Remove AdvancedLogger MmCoreArm dependence on global variables.

AdvLoggerPkg/Library/AdvancedLoggerLib/MmCoreArm/AdvancedLoggerLib.c

@@ -15,63 +15,13 @@
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/SynchronizationLib.h>
-#include <Library/MmuLib.h>
 
 #include "../AdvancedLoggerCommon.h"
 
-#define ADV_LOGGER_MIN_SIZE  (65536)
-
-STATIC ADVANCED_LOGGER_INFO  *mLoggerInfo = NULL;
-STATIC UINT32                mBufferSize  = 0;
-STATIC EFI_PHYSICAL_ADDRESS  mMaxAddress  = 0;
-STATIC BOOLEAN               mInitialized = FALSE;
-
-/**
-  Validate Info Blocks
-
-  The address of the ADVANCE_LOGGER_INFO block pointer is captured during the first debug print.  The
-  pointers LogBuffer and LogCurrent, and LogBufferSize, could be written to by untrusted code.  Here,
-  we check that the pointers are within the allocated mLoggerInfo space, and that LogBufferSize, which
-  is used in multiple places to see if a new message will fit into the log buffer, is valid.
-
-  @param          NONE
-
-  @return         BOOLEAN     TRUE = mLoggerInfo Block passes security checks
-  @return         BOOLEAN     FALSE= mLoggerInfo Block failed security checks
-
-**/
-STATIC
-BOOLEAN
-ValidateInfoBlock (
-  VOID
-  )
-{
-  if (mLoggerInfo == NULL) {
-    return FALSE;
-  }
-
-  if (mLoggerInfo->Signature != ADVANCED_LOGGER_SIGNATURE) {
-    return FALSE;
-  }
-
-  if (mLoggerInfo->LogBuffer != (PA_FROM_PTR (mLoggerInfo + 1))) {
-    return FALSE;
-  }
-
-  if ((mLoggerInfo->LogCurrent > mMaxAddress) ||
-      (mLoggerInfo->LogCurrent < mLoggerInfo->LogBuffer))
-  {
-    return FALSE;
-  }
-
-  if (mBufferSize == 0) {
-    mBufferSize = mLoggerInfo->LogBufferSize;
-  } else if (mLoggerInfo->LogBufferSize != mBufferSize) {
-    return FALSE;
-  }
-
-  return TRUE;
-}
+//
+// NO GLOBALS! This routine may run before data sections are writable, and so
+// cannot presume globals will be available.
+//
 
 /**
   The logger Information Block is carved from the Trust Zone at a specific fixed address.
@@ -87,8 +37,8 @@ ValidateInfoBlock (
   PcdAdvancedLoggerCarBase     -- NOT USED, leave at default
   PcdAdvancedLoggerPreMemPages -- NOT USED, leave at default
 
-  NOTE:  A debug statement here will cause recursion.  Insure that the recursion will be
-         a straight path just to return the existing mLoggerInfo.
+  NOTE:  A debug statement here will cause recursion. Avoid debug statements
+         or calls to external functions that may contain debug prints.
 
   @param       - None
 
@@ -102,48 +52,52 @@ AdvancedLoggerGetLoggerInfo (
   VOID
   )
 {
-  EFI_STATUS            Status;
-  EFI_PHYSICAL_ADDRESS  Address;
+  ADVANCED_LOGGER_INFO  *LoggerInfo;
+  EFI_PHYSICAL_ADDRESS  MaxAddress;
 
   ASSERT (FeaturePcdGet (PcdAdvancedLoggerFixedInRAM));
   if (!FeaturePcdGet (PcdAdvancedLoggerFixedInRAM)) {
     return NULL;
   }
 
