULL) {
> +          return EFI_OUT_OF_RESOURCES;
> +        }
> +
> +        if ((*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
> +          //
> +          // We are splitting an existing block entry, so we have to populate
> +          // the new table with the attributes of the block entry it replaces.
> +          //
> +          Status = UpdateRegionMappingRecursive (RegionStart & ~BlockMask,
> +                     (RegionStart | BlockMask) + 1, *Entry & TT_ATTRIBUTES_MASK,
> +                     0, TranslationTable, Level + 1);
> +          if (EFI_ERROR (Status)) {
> +            //
> +            // The range we passed to UpdateRegionMappingRecursive () is block
> +            // aligned, so it is guaranteed that no further pages were allocated
> +            // by it, and so we only have to free the page we allocated here.
> +            //
> +            FreePages (TranslationTable, 1);
> +            return Status;
> +          }
> +        } else {
> +          ZeroMem (TranslationTable, EFI_PAGE_SIZE);
> +        }
> +      } else {
> +        TranslationTable = (VOID *)(UINTN)(*Entry & TT_ADDRESS_MASK_BLOCK_ENTRY);
> +      }
> +
> +      //
> +      // Recurse to the next level
> +      //
> +      Status = UpdateRegionMappingRecursive (RegionStart, BlockEnd,
> +                 AttributeSetMask, AttributeClearMask, TranslationTable,
> +                 Level + 1);
> +      if (EFI_ERROR (Status)) {
> +        if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
> +          //
> +          // We are creating a new table entry, so on failure, we can free all
> +          // allocations we made recursively, given that the whole subhierarchy
> +          // has not been wired into the live page tables yet. (This is not
> +          // possible for existing table entries, since we cannot revert the
> +          // modifications we made to the subhierarchy it represents.)
> +          //
> +          FreePageTablesRecursive (TranslationTable);
> +        }
> +        return Status;
> +      }
> +
> +      if ((*Entry & TT_TYPE_MASK) != TT_TYPE_TABLE_ENTRY) {
> +        EntryValue = (UINTN)TranslationTable | TT_TYPE_TABLE_ENTRY;
> +        ReplaceTableEntry (Entry, EntryValue, RegionStart,
> +                           (*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY);
> +      }
> +    } else {
> +      EntryValue = (*Entry & AttributeClearMask) | AttributeSetMask;
> +      EntryValue |= RegionStart;
> +      EntryValue |= (Level == 3) ? TT_TYPE_BLOCK_ENTRY_LEVEL3
> +                                 : TT_TYPE_BLOCK_ENTRY;
> +
> +      ReplaceTableEntry (Entry, EntryValue, RegionStart, FALSE);
> +    }
> +  }
> +  return EFI_SUCCESS;
> +}
> +
>  STATIC
>  VOID
>  LookupAddresstoRootTable (
> @@ -164,230 +295,28 @@ LookupAddresstoRootTable (
>    GetRootTranslationTableInfo (*T0SZ, NULL, TableEntryCount);
>  }
>  
> -STATIC
> -UINT64*
> -GetBlockEntryListFromAddress (
> -  IN  UINT64       *RootTable,
> -  IN  UINT64        RegionStart,
> -  OUT UINTN        *TableLevel,
> -  IN OUT UINT64    *BlockEntrySize,
> -  OUT UINT64      **LastBlockEntry
> -  )
> -{
> -  UINTN   RootTableLevel;
> -  UINTN   RootTableEntryCount;
> -  UINT64 *TranslationTable;
> -  UINT64 *BlockEntry;
> -  UINT64 *SubTableBlockEntry;
> -  UINT64  BlockEntryAddress;
> -  UINTN   BaseAddressAlignment;
> -  UINTN   PageLevel;
> -  UINTN   Index;
> -  UINTN   IndexLevel;
> -  UINTN   T0SZ;
> -  UINT64  Attributes;
> -  UINT64  TableAttributes;
> -
> -  // Initialize variable
> -  BlockEntry = NULL;
> -
> -  // Ensure the parameters are valid
> -  if (!(TableLevel && BlockEntrySize && LastBlockEntry)) {
> -    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
> -    return NULL;
> -  }
> -
> -  // Ensure the Region is aligned on 4KB boundary
> -  if ((RegionStart & (SIZE_4KB - 1)) != 0) {
> -    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
> -    return NULL;
> -  }
> -
> -  // Ensure the required size is aligned on 4KB boundary and not 0
> -  if ((*BlockEntrySize & (SIZE_4KB - 1)) != 0 || *BlockEntrySize == 0) {
> -    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
> -    return NULL;
> -  }
> -
> -  T0SZ = ArmGetTCR () & TCR_T0SZ_MASK;
> -  // Get the Table info from T0SZ
> -  GetRootTranslationTableInfo (T0SZ, &RootTableLevel, &RootTableEntryCount);
> -
> -  // If the start address is 0x0 then we use the size of the region to identify the alignment
> -  if (RegionStart == 0) {
> -    // Identify the highest possible alignment for the Region Size
