mirror of https://github.com/acidanthera/audk.git
69 lines
2.9 KiB
C
69 lines
2.9 KiB
C
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/** @file
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IA-32/x64 AsmEnablePaging32()
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Copyright (c) 2006, Intel Corporation<BR>
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All rights reserved. This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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Module Name: x86EnablePaging32.c
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**/
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#include "BaseLibInternals.h"
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/**
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Enables the 32-bit paging mode on the CPU.
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Enables the 32-bit paging mode on the CPU. CR0, CR3, CR4, and the page tables
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must be properly initialized prior to calling this service. This function
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assumes the current execution mode is 32-bit protected mode. This function is
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only available on IA-32. After the 32-bit paging mode is enabled, control is
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transferred to the function specified by EntryPoint using the new stack
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specified by NewStack and passing in the parameters specified by Context1 and
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Context2. Context1 and Context2 are optional and may be NULL. The function
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EntryPoint must never return.
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If the current execution mode is not 32-bit protected mode, then ASSERT().
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If EntryPoint is NULL, then ASSERT().
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If NewStack is NULL, then ASSERT().
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There are a number of constraints that must be followed before calling this
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function:
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1) Interrupts must be disabled.
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2) The caller must be in 32-bit protected mode with flat descriptors. This
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means all descriptors must have a base of 0 and a limit of 4GB.
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3) CR0 and CR4 must be compatible with 32-bit protected mode with flat
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descriptors.
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4) CR3 must point to valid page tables that will be used once the transition
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is complete, and those page tables must guarantee that the pages for this
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function and the stack are identity mapped.
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@param EntryPoint A pointer to function to call with the new stack after
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paging is enabled.
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@param Context1 A pointer to the context to pass into the EntryPoint
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function as the first parameter after paging is enabled.
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@param Context2 A pointer to the context to pass into the EntryPoint
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function as the second parameter after paging is enabled.
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@param NewStack A pointer to the new stack to use for the EntryPoint
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function after paging is enabled.
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**/
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VOID
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EFIAPI
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AsmEnablePaging32 (
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IN SWITCH_STACK_ENTRY_POINT EntryPoint,
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IN VOID *Context1, OPTIONAL
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IN VOID *Context2, OPTIONAL
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IN VOID *NewStack
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)
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{
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ASSERT (EntryPoint != NULL);
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ASSERT (NewStack != NULL);
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InternalX86EnablePaging32 (EntryPoint, Context1, Context2, NewStack);
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}
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