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-rw-r--r--MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c8
-rw-r--r--MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c299
-rw-r--r--MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h61
3 files changed, 364 insertions, 4 deletions
diff --git a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
index 441096ad0f..0ec60893ee 100644
--- a/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
+++ b/MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c
@@ -99,7 +99,7 @@ Create4GPageTablesIa32Pae (
NumberOfPdpEntriesNeeded = (UINT32) LShiftU64 (1, (PhysicalAddressBits - 30));
TotalPagesNum = NumberOfPdpEntriesNeeded + 1;
- PageAddress = (UINTN) AllocatePages (TotalPagesNum);
+ PageAddress = (UINTN) AllocatePageTableMemory (TotalPagesNum);
ASSERT (PageAddress != 0);
PageMap = (VOID *) PageAddress;
@@ -149,6 +149,12 @@ Create4GPageTablesIa32Pae (
);
}
+ //
+ // Protect the page table by marking the memory used for page table to be
+ // read-only.
+ //
+ EnablePageTableProtection ((UINTN)PageMap, FALSE);
+
return (UINTN) PageMap;
}
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 7f63144510..26116e420c 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -31,6 +31,11 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#include "DxeIpl.h"
#include "VirtualMemory.h"
+//
+// Global variable to keep track current available memory used as page table.
+//
+PAGE_TABLE_POOL *mPageTablePool = NULL;
+
/**
Clear legacy memory located at the first 4K-page, if available.
@@ -151,6 +156,110 @@ ToSplitPageTable (
return FALSE;
}
/**
+ Initialize a buffer pool for page table use only.
+
+ To reduce the potential split operation on page table, the pages reserved for
+ page table should be allocated in the times of PAGE_TABLE_POOL_UNIT_PAGES and
+ at the boundary of PAGE_TABLE_POOL_ALIGNMENT. So the page pool is always
+ initialized with number of pages greater than or equal to the given PoolPages.
+
+ Once the pages in the pool are used up, this method should be called again to
+ reserve at least another PAGE_TABLE_POOL_UNIT_PAGES. But usually this won't
+ happen in practice.
+
+ @param PoolPages The least page number of the pool to be created.
+
+ @retval TRUE The pool is initialized successfully.
+ @retval FALSE The memory is out of resource.
+**/
+BOOLEAN
+InitializePageTablePool (
+ IN UINTN PoolPages
+ )
+{
+ VOID *Buffer;
+
+ //
+ // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
+ // header.
+ //
+ PoolPages += 1; // Add one page for header.
+ PoolPages = ((PoolPages - 1) / PAGE_TABLE_POOL_UNIT_PAGES + 1) *
+ PAGE_TABLE_POOL_UNIT_PAGES;
+ Buffer = AllocateAlignedPages (PoolPages, PAGE_TABLE_POOL_ALIGNMENT);
+ if (Buffer == NULL) {
+ DEBUG ((DEBUG_ERROR, "ERROR: Out of aligned pages\r\n"));
+ return FALSE;
+ }
+
+ //
+ // Link all pools into a list for easier track later.
+ //
+ if (mPageTablePool == NULL) {
+ mPageTablePool = Buffer;
+ mPageTablePool->NextPool = mPageTablePool;
+ } else {
+ ((PAGE_TABLE_POOL *)Buffer)->NextPool = mPageTablePool->NextPool;
+ mPageTablePool->NextPool = Buffer;
+ mPageTablePool = Buffer;
+ }
+
+ //
+ // Reserve one page for pool header.
+ //
+ mPageTablePool->FreePages = PoolPages - 1;
+ mPageTablePool->Offset = EFI_PAGES_TO_SIZE (1);
+
+ return TRUE;
+}
+
+/**
+ This API provides a way to allocate memory for page table.
+
+ This API can be called more than once to allocate memory for page tables.
+
+ Allocates the number of 4KB pages and returns a pointer to the allocated
+ buffer. The buffer returned is aligned on a 4KB boundary.
+
+ If Pages is 0, then NULL is returned.
+ If there is not enough memory remaining to satisfy the request, then NULL is
+ returned.
