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audk/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c

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/** @file
UEFI Heap Guard functions.
Copyright (c) 2017-2018, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "DxeMain.h"
#include "Imem.h"
#include "HeapGuard.h"
//
// Global to avoid infinite reentrance of memory allocation when updating
// page table attributes, which may need allocate pages for new PDE/PTE.
//
GLOBAL_REMOVE_IF_UNREFERENCED BOOLEAN mOnGuarding = FALSE;
//
// Pointer to table tracking the Guarded memory with bitmap, in which '1'
// is used to indicate memory guarded. '0' might be free memory or Guard
// page itself, depending on status of memory adjacent to it.
//
GLOBAL_REMOVE_IF_UNREFERENCED UINT64 mGuardedMemoryMap = 0;
//
// Current depth level of map table pointed by mGuardedMemoryMap.
// mMapLevel must be initialized at least by 1. It will be automatically
// updated according to the address of memory just tracked.
//
GLOBAL_REMOVE_IF_UNREFERENCED UINTN mMapLevel = 1;
//
// Shift and mask for each level of map table
//
GLOBAL_REMOVE_IF_UNREFERENCED UINTN mLevelShift[GUARDED_HEAP_MAP_TABLE_DEPTH]
= GUARDED_HEAP_MAP_TABLE_DEPTH_SHIFTS;
GLOBAL_REMOVE_IF_UNREFERENCED UINTN mLevelMask[GUARDED_HEAP_MAP_TABLE_DEPTH]
= GUARDED_HEAP_MAP_TABLE_DEPTH_MASKS;
/**
Set corresponding bits in bitmap table to 1 according to the address.
@param[in] Address Start address to set for.
@param[in] BitNumber Number of bits to set.
@param[in] BitMap Pointer to bitmap which covers the Address.
@return VOID.
**/
STATIC
VOID
SetBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN BitNumber,
IN UINT64 *BitMap
)
{
UINTN Lsbs;
UINTN Qwords;
UINTN Msbs;
UINTN StartBit;
UINTN EndBit;
StartBit = (UINTN)GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address);
EndBit = (StartBit + BitNumber - 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
if ((StartBit + BitNumber) >= GUARDED_HEAP_MAP_ENTRY_BITS) {
Msbs = (GUARDED_HEAP_MAP_ENTRY_BITS - StartBit) %
GUARDED_HEAP_MAP_ENTRY_BITS;
Lsbs = (EndBit + 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
Qwords = (BitNumber - Msbs) / GUARDED_HEAP_MAP_ENTRY_BITS;
} else {
Msbs = BitNumber;
Lsbs = 0;
Qwords = 0;
}
if (Msbs > 0) {
*BitMap |= LShiftU64 (LShiftU64 (1, Msbs) - 1, StartBit);
BitMap += 1;
}
if (Qwords > 0) {
SetMem64 ((VOID *)BitMap, Qwords * GUARDED_HEAP_MAP_ENTRY_BYTES,
(UINT64)-1);
BitMap += Qwords;
}
if (Lsbs > 0) {
*BitMap |= (LShiftU64 (1, Lsbs) - 1);
}
}
/**
Set corresponding bits in bitmap table to 0 according to the address.
@param[in] Address Start address to set for.
@param[in] BitNumber Number of bits to set.
@param[in] BitMap Pointer to bitmap which covers the Address.
@return VOID.
**/
STATIC
VOID
ClearBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN BitNumber,
IN UINT64 *BitMap
)
{
UINTN Lsbs;
UINTN Qwords;
UINTN Msbs;
UINTN StartBit;
UINTN EndBit;
StartBit = (UINTN)GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address);
EndBit = (StartBit + BitNumber - 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
if ((StartBit + BitNumber) >= GUARDED_HEAP_MAP_ENTRY_BITS) {
Msbs = (GUARDED_HEAP_MAP_ENTRY_BITS - StartBit) %
GUARDED_HEAP_MAP_ENTRY_BITS;
Lsbs = (EndBit + 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
Qwords = (BitNumber - Msbs) / GUARDED_HEAP_MAP_ENTRY_BITS;
} else {
Msbs = BitNumber;
Lsbs = 0;
Qwords = 0;
}
if (Msbs > 0) {
*BitMap &= ~LShiftU64 (LShiftU64 (1, Msbs) - 1, StartBit);
BitMap += 1;
}
if (Qwords > 0) {
SetMem64 ((VOID *)BitMap, Qwords * GUARDED_HEAP_MAP_ENTRY_BYTES, 0);
BitMap += Qwords;
}
if (Lsbs > 0) {
*BitMap &= ~(LShiftU64 (1, Lsbs) - 1);
}
}
/**
Get corresponding bits in bitmap table according to the address.
The value of bit 0 corresponds to the status of memory at given Address.