-  if (!mInitialized) {
-    // If this is the first time for MM core to get here, the memory attributes of this module
-    // may not be fully set yet. Thus set the memory for global variables attributes to RW first.
-    Address = ALIGN_VALUE ((EFI_PHYSICAL_ADDRESS)(UINTN)&mInitialized - EFI_PAGE_SIZE + 1, EFI_PAGE_SIZE);
-    Status  = MmuSetAttributes (Address, EFI_PAGE_SIZE, EFI_MEMORY_XP);
-    ASSERT_EFI_ERROR (Status);
-    Status = MmuClearAttributes (Address, EFI_PAGE_SIZE, EFI_MEMORY_RO);
-    ASSERT_EFI_ERROR (Status);
-
-    Address = ALIGN_VALUE ((EFI_PHYSICAL_ADDRESS)(UINTN)&mLoggerInfo - EFI_PAGE_SIZE + 1, EFI_PAGE_SIZE);
-    Status  = MmuSetAttributes (Address, EFI_PAGE_SIZE, EFI_MEMORY_XP);
-    ASSERT_EFI_ERROR (Status);
-    Status = MmuClearAttributes (Address, EFI_PAGE_SIZE, EFI_MEMORY_RO);
-    ASSERT_EFI_ERROR (Status);
-
-    mInitialized = TRUE;            // Only allow initialization once
-    mLoggerInfo  = (ADVANCED_LOGGER_INFO *)(VOID *)FixedPcdGet64 (PcdAdvancedLoggerBase);
-    ASSERT (mLoggerInfo != NULL);
-    if (mLoggerInfo == NULL) {
-      return NULL;
-    }
-
-    mLoggerInfo->HwPrintLevel = FixedPcdGet32 (PcdAdvancedLoggerHdwPortDebugPrintErrorLevel);
-
-    mMaxAddress = mLoggerInfo->LogBuffer + mLoggerInfo->LogBufferSize;
-    mBufferSize = mLoggerInfo->LogBufferSize;
+  LoggerInfo = (ADVANCED_LOGGER_INFO *)(VOID *)FixedPcdGet64 (PcdAdvancedLoggerBase);
+  if (LoggerInfo == NULL) {
+    return NULL;
+  }
+
+  //
+  // The pointers LogBuffer and LogCurrent, and LogBufferSize, could be written
+  // to by untrusted code.  Here, we check that the pointers are within the
+  // allocated LoggerInfo space, and that LogBufferSize, which is used in
+  // multiple places to see if a new message will fit into the log buffer, is
+  // valid.
+  //
+
+  if (LoggerInfo->Signature != ADVANCED_LOGGER_SIGNATURE) {
+    return NULL;
+  }
+
+  // Ensure the start of the log is in the correct location.
+  if (LoggerInfo->LogBuffer != (PA_FROM_PTR (LoggerInfo + 1))) {
+    return NULL;
   }
 
-  if (((mLoggerInfo) != NULL) && !ValidateInfoBlock ()) {
-    mLoggerInfo = NULL;
-    DEBUG ((DEBUG_ERROR, "%a: LoggerInfo marked invalid\n", __FUNCTION__));
+  // Make sure the size of the buffer does not overrun it's fixed size.
+  MaxAddress = LoggerInfo->LogBuffer + LoggerInfo->LogBufferSize;
+  if ((MaxAddress - PA_FROM_PTR (LoggerInfo)) >
+      (FixedPcdGet32 (PcdAdvancedLoggerPages) * EFI_PAGE_SIZE))
+  {
+    return NULL;
+  }
+
+  // Ensure the current pointer does not overrun.
+  if ((LoggerInfo->LogCurrent > MaxAddress) ||
+      (LoggerInfo->LogCurrent < LoggerInfo->LogBuffer))
+  {
+    return NULL;
   }
 
-  return mLoggerInfo;
+  return LoggerInfo;
 }
 
 /**

AdvLoggerPkg/Library/AdvancedLoggerLib/MmCoreArm/AdvancedLoggerLib.inf

@@ -36,7 +36,6 @@
   BaseMemoryLib
   DebugLib
   SynchronizationLib
-  MmuLib
 
 [Guids]
   gAdvancedLoggerHobGuid