UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 46 ++++++++--- UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 96 +++++++++++----------- UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 13 ++- 3 files changed, 94 insertions(+), 61 deletions(-)
Shadow stack will stop update after CET disable (DisableCet in
DisableReadOnlyPageWriteProtect), but normal smi stack will be
continue updated with the function return and enter
(DisableReadOnlyPageWriteProtect & EnableReadOnlyPageWriteProtect),
thus leading stack mismatch after CET re-enabled (EnableCet in
EnableReadOnlyPageWriteProtect).
Normal smi stack and shadow stack must be matched when CET enable,
otherwise CP Exception will happen, which is caused by a near RET
instruction (See SDM Vol 3, 6.15-Control Protection Exception).
With above requirement, define below 2 macros instead of functions
for WP & CET operation:
WRITE_UNPROTECT_RO_PAGES (Wp, Cet)
WRITE_PROTECT_RO_PAGES (Wp, Cet)
Because "CET" feature disable & enable must be in the same
function to avoid shadow stack and normal SMI stack mismatch.
Note: WRITE_UNPROTECT_RO_PAGES () must be called pair with
WRITE_PROTECT_RO_PAGES () in same function.
Change-Id: I4e126697efcd8dbfb4887da034d8691bfca969e3
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zeng Star <star.zeng@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
---
UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 46 ++++++++---
UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 96 +++++++++++-----------
UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 13 ++-
3 files changed, 94 insertions(+), 61 deletions(-)
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
index 654935dc76..5d167899ff 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
@@ -1551,29 +1551,51 @@ VOID
SmmWaitForApArrival (
VOID
);
/**
- 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.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[out] WriteProtect If Cr0.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
);
+///
+/// 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.
+///
+#define WRITE_UNPROTECT_RO_PAGES(Wp, Cet) \
+{ \
+ Cet = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0); \
+ if (Cet) { \
+ DisableCet (); \
+ } \
+ SmmWriteUnprotectReadOnlyPage(&Wp); \
+}
+
+#define WRITE_PROTECT_RO_PAGES(Wp, Cet) \
+{ \
+ SmmWriteProtectReadOnlyPage(Wp); \
+ if (Cet) { \
+ EnableCet (); \
+ } \
+}
+
#endif
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index 6f49866615..8edfddd3ea 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -39,64 +39,47 @@ PAGE_TABLE_POOL *mPageTablePool = NULL;
// If memory used by SMM page table has been mareked as ReadOnly.
//
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.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) ? TRUE : FALSE;
+ if (*WriteProtect) {
Cr0.Bits.WP = 0;
AsmWriteCr0 (Cr0.UintN);
}
}
/**
- Enable Write Protect on pages marked as read-only.
+ Write protect read-only pages.
+
+ @param[out] WriteProtect If Cr0.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 ();
- }
}
}
/**
Initialize a buffer pool for page table use only.
@@ -119,11 +102,11 @@ BOOLEAN
InitializePageTablePool (
IN UINTN PoolPages
)
{
VOID *Buffer;
- BOOLEAN WpEnabled;
+ BOOLEAN WriteProtect;
BOOLEAN CetEnabled;
//
// Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
// header.
@@ -157,13 +140,21 @@ InitializePageTablePool (
//
// If page table memory has been marked as RO, mark the new pool pages as read-only.
//
if (mIsReadOnlyPageTable) {
- DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
+ //
+ // CET must be disabled if WP is disabled.
+ //
+ WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);
+
SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
- EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
+
+ //
+ // Enable the WP and restore CET to enable
+ //
+ WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
}
return TRUE;
}
@@ -1009,11 +1000,11 @@ SetMemMapAttributes (
UINTN PageTable;
EFI_STATUS Status;
IA32_MAP_ENTRY *Map;
UINTN Count;
UINT64 MemoryAttribute;
- BOOLEAN WpEnabled;
+ BOOLEAN WriteProtect;
BOOLEAN CetEnabled;
SmmGetSystemConfigurationTable (&gEdkiiPiSmmMemoryAttributesTableGuid, (VOID **)&MemoryAttributesTable);
if (MemoryAttributesTable == NULL) {
DEBUG ((DEBUG_INFO, "MemoryAttributesTable - NULL\n"));
@@ -1055,11 +1046,14 @@ SetMemMapAttributes (
Status = PageTableParse (PageTable, mPagingMode, Map, &Count);
}
ASSERT_RETURN_ERROR (Status);
- DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
+ //
+ // CET must be disabled if WP is disabled.