> -    BaseAddressAlignment = LowBitSet64 (*BlockEntrySize);
> -  } else {
> -    // Identify the highest possible alignment for the Base Address
> -    BaseAddressAlignment = LowBitSet64 (RegionStart);
> -  }
> -
> -  // Identify the Page Level the RegionStart must belong to. Note that PageLevel
> -  // should be at least 1 since block translations are not supported at level 0
> -  PageLevel = MAX (3 - ((BaseAddressAlignment - 12) / 9), 1);
> -
> -  // If the required size is smaller than the current block size then we need to go to the page below.
> -  // The PageLevel was calculated on the Base Address alignment but did not take in account the alignment
> -  // of the allocation size
> -  while (*BlockEntrySize < TT_BLOCK_ENTRY_SIZE_AT_LEVEL (PageLevel)) {
> -    // It does not fit so we need to go a page level above
> -    PageLevel++;
> -  }
> -
> -  //
> -  // Get the Table Descriptor for the corresponding PageLevel. We need to decompose RegionStart to get appropriate entries
> -  //
> -
> -  TranslationTable = RootTable;
> -  for (IndexLevel = RootTableLevel; IndexLevel <= PageLevel; IndexLevel++) {
> -    BlockEntry = (UINT64*)TT_GET_ENTRY_FOR_ADDRESS (TranslationTable, IndexLevel, RegionStart);
> -
> -    if ((IndexLevel != 3) && ((*BlockEntry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY)) {
> -      // Go to the next table
> -      TranslationTable = (UINT64*)(*BlockEntry & TT_ADDRESS_MASK_DESCRIPTION_TABLE);
> -
> -      // If we are at the last level then update the last level to next level
> -      if (IndexLevel == PageLevel) {
> -        // Enter the next level
> -        PageLevel++;
> -      }
> -    } else if ((*BlockEntry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
> -      // If we are not at the last level then we need to split this BlockEntry
> -      if (IndexLevel != PageLevel) {
> -        // Retrieve the attributes from the block entry
> -        Attributes = *BlockEntry & TT_ATTRIBUTES_MASK;
> -
> -        // Convert the block entry attributes into Table descriptor attributes
> -        TableAttributes = TT_TABLE_AP_NO_PERMISSION;
> -        if (Attributes & TT_NS) {
> -          TableAttributes = TT_TABLE_NS;
> -        }
> -
> -        // Get the address corresponding at this entry
> -        BlockEntryAddress = RegionStart;
> -        BlockEntryAddress = BlockEntryAddress >> TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel);
> -        // Shift back to right to set zero before the effective address
> -        BlockEntryAddress = BlockEntryAddress << TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel);
> -
> -        // Set the correct entry type for the next page level
> -        if ((IndexLevel + 1) == 3) {
> -          Attributes |= TT_TYPE_BLOCK_ENTRY_LEVEL3;
> -        } else {
> -          Attributes |= TT_TYPE_BLOCK_ENTRY;
> -        }
> -
> -        // Create a new translation table
> -        TranslationTable = AllocatePages (1);
> -        if (TranslationTable == NULL) {
> -          return NULL;
> -        }
> -
> -        // Populate the newly created lower level table
> -        SubTableBlockEntry = TranslationTable;
> -        for (Index = 0; Index < TT_ENTRY_COUNT; Index++) {
> -          *SubTableBlockEntry = Attributes | (BlockEntryAddress + (Index << TT_ADDRESS_OFFSET_AT_LEVEL(IndexLevel + 1)));
> -          SubTableBlockEntry++;
> -        }
> -
> -        // Fill the BlockEntry with the new TranslationTable
> -        ReplaceLiveEntry (BlockEntry,
> -          (UINTN)TranslationTable | TableAttributes | TT_TYPE_TABLE_ENTRY,
> -          RegionStart);
> -      }
> -    } else {
> -      if (IndexLevel != PageLevel) {
> -        //
> -        // Case when we have an Invalid Entry and we are at a page level above of the one targetted.
> -        //
> -
> -        // Create a new translation table
> -        TranslationTable = AllocatePages (1);
> -        if (TranslationTable == NULL) {
> -          return NULL;
> -        }
> -
> -        ZeroMem (TranslationTable, TT_ENTRY_COUNT * sizeof(UINT64));
> -
> -        // Fill the new BlockEntry with the TranslationTable
> -        *BlockEntry = ((UINTN)TranslationTable & TT_ADDRESS_MASK_DESCRIPTION_TABLE) | TT_TYPE_TABLE_ENTRY;
> -      }
> -    }
> -  }
> -
> -  // Expose the found PageLevel to the caller
> -  *TableLevel = PageLevel;
> -
> -  // Now, we have the Table Level we can get the Block Size associated to this table
> -  *BlockEntrySize = TT_BLOCK_ENTRY_SIZE_AT_LEVEL (PageLevel);
