Jian J Wang 9189ec20b9 MdeModulePkg/DxeIpl: Implement NULL pointer detection
NULL pointer detection is done by making use of paging mechanism of CPU.
During page table setup, if enabled, the first 4-K page (0-4095) will be
marked as NOT PRESENT. Any code which unintentionally access memory between
0-4095 will trigger a Page Fault exception which warns users that there's
potential illegal code in BIOS.

This also means that legacy code which has to access memory between 0-4095
should be cautious to temporarily disable this feature before the access
and re-enable it afterwards; or disalbe this feature at all.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Ayellet Wolman <ayellet.wolman@intel.com>
Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
2017-10-11 16:39:00 +08:00

125 lines
3.7 KiB
C

/** @file
x64-specifc functionality for DxeLoad.
Copyright (c) 2006 - 2015, 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 "DxeIpl.h"
#include "X64/VirtualMemory.h"
/**
Transfers control to DxeCore.
This function performs a CPU architecture specific operations to execute
the entry point of DxeCore with the parameters of HobList.
It also installs EFI_END_OF_PEI_PPI to signal the end of PEI phase.
@param DxeCoreEntryPoint The entry point of DxeCore.
@param HobList The start of HobList passed to DxeCore.
**/
VOID
HandOffToDxeCore (
IN EFI_PHYSICAL_ADDRESS DxeCoreEntryPoint,
IN EFI_PEI_HOB_POINTERS HobList
)
{
VOID *BaseOfStack;
VOID *TopOfStack;
EFI_STATUS Status;
UINTN PageTables;
UINT32 Index;
EFI_VECTOR_HANDOFF_INFO *VectorInfo;
EFI_PEI_VECTOR_HANDOFF_INFO_PPI *VectorHandoffInfoPpi;
if (IsNullDetectionEnabled ()) {
ClearFirst4KPage (HobList.Raw);
}
//
// Get Vector Hand-off Info PPI and build Guided HOB
//
Status = PeiServicesLocatePpi (
&gEfiVectorHandoffInfoPpiGuid,
0,
NULL,
(VOID **)&VectorHandoffInfoPpi
);
if (Status == EFI_SUCCESS) {
DEBUG ((EFI_D_INFO, "Vector Hand-off Info PPI is gotten, GUIDed HOB is created!\n"));
VectorInfo = VectorHandoffInfoPpi->Info;
Index = 1;
while (VectorInfo->Attribute != EFI_VECTOR_HANDOFF_LAST_ENTRY) {
VectorInfo ++;
Index ++;
}
BuildGuidDataHob (
&gEfiVectorHandoffInfoPpiGuid,
VectorHandoffInfoPpi->Info,
sizeof (EFI_VECTOR_HANDOFF_INFO) * Index
);
}
//
// Allocate 128KB for the Stack
//
BaseOfStack = AllocatePages (EFI_SIZE_TO_PAGES (STACK_SIZE));
ASSERT (BaseOfStack != NULL);
//
// Compute the top of the stack we were allocated. Pre-allocate a UINTN
// for safety.
//
TopOfStack = (VOID *) ((UINTN) BaseOfStack + EFI_SIZE_TO_PAGES (STACK_SIZE) * EFI_PAGE_SIZE - CPU_STACK_ALIGNMENT);
TopOfStack = ALIGN_POINTER (TopOfStack, CPU_STACK_ALIGNMENT);
PageTables = 0;
if (FeaturePcdGet (PcdDxeIplBuildPageTables)) {
//
// Create page table and save PageMapLevel4 to CR3
//
PageTables = CreateIdentityMappingPageTables ((EFI_PHYSICAL_ADDRESS) (UINTN) BaseOfStack, STACK_SIZE);
} else {
//
// Set NX for stack feature also require PcdDxeIplBuildPageTables be TRUE
// for the DxeIpl and the DxeCore are both X64.
//
ASSERT (PcdGetBool (PcdSetNxForStack) == FALSE);
}
//
// End of PEI phase signal
//
Status = PeiServicesInstallPpi (&gEndOfPeiSignalPpi);
ASSERT_EFI_ERROR (Status);
if (FeaturePcdGet (PcdDxeIplBuildPageTables)) {
AsmWriteCr3 (PageTables);
}
//
// Update the contents of BSP stack HOB to reflect the real stack info passed to DxeCore.
//
UpdateStackHob ((EFI_PHYSICAL_ADDRESS)(UINTN) BaseOfStack, STACK_SIZE);
//
// Transfer the control to the entry point of DxeCore.
//
SwitchStack (
(SWITCH_STACK_ENTRY_POINT)(UINTN)DxeCoreEntryPoint,
HobList.Raw,
NULL,
TopOfStack
);
}