[PATCH 2/2] UefiCpuPkg/CpuDxe: Fix multiple entries of RT_CODE in memory map

[Jian J Wang <jian.j.wang@intel.com>]

> v6:
>    Add ExecuteDisable feature check to include/exclude EFI_MEMORY_XP

> v5:
>    Coding style clean-up

> v4:
> a. Remove DoUpdate and check attributes mismatch all the time to avoid
>    a logic hole
> b. Add warning message if failed to update capability
> c. Add local variable to hold new attributes to make code cleaner

> v3:
> a. Add comment to explain more on updating memory capabilities
> b. Fix logic hole in updating attributes
> c. Instead of checking illegal memory space address and size, use return
>    status of gDS->SetMemorySpaceCapabilities() to skip memory block which
>    cannot be updated with new capabilities.

> v2
> a. Fix an issue which will cause setting capability failure if size is smaller
>    than a page.

More than one entry of RT_CODE memory might cause boot problem for some
old OSs. This patch will fix this issue to keep OS compatibility as much
as possible.

More detailed information, please refer to
    https://bugzilla.tianocore.org/show_bug.cgi?id=753

Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
 UefiCpuPkg/CpuDxe/CpuPageTable.c | 94 +++++++++++++++++++++++++++++++---------
 1 file changed, 73 insertions(+), 21 deletions(-)

diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c b/UefiCpuPkg/CpuDxe/CpuPageTable.c
index d312eb66f8..3297c1900b 100644
--- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
+++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
@@ -769,6 +769,20 @@ AssignMemoryPageAttributes (
   return Status;
 }
 
+/**
+ Check if Execute Disable feature is enabled or not.
+**/
+BOOLEAN
+IsExecuteDisableEnabled (
+  VOID
+  )
+{
+  MSR_CORE_IA32_EFER_REGISTER    MsrEfer;
+
+  MsrEfer.Uint64 = AsmReadMsr64 (MSR_IA32_EFER);
+  return (MsrEfer.Bits.NXE == 1);
+}
+
 /**
   Update GCD memory space attributes according to current page table setup.
 **/
@@ -790,7 +804,7 @@ RefreshGcdMemoryAttributesFromPaging (
   UINT64                              PageStartAddress;
   UINT64                              Attributes;
   UINT64                              Capabilities;
-  BOOLEAN                             DoUpdate;
+  UINT64                              NewAttributes;
   UINTN                               Index;
 
   //
@@ -802,17 +816,50 @@ RefreshGcdMemoryAttributesFromPaging (
 
   GetCurrentPagingContext (&PagingContext);
 
-  DoUpdate      = FALSE;
-  Capabilities  = 0;
-  Attributes    = 0;
-  BaseAddress   = 0;
-  PageLength    = 0;
+  Attributes      = 0;
+  NewAttributes   = 0;
+  BaseAddress     = 0;
+  PageLength      = 0;
+
+  if (IsExecuteDisableEnabled ()) {
+    Capabilities = EFI_MEMORY_RO | EFI_MEMORY_RP | EFI_MEMORY_XP;
+  } else {
+    Capabilities = EFI_MEMORY_RO | EFI_MEMORY_RP;
+  }
 
   for (Index = 0; Index < NumberOfDescriptors; Index++) {
     if (MemorySpaceMap[Index].GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
       continue;
     }
 
+    //
+    // Sync the actual paging related capabilities back to GCD service first.
+    // As a side effect (good one), this can also help to avoid unnecessary
+    // memory map entries due to the different capabilities of the same type
+    // memory, such as multiple RT_CODE and RT_DATA entries in memory map,
+    // which could cause boot failure of some old Linux distro (before v4.3).
+    //
+    Status = gDS->SetMemorySpaceCapabilities (
+                    MemorySpaceMap[Index].BaseAddress,
+                    MemorySpaceMap[Index].Length,
+                    MemorySpaceMap[Index].Capabilities | Capabilities
+                    );
+    if (EFI_ERROR (Status)) {
+      //
+      // If we cannot udpate the capabilities, we cannot update its
+      // attributes either. So just simply skip current block of memory.
+      //
+      DEBUG ((
+        DEBUG_WARN,
+        "Failed to update capability: [%lu] %016lx - %016lx (%016lx -> %016lx)\r\n",
+        (UINT64)Index, MemorySpaceMap[Index].BaseAddress,
+        MemorySpaceMap[Index].BaseAddress + MemorySpaceMap[Index].Length - 1,
+        MemorySpaceMap[Index].Capabilities,
+        MemorySpaceMap[Index].Capabilities | Capabilities
+        ));
+      continue;
+    }
+
     if (MemorySpaceMap[Index].BaseAddress >= (BaseAddress + PageLength)) {
       //
       // Current memory space starts at a new page. Resetting PageLength will
@@ -826,7 +873,9 @@ RefreshGcdMemoryAttributesFromPaging (
       PageLength -= (MemorySpaceMap[Index].BaseAddress - BaseAddress);
     }
 
-    // Sync real page attributes to GCD
+    //
+    // Sync actual page attributes to GCD
+    //
     BaseAddress       = MemorySpaceMap[Index].BaseAddress;
     MemorySpaceLength = MemorySpaceMap[Index].Length;
     while (MemorySpaceLength > 0) {
@@ -842,23 +891,26 @@ RefreshGcdMemoryAttributesFromPaging (
         PageStartAddress  = (*PageEntry) & (UINT64)PageAttributeToMask(PageAttribute);
         PageLength        = PageAttributeToLength (PageAttribute) - (BaseAddress - PageStartAddress);
         Attributes        = GetAttributesFromPageEntry (PageEntry);
-
-        if (Attributes != (MemorySpaceMap[Index].Attributes & EFI_MEMORY_PAGETYPE_MASK)) {
-          DoUpdate = TRUE;
-          Attributes |= (MemorySpaceMap[Index].Attributes & ~EFI_MEMORY_PAGETYPE_MASK);
-          Capabilities = Attributes | MemorySpaceMap[Index].Capabilities;
-        } else {
-          DoUpdate = FALSE;
-        }
       }
 
       Length = MIN (PageLength, MemorySpaceLength);
-      if (DoUpdate) {
-        gDS->SetMemorySpaceCapabilities (BaseAddress, Length, Capabilities);
-        gDS->SetMemorySpaceAttributes (BaseAddress, Length, Attributes);
-        DEBUG ((DEBUG_INFO, "Update memory space attribute: [%02d] %016lx - %016lx (%08lx -> %08lx)\r\n",
-                             Index, BaseAddress, BaseAddress + Length - 1,
-                             MemorySpaceMap[Index].Attributes, Attributes));
+      if (Attributes != (MemorySpaceMap[Index].Attributes &
+                         EFI_MEMORY_PAGETYPE_MASK)) {
+        NewAttributes = (MemorySpaceMap[Index].Attributes &
+                         ~EFI_MEMORY_PAGETYPE_MASK) | Attributes;
+        Status = gDS->SetMemorySpaceAttributes (
+                        BaseAddress,
+                        Length,
+                        NewAttributes
+                        );
+        ASSERT_EFI_ERROR (Status);
+        DEBUG ((
+          DEBUG_INFO,
+          "Updated memory space attribute: [%lu] %016lx - %016lx (%016lx -> %016lx)\r\n",
+          (UINT64)Index, BaseAddress, BaseAddress + Length - 1,
+          MemorySpaceMap[Index].Attributes,
+          NewAttributes
+          ));
       }
 
       PageLength        -= Length;
-- 
2.14.1.windows.1