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UefiCpuPkg/PiSmmCpuDxeSmm: Add a new mIsShadowStack flag 

This patch is code refactoring and doesn't change any functionality.
Add a new mIsShadowStack 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.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
This commit is contained in:
Dun Tan 2022-08-09 15:22:07 +08:00 committed by mergify[bot]
parent 74f44d920a
commit 83d5871184
1 changed files with 6 additions and 4 deletions
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10
UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
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@ -32,7 +32,8 @@ PAGE_ATTRIBUTE_TABLE mPageAttributeTable[] = {
{ Page1G, SIZE_1GB, PAGING_1G_ADDRESS_MASK_64 },
};
UINTN mInternalCr3;
UINTN mInternalCr3;
BOOLEAN 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;
}