+ //
+ WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);
MemoryMap = MemoryMapStart;
for (Index = 0; Index < MemoryMapEntryCount; Index++) {
DEBUG ((DEBUG_VERBOSE, "SetAttribute: Memory Entry - 0x%lx, 0x%x\n", MemoryMap->PhysicalStart, MemoryMap->NumberOfPages));
if (MemoryMap->Type == EfiRuntimeServicesCode) {
@@ -1085,11 +1079,15 @@ SetMemMapAttributes (
);
MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, DescriptorSize);
}
- EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
+ //
+ // Enable the WP and restore CET to enable
+ //
+ WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
+
FreePool (Map);
PatchSmmSaveStateMap ();
PatchGdtIdtMap ();
@@ -1392,18 +1390,21 @@ SetUefiMemMapAttributes (
EFI_STATUS Status;
EFI_MEMORY_DESCRIPTOR *MemoryMap;
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);
+ //
+ // CET must be disabled if WP is disabled.
+ //
+ WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);
if (mUefiMemoryMap != NULL) {
MemoryMapEntryCount = mUefiMemoryMapSize/mUefiDescriptorSize;
MemoryMap = mUefiMemoryMap;
for (Index = 0; Index < MemoryMapEntryCount; Index++) {
@@ -1479,11 +1480,14 @@ SetUefiMemMapAttributes (
Entry = NEXT_MEMORY_DESCRIPTOR (Entry, mUefiMemoryAttributesTable->DescriptorSize);
}
}
- EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
+ //
+ // Enable the WP and restore CET to enable
+ //
+ WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
//
// Do not free mUefiMemoryAttributesTable, it will be checked in IsSmmCommBufferForbiddenAddress().
//
@@ -1870,34 +1874,34 @@ IfReadOnlyPageTableNeeded (
VOID
SetPageTableAttributes (
VOID
)
{
- BOOLEAN WpEnabled;
+ BOOLEAN WriteProtect;
BOOLEAN CetEnabled;
if (!IfReadOnlyPageTableNeeded ()) {
return;
}
PERF_FUNCTION_BEGIN ();
DEBUG ((DEBUG_INFO, "SetPageTableAttributes\n"));
//
- // 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*.
+ // CET must be disabled if WP is disabled.
//
- DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
+ WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);
// Set memory used by page table as Read Only.
DEBUG ((DEBUG_INFO, "Start...\n"));
EnablePageTableProtection ();
//
- // Enable write protection, after page table attribute updated.
+ // Enable the WP and restore CET to enable
//
- EnableReadOnlyPageWriteProtect (TRUE, CetEnabled);
+ WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
+
mIsReadOnlyPageTable = TRUE;
//
// Flush TLB after mark all page table pool as read only.
//
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
index 7ac3c66f91..8f6a2d440e 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c
@@ -592,11 +592,11 @@ InitPaging (
UINT64 Base;
UINT64 Length;
UINT64 Limit;
UINT64 PreviousAddress;
UINT64 MemoryAttrMask;
- BOOLEAN WpEnabled;
+ BOOLEAN WriteProtect;
BOOLEAN CetEnabled;
PERF_FUNCTION_BEGIN ();
PageTable = AsmReadCr3 ();
@@ -604,11 +604,15 @@ InitPaging (
Limit = BASE_4GB;
} else {
Limit = (IsRestrictedMemoryAccess ()) ? LShiftU64 (1, mPhysicalAddressBits) : BASE_4GB;
}
- DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled);
+ //
+ // CET must be disabled if WP is disabled.
+ //
+ WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled);
+
//
// [0, 4k] may be non-present.
