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/** @file
Implementation of SetJump() on IA-32.
Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
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"
/**
Worker function that checks ASSERT condition for JumpBuffer
Checks ASSERT condition for JumpBuffer.
If JumpBuffer is NULL, then ASSERT().
For IPF CPUs, if JumpBuffer is not aligned on a 16-byte boundary, then ASSERT().
@param JumpBuffer A pointer to CPU context buffer.
**/
VOID
EFIAPI
InternalAssertJumpBuffer (
IN BASE_LIBRARY_JUMP_BUFFER *JumpBuffer
);
/**
Saves the current CPU context that can be restored with a call to LongJump()
and returns 0.
Saves the current CPU context in the buffer specified by JumpBuffer and
returns 0. The initial call to SetJump() must always return 0. Subsequent
calls to LongJump() cause a non-zero value to be returned by SetJump().
If JumpBuffer is NULL, then ASSERT().
For IPF CPUs, if JumpBuffer is not aligned on a 16-byte boundary, then ASSERT().
@param JumpBuffer A pointer to CPU context buffer.
@retval 0 Indicates a return from SetJump().
**/
_declspec (naked)
RETURNS_TWICE
UINTN
EFIAPI
SetJump (
OUT BASE_LIBRARY_JUMP_BUFFER *JumpBuffer
)
{
_asm {
push [esp + 4]
call InternalAssertJumpBuffer
pop ecx
pop ecx
mov edx, [esp]
xor eax, eax
mov [edx + 24], eax ; save 0 to SSP
mov eax, [PcdGet32 (PcdControlFlowEnforcementPropertyMask)]
test eax, eax
jz CetDone
_emit 0x0F
_emit 0x20
_emit 0xE0 ; mov eax, cr4
bt eax, 23 ; check if CET is enabled
jnc CetDone
mov eax, 1
_emit 0xF3
_emit 0x0F
_emit 0xAE
_emit 0xE8 ; INCSSP EAX to read original SSP
_emit 0xF3
_emit 0x0F
_emit 0x1E
_emit 0xC8 ; READSSP EAX
mov [edx + 0x24], eax ; save SSP
CetDone:
mov [edx], ebx
mov [edx + 4], esi
mov [edx + 8], edi
mov [edx + 12], ebp
mov [edx + 16], esp
mov [edx + 20], ecx
xor eax, eax
jmp ecx
}
}
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