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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(
      <code accessing page 0>
    );

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
This commit is contained in:
Jian J Wang 2017-12-05 15:57:38 +08:00 committed by Star Zeng
parent 2b55daaef0
commit 7619eed8aa
1 changed files with 36 additions and 0 deletions
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36
IntelFrameworkPkg/Include/Protocol/LegacyBios.h
View File

@ -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