| Vishal Bhoj | 82c8071 | 2015-12-15 21:13:33 +0530 | [diff] [blame^] | 1 | /** @file
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| 2 | IA-32/x64 AsmDisablePaging32()
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| 3 |
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| 4 | Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
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| 5 | This program and the accompanying materials
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| 6 | are licensed and made available under the terms and conditions of the BSD License
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| 7 | which accompanies this distribution. The full text of the license may be found at
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| 8 | http://opensource.org/licenses/bsd-license.php.
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| 9 |
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| 10 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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| 11 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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| 12 |
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| 13 | **/
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| 14 |
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| 15 |
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| 16 |
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| 17 |
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| 18 | #include "BaseLibInternals.h"
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| 19 |
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| 20 | /**
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| 21 | Disables the 32-bit paging mode on the CPU.
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| 22 |
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| 23 | Disables the 32-bit paging mode on the CPU and returns to 32-bit protected
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| 24 | mode. This function assumes the current execution mode is 32-paged protected
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| 25 | mode. This function is only available on IA-32. After the 32-bit paging mode
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| 26 | is disabled, control is transferred to the function specified by EntryPoint
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| 27 | using the new stack specified by NewStack and passing in the parameters
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| 28 | specified by Context1 and Context2. Context1 and Context2 are optional and
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| 29 | may be NULL. The function EntryPoint must never return.
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| 30 |
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| 31 | If the current execution mode is not 32-bit paged mode, then ASSERT().
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| 32 | If EntryPoint is NULL, then ASSERT().
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| 33 | If NewStack is NULL, then ASSERT().
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| 34 |
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| 35 | There are a number of constraints that must be followed before calling this
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| 36 | function:
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| 37 | 1) Interrupts must be disabled.
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| 38 | 2) The caller must be in 32-bit paged mode.
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| 39 | 3) CR0, CR3, and CR4 must be compatible with 32-bit paged mode.
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| 40 | 4) CR3 must point to valid page tables that guarantee that the pages for
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| 41 | this function and the stack are identity mapped.
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| 42 |
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| 43 | @param EntryPoint A pointer to function to call with the new stack after
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| 44 | paging is disabled.
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| 45 | @param Context1 A pointer to the context to pass into the EntryPoint
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| 46 | function as the first parameter after paging is disabled.
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| 47 | @param Context2 A pointer to the context to pass into the EntryPoint
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| 48 | function as the second parameter after paging is
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| 49 | disabled.
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| 50 | @param NewStack A pointer to the new stack to use for the EntryPoint
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| 51 | function after paging is disabled.
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| 52 |
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| 53 | **/
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| 54 | VOID
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| 55 | EFIAPI
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| 56 | AsmDisablePaging32 (
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| 57 | IN SWITCH_STACK_ENTRY_POINT EntryPoint,
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| 58 | IN VOID *Context1, OPTIONAL
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| 59 | IN VOID *Context2, OPTIONAL
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| 60 | IN VOID *NewStack
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| 61 | )
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| 62 | {
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| 63 | ASSERT (EntryPoint != NULL);
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| 64 | ASSERT (NewStack != NULL);
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| 65 | InternalX86DisablePaging32 (EntryPoint, Context1, Context2, NewStack);
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| 66 | }
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