No more than 64 bits can be retrieved in one call.
@param[in] Address Start address to retrieve bits for.
@param[in] BitNumber Number of bits to get.
@param[in] BitMap Pointer to bitmap which covers the Address.
@return An integer containing the bits information.
**/
STATIC
UINT64
GetBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN BitNumber,
IN UINT64 *BitMap
)
{
UINTN StartBit;
UINTN EndBit;
UINTN Lsbs;
UINTN Msbs;
UINT64 Result;
ASSERT (BitNumber <= GUARDED_HEAP_MAP_ENTRY_BITS);
StartBit = (UINTN)GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address);
EndBit = (StartBit + BitNumber - 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
if ((StartBit + BitNumber) > GUARDED_HEAP_MAP_ENTRY_BITS) {
Msbs = GUARDED_HEAP_MAP_ENTRY_BITS - StartBit;
Lsbs = (EndBit + 1) % GUARDED_HEAP_MAP_ENTRY_BITS;
} else {
Msbs = BitNumber;
Lsbs = 0;
}
if (StartBit == 0 && BitNumber == GUARDED_HEAP_MAP_ENTRY_BITS) {
Result = *BitMap;
} else {
Result = RShiftU64((*BitMap), StartBit) & (LShiftU64(1, Msbs) - 1);
if (Lsbs > 0) {
BitMap += 1;
Result |= LShiftU64 ((*BitMap) & (LShiftU64 (1, Lsbs) - 1), Msbs);
}
}
return Result;
}
/**
Locate the pointer of bitmap from the guarded memory bitmap tables, which
covers the given Address.
@param[in] Address Start address to search the bitmap for.
@param[in] AllocMapUnit Flag to indicate memory allocation for the table.
@param[out] BitMap Pointer to bitmap which covers the Address.
@return The bit number from given Address to the end of current map table.
**/
UINTN
FindGuardedMemoryMap (
IN EFI_PHYSICAL_ADDRESS Address,
IN BOOLEAN AllocMapUnit,
OUT UINT64 **BitMap
)
{
UINTN Level;
UINT64 *GuardMap;
UINT64 MapMemory;
UINTN Index;
UINTN Size;
UINTN BitsToUnitEnd;
EFI_STATUS Status;
//
// Adjust current map table depth according to the address to access
//
while (AllocMapUnit &&
mMapLevel < GUARDED_HEAP_MAP_TABLE_DEPTH &&
RShiftU64 (
Address,
mLevelShift[GUARDED_HEAP_MAP_TABLE_DEPTH - mMapLevel - 1]
) != 0) {
if (mGuardedMemoryMap != 0) {
Size = (mLevelMask[GUARDED_HEAP_MAP_TABLE_DEPTH - mMapLevel - 1] + 1)
* GUARDED_HEAP_MAP_ENTRY_BYTES;
Status = CoreInternalAllocatePages (
AllocateAnyPages,
EfiBootServicesData,
EFI_SIZE_TO_PAGES (Size),
&MapMemory,
FALSE
);
ASSERT_EFI_ERROR (Status);
ASSERT (MapMemory != 0);
SetMem ((VOID *)(UINTN)MapMemory, Size, 0);
*(UINT64 *)(UINTN)MapMemory = mGuardedMemoryMap;
mGuardedMemoryMap = MapMemory;
}
mMapLevel++;
}
GuardMap = &mGuardedMemoryMap;
for (Level = GUARDED_HEAP_MAP_TABLE_DEPTH - mMapLevel;
Level < GUARDED_HEAP_MAP_TABLE_DEPTH;
++Level) {
if (*GuardMap == 0) {
if (!AllocMapUnit) {
GuardMap = NULL;
break;
}
Size = (mLevelMask[Level] + 1) * GUARDED_HEAP_MAP_ENTRY_BYTES;
Status = CoreInternalAllocatePages (
AllocateAnyPages,
EfiBootServicesData,
EFI_SIZE_TO_PAGES (Size),
&MapMemory,
FALSE
);
ASSERT_EFI_ERROR (Status);
ASSERT (MapMemory != 0);
SetMem ((VOID *)(UINTN)MapMemory, Size, 0);
*GuardMap = MapMemory;
}
Index = (UINTN)RShiftU64 (Address, mLevelShift[Level]);
Index &= mLevelMask[Level];
GuardMap = (UINT64 *)(UINTN)((*GuardMap) + Index * sizeof (UINT64));
}
BitsToUnitEnd = GUARDED_HEAP_MAP_BITS - GUARDED_HEAP_MAP_BIT_INDEX (Address);
*BitMap = GuardMap;
return BitsToUnitEnd;
}
/**
Set corresponding bits in bitmap table to 1 according to given memory range.