> -
> -  // The last block of the root table depends on the number of entry in this table,
> -  // otherwise it is always the (TT_ENTRY_COUNT - 1)th entry in the table.
> -  *LastBlockEntry = TT_LAST_BLOCK_ADDRESS(TranslationTable,
> -      (PageLevel == RootTableLevel) ? RootTableEntryCount : TT_ENTRY_COUNT);
> -
> -  return BlockEntry;
> -}
> -
>  STATIC
>  EFI_STATUS
>  UpdateRegionMapping (
> -  IN  UINT64  *RootTable,
>    IN  UINT64  RegionStart,
>    IN  UINT64  RegionLength,
> -  IN  UINT64  Attributes,
> -  IN  UINT64  BlockEntryMask
> +  IN  UINT64  AttributeSetMask,
> +  IN  UINT64  AttributeClearMask
>    )
>  {
> -  UINT32  Type;
> -  UINT64  *BlockEntry;
> -  UINT64  *LastBlockEntry;
> -  UINT64  BlockEntrySize;
> -  UINTN   TableLevel;
> +  UINTN     RootTableLevel;
> +  UINTN     T0SZ;
>  
> -  // Ensure the Length is aligned on 4KB boundary
> -  if ((RegionLength == 0) || ((RegionLength & (SIZE_4KB - 1)) != 0)) {
> -    ASSERT_EFI_ERROR (EFI_INVALID_PARAMETER);
> +  if (((RegionStart | RegionLength) & EFI_PAGE_MASK)) {
>      return EFI_INVALID_PARAMETER;
>    }
>  
> -  do {
> -    // Get the first Block Entry that matches the Virtual Address and also the information on the Table Descriptor
> -    // such as the size of the Block Entry and the address of the last BlockEntry of the Table Descriptor
> -    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
> -      return EFI_OUT_OF_RESOURCES;
> -    }
> +  T0SZ = ArmGetTCR () & TCR_T0SZ_MASK;
> +  GetRootTranslationTableInfo (T0SZ, &RootTableLevel, NULL);
>  
> -    if (TableLevel != 3) {
> -      Type = TT_TYPE_BLOCK_ENTRY;
> -    } else {
> -      Type = TT_TYPE_BLOCK_ENTRY_LEVEL3;
> -    }
> -
> -    do {
> -      // Fill the Block Entry with attribute and output block address
> -      *BlockEntry &= BlockEntryMask;
> -      *BlockEntry |= (RegionStart & TT_ADDRESS_MASK_BLOCK_ENTRY) | Attributes | Type;
> -
> -      ArmUpdateTranslationTableEntry (BlockEntry, (VOID *)RegionStart);
> -
> -      // Go to the next BlockEntry
> -      RegionStart += BlockEntrySize;
> -      RegionLength -= BlockEntrySize;
> -      BlockEntry++;
> -
> -      // Break the inner loop when next block is a table
> -      // Rerun GetBlockEntryListFromAddress to avoid page table memory leak
> -      if (TableLevel != 3 && BlockEntry <= LastBlockEntry &&
> -          (*BlockEntry & TT_TYPE_MASK) == TT_TYPE_TABLE_ENTRY) {
> -            break;
> -      }
> -    } while ((RegionLength >= BlockEntrySize) && (BlockEntry <= LastBlockEntry));
> -  } while (RegionLength != 0);
> -
> -  return EFI_SUCCESS;
> +  return UpdateRegionMappingRecursive (RegionStart, RegionStart + RegionLength,
> +           AttributeSetMask, AttributeClearMask, ArmGetTTBR0BaseAddress (),
> +           RootTableLevel);
>  }
>  
>  STATIC
> @@ -398,7 +327,6 @@ FillTranslationTable (
>    )
>  {
>    return UpdateRegionMapping (
> -           RootTable,
>             MemoryRegion->VirtualBase,
>             MemoryRegion->Length,
>             ArmMemoryAttributeToPageAttribute (MemoryRegion->Attributes) | TT_AF,
> @@ -455,8 +383,6 @@ ArmSetMemoryAttributes (
>    IN UINT64                    Attributes
>    )
>  {
> -  EFI_STATUS                   Status;
> -  UINT64                      *TranslationTable;
>    UINT64                       PageAttributes;
>    UINT64                       PageAttributeMask;
>  
> @@ -473,19 +399,8 @@ ArmSetMemoryAttributes (
>                            TT_PXN_MASK | TT_XN_MASK);
>    }
>  
> -  TranslationTable = ArmGetTTBR0BaseAddress ();
> -
> -  Status = UpdateRegionMapping (
> -             TranslationTable,
> -             BaseAddress,
> -             Length,
> -             PageAttributes,
> -             PageAttributeMask);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  return EFI_SUCCESS;
> +  return UpdateRegionMapping (BaseAddress, Length, PageAttributes,
> +           PageAttributeMask);
>  }
>  
>  STATIC
> @@ -497,17 +412,7 @@ SetMemoryRegionAttribute (
>    IN  UINT64                    BlockEntryMask
>    )
>  {
> -  EFI_STATUS                   Status;
> -  UINT64                       *RootTable;
> -
> -  RootTable = ArmGetTTBR0BaseAddress ();
> -
> -  Status = UpdateRegionMapping (RootTable, BaseAddress, Length, Attributes, BlockEntryMask);
> -  if (EFI_ERROR (Status)) {
> -    return Status;
> -  }
> -
> -  return EFI_SUCCESS;
> +  return UpdateRegionMapping (BaseAddress, Length, Attributes, BlockEntryMask);
>  }
>  
>  EFI_STATUS
> -- 
> 2.17.1
> 