+
+ @param Pages The number of 4 KB pages to allocate.
+
+ @return A pointer to the allocated buffer or NULL if allocation fails.
+
+**/
+VOID *
+AllocatePageTableMemory (
+ IN UINTN Pages
+ )
+{
+ VOID *Buffer;
+
+ if (Pages == 0) {
+ return NULL;
+ }
+
+ //
+ // Renew the pool if necessary.
+ //
+ if (mPageTablePool == NULL ||
+ Pages > mPageTablePool->FreePages) {
+ if (!InitializePageTablePool (Pages)) {
+ return NULL;
+ }
+ }
+
+ Buffer = (UINT8 *)mPageTablePool + mPageTablePool->Offset;
+
+ mPageTablePool->Offset += EFI_PAGES_TO_SIZE (Pages);
+ mPageTablePool->FreePages -= Pages;
+
+ return Buffer;
+}
+
+/**
Split 2M page to 4K.
@param[in] PhysicalAddress Start physical address the 2M page covered.
@@ -177,7 +286,7 @@ Split2MPageTo4K (
//
AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) & PAGING_1G_ADDRESS_MASK_64;
- PageTableEntry = AllocatePages (1);
+ PageTableEntry = AllocatePageTableMemory (1);
ASSERT (PageTableEntry != NULL);
//
@@ -238,7 +347,7 @@ Split1GPageTo2M (
//
AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) & PAGING_1G_ADDRESS_MASK_64;
- PageDirectoryEntry = AllocatePages (1);
+ PageDirectoryEntry = AllocatePageTableMemory (1);
ASSERT (PageDirectoryEntry != NULL);
//
@@ -266,6 +375,184 @@ Split1GPageTo2M (
}
/**
+ Set one page of page table pool memory to be read-only.
+
+ @param[in] PageTableBase Base address of page table (CR3).
+ @param[in] Address Start address of a page to be set as read-only.
+ @param[in] Level4Paging Level 4 paging flag.
+
+**/
+VOID
+SetPageTablePoolReadOnly (
+ IN UINTN PageTableBase,
+ IN EFI_PHYSICAL_ADDRESS Address,
+ IN BOOLEAN Level4Paging
+ )
+{
+ UINTN Index;
+ UINTN EntryIndex;
+ UINT64 AddressEncMask;
+ EFI_PHYSICAL_ADDRESS PhysicalAddress;
+ UINT64 *PageTable;
+ UINT64 *NewPageTable;
+ UINT64 PageAttr;
+ UINT64 LevelSize[5];
+ UINT64 LevelMask[5];
+ UINTN LevelShift[5];
+ UINTN Level;
+ UINT64 PoolUnitSize;
+
+ ASSERT (PageTableBase != 0);
+
+ //
+ // Since the page table is always from page table pool, which is always
+ // located at the boundary of PcdPageTablePoolAlignment, we just need to
+ // set the whole pool unit to be read-only.
+ //
+ Address = Address & PAGE_TABLE_POOL_ALIGN_MASK;
+
+ LevelShift[1] = PAGING_L1_ADDRESS_SHIFT;
+ LevelShift[2] = PAGING_L2_ADDRESS_SHIFT;
+ LevelShift[3] = PAGING_L3_ADDRESS_SHIFT;
+ LevelShift[4] = PAGING_L4_ADDRESS_SHIFT;
+
+ LevelMask[1] = PAGING_4K_ADDRESS_MASK_64;
+ LevelMask[2] = PAGING_2M_ADDRESS_MASK_64;
+ LevelMask[3] = PAGING_1G_ADDRESS_MASK_64;
+ LevelMask[4] = PAGING_1G_ADDRESS_MASK_64;
+
+ LevelSize[1] = SIZE_4KB;
+ LevelSize[2] = SIZE_2MB;
+ LevelSize[3] = SIZE_1GB;
+ LevelSize[4] = SIZE_512GB;
+
+ AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) &
+ PAGING_1G_ADDRESS_MASK_64;
+ PageTable = (UINT64 *)(UINTN)PageTableBase;
+ PoolUnitSize = PAGE_TABLE_POOL_UNIT_SIZE;
+
+ for (Level = (Level4Paging) ? 4 : 3; Level > 0; --Level) {
+ Index = ((UINTN)RShiftU64 (Address, LevelShift[Level]));
+ Index &= PAGING_PAE_INDEX_MASK;
+
+ PageAttr = PageTable[Index];
+ if ((PageAttr & IA32_PG_PS) == 0) {
+ //
+ // Go to next level of table.