//
PreviousAddress = ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT1) != 0) ? BASE_4KB : 0;
@@ -670,11 +674,14 @@ InitPaging (
//
Status = ConvertMemoryPageAttributes (PageTable, mPagingMode, PreviousAddress, Limit - PreviousAddress, MemoryAttrMask, TRUE, NULL);
ASSERT_RETURN_ERROR (Status);
}
- EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled);
+ //
+ // Enable the WP and restore CET to enable
+ //
+ WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled);
//
// Flush TLB
//
CpuFlushTlb ();
--
2.16.2.windows.1
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Hi Jiaxin, looks great; now I'm only asking for a few light touch-ups: On 11/3/23 19:37, Jiaxin Wu wrote: > Shadow stack will stop update after CET disable (DisableCet in > DisableReadOnlyPageWriteProtect), but normal smi stack will be > continue updated with the function return and enter > (DisableReadOnlyPageWriteProtect & EnableReadOnlyPageWriteProtect), > thus leading stack mismatch after CET re-enabled (EnableCet in > EnableReadOnlyPageWriteProtect). > > Normal smi stack and shadow stack must be matched when CET enable, > otherwise CP Exception will happen, which is caused by a near RET > instruction (See SDM Vol 3, 6.15-Control Protection Exception). > > With above requirement, define below 2 macros instead of functions > for WP & CET operation: > WRITE_UNPROTECT_RO_PAGES (Wp, Cet) > WRITE_PROTECT_RO_PAGES (Wp, Cet) > Because "CET" feature disable & enable must be in the same > function to avoid shadow stack and normal SMI stack mismatch. > > Note: WRITE_UNPROTECT_RO_PAGES () must be called pair with > WRITE_PROTECT_RO_PAGES () in same function. > > Change-Id: I4e126697efcd8dbfb4887da034d8691bfca969e3 (1) Please drop the Change-Id line; it is not meaningful in the upstream repo. > Cc: Eric Dong <eric.dong@intel.com> > Cc: Ray Ni <ray.ni@intel.com> > Cc: Zeng Star <star.zeng@intel.com> > Cc: Gerd Hoffmann <kraxel@redhat.com> > Cc: Rahul Kumar <rahul1.kumar@intel.com> > Cc: Laszlo Ersek <lersek@redhat.com> > Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 46 ++++++++--- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 96 +++++++++++----------- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 13 ++- > 3 files changed, 94 insertions(+), 61 deletions(-) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > index 654935dc76..5d167899ff 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > @@ -1551,29 +1551,51 @@ VOID > SmmWaitForApArrival ( > VOID > ); > > /** > - 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.WP is enabled. (2) The comment references to the WP bit are not consistent. We should either stick with Cr0.WP or Cr0.Bits.WP, but not mix them. I understand this inconsistency exists pre-patch, but because we're modifying the same sentences, I think it would be OK to clean up the WP bit references as well, at the same time. > > - @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[out] WriteProtect If Cr0.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 > ); (3) If, under (2), you opt for preserving "Cr0.Bits.WP", then please use that term here too. > > +/// > +/// 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. > +/// > +#define WRITE_UNPROTECT_RO_PAGES(Wp, Cet) \ > +{ \ > + Cet = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0); \ > + if (Cet) { \ > + DisableCet (); \ > + } \ > + SmmWriteUnprotectReadOnlyPage(&Wp); \ > +} > + > +#define WRITE_PROTECT_RO_PAGES(Wp, Cet) \ > +{ \ > + SmmWriteProtectReadOnlyPage(Wp); \ > + if (Cet) { \ > + EnableCet (); \ > + } \ > +} > + > #endif (4) Assuming the ECC Check Plugin tolerates it, I recommend adding two entries to the documentation here: /// @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(). I recommend this because it clarifies that neither Wp nor Cet are supposed to have side effects (for example, "Cet" is evaluated multiple times in WRITE_UNPROTECT_RO_PAGES(), so calling the macro with something like *CetVariable++ would not work well). (5) A space character is missing right after each of "SmmWriteUnprotectReadOnlyPage" and "SmmWriteProtectReadOnlyPage", before the parens. (6) It would be more idiomatic to #define these macros