[PATCH v4 2/2] ArmPkg/ArmMmuLib AARCH64: invalidate page tables before populating them

[Ard Biesheuvel]

As it turns out, ARMv8 also permits accesses made with the MMU and
caches off to hit in the caches, so to ensure that any modifications
we make before enabling the MMU are visible afterwards as well, we
should invalidate page tables right after allocation like we do now on
ARM, if the MMU is still disabled at that point.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>
---
 ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index 00a38bc31d0a..221175ca6535 100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -204,6 +204,14 @@ UpdateRegionMappingRecursive (
           return EFI_OUT_OF_RESOURCES;
         }
 
+        if (!ArmMmuEnabled ()) {
+          //
+          // Make sure we are not inadvertently hitting in the caches
+          // when populating the page tables.
+          //
+          InvalidateDataCacheRange (TranslationTable, EFI_PAGE_SIZE);
+        }
+
         if ((*Entry & TT_TYPE_MASK) == TT_TYPE_BLOCK_ENTRY) {
           //
           // We are splitting an existing block entry, so we have to populate
@@ -602,6 +610,12 @@ ArmConfigureMmu (
     *TranslationTableSize = RootTableEntryCount * sizeof(UINT64);
   }
 
+  //
+  // Make sure we are not inadvertently hitting in the caches
+  // when populating the page tables.
+  //
+  InvalidateDataCacheRange (TranslationTable,
+    RootTableEntryCount * sizeof(UINT64));
   ZeroMem (TranslationTable, RootTableEntryCount * sizeof(UINT64));
 
   TranslationTableAttribute = TT_ATTR_INDX_INVALID;
-- 
2.17.1

Re: [edk2-devel] [PATCH v4 0/2] ArmPkg/ArmMmuLib: rewrite and improve cache handling with MMU off

[Laszlo Ersek]

On 03/07/20 09:38, Ard Biesheuvel wrote:
> I finally got fed up with the state of the AArch64 MMU handling code, and
> decided to rewrite it before rebasing the cache invalidation fix onto
> it.
> 
> Changes since v3:
> - move code for better diffing
> - free allocated page tables on failure if it is safe to do so
> - some minor style tweaks
> - add Leif's ack to #2
> 
> Ard Biesheuvel (2):
>   ArmPkg/ArmMmuLib AARCH64: rewrite page table code
>   ArmPkg/ArmMmuLib AARCH64: invalidate page tables before populating
>     them
> 
>  .../Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 405 +++++++-----------
>  1 file changed, 162 insertions(+), 243 deletions(-)
> 

Commit range
a3e25cc8a1dd3d1ea24ed02f90c44221e015e965..748fea6279efc20de3fef483deb4b774f3c34906,
via <https://github.com/tianocore/edk2/pull/431>.

Thanks
Laszlo