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Fix CP Exception when CET enable #4867

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merged 1 commit into from
Nov 10, 2023
Merged

Fix CP Exception when CET enable #4867

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59 changes: 47 additions & 12 deletions UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1553,27 +1553,62 @@ SmmWaitForApArrival (
);

/**
Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1.
Write unprotect read-only pages if Cr0.Bits.WP is 1.

@param[out] WriteProtect If Cr0.Bits.WP is enabled.

@param[out] WpEnabled If Cr0.WP is enabled.
@param[out] CetEnabled If CET is enabled.
**/
VOID
DisableReadOnlyPageWriteProtect (
OUT BOOLEAN *WpEnabled,
OUT BOOLEAN *CetEnabled
SmmWriteUnprotectReadOnlyPage (
OUT BOOLEAN *WriteProtect
);

/**
Enable Write Protect on pages marked as read-only.
Write protect read-only pages.

@param[in] WriteProtect If Cr0.Bits.WP should be enabled.

@param[out] WpEnabled If Cr0.WP should be enabled.
@param[out] CetEnabled If CET should be enabled.
**/
VOID
EnableReadOnlyPageWriteProtect (
BOOLEAN WpEnabled,
BOOLEAN CetEnabled
SmmWriteProtectReadOnlyPage (
IN BOOLEAN WriteProtect
);

///
/// Define macros to encapsulate the write unprotect/protect
/// read-only pages.
/// Below pieces of logic are defined as macros and not functions
/// because "CET" feature disable & enable must be in the same
/// function to avoid shadow stack and normal SMI stack mismatch,
/// thus WRITE_UNPROTECT_RO_PAGES () must be called pair with
/// WRITE_PROTECT_RO_PAGES () in same function.
///
/// @param[in,out] Wp A BOOLEAN variable local to the containing
/// function, carrying write protection status from
/// WRITE_UNPROTECT_RO_PAGES() to
/// WRITE_PROTECT_RO_PAGES().
///
/// @param[in,out] Cet A BOOLEAN variable local to the containing
/// function, carrying control flow integrity
/// enforcement status from
/// WRITE_UNPROTECT_RO_PAGES() to
/// WRITE_PROTECT_RO_PAGES().
///
#define WRITE_UNPROTECT_RO_PAGES(Wp, Cet) \
do { \
Cet = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0); \
if (Cet) { \
DisableCet (); \
} \
SmmWriteUnprotectReadOnlyPage (&Wp); \
} while (FALSE)

#define WRITE_PROTECT_RO_PAGES(Wp, Cet) \
do { \
SmmWriteProtectReadOnlyPage (Wp); \
if (Cet) { \
EnableCet (); \
} \
} while (FALSE)

#endif
73 changes: 30 additions & 43 deletions UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,60 +41,43 @@ PAGE_TABLE_POOL *mPageTablePool = NULL;
BOOLEAN mIsReadOnlyPageTable = FALSE;

/**
Disable Write Protect on pages marked as read-only if Cr0.Bits.WP is 1.
Write unprotect read-only pages if Cr0.Bits.WP is 1.

@param[out] WriteProtect If Cr0.Bits.WP is enabled.

@param[out] WpEnabled If Cr0.WP is enabled.
@param[out] CetEnabled If CET is enabled.
**/
VOID
DisableReadOnlyPageWriteProtect (
OUT BOOLEAN *WpEnabled,
OUT BOOLEAN *CetEnabled
SmmWriteUnprotectReadOnlyPage (
OUT BOOLEAN *WriteProtect
)
{
IA32_CR0 Cr0;

*CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
Cr0.UintN = AsmReadCr0 ();
*WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE;
if (*WpEnabled) {
if (*CetEnabled) {
//
// CET must be disabled if WP is disabled. Disable CET before clearing CR0.WP.
//
DisableCet ();
}

Cr0.UintN = AsmReadCr0 ();
*WriteProtect = (Cr0.Bits.WP != 0);
if (*WriteProtect) {
Cr0.Bits.WP = 0;
AsmWriteCr0 (Cr0.UintN);
}
}

/**
Enable Write Protect on pages marked as read-only.
Write protect read-only pages.

@param[in] WriteProtect If Cr0.Bits.WP should be enabled.