as: do { \ ... \ } while (FALSE) because this replacement text is more suitable to be followed by a semicolon ";". > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > index 6f49866615..8edfddd3ea 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > @@ -39,64 +39,47 @@ PAGE_TABLE_POOL *mPageTablePool = NULL; > // If memory used by SMM page table has been mareked as ReadOnly. > // > 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.WP is enabled. > > - @param[out] WpEnabled If Cr0.WP is enabled. > - @param[out] CetEnabled If CET is enabled. > **/ > VOID (7) If you decide to touch up the function comment in the header file, then please keep this in sync. > -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) ? TRUE : FALSE; (8) Can you remove the " ? TRUE : FALSE" part? > + if (*WriteProtect) { > Cr0.Bits.WP = 0; > AsmWriteCr0 (Cr0.UintN); > } > } > > /** > - Enable Write Protect on pages marked as read-only. > + Write protect read-only pages. > + > + @param[out] WriteProtect If Cr0.WP should be enabled. > > - @param[out] WpEnabled If Cr0.WP should be enabled. > - @param[out] CetEnabled If CET should be enabled. > **/ (9) If you decide to touch up the function comment in the header file, then please keep this in sync. > 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 (); > - } > } > } > > /** > Initialize a buffer pool for page table use only. > @@ -119,11 +102,11 @@ BOOLEAN > InitializePageTablePool ( > IN UINTN PoolPages > ) > { > VOID *Buffer; > - BOOLEAN WpEnabled; > + BOOLEAN WriteProtect; > BOOLEAN CetEnabled; > > // > // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for > // header. > @@ -157,13 +140,21 @@ InitializePageTablePool ( > > // > // If page table memory has been marked as RO, mark the new pool pages as read-only. > // > if (mIsReadOnlyPageTable) { > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > + // > + // CET must be disabled if WP is disabled. > + // > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > + > SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO); > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > + > + // > + // Enable the WP and restore CET to enable > + // > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > } > > return TRUE; > } > (10) Here on the other hand I suggest *removing* these comments. The macros are really well defined at this point, so I think just invoking the macros should suffice. Up to you, anyway; if you'd like to keep the comments, I won't insist. :) If you decide to remove the comments, then please keep the rest of the patch (below) consistent as well. > @@ -1009,11 +1000,11 @@ SetMemMapAttributes ( > UINTN PageTable; > EFI_STATUS Status; > IA32_MAP_ENTRY *Map; > UINTN Count; > UINT64 MemoryAttribute; > - BOOLEAN WpEnabled; > + BOOLEAN WriteProtect; > BOOLEAN CetEnabled; > > SmmGetSystemConfigurationTable (&gEdkiiPiSmmMemoryAttributesTableGuid, (VOID **)&MemoryAttributesTable); > if (MemoryAttributesTable == NULL) { > DEBUG ((DEBUG_INFO, "MemoryAttributesTable - NULL\n")); > @@ -1055,11 +1046,14 @@ SetMemMapAttributes ( > Status = PageTableParse (PageTable, mPagingMode, Map, &Count); > } > > ASSERT_RETURN_ERROR (Status); > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > + // > + // CET must be disabled if WP is disabled. > + // > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > MemoryMap = MemoryMapStart; > for (Index = 0; Index < MemoryMapEntryCount; Index++) { > DEBUG ((DEBUG_VERBOSE, "SetAttribute: Memory Entry - 0x%lx, 0x%x\n", MemoryMap->PhysicalStart, MemoryMap->NumberOfPages)); > if (MemoryMap->Type == EfiRuntimeServicesCode) { > @@ -1085,11 +1079,15 @@ SetMemMapAttributes ( > ); > > MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, DescriptorSize); > } > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > + // > + // Enable the WP and restore CET to enable > + // > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > + > FreePool (Map); > > PatchSmmSaveStateMap (); > PatchGdtIdtMap (); > > @@ -1392,18 +1390,21 @@ SetUefiMemMapAttributes ( > EFI_STATUS Status; > EFI_MEMORY_DESCRIPTOR *MemoryMap; > 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); > + // > + // CET must be