IntelFrameworkModulePkg/Csm: Add code to bypass NULL pointer detection

[mirror_edk2.git] / IntelFrameworkModulePkg / Csm / LegacyBiosDxe / LegacyPci.c

diff --git a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
index 8ffdf0c1ff9551ad06f0bc8070b3d26243d3b442..d38cef3e33e26f5d3b0f85d4e0d24c0b909091a9 100644 (file)
--- a/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
+++ b/IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyPci.c
@@ -2279,6 +2279,7 @@ LegacyBiosInstallRom (
   UINTN                 Function;\r
   EFI_IA32_REGISTER_SET Regs;\r
   UINT8                 VideoMode;\r
+  UINT8                 OldVideoMode;\r
   EFI_TIME              BootTime;\r
   UINT32                *BdaPtr;\r
   UINT32                LocalTime;\r
@@ -2299,6 +2300,7 @@ LegacyBiosInstallRom (
   Device          = 0;\r
   Function        = 0;\r
   VideoMode       = 0;\r
+  OldVideoMode    = 0;\r
   PhysicalAddress = 0;\r
   MaxRomAddr      = PcdGet32 (PcdEndOpromShadowAddress);\r
 \r
@@ -2401,6 +2403,8 @@ LegacyBiosInstallRom (
   // 2. BBS compliants drives will not change 40:75 until boot time.\r
   // 3. Onboard IDE controllers will change 40:75\r
   //\r
+  DisableNullDetection ();\r
+\r
   LocalDiskStart = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);\r
   if ((Private->Disk4075 + 0x80) < LocalDiskStart) {\r
     //\r
@@ -2426,6 +2430,9 @@ LegacyBiosInstallRom (
     //\r
     VideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));\r
   }\r
+\r
+  EnableNullDetection ();\r
+\r
   //\r
   // Notify the platform that we are about to scan the ROM\r
   //\r
@@ -2466,9 +2473,11 @@ LegacyBiosInstallRom (
   // Multiply result by 18.2 for number of ticks since midnight.\r
   // Use 182/10 to avoid floating point math.\r
   //\r
+  DisableNullDetection ();\r
   LocalTime = (LocalTime * 182) / 10;\r
   BdaPtr    = (UINT32 *) ((UINTN) 0x46C);\r
   *BdaPtr   = LocalTime;\r
+  EnableNullDetection ();\r
   \r
   //\r
   // Pass in handoff data\r
@@ -2564,7 +2573,11 @@ LegacyBiosInstallRom (
     //\r
     // Set mode settings since PrepareToScanRom may change mode\r
     //\r
-    if (VideoMode != *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE))) {\r
+    DisableNullDetection ();\r
+    OldVideoMode = *(UINT8 *) ((UINTN) (0x400 + BDA_VIDEO_MODE));\r
+    EnableNullDetection ();\r
+\r
+    if (VideoMode != OldVideoMode) {\r
       //\r
       // The active video mode is changed, restore it to original mode.\r
       //\r
@@ -2604,7 +2617,9 @@ LegacyBiosInstallRom (
     }\r
   }\r
 \r
+  DisableNullDetection ();\r
   LocalDiskEnd = (UINT8) ((*(UINT8 *) ((UINTN) 0x475)) + 0x80);\r
+  EnableNullDetection ();\r
   \r
   //\r
   // Allow platform to perform any required actions after the\r