@param[out] WpEnabled If Cr0.WP should be enabled.
@param[out] CetEnabled If CET should be enabled.
**/
VOID
EnableReadOnlyPageWriteProtect (
BOOLEAN WpEnabled,
BOOLEAN CetEnabled
SmmWriteProtectReadOnlyPage (
IN BOOLEAN WriteProtect
)
{
IA32_CR0 Cr0;

if (WpEnabled) {
if (WriteProtect) {
Cr0.UintN = AsmReadCr0 ();
Cr0.Bits.WP = 1;
AsmWriteCr0 (Cr0.UintN);

if (CetEnabled) {
//
// re-enable CET.
//
EnableCet ();
}
}
}

Expand All @@ -121,7 +104,7 @@ InitializePageTablePool (
)
{
VOID *Buffer;
BOOLEAN WpEnabled;
BOOLEAN WriteProtect;
BOOLEAN CetEnabled;

//
Expand Down Expand Up @@ -159,9 +142,11 @@ InitializePageTablePool (
// If page table memory has been marked as RO, mark the new pool pages as read-only.
//
if (mIsReadOnlyPageTable) {
DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);

SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);

WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
}

return TRUE;
Expand Down Expand Up @@ -1011,7 +996,7 @@ SetMemMapAttributes (
IA32_MAP_ENTRY *Map;
UINTN Count;
UINT64 MemoryAttribute;
BOOLEAN WpEnabled;
BOOLEAN WriteProtect;
BOOLEAN CetEnabled;

SmmGetSystemConfigurationTable (&gEdkiiPiSmmMemoryAttributesTableGuid, (VOID **)&MemoryAttributesTable);
Expand Down Expand Up @@ -1057,7 +1042,7 @@ SetMemMapAttributes (

ASSERT_RETURN_ERROR (Status);

DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);

MemoryMap = MemoryMapStart;
for (Index = 0; Index < MemoryMapEntryCount; Index++) {
Expand Down Expand Up @@ -1087,7 +1072,8 @@ SetMemMapAttributes (
MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, DescriptorSize);
}

EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);

FreePool (Map);

PatchSmmSaveStateMap ();
Expand Down Expand Up @@ -1394,14 +1380,14 @@ SetUefiMemMapAttributes (
UINTN MemoryMapEntryCount;
UINTN Index;
EFI_MEMORY_DESCRIPTOR *Entry;
BOOLEAN WpEnabled;
BOOLEAN WriteProtect;
BOOLEAN CetEnabled;

PERF_FUNCTION_BEGIN ();

DEBUG ((DEBUG_INFO, "SetUefiMemMapAttributes\n"));

DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);

if (mUefiMemoryMap != NULL) {
MemoryMapEntryCount = mUefiMemoryMapSize/mUefiDescriptorSize;
Expand Down Expand Up @@ -1481,7 +1467,7 @@ SetUefiMemMapAttributes (
}
}

EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);

//
// Do not free mUefiMemoryAttributesTable, it will be checked in IsSmmCommBufferForbiddenAddress().
Expand Down Expand Up @@ -1872,7 +1858,7 @@ SetPageTableAttributes (
VOID
)
{
BOOLEAN WpEnabled;
BOOLEAN WriteProtect;
BOOLEAN CetEnabled;

if (!IfReadOnlyPageTableNeeded ()) {
Expand All @@ -1886,7 +1872,7 @@ SetPageTableAttributes (
// Disable write protection, because we need mark page table to be write protected.
// We need *write* page table memory, to mark itself to be *read only*.
//
DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);

// Set memory used by page table as Read Only.
DEBUG ((DEBUG_INFO, "Start...\n"));
Expand All @@ -1895,7 +1881,8 @@ SetPageTableAttributes (
//
// Enable write protection, after page table attribute updated.
//
EnableReadOnlyPageWriteProtect (TRUE, CetEnabled);
WRITE_PROTECT_RO_PAGES (TRUE, CetEnabled);

mIsReadOnlyPageTable = TRUE;

//
Expand Down
7 changes: 4 additions & 3 deletions UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -594,7 +594,7 @@ InitPaging (
UINT64 Limit;
UINT64 PreviousAddress;
UINT64 MemoryAttrMask;
BOOLEAN WpEnabled;
BOOLEAN WriteProtect;
BOOLEAN CetEnabled;

PERF_FUNCTION_BEGIN ();
Expand All @@ -606,7 +606,8 @@ InitPaging (
Limit = (IsRestrictedMemoryAccess ()) ? LShiftU64 (1, mPhysicalAddressBits) : BASE_4GB;
}

DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);

//
// [0, 4k] may be non-present.
//
Expand Down Expand Up @@ -672,7 +673,7 @@ InitPaging (
ASSERT_RETURN_ERROR (Status);
}

EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);

//
// Flush TLB
Expand Down