disabled if WP is disabled. > + // > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > if (mUefiMemoryMap != NULL) { > MemoryMapEntryCount = mUefiMemoryMapSize/mUefiDescriptorSize; > MemoryMap = mUefiMemoryMap; > for (Index = 0; Index < MemoryMapEntryCount; Index++) { > @@ -1479,11 +1480,14 @@ SetUefiMemMapAttributes ( > > Entry = NEXT_MEMORY_DESCRIPTOR (Entry, mUefiMemoryAttributesTable->DescriptorSize); > } > } > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > + // > + // Enable the WP and restore CET to enable > + // > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > // > // Do not free mUefiMemoryAttributesTable, it will be checked in IsSmmCommBufferForbiddenAddress(). > // > > @@ -1870,34 +1874,34 @@ IfReadOnlyPageTableNeeded ( > VOID > SetPageTableAttributes ( > VOID > ) > { > - BOOLEAN WpEnabled; > + BOOLEAN WriteProtect; > BOOLEAN CetEnabled; > > if (!IfReadOnlyPageTableNeeded ()) { > return; > } > > PERF_FUNCTION_BEGIN (); > DEBUG ((DEBUG_INFO, "SetPageTableAttributes\n")); > > // > - // 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*. (11) These two comment lines seem important, and not related to the patch -- they explain *why* we are doing the WP / CET twiddling. So I recommend keeping these (and only removing the comment line below)! > + // CET must be disabled if WP is disabled. > // > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > // Set memory used by page table as Read Only. > DEBUG ((DEBUG_INFO, "Start...\n")); > EnablePageTableProtection (); > > // > - // Enable write protection, after page table attribute updated. > + // Enable the WP and restore CET to enable (12) same as (11) here. > // > - EnableReadOnlyPageWriteProtect (TRUE, CetEnabled); > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > + (13) Whoa, the *original* EnableReadOnlyPageWriteProtect() call passes the TRUE constant, not WpEnabled! Was that intentional, or an independent oversight? If it was an independent oversight in the original code, then I agree we can fix it, and I'm not even asking for a separate patch, but please mention it in the commit message. > mIsReadOnlyPageTable = TRUE; > > // > // Flush TLB after mark all page table pool as read only. > // > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > index 7ac3c66f91..8f6a2d440e 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > @@ -592,11 +592,11 @@ InitPaging ( > UINT64 Base; > UINT64 Length; > UINT64 Limit; > UINT64 PreviousAddress; > UINT64 MemoryAttrMask; > - BOOLEAN WpEnabled; > + BOOLEAN WriteProtect; > BOOLEAN CetEnabled; > > PERF_FUNCTION_BEGIN (); > > PageTable = AsmReadCr3 (); > @@ -604,11 +604,15 @@ InitPaging ( > Limit = BASE_4GB; > } else { > Limit = (IsRestrictedMemoryAccess ()) ? LShiftU64 (1, mPhysicalAddressBits) : BASE_4GB; > } > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > + // > + // CET must be disabled if WP is disabled. > + // > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > + > // > // [0, 4k] may be non-present. > // > PreviousAddress = ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & BIT1) != 0) ? BASE_4KB : 0; > > @@ -670,11 +674,14 @@ InitPaging ( > // > Status = ConvertMemoryPageAttributes (PageTable, mPagingMode, PreviousAddress, Limit - PreviousAddress, MemoryAttrMask, TRUE, NULL); > ASSERT_RETURN_ERROR (Status); > } > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > + // > + // Enable the WP and restore CET to enable > + // > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > // > // Flush TLB > // > CpuFlushTlb (); Thanks! Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#110680): https://edk2.groups.io/g/devel/message/110680 Mute This Topic: https://groups.io/mt/102370465/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/leave/3901457/1787277/102458076/xyzzy [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