@param[in] Address Memory address to guard from.
@param[in] NumberOfPages Number of pages to guard.
@return VOID.
**/
VOID
EFIAPI
SetGuardedMemoryBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN NumberOfPages
)
{
UINT64 *BitMap;
UINTN Bits;
UINTN BitsToUnitEnd;
while (NumberOfPages > 0) {
BitsToUnitEnd = FindGuardedMemoryMap (Address, TRUE, &BitMap);
ASSERT (BitMap != NULL);
if (NumberOfPages > BitsToUnitEnd) {
// Cross map unit
Bits = BitsToUnitEnd;
} else {
Bits = NumberOfPages;
}
SetBits (Address, Bits, BitMap);
NumberOfPages -= Bits;
Address += EFI_PAGES_TO_SIZE (Bits);
}
}
/**
Clear corresponding bits in bitmap table according to given memory range.
@param[in] Address Memory address to unset from.
@param[in] NumberOfPages Number of pages to unset guard.
@return VOID.
**/
VOID
EFIAPI
ClearGuardedMemoryBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN NumberOfPages
)
{
UINT64 *BitMap;
UINTN Bits;
UINTN BitsToUnitEnd;
while (NumberOfPages > 0) {
BitsToUnitEnd = FindGuardedMemoryMap (Address, TRUE, &BitMap);
ASSERT (BitMap != NULL);
if (NumberOfPages > BitsToUnitEnd) {
// Cross map unit
Bits = BitsToUnitEnd;
} else {
Bits = NumberOfPages;
}
ClearBits (Address, Bits, BitMap);
NumberOfPages -= Bits;
Address += EFI_PAGES_TO_SIZE (Bits);
}
}
/**
Retrieve corresponding bits in bitmap table according to given memory range.
@param[in] Address Memory address to retrieve from.
@param[in] NumberOfPages Number of pages to retrieve.
@return An integer containing the guarded memory bitmap.
**/
UINTN
GetGuardedMemoryBits (
IN EFI_PHYSICAL_ADDRESS Address,
IN UINTN NumberOfPages
)
{
UINT64 *BitMap;
UINTN Bits;
UINTN Result;
UINTN Shift;
UINTN BitsToUnitEnd;
ASSERT (NumberOfPages <= GUARDED_HEAP_MAP_ENTRY_BITS);
Result = 0;
Shift = 0;
while (NumberOfPages > 0) {
BitsToUnitEnd = FindGuardedMemoryMap (Address, FALSE, &BitMap);
if (NumberOfPages > BitsToUnitEnd) {
// Cross map unit
Bits = BitsToUnitEnd;
} else {
Bits = NumberOfPages;
}
if (BitMap != NULL) {
Result |= LShiftU64 (GetBits (Address, Bits, BitMap), Shift);
}
Shift += Bits;
NumberOfPages -= Bits;
Address += EFI_PAGES_TO_SIZE (Bits);
}
return Result;
}
/**
Get bit value in bitmap table for the given address.
@param[in] Address The address to retrieve for.
@return 1 or 0.
**/
UINTN
EFIAPI
GetGuardMapBit (
IN EFI_PHYSICAL_ADDRESS Address
)
{
UINT64 *GuardMap;
FindGuardedMemoryMap (Address, FALSE, &GuardMap);
if (GuardMap != NULL) {
if (RShiftU64 (*GuardMap,
GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address)) & 1) {
return 1;
}
}
return 0;
}
/**
Check to see if the page at the given address is a Guard page or not.
@param[in] Address The address to check for.
@return TRUE The page at Address is a Guard page.
@return FALSE The page at Address is not a Guard page.
**/
BOOLEAN
EFIAPI
IsGuardPage (
IN EFI_PHYSICAL_ADDRESS Address
)
{
UINTN BitMap;
//
// There must be at least one guarded page before and/or after given
// address if it's a Guard page. The bitmap pattern should be one of
// 001, 100 and 101
//
BitMap = GetGuardedMemoryBits (Address - EFI_PAGE_SIZE, 3);
return ((BitMap == BIT0) || (BitMap == BIT2) || (BitMap == (BIT2 | BIT0)));
}
/**
Check to see if the page at the given address is guarded or not.
@param[in] Address The address to check for.
@return TRUE The page at Address is guarded.
@return FALSE The page at Address is not guarded.
**/
BOOLEAN
EFIAPI
IsMemoryGuarded (
IN EFI_PHYSICAL_ADDRESS Address
)
{
return (GetGuardMapBit (Address) == 1);
}
/**
Set the page at the given address to be a Guard page.
This is done by changing the page table attribute to be NOT PRSENT.
