mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-30 12:43:41 +01:00
76 lines
2.6 KiB
C
76 lines
2.6 KiB
C
/** @file
|
|
AsmEnablePaging32 function
|
|
|
|
Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
|
|
**/
|
|
|
|
#include "BaseLibInternals.h"
|
|
|
|
/**
|
|
Enables the 32-bit paging mode on the CPU.
|
|
|
|
Enables the 32-bit paging mode on the CPU. CR0, CR3, CR4, and the page tables
|
|
must be properly initialized prior to calling this service. This function
|
|
assumes the current execution mode is 32-bit protected mode. This function is
|
|
only available on IA-32. After the 32-bit paging mode is enabled, 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 protected mode with flat descriptors. This
|
|
means all descriptors must have a base of 0 and a limit of 4GB.
|
|
3) CR0 and CR4 must be compatible with 32-bit protected mode with flat
|
|
descriptors.
|
|
4) CR3 must point to valid page tables that will be used once the transition
|
|
is complete, and those page tables must 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 enabled.
|
|
@param Context1 A pointer to the context to pass into the EntryPoint
|
|
function as the first parameter after paging is enabled.
|
|
@param Context2 A pointer to the context to pass into the EntryPoint
|
|
function as the second parameter after paging is enabled.
|
|
@param NewStack A pointer to the new stack to use for the EntryPoint
|
|
function after paging is enabled.
|
|
|
|
**/
|
|
__declspec (naked)
|
|
VOID
|
|
EFIAPI
|
|
InternalX86EnablePaging32 (
|
|
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
|
|
cli
|
|
mov eax, cr0
|
|
bts eax, 31
|
|
mov esp, NewStack
|
|
mov cr0, eax
|
|
push edi
|
|
popfd
|
|
push edx
|
|
push ecx
|
|
call ebx
|
|
jmp $
|
|
}
|
|
}
|
|
|