Thanks Laszlo, all fixed in version 3. > -----Original Message----- > From: Laszlo Ersek <lersek@redhat.com> > Sent: Sunday, November 5, 2023 7:01 PM > To: Wu, Jiaxin <jiaxin.wu@intel.com>; devel@edk2.groups.io > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Zeng, Star > <star.zeng@intel.com>; Gerd Hoffmann <kraxel@redhat.com>; Kumar, Rahul R > <rahul.r.kumar@intel.com> > Subject: Re: [PATCH v2] UefiCpuPkg/PiSmmCpuDxeSmm: Fix CP Exception > when CET enable > > Hi Jiaxin, > > looks great; now I'm only asking for a few light touch-ups: > > On 11/3/23 19:37, Jiaxin Wu wrote: > > Shadow stack will stop update after CET disable (DisableCet in > > DisableReadOnlyPageWriteProtect), but normal smi stack will be > > continue updated with the function return and enter > > (DisableReadOnlyPageWriteProtect & EnableReadOnlyPageWriteProtect), > > thus leading stack mismatch after CET re-enabled (EnableCet in > > EnableReadOnlyPageWriteProtect). > > > > Normal smi stack and shadow stack must be matched when CET enable, > > otherwise CP Exception will happen, which is caused by a near RET > > instruction (See SDM Vol 3, 6.15-Control Protection Exception). > > > > With above requirement, define below 2 macros instead of functions > > for WP & CET operation: > > WRITE_UNPROTECT_RO_PAGES (Wp, Cet) > > WRITE_PROTECT_RO_PAGES (Wp, Cet) > > Because "CET" feature disable & enable must be in the same > > function to avoid shadow stack and normal SMI stack mismatch. > > > > Note: WRITE_UNPROTECT_RO_PAGES () must be called pair with > > WRITE_PROTECT_RO_PAGES () in same function. > > > > Change-Id: I4e126697efcd8dbfb4887da034d8691bfca969e3 > > (1) Please drop the Change-Id line; it is not meaningful in the upstream > repo. > > > Cc: Eric Dong <eric.dong@intel.com> > > Cc: Ray Ni <ray.ni@intel.com> > > Cc: Zeng Star <star.zeng@intel.com> > > Cc: Gerd Hoffmann <kraxel@redhat.com> > > Cc: Rahul Kumar <rahul1.kumar@intel.com> > > Cc: Laszlo Ersek <lersek@redhat.com> > > Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com> > > --- > > UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 46 > ++++++++--- > > UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 96 > +++++++++++----------- > > UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c | 13 ++- > > 3 files changed, 94 insertions(+), 61 deletions(-) > > > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > > index 654935dc76..5d167899ff 100644 > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h > > @@ -1551,29 +1551,51 @@ VOID > > SmmWaitForApArrival ( > > VOID > > ); > > > > /** > > - 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.WP is enabled. > > (2) The comment references to the WP bit are not consistent. We should > either stick with Cr0.WP or Cr0.Bits.WP, but not mix them. > > I understand this inconsistency exists pre-patch, but because we're > modifying the same sentences, I think it would be OK to clean up the WP > bit references as well, at the same time. > > > > > - @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[out] WriteProtect If Cr0.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 > > ); > > (3) If, under (2), you opt for preserving "Cr0.Bits.WP", then please use > that term here too. > > > > > +/// > > +/// 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. > > +/// > > +#define WRITE_UNPROTECT_RO_PAGES(Wp, Cet) \ > > +{ \ > > + Cet = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0); \ > > + if (Cet) { \ > > + DisableCet (); \ > > + } \ > > + SmmWriteUnprotectReadOnlyPage(&Wp); \ > > +} > > + > > +#define WRITE_PROTECT_RO_PAGES(Wp, Cet) \ > > +{ \ > > + SmmWriteProtectReadOnlyPage(Wp); \ > > + if (Cet) { \ > > + EnableCet (); \ > > + } \ > > +} > > + > > #endif > > (4) Assuming the ECC Check Plugin tolerates it, I recommend adding two > entries to the documentation here: > > /// @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(). > > I recommend this because it clarifies that neither Wp nor Cet are > supposed to have side effects (for example, "Cet" is evaluated multiple > times in WRITE_UNPROTECT_RO_PAGES(), so calling the macro with > something > like *CetVariable++ would not work well). > > > (5) A space character is missing right after each of > "SmmWriteUnprotectReadOnlyPage" and "SmmWriteProtectReadOnlyPage", > before the parens. > > > (6) It would be more idiomatic to #define these macros as: > > do { \ > ... \ > } while (FALSE) > > because this replacement text is more suitable to be followed by a > semicolon ";". > > > > diff --git > a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > > index 6f49866615..8edfddd3ea 100644 > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > > @@ -39,64 +39,47 @@ PAGE_TABLE_POOL *mPageTablePool = NULL; > > // If memory used by SMM page table has been mareked as ReadOnly. > > // > > 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.WP is enabled. > > > > - @param[out] WpEnabled If Cr0.WP is enabled. > > - @param[out] CetEnabled If CET is enabled. > > **/ > > VOID > > (7) If you decide to touch up the function comment in the header file, > then please keep this in sync. > > > > -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) ? TRUE : FALSE; > > (8) Can you remove the " ? TRUE : FALSE" part? > > > > + if (*WriteProtect) { > > Cr0.Bits.WP = 0; > > AsmWriteCr0 (Cr0.UintN); > > } > > } > > > > /** > > - Enable Write Protect on pages marked as read-only. > > + Write protect read-only pages. > > + > > + @param[out] WriteProtect If Cr0.WP should be enabled. > > > > - @param[out] WpEnabled If Cr0.WP should be enabled. > > - @param[out] CetEnabled If CET should be enabled. > > **/ > > (9) If you decide to touch up the function comment in the header file, > then please keep this in sync. > > > 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 (); > > - } > > } > > } > > > > /** > > Initialize a buffer pool for page table use only. > > @@ -119,11 +102,11 @@ BOOLEAN > > InitializePageTablePool ( > > IN UINTN PoolPages > > ) > > { > > VOID *Buffer; > > - BOOLEAN WpEnabled; > > + BOOLEAN WriteProtect; > > BOOLEAN CetEnabled; > > > > // > > // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one > page for > > // header. > > @@ -157,13 +140,21 @@ InitializePageTablePool ( > > > > // > > // If page table memory has been marked as RO, mark the new pool pages > as read-only. > > // > > if (mIsReadOnlyPageTable) { > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > > + // > > + // CET must be disabled if WP is disabled. > > + // > > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > + > > SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, > EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO); > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > > + > > + // > > + // Enable the WP and restore CET to enable > > + // > > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > } > > > > return TRUE; > > } > > > > (10) Here on the other hand I suggest *removing* these comments. The > macros are really well defined at this point, so I think just invoking > the macros should suffice. Up to you, anyway; if you'd like to keep the > comments, I won't insist. :) > > If you decide to remove the comments, then please keep the rest of the > patch (below) consistent as well. > > > @@ -1009,11 +1000,11 @@ SetMemMapAttributes ( > > UINTN PageTable; > > EFI_STATUS Status; > > IA32_MAP_ENTRY *Map; > > UINTN Count; > > UINT64 MemoryAttribute; > > - BOOLEAN WpEnabled; > > + BOOLEAN WriteProtect; > > BOOLEAN CetEnabled; > > > > SmmGetSystemConfigurationTable > (&gEdkiiPiSmmMemoryAttributesTableGuid, (VOID > **)&MemoryAttributesTable); > > if (MemoryAttributesTable == NULL) { > > DEBUG ((DEBUG_INFO, "MemoryAttributesTable - NULL\n")); > > @@ -1055,11 +1046,14 @@ SetMemMapAttributes ( > > Status = PageTableParse (PageTable, mPagingMode, Map, &Count); > > } > > > > ASSERT_RETURN_ERROR (Status); > > > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > > + // > > + // CET must be disabled if WP is disabled. > > + // > > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > > > MemoryMap = MemoryMapStart; > > for (Index = 0; Index < MemoryMapEntryCount; Index++) { > > DEBUG ((DEBUG_VERBOSE, "SetAttribute: Memory Entry - 0x%lx, > 0x%x\n", MemoryMap->PhysicalStart, MemoryMap->NumberOfPages)); > > if (MemoryMap->Type == EfiRuntimeServicesCode) { > > @@ -1085,11 +1079,15 @@ SetMemMapAttributes ( > > ); > > > > MemoryMap = NEXT_MEMORY_DESCRIPTOR (MemoryMap, > DescriptorSize); > > } > > > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > > + // > > + // Enable the WP and restore CET to enable > > + // > > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > + > > FreePool (Map); > > > > PatchSmmSaveStateMap (); > > PatchGdtIdtMap (); > > > > @@ -1392,18 +1390,21 @@ SetUefiMemMapAttributes ( > > EFI_STATUS Status; > > EFI_MEMORY_DESCRIPTOR *MemoryMap; > > 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); > > + // > > + // CET must be disabled if WP is disabled. > > + // > > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > > > if (mUefiMemoryMap != NULL) { > > MemoryMapEntryCount = mUefiMemoryMapSize/mUefiDescriptorSize; > > MemoryMap = mUefiMemoryMap; > > for (Index = 0; Index < MemoryMapEntryCount; Index++) { > > @@ -1479,11 +1480,14 @@ SetUefiMemMapAttributes ( > > > > Entry = NEXT_MEMORY_DESCRIPTOR (Entry, > mUefiMemoryAttributesTable->DescriptorSize); > > } > > } > > > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > > + // > > + // Enable the WP and restore CET to enable > > + // > > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > > > // > > // Do not free mUefiMemoryAttributesTable, it will be checked in > IsSmmCommBufferForbiddenAddress(). > > // > > > > @@ -1870,34 +1874,34 @@ IfReadOnlyPageTableNeeded ( > > VOID > > SetPageTableAttributes ( > > VOID > > ) > > { > > - BOOLEAN WpEnabled; > > + BOOLEAN WriteProtect; > > BOOLEAN CetEnabled; > > > > if (!IfReadOnlyPageTableNeeded ()) { > > return; > > } > > > > PERF_FUNCTION_BEGIN (); > > DEBUG ((DEBUG_INFO, "SetPageTableAttributes\n")); > > > > // > > - // 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*. > > (11) These two comment lines seem important, and not related to the > patch -- they explain *why* we are doing the WP / CET twiddling. So I > recommend keeping these (and only removing the comment line below)! > > > + // CET must be disabled if WP is disabled. > > // > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > > > // Set memory used by page table as Read Only. > > DEBUG ((DEBUG_INFO, "Start...\n")); > > EnablePageTableProtection (); > > > > // > > - // Enable write protection, after page table attribute updated. > > + // Enable the WP and restore CET to enable > > (12) same as (11) here. > > > // > > - EnableReadOnlyPageWriteProtect (TRUE, CetEnabled); > > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > + > > (13) Whoa, the *original* EnableReadOnlyPageWriteProtect() call passes > the TRUE constant, not WpEnabled! > > Was that intentional, or an independent oversight? > > If it was an independent oversight in the original code, then I agree we > can fix it, and I'm not even asking for a separate patch, but please > mention it in the commit message. > > > mIsReadOnlyPageTable = TRUE; > > > > // > > // Flush TLB after mark all page table pool as read only. > > // > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > > index 7ac3c66f91..8f6a2d440e 100644 > > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmProfile.c > > @@ -592,11 +592,11 @@ InitPaging ( > > UINT64 Base; > > UINT64 Length; > > UINT64 Limit; > > UINT64 PreviousAddress; > > UINT64 MemoryAttrMask; > > - BOOLEAN WpEnabled; > > + BOOLEAN WriteProtect; > > BOOLEAN CetEnabled; > > > > PERF_FUNCTION_BEGIN (); > > > > PageTable = AsmReadCr3 (); > > @@ -604,11 +604,15 @@ InitPaging ( > > Limit = BASE_4GB; > > } else { > > Limit = (IsRestrictedMemoryAccess ()) ? LShiftU64 (1, > mPhysicalAddressBits) : BASE_4GB; > > } > > > > - DisableReadOnlyPageWriteProtect (&WpEnabled, &CetEnabled); > > + // > > + // CET must be disabled if WP is disabled. > > + // > > + WRITE_UNPROTECT_RO_PAGES (WriteProtect, CetEnabled); > > + > > // > > // [0, 4k] may be non-present. > > // > > PreviousAddress = ((PcdGet8 (PcdNullPointerDetectionPropertyMask) & > BIT1) != 0) ? BASE_4KB : 0; > > > > @@ -670,11 +674,14 @@ InitPaging ( > > // > > Status = ConvertMemoryPageAttributes (PageTable, mPagingMode, > PreviousAddress, Limit - PreviousAddress, MemoryAttrMask, TRUE, NULL); > > ASSERT_RETURN_ERROR (Status); > > } > > > > - EnableReadOnlyPageWriteProtect (WpEnabled, CetEnabled); > > + // > > + // Enable the WP and restore CET to enable > > + // > > + WRITE_PROTECT_RO_PAGES (WriteProtect, CetEnabled); > > > > // > > // Flush TLB > > // > > CpuFlushTlb (); > > Thanks! > Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. 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