@param[in] BaseAddress Page address to Guard at
@return VOID
**/
VOID
EFIAPI
SetGuardPage (
IN EFI_PHYSICAL_ADDRESS BaseAddress
)
{
EFI_STATUS Status;
if (gCpu == NULL) {
return;
}
//
// Set flag to make sure allocating memory without GUARD for page table
// operation; otherwise infinite loops could be caused.
//
mOnGuarding = TRUE;
//
// Note: This might overwrite other attributes needed by other features,
// such as NX memory protection.
//
Status = gCpu->SetMemoryAttributes (gCpu, BaseAddress, EFI_PAGE_SIZE, EFI_MEMORY_RP);
ASSERT_EFI_ERROR (Status);
mOnGuarding = FALSE;
}
/**
Unset the Guard page at the given address to the normal memory.
This is done by changing the page table attribute to be PRSENT.
@param[in] BaseAddress Page address to Guard at.
@return VOID.
**/
VOID
EFIAPI
UnsetGuardPage (
IN EFI_PHYSICAL_ADDRESS BaseAddress
)
{
UINT64 Attributes;
EFI_STATUS Status;
if (gCpu == NULL) {
return;
}
//
// Once the Guard page is unset, it will be freed back to memory pool. NX
// memory protection must be restored for this page if NX is enabled for free
// memory.
//
Attributes = 0;
if ((PcdGet64 (PcdDxeNxMemoryProtectionPolicy) & (1 << EfiConventionalMemory)) != 0) {
Attributes |= EFI_MEMORY_XP;
}
//
// Set flag to make sure allocating memory without GUARD for page table
// operation; otherwise infinite loops could be caused.
//
mOnGuarding = TRUE;
//
// Note: This might overwrite other attributes needed by other features,
// such as memory protection (NX). Please make sure they are not enabled
// at the same time.
//
Status = gCpu->SetMemoryAttributes (gCpu, BaseAddress, EFI_PAGE_SIZE, Attributes);
ASSERT_EFI_ERROR (Status);
mOnGuarding = FALSE;
}
/**
Check to see if the memory at the given address should be guarded or not.
@param[in] MemoryType Memory type to check.
@param[in] AllocateType Allocation type to check.
@param[in] PageOrPool Indicate a page allocation or pool allocation.
@return TRUE The given type of memory should be guarded.
@return FALSE The given type of memory should not be guarded.
**/
BOOLEAN
IsMemoryTypeToGuard (
IN EFI_MEMORY_TYPE MemoryType,
IN EFI_ALLOCATE_TYPE AllocateType,
IN UINT8 PageOrPool
)
{
UINT64 TestBit;
UINT64 ConfigBit;
if (AllocateType == AllocateAddress) {
return FALSE;
}
if ((PcdGet8 (PcdHeapGuardPropertyMask) & PageOrPool) == 0) {
return FALSE;
}
if (PageOrPool == GUARD_HEAP_TYPE_POOL) {
ConfigBit = PcdGet64 (PcdHeapGuardPoolType);
} else if (PageOrPool == GUARD_HEAP_TYPE_PAGE) {
ConfigBit = PcdGet64 (PcdHeapGuardPageType);
} else {
ConfigBit = (UINT64)-1;
}
if ((UINT32)MemoryType >= MEMORY_TYPE_OS_RESERVED_MIN) {
TestBit = BIT63;
} else if ((UINT32) MemoryType >= MEMORY_TYPE_OEM_RESERVED_MIN) {
TestBit = BIT62;
} else if (MemoryType < EfiMaxMemoryType) {
TestBit = LShiftU64 (1, MemoryType);
} else if (MemoryType == EfiMaxMemoryType) {
TestBit = (UINT64)-1;
} else {
TestBit = 0;
}
return ((ConfigBit & TestBit) != 0);
}
/**
Check to see if the pool at the given address should be guarded or not.
@param[in] MemoryType Pool type to check.
@return TRUE The given type of pool should be guarded.
@return FALSE The given type of pool should not be guarded.
**/
BOOLEAN
IsPoolTypeToGuard (
IN EFI_MEMORY_TYPE MemoryType
)
{
return IsMemoryTypeToGuard (MemoryType, AllocateAnyPages,
GUARD_HEAP_TYPE_POOL);
}
/**
Check to see if the page at the given address should be guarded or not.
@param[in] MemoryType Page type to check.
@param[in] AllocateType Allocation type to check.
@return TRUE The given type of page should be guarded.
@return FALSE The given type of page should not be guarded.
**/
BOOLEAN
IsPageTypeToGuard (
IN EFI_MEMORY_TYPE MemoryType,
IN EFI_ALLOCATE_TYPE AllocateType
)
{
return IsMemoryTypeToGuard (MemoryType, AllocateType, GUARD_HEAP_TYPE_PAGE);
}
/**
Check to see if the heap guard is enabled for page and/or pool allocation.
