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77 lines
2.2 KiB
77 lines
2.2 KiB
4 years ago
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/** @file
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Implementation of _LongJump() on IA-32.
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Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
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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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**/
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#include "BaseLibInternals.h"
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/**
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Restores the CPU context that was saved with SetJump().
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Restores the CPU context from the buffer specified by JumpBuffer.
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This function never returns to the caller.
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Instead is resumes execution based on the state of JumpBuffer.
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@param JumpBuffer A pointer to CPU context buffer.
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@param Value The value to return when the SetJump() context is restored.
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**/
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__declspec (naked)
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VOID
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EFIAPI
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InternalLongJump (
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IN BASE_LIBRARY_JUMP_BUFFER *JumpBuffer,
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IN UINTN Value
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)
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{
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_asm {
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mov eax, [PcdGet32 (PcdControlFlowEnforcementPropertyMask)]
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test eax, eax
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jz CetDone
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_emit 0x0F
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_emit 0x20
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_emit 0xE0 ; mov eax, cr4
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bt eax, 23 ; check if CET is enabled
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jnc CetDone
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mov edx, [esp + 4] ; edx = JumpBuffer
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mov edx, [edx + 24] ; edx = target SSP
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_emit 0xF3
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_emit 0x0F
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_emit 0x1E
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_emit 0xC8 ; READSSP EAX
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sub edx, eax ; edx = delta
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mov eax, edx ; eax = delta
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shr eax, 2 ; eax = delta/sizeof(UINT32)
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_emit 0xF3
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_emit 0x0F
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_emit 0xAE
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_emit 0xE8 ; INCSSP EAX
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CetDone:
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pop eax ; skip return address
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pop edx ; edx <- JumpBuffer
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pop eax ; eax <- Value
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mov ebx, [edx]
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mov esi, [edx + 4]
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mov edi, [edx + 8]
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mov ebp, [edx + 12]
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mov esp, [edx + 16]
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jmp dword ptr [edx + 20]
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}
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}
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