Reviewed-by: Ray Ni <ray...@intel.com> > -----Original Message----- > From: Tan, Dun <dun....@intel.com> > Sent: Wednesday, August 10, 2022 1:37 PM > To: devel@edk2.groups.io > Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Kumar, > Rahul R <rahul.r.ku...@intel.com> > Subject: [Patch V2 1/2] UefiCpuPkg/PiSmmCpuDxeSmm: Add a new > mIsShadowStack flag > > This patch is code refactoring and doesn't change any functionality. > Add a new IsShadowStack flag to identify whether current memory is > shadow stack. Previous smm code logic regards a RO range as shadow > stack and set the dirty bit in corresponding page table entry if > mInternalCr3 is not 0, which may be confusing. > > Signed-off-by: Dun Tan <dun....@intel.com> > Cc: Eric Dong <eric.d...@intel.com> > Cc: Ray Ni <ray...@intel.com> > Cc: Rahul Kumar <rahul1.ku...@intel.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 8 > +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git > a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > index 1f7cc15727..237742d7e6 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > @@ -33,6 +33,7 @@ PAGE_ATTRIBUTE_TABLE mPageAttributeTable[] = { > }; > > UINTN mInternalCr3; > +UINTN mIsShadowStack = FALSE; > > /** > Set the internal page table base address. > @@ -249,7 +250,7 @@ ConvertPageEntryAttribute ( > if ((Attributes & EFI_MEMORY_RO) != 0) { > if (IsSet) { > NewPageEntry &= ~(UINT64)IA32_PG_RW; > - if (mInternalCr3 != 0) { > + if (mIsShadowStack) { > // Environment setup > // ReadOnly page need set Dirty bit for shadow stack > NewPageEntry |= IA32_PG_D; > @@ -734,10 +735,11 @@ SetShadowStack ( > EFI_STATUS Status; > > SetPageTableBase (Cr3); > - > - Status = SmmSetMemoryAttributes (BaseAddress, Length, > EFI_MEMORY_RO); > + mIsShadowStack = TRUE; > + Status = SmmSetMemoryAttributes (BaseAddress, Length, > EFI_MEMORY_RO); > > SetPageTableBase (0); > + mIsShadowStack = FALSE; > > return Status; > } > -- > 2.31.1.windows.1
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