@return TRUE/FALSE.
**/
BOOLEAN
IsHeapGuardEnabled (
VOID
)
{
return IsMemoryTypeToGuard (EfiMaxMemoryType, AllocateAnyPages,
GUARD_HEAP_TYPE_POOL|GUARD_HEAP_TYPE_PAGE);
}
/**
Set head Guard and tail Guard for the given memory range.
@param[in] Memory Base address of memory to set guard for.
@param[in] NumberOfPages Memory size in pages.
@return VOID
**/
VOID
SetGuardForMemory (
IN EFI_PHYSICAL_ADDRESS Memory,
IN UINTN NumberOfPages
)
{
EFI_PHYSICAL_ADDRESS GuardPage;
//
// Set tail Guard
//
GuardPage = Memory + EFI_PAGES_TO_SIZE (NumberOfPages);
if (!IsGuardPage (GuardPage)) {
SetGuardPage (GuardPage);
}
// Set head Guard
GuardPage = Memory - EFI_PAGES_TO_SIZE (1);
if (!IsGuardPage (GuardPage)) {
SetGuardPage (GuardPage);
}
//
// Mark the memory range as Guarded
//
SetGuardedMemoryBits (Memory, NumberOfPages);
}
/**
Unset head Guard and tail Guard for the given memory range.
@param[in] Memory Base address of memory to unset guard for.
@param[in] NumberOfPages Memory size in pages.
@return VOID
**/
VOID
UnsetGuardForMemory (
IN EFI_PHYSICAL_ADDRESS Memory,
IN UINTN NumberOfPages
)
{
EFI_PHYSICAL_ADDRESS GuardPage;
UINT64 GuardBitmap;
if (NumberOfPages == 0) {
return;
}
//
// Head Guard must be one page before, if any.
//
// MSB-> 1 0 <-LSB
// -------------------
// Head Guard -> 0 1 -> Don't free Head Guard (shared Guard)
// Head Guard -> 0 0 -> Free Head Guard either (not shared Guard)
// 1 X -> Don't free first page (need a new Guard)
// (it'll be turned into a Guard page later)
// -------------------
// Start -> -1 -2
//
GuardPage = Memory - EFI_PAGES_TO_SIZE (1);
GuardBitmap = GetGuardedMemoryBits (Memory - EFI_PAGES_TO_SIZE (2), 2);
if ((GuardBitmap & BIT1) == 0) {
//
// Head Guard exists.
//
if ((GuardBitmap & BIT0) == 0) {
//
// If the head Guard is not a tail Guard of adjacent memory block,
// unset it.
//
UnsetGuardPage (GuardPage);
}
} else {
//
// Pages before memory to free are still in Guard. It's a partial free
// case. Turn first page of memory block to free into a new Guard.
//
SetGuardPage (Memory);
}
//
// Tail Guard must be the page after this memory block to free, if any.
//
// MSB-> 1 0 <-LSB
// --------------------
// 1 0 <- Tail Guard -> Don't free Tail Guard (shared Guard)
// 0 0 <- Tail Guard -> Free Tail Guard either (not shared Guard)
// X 1 -> Don't free last page (need a new Guard)
// (it'll be turned into a Guard page later)
// --------------------
// +1 +0 <- End
//
GuardPage = Memory + EFI_PAGES_TO_SIZE (NumberOfPages);
GuardBitmap = GetGuardedMemoryBits (GuardPage, 2);
if ((GuardBitmap & BIT0) == 0) {
//
// Tail Guard exists.
//
if ((GuardBitmap & BIT1) == 0) {
//
// If the tail Guard is not a head Guard of adjacent memory block,
// free it; otherwise, keep it.
//
UnsetGuardPage (GuardPage);
}
} else {
//
// Pages after memory to free are still in Guard. It's a partial free
// case. We need to keep one page to be a head Guard.
//
SetGuardPage (GuardPage - EFI_PAGES_TO_SIZE (1));
}
//
// No matter what, we just clear the mark of the Guarded memory.
//
ClearGuardedMemoryBits(Memory, NumberOfPages);
}
/**
Adjust address of free memory according to existing and/or required Guard.
This function will check if there're existing Guard pages of adjacent
memory blocks, and try to use it as the Guard page of the memory to be
allocated.
@param[in] Start Start address of free memory block.
@param[in] Size Size of free memory block.
@param[in] SizeRequested Size of memory to allocate.
@return The end address of memory block found.
@return 0 if no enough space for the required size of memory and its Guard.
**/
UINT64
AdjustMemoryS (
IN UINT64 Start,
IN UINT64 Size,
IN UINT64 SizeRequested
)
{
UINT64 Target;
//
// UEFI spec requires that allocated pool must be 8-byte aligned. If it's
// indicated to put the pool near the Tail Guard, we need extra bytes to
// make sure alignment of the returned pool address.
