373ade0eb6
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7148 6f19259b-4bc3-4df7-8a09-765794883524
78 lines
2.9 KiB
C
78 lines
2.9 KiB
C
/** @file
|
|
AsmDisablePaging32 function.
|
|
|
|
Copyright (c) 2006 - 2008, Intel Corporation<BR>
|
|
All rights reserved. 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 "BaseLibInternals.h"
|
|
|
|
/**
|
|
Disables the 32-bit paging mode on the CPU.
|
|
|
|
Disables the 32-bit paging mode on the CPU and returns to 32-bit protected
|
|
mode. This function assumes the current execution mode is 32-paged protected
|
|
mode. This function is only available on IA-32. After the 32-bit paging mode
|
|
is disabled, control is transferred to the function specified by EntryPoint
|
|
using the new stack specified by NewStack and passing in the parameters
|
|
specified by Context1 and Context2. Context1 and Context2 are optional and
|
|
may be NULL. The function EntryPoint must never return.
|
|
|
|
There are a number of constraints that must be followed before calling this
|
|
function:
|
|
1) Interrupts must be disabled.
|
|
2) The caller must be in 32-bit paged mode.
|
|
3) CR0, CR3, and CR4 must be compatible with 32-bit paged mode.
|
|
4) CR3 must point to valid page tables that guarantee that the pages for
|
|
this function and the stack are identity mapped.
|
|
|
|
@param EntryPoint A pointer to function to call with the new stack after
|
|
paging is disabled.
|
|
@param Context1 A pointer to the context to pass into the EntryPoint
|
|
function as the first parameter after paging is disabled.
|
|
@param Context2 A pointer to the context to pass into the EntryPoint
|
|
function as the second parameter after paging is
|
|
disabled.
|
|
@param NewStack A pointer to the new stack to use for the EntryPoint
|
|
function after paging is disabled.
|
|
|
|
**/
|
|
__declspec (naked)
|
|
VOID
|
|
EFIAPI
|
|
InternalX86DisablePaging32 (
|
|
IN SWITCH_STACK_ENTRY_POINT EntryPoint,
|
|
IN VOID *Context1, OPTIONAL
|
|
IN VOID *Context2, OPTIONAL
|
|
IN VOID *NewStack
|
|
)
|
|
{
|
|
_asm {
|
|
push ebp
|
|
mov ebp, esp
|
|
mov ebx, EntryPoint
|
|
mov ecx, Context1
|
|
mov edx, Context2
|
|
pushfd
|
|
pop edi // save EFLAGS to edi
|
|
cli
|
|
mov eax, cr0
|
|
btr eax, 31
|
|
mov esp, NewStack
|
|
mov cr0, eax
|
|
push edi
|
|
popfd // restore EFLAGS from edi
|
|
push edx
|
|
push ecx
|
|
call ebx
|
|
jmp $ // EntryPoint() should not return
|
|
}
|
|
}
|