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>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
---
IntelFrameworkPkg/Include/Protocol/LegacyBios.h | 34 +++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
index 641f101bce..f77c92ba21 100644
--- a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
+++ b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h
@@ -1518,6 +1518,40 @@ 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_; \
+ \
+ Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_); \
+ if (!EFI_ERROR (Status_)) { \
+ if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) { \
+ Status_ = gDS->SetMemorySpaceAttributes ( \
+ 0, \
+ EFI_PAGES_TO_SIZE(1), \
+ Desc_.Attributes &= ~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
--
2.15.1.windows.2
_______________________________________________
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On 12/6/2017 3:31 PM, Jian J Wang wrote: > 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> > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Jian J Wang <jian.j.wang@intel.com> > --- > IntelFrameworkPkg/Include/Protocol/LegacyBios.h | 34 +++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > > diff --git a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > index 641f101bce..f77c92ba21 100644 > --- a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > +++ b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > @@ -1518,6 +1518,40 @@ 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_; \ > + \ > + Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_); \ > + if (!EFI_ERROR (Status_)) { \ > + if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) { \ > + Status_ = gDS->SetMemorySpaceAttributes ( \ > + 0, \ > + EFI_PAGES_TO_SIZE(1), \ > + Desc_.Attributes &= ~EFI_MEMORY_RP \ &= is used here so Desc_.Attributes is updated to have RP cleared. Then the below if will be always FALSE. > + ); \ > + 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 > -- Thanks, Ray _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
Good catch. I think it's a typo not on purpose. Many thanks! > -----Original Message----- > From: Ni, Ruiyu > Sent: Wednesday, December 06, 2017 5:31 PM > To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org > Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming > <liming.gao@intel.com> > Subject: Re: [edk2] [PATCH 1/3] IntelFrameworkPkg/LegacyBios.h: Add a macro > to guarantee page 0 access > > On 12/6/2017 3:31 PM, Jian J Wang wrote: > > 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> > > Contributed-under: TianoCore Contribution Agreement 1.1 > > Signed-off-by: Jian J Wang <jian.j.wang@intel.com> > > --- > > IntelFrameworkPkg/Include/Protocol/LegacyBios.h | 34 > +++++++++++++++++++++++++ > > 1 file changed, 34 insertions(+) > > > > diff --git a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > > index 641f101bce..f77c92ba21 100644 > > --- a/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > > +++ b/IntelFrameworkPkg/Include/Protocol/LegacyBios.h > > @@ -1518,6 +1518,40 @@ 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_; \ > > + \ > > + Status_ = gDS->GetMemorySpaceDescriptor (0, &Desc_); \ > > + if (!EFI_ERROR (Status_)) { \ > > + if ((Desc_.Attributes & EFI_MEMORY_RP) != 0) { \ > > + Status_ = gDS->SetMemorySpaceAttributes ( \ > > + 0, \ > > + EFI_PAGES_TO_SIZE(1), \ > > + Desc_.Attributes &= ~EFI_MEMORY_RP \ > > &= is used here so Desc_.Attributes is updated to have RP cleared. > Then the below if will be always FALSE. > > > + ); \ > > + 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 > > > > > -- > Thanks, > Ray _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
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