//
if ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) == 0) {
SizeRequested = ALIGN_VALUE(SizeRequested, 8);
}
Target = Start + Size - SizeRequested;
ASSERT (Target >= Start);
if (Target == 0) {
return 0;
}
if (!IsGuardPage (Start + Size)) {
// No Guard at tail to share. One more page is needed.
Target -= EFI_PAGES_TO_SIZE (1);
}
// Out of range?
if (Target < Start) {
return 0;
}
// At the edge?
if (Target == Start) {
if (!IsGuardPage (Target - EFI_PAGES_TO_SIZE (1))) {
// No enough space for a new head Guard if no Guard at head to share.
return 0;
}
}
// OK, we have enough pages for memory and its Guards. Return the End of the
// free space.
return Target + SizeRequested - 1;
}
/**
Adjust the start address and number of pages to free according to Guard.
The purpose of this function is to keep the shared Guard page with adjacent
memory block if it's still in guard, or free it if no more sharing. Another
is to reserve pages as Guard pages in partial page free situation.
@param[in,out] Memory Base address of memory to free.
@param[in,out] NumberOfPages Size of memory to free.
@return VOID.
**/
VOID
AdjustMemoryF (
IN OUT EFI_PHYSICAL_ADDRESS *Memory,
IN OUT UINTN *NumberOfPages
)
{
EFI_PHYSICAL_ADDRESS Start;
EFI_PHYSICAL_ADDRESS MemoryToTest;
UINTN PagesToFree;
UINT64 GuardBitmap;
if (Memory == NULL || NumberOfPages == NULL || *NumberOfPages == 0) {
return;
}
Start = *Memory;
PagesToFree = *NumberOfPages;
//
// Head Guard must be one page before, if any.
//
// MSB-> 1 0 <-LSB
// -------------------
// Head Guard -> 0 1 -> Don't free Head Guard (shared Guard)
// Head Guard -> 0 0 -> Free Head Guard either (not shared Guard)
// 1 X -> Don't free first page (need a new Guard)
// (it'll be turned into a Guard page later)
// -------------------
// Start -> -1 -2
//
MemoryToTest = Start - EFI_PAGES_TO_SIZE (2);
GuardBitmap = GetGuardedMemoryBits (MemoryToTest, 2);
if ((GuardBitmap & BIT1) == 0) {
//
// Head Guard exists.
//
if ((GuardBitmap & BIT0) == 0) {
//
// If the head Guard is not a tail Guard of adjacent memory block,
// free it; otherwise, keep it.
//
Start -= EFI_PAGES_TO_SIZE (1);
PagesToFree += 1;
}
} else {
//
// No Head Guard, and pages before memory to free are still in Guard. It's a
// partial free case. We need to keep one page to be a tail Guard.
//
Start += EFI_PAGES_TO_SIZE (1);
PagesToFree -= 1;
}
//
// Tail Guard must be the page after this memory block to free, if any.
//
// MSB-> 1 0 <-LSB
// --------------------
// 1 0 <- Tail Guard -> Don't free Tail Guard (shared Guard)
// 0 0 <- Tail Guard -> Free Tail Guard either (not shared Guard)
// X 1 -> Don't free last page (need a new Guard)
// (it'll be turned into a Guard page later)
// --------------------
// +1 +0 <- End
//
MemoryToTest = Start + EFI_PAGES_TO_SIZE (PagesToFree);
GuardBitmap = GetGuardedMemoryBits (MemoryToTest, 2);
if ((GuardBitmap & BIT0) == 0) {
//
// Tail Guard exists.
//
if ((GuardBitmap & BIT1) == 0) {
//
// If the tail Guard is not a head Guard of adjacent memory block,
// free it; otherwise, keep it.
//
PagesToFree += 1;
}
} else if (PagesToFree > 0) {
//
// No Tail Guard, and pages after memory to free are still in Guard. It's a
// partial free case. We need to keep one page to be a head Guard.
//
PagesToFree -= 1;
}
*Memory = Start;
*NumberOfPages = PagesToFree;
}
/**
Adjust the base and number of pages to really allocate according to Guard.
@param[in,out] Memory Base address of free memory.
@param[in,out] NumberOfPages Size of memory to allocate.
@return VOID.
**/
VOID
AdjustMemoryA (
IN OUT EFI_PHYSICAL_ADDRESS *Memory,
IN OUT UINTN *NumberOfPages
)
{
//
// FindFreePages() has already taken the Guard into account. It's safe to
// adjust the start address and/or number of pages here, to make sure that
// the Guards are also "allocated".
//
if (!IsGuardPage (*Memory + EFI_PAGES_TO_SIZE (*NumberOfPages))) {
// No tail Guard, add one.