+ //
+ PageTable = (UINT64 *)(UINTN)(PageAttr & ~AddressEncMask &
+ PAGING_4K_ADDRESS_MASK_64);
+ continue;
+ }
+
+ if (PoolUnitSize >= LevelSize[Level]) {
+ //
+ // Clear R/W bit if current page granularity is not larger than pool unit
+ // size.
+ //
+ if ((PageAttr & IA32_PG_RW) != 0) {
+ while (PoolUnitSize > 0) {
+ //
+ // PAGE_TABLE_POOL_UNIT_SIZE and PAGE_TABLE_POOL_ALIGNMENT are fit in
+ // one page (2MB). Then we don't need to update attributes for pages
+ // crossing page directory. ASSERT below is for that purpose.
+ //
+ ASSERT (Index < EFI_PAGE_SIZE/sizeof (UINT64));
+
+ PageTable[Index] &= ~(UINT64)IA32_PG_RW;
+ PoolUnitSize -= LevelSize[Level];
+
+ ++Index;
+ }
+ }
+
+ break;
+
+ } else {
+ //
+ // The smaller granularity of page must be needed.
+ //
+ NewPageTable = AllocatePageTableMemory (1);
+ ASSERT (NewPageTable != NULL);
+
+ PhysicalAddress = PageAttr & LevelMask[Level];
+ for (EntryIndex = 0;
+ EntryIndex < EFI_PAGE_SIZE/sizeof (UINT64);
+ ++EntryIndex) {
+ NewPageTable[EntryIndex] = PhysicalAddress | AddressEncMask |
+ IA32_PG_P | IA32_PG_RW;
+ if (Level > 1) {
+ NewPageTable[EntryIndex] |= IA32_PG_PS;
+ }
+ PhysicalAddress += LevelSize[Level];
+ }
+
+ PageTable[Index] = (UINT64)(UINTN)NewPageTable | AddressEncMask |
+ IA32_PG_P | IA32_PG_RW;
+ PageTable = NewPageTable;
+ }
+ }
+}
+
+/**
+ Prevent the memory pages used for page table from been overwritten.
+
+ @param[in] PageTableBase Base address of page table (CR3).
+ @param[in] Level4Paging Level 4 paging flag.
+
+**/
+VOID
+EnablePageTableProtection (
+ IN UINTN PageTableBase,
+ IN BOOLEAN Level4Paging
+ )
+{
+ PAGE_TABLE_POOL *HeadPool;
+ PAGE_TABLE_POOL *Pool;
+ UINT64 PoolSize;
+ EFI_PHYSICAL_ADDRESS Address;
+
+ if (mPageTablePool == NULL) {
+ return;
+ }
+
+ //
+ // Disable write protection, because we need to mark page table to be write
+ // protected.
+ //
+ AsmWriteCr0 (AsmReadCr0() & ~CR0_WP);
+
+ //
+ // SetPageTablePoolReadOnly might update mPageTablePool. It's safer to
+ // remember original one in advance.
+ //
+ HeadPool = mPageTablePool;
+ Pool = HeadPool;
+ do {
+ Address = (EFI_PHYSICAL_ADDRESS)(UINTN)Pool;
+ PoolSize = Pool->Offset + EFI_PAGES_TO_SIZE (Pool->FreePages);
+
+ //
+ // The size of one pool must be multiple of PAGE_TABLE_POOL_UNIT_SIZE, which
+ // is one of page size of the processor (2MB by default). Let's apply the
+ // protection to them one by one.
