From 7619eed8aa260c9527d72ccd525ce70060b64f1f Mon Sep 17 00:00:00 2001 From: Jian J Wang Date: Tue, 5 Dec 2017 15:57:38 +0800 Subject: [PATCH 1/1] IntelFrameworkPkg/LegacyBios.h: Add a macro to guarantee page 0 access Due to the introduction of NULL pointer detection feature, page 0 will be disabled if the feature is enabled, which will cause legacy code failed to update legacy data in page 0. This macro is introduced to make sure the page 0 is enabled before those code and restore the original status of it afterwards. Another reason to introduce this macro is to eliminate the dependency on the PcdNullPointerDetectionPropertyMask. Because this is a new PCD, it could cause some backward compatibility issue for some old packages. This macro will simply check if the page 0 is disabled or not. If it's disabled, it will enable it before code updating page 0 and disable it afterwards. Otherwise, this macro will do nothing to page 0. The usage of the macro will be look like (similar to DEBUG_CODE macro): ACCESS_PAGE0_CODE( ); Cc: Liming Gao Cc: Michael D Kinney Cc: Ruiyu Ni Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang Reviewed-by: Ruiyu Ni --- .../Include/Protocol/LegacyBios.h | 36 +++++++++++++++++++ 1 file changed, 36 insertions(+) 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 -- 2.39.2