*NumberOfPages += 1;
}
if (!IsGuardPage (*Memory - EFI_PAGE_SIZE)) {
// No head Guard, add one.
*Memory -= EFI_PAGE_SIZE;
*NumberOfPages += 1;
}
}
/**
Adjust the pool head position to make sure the Guard page is adjavent to
pool tail or pool head.
@param[in] Memory Base address of memory allocated.
@param[in] NoPages Number of pages actually allocated.
@param[in] Size Size of memory requested.
(plus pool head/tail overhead)
@return Address of pool head.
**/
VOID *
AdjustPoolHeadA (
IN EFI_PHYSICAL_ADDRESS Memory,
IN UINTN NoPages,
IN UINTN Size
)
{
if (Memory == 0 || (PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {
//
// Pool head is put near the head Guard
//
return (VOID *)(UINTN)Memory;
}
//
// Pool head is put near the tail Guard
//
Size = ALIGN_VALUE (Size, 8);
return (VOID *)(UINTN)(Memory + EFI_PAGES_TO_SIZE (NoPages) - Size);
}
/**
Get the page base address according to pool head address.
@param[in] Memory Head address of pool to free.
@return Address of pool head.
**/
VOID *
AdjustPoolHeadF (
IN EFI_PHYSICAL_ADDRESS Memory
)
{
if (Memory == 0 || (PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) != 0) {
//
// Pool head is put near the head Guard
//
return (VOID *)(UINTN)Memory;
}
//
// Pool head is put near the tail Guard
//
return (VOID *)(UINTN)(Memory & ~EFI_PAGE_MASK);
}
/**
Allocate or free guarded memory.
@param[in] Start Start address of memory to allocate or free.
@param[in] NumberOfPages Memory size in pages.
@param[in] NewType Memory type to convert to.
@return VOID.
**/
EFI_STATUS
CoreConvertPagesWithGuard (
IN UINT64 Start,
IN UINTN NumberOfPages,
IN EFI_MEMORY_TYPE NewType
)
{
UINT64 OldStart;
UINTN OldPages;
if (NewType == EfiConventionalMemory) {
OldStart = Start;
OldPages = NumberOfPages;
AdjustMemoryF (&Start, &NumberOfPages);
//
// It's safe to unset Guard page inside memory lock because there should
// be no memory allocation occurred in updating memory page attribute at
// this point. And unsetting Guard page before free will prevent Guard
// page just freed back to pool from being allocated right away before
// marking it usable (from non-present to present).
//
UnsetGuardForMemory (OldStart, OldPages);
if (NumberOfPages == 0) {
return EFI_SUCCESS;
}
} else {
AdjustMemoryA (&Start, &NumberOfPages);
}
return CoreConvertPages (Start, NumberOfPages, NewType);
}
/**
Set all Guard pages which cannot be set before CPU Arch Protocol installed.
**/
VOID
SetAllGuardPages (
VOID
)
{
UINTN Entries[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINTN Shifts[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINTN Indices[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 Tables[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 Addresses[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 TableEntry;
UINT64 Address;
UINT64 GuardPage;
INTN Level;
UINTN Index;
BOOLEAN OnGuarding;
if (mGuardedMemoryMap == 0 ||
mMapLevel == 0 ||
mMapLevel > GUARDED_HEAP_MAP_TABLE_DEPTH) {
return;
}
CopyMem (Entries, mLevelMask, sizeof (Entries));
CopyMem (Shifts, mLevelShift, sizeof (Shifts));
SetMem (Tables, sizeof(Tables), 0);
SetMem (Addresses, sizeof(Addresses), 0);
SetMem (Indices, sizeof(Indices), 0);
Level = GUARDED_HEAP_MAP_TABLE_DEPTH - mMapLevel;
Tables[Level] = mGuardedMemoryMap;
Address = 0;
OnGuarding = FALSE;
DEBUG_CODE (
DumpGuardedMemoryBitmap ();
);
while (TRUE) {
if (Indices[Level] > Entries[Level]) {
Tables[Level] = 0;
Level -= 1;
} else {
TableEntry = ((UINT64 *)(UINTN)(Tables[Level]))[Indices[Level]];
Address = Addresses[Level];
if (TableEntry == 0) {
OnGuarding = FALSE;
} else if (Level < GUARDED_HEAP_MAP_TABLE_DEPTH - 1) {
Level += 1;
Tables[Level] = TableEntry;
Addresses[Level] = Address;
Indices[Level] = 0;
continue;
} else {
Index = 0;
while (Index < GUARDED_HEAP_MAP_ENTRY_BITS) {
if ((TableEntry & 1) == 1) {
if (OnGuarding) {
GuardPage = 0;
} else {
GuardPage = Address - EFI_PAGE_SIZE;
}
OnGuarding = TRUE;
} else {
if (OnGuarding) {
GuardPage = Address;
} else {
GuardPage = 0;
}
OnGuarding = FALSE;
}
if (GuardPage != 0) {
SetGuardPage (GuardPage);
}
if (TableEntry == 0) {
break;
}
TableEntry = RShiftU64 (TableEntry, 1);
Address += EFI_PAGE_SIZE;
Index += 1;
}
}
}
if (Level < (GUARDED_HEAP_MAP_TABLE_DEPTH - (INTN)mMapLevel)) {
break;
}
Indices[Level] += 1;
Address = (Level == 0) ? 0 : Addresses[Level - 1];
Addresses[Level] = Address | LShiftU64(Indices[Level], Shifts[Level]);
}
}
/**
Notify function used to set all Guard pages before CPU Arch Protocol installed.