+ //
+ while (PoolSize > 0) {
+ SetPageTablePoolReadOnly(PageTableBase, Address, Level4Paging);
+ Address += PAGE_TABLE_POOL_UNIT_SIZE;
+ PoolSize -= PAGE_TABLE_POOL_UNIT_SIZE;
+ }
+
+ Pool = Pool->NextPool;
+ } while (Pool != HeadPool);
+
+ //
+ // Enable write protection, after page table attribute updated.
+ //
+ AsmWriteCr0 (AsmReadCr0() | CR0_WP);
+}
+
+/**
Allocates and fills in the Page Directory and Page Table Entries to
establish a 1:1 Virtual to Physical mapping.
@@ -360,7 +647,7 @@ CreateIdentityMappingPageTables (
} else {
TotalPagesNum = NumberOfPml4EntriesNeeded + 1;
}
- BigPageAddress = (UINTN) AllocatePages (TotalPagesNum);
+ BigPageAddress = (UINTN) AllocatePageTableMemory (TotalPagesNum);
ASSERT (BigPageAddress != 0);
//
@@ -455,6 +742,12 @@ CreateIdentityMappingPageTables (
);
}
+ //
+ // Protect the page table by marking the memory used for page table to be
+ // read-only.
+ //
+ EnablePageTableProtection ((UINTN)PageMap, TRUE);
+
if (PcdGetBool (PcdSetNxForStack)) {
EnableExecuteDisableBit ();
}
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h
index 26a2100f0b..e7959b2cf0 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h
@@ -148,11 +148,37 @@ typedef union {
#pragma pack()
+#define CR0_WP BIT16
+
#define IA32_PG_P BIT0
#define IA32_PG_RW BIT1
+#define IA32_PG_PS BIT7
+
+#define PAGING_PAE_INDEX_MASK 0x1FF
+#define PAGING_4K_ADDRESS_MASK_64 0x000FFFFFFFFFF000ull
+#define PAGING_2M_ADDRESS_MASK_64 0x000FFFFFFFE00000ull
#define PAGING_1G_ADDRESS_MASK_64 0x000FFFFFC0000000ull
+#define PAGING_L1_ADDRESS_SHIFT 12
+#define PAGING_L2_ADDRESS_SHIFT 21
+#define PAGING_L3_ADDRESS_SHIFT 30
+#define PAGING_L4_ADDRESS_SHIFT 39
+
+#define PAGING_PML4E_NUMBER 4
+
+#define PAGE_TABLE_POOL_ALIGNMENT BASE_2MB
+#define PAGE_TABLE_POOL_UNIT_SIZE SIZE_2MB
+#define PAGE_TABLE_POOL_UNIT_PAGES EFI_SIZE_TO_PAGES (PAGE_TABLE_POOL_UNIT_SIZE)
+#define PAGE_TABLE_POOL_ALIGN_MASK \
+ (~(EFI_PHYSICAL_ADDRESS)(PAGE_TABLE_POOL_ALIGNMENT - 1))
+
+typedef struct {
+ VOID *NextPool;
+ UINTN Offset;
+ UINTN FreePages;
+} PAGE_TABLE_POOL;
+
/**
Enable Execute Disable Bit.
@@ -252,4 +278,39 @@ IsNullDetectionEnabled (
VOID
);
+/**
+ Prevent the memory pages used for page table from been overwritten.
+
+ @param[in] PageTableBase Base address of page table (CR3).
+ @param[in] Level4Paging Level 4 paging flag.
+
+**/
+VOID
+EnablePageTableProtection (
+ IN UINTN PageTableBase,
+ IN BOOLEAN Level4Paging
+ );
+
+/**
+ This API provides a way to allocate memory for page table.
+
+ This API can be called more than once to allocate memory for page tables.
+
+ Allocates the number of 4KB pages and returns a pointer to the allocated
+ buffer. The buffer returned is aligned on a 4KB boundary.
+
+ If Pages is 0, then NULL is returned.
+ If there is not enough memory remaining to satisfy the request, then NULL is
+ returned.
+
+ @param Pages The number of 4 KB pages to allocate.
+
+ @return A pointer to the allocated buffer or NULL if allocation fails.
+
+**/
+VOID *
+AllocatePageTableMemory (
+ IN UINTN Pages
+ );
+
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-20 07:11:41 +0000