X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=blobdiff_plain;f=IntelFrameworkPkg%2FInclude%2FProtocol%2FLegacyBios.h;h=00a149e38783c24089e0ba0afbc4186c7af3da55;hp=641f101bcedeb27902828cd0fb1827294e57bca0;hb=7619eed8aa260c9527d72ccd525ce70060b64f1f;hpb=2b55daaef0f3f53059c5c858ca6fd53b03eb5d4c

diff --git a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
index 641f101bce..00a149e387 100644
--- a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
+++ b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
@@ -1518,6 +1518,42 @@ struct _EFI_LEGACY_BIOS_PROTOCOL {
   EFI_LEGACY_BIOS_BOOT_UNCONVENTIONAL_DEVICE  BootUnconventionalDevice;
 };
 
+//
+// Legacy BIOS needs to access memory in page 0 (0-4095), which is disabled if
+// NULL pointer detection feature is enabled. Following macro can be used to
+// enable/disable page 0 before/after accessing it.
+//
+#define ACCESS_PAGE0_CODE(statements)                           \
+  do {                                                          \
+    EFI_STATUS                            Status_;              \
+    EFI_GCD_MEMORY_SPACE_DESCRIPTOR       Desc_;                \
+                                                                \
+    Desc_.Attributes = 0;                                       \
+    Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_);        \
+    ASSERT_EFI_ERROR (Status_);                                 \
+    if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
+      Status_ = gDS->SetMemorySpaceAttributes (                 \
+                      0,                                        \
+                      EFI_PAGES_TO_SIZE(1),                     \
+                      Desc_.Attributes & ~(UINT64)EFI_MEMORY_RP \
+                      );                                        \
+      ASSERT_EFI_ERROR (Status_);                               \
+    }                                                           \
+                                                                \
+    {                                                           \
+      statements;                                               \
+    }                                                           \
+                                                                \
+    if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) {              \
+      Status_ = gDS->SetMemorySpaceAttributes (                 \
+                      0,                                        \
+                      EFI_PAGES_TO_SIZE(1),                     \
+                      Desc_.Attributes                          \
+                      );                                        \
+      ASSERT_EFI_ERROR (Status_);                               \
+    }                                                           \
+  } while (FALSE)
+
 extern EFI_GUID gEfiLegacyBiosProtocolGuid;
 
 #endif