**/
VOID
HeapGuardCpuArchProtocolNotify (
VOID
)
{
ASSERT (gCpu != NULL);
SetAllGuardPages ();
}
/**
Helper function to convert a UINT64 value in binary to a string.
@param[in] Value Value of a UINT64 integer.
@param[out] BinString String buffer to contain the conversion result.
@return VOID.
**/
VOID
Uint64ToBinString (
IN UINT64 Value,
OUT CHAR8 *BinString
)
{
UINTN Index;
if (BinString == NULL) {
return;
}
for (Index = 64; Index > 0; --Index) {
BinString[Index - 1] = '0' + (Value & 1);
Value = RShiftU64 (Value, 1);
}
BinString[64] = '\0';
}
/**
Dump the guarded memory bit map.
**/
VOID
EFIAPI
DumpGuardedMemoryBitmap (
VOID
)
{
UINTN Entries[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINTN Shifts[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINTN Indices[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 Tables[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 Addresses[GUARDED_HEAP_MAP_TABLE_DEPTH];
UINT64 TableEntry;
UINT64 Address;
INTN Level;
UINTN RepeatZero;
CHAR8 String[GUARDED_HEAP_MAP_ENTRY_BITS + 1];
CHAR8 *Ruler1;
CHAR8 *Ruler2;
if (mGuardedMemoryMap == 0 ||
mMapLevel == 0 ||
mMapLevel > GUARDED_HEAP_MAP_TABLE_DEPTH) {
return;
}
Ruler1 = " 3 2 1 0";
Ruler2 = "FEDCBA9876543210FEDCBA9876543210FEDCBA9876543210FEDCBA9876543210";
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, "============================="
" Guarded Memory Bitmap "
"==============================\r\n"));
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, " %a\r\n", Ruler1));
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, " %a\r\n", Ruler2));
CopyMem (Entries, mLevelMask, sizeof (Entries));
CopyMem (Shifts, mLevelShift, sizeof (Shifts));
SetMem (Indices, sizeof(Indices), 0);
SetMem (Tables, sizeof(Tables), 0);
SetMem (Addresses, sizeof(Addresses), 0);
Level = GUARDED_HEAP_MAP_TABLE_DEPTH - mMapLevel;
Tables[Level] = mGuardedMemoryMap;
Address = 0;
RepeatZero = 0;
while (TRUE) {
if (Indices[Level] > Entries[Level]) {
Tables[Level] = 0;
Level -= 1;
RepeatZero = 0;
DEBUG ((
HEAP_GUARD_DEBUG_LEVEL,
"========================================="
"=========================================\r\n"
));
} else {
TableEntry = ((UINT64 *)(UINTN)Tables[Level])[Indices[Level]];
Address = Addresses[Level];
if (TableEntry == 0) {
if (Level == GUARDED_HEAP_MAP_TABLE_DEPTH - 1) {
if (RepeatZero == 0) {
Uint64ToBinString(TableEntry, String);
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, "%016lx: %a\r\n", Address, String));
} else if (RepeatZero == 1) {
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, "... : ...\r\n"));
}
RepeatZero += 1;
}
} else if (Level < GUARDED_HEAP_MAP_TABLE_DEPTH - 1) {
Level += 1;
Tables[Level] = TableEntry;
Addresses[Level] = Address;
Indices[Level] = 0;
RepeatZero = 0;
continue;
} else {
RepeatZero = 0;
Uint64ToBinString(TableEntry, String);
DEBUG ((HEAP_GUARD_DEBUG_LEVEL, "%016lx: %a\r\n", Address, String));
}
}
if (Level < (GUARDED_HEAP_MAP_TABLE_DEPTH - (INTN)mMapLevel)) {
break;
}
Indices[Level] += 1;
Address = (Level == 0) ? 0 : Addresses[Level - 1];
Addresses[Level] = Address | LShiftU64(Indices[Level], Shifts[Level]);
}
}
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