mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-12-17 15:18:06 +01:00
84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/** @file
|
|
IA-32/x64 PatchInstructionX86()
|
|
|
|
Copyright (C) 2018, Intel Corporation. All rights reserved.<BR>
|
|
Copyright (C) 2018, Red Hat, Inc.
|
|
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
**/
|
|
|
|
#include "BaseLibInternals.h"
|
|
|
|
/**
|
|
Patch the immediate operand of an IA32 or X64 instruction such that the byte,
|
|
word, dword or qword operand is encoded at the end of the instruction's
|
|
binary representation.
|
|
|
|
This function should be used to update object code that was compiled with
|
|
NASM from assembly source code. Example:
|
|
|
|
NASM source code:
|
|
|
|
mov eax, strict dword 0 ; the imm32 zero operand will be patched
|
|
ASM_PFX(gPatchCr3):
|
|
mov cr3, eax
|
|
|
|
C source code:
|
|
|
|
X86_ASSEMBLY_PATCH_LABEL gPatchCr3;
|
|
PatchInstructionX86 (gPatchCr3, AsmReadCr3 (), 4);
|
|
|
|
@param[out] InstructionEnd Pointer right past the instruction to patch. The
|
|
immediate operand to patch is expected to
|
|
comprise the trailing bytes of the instruction.
|
|
If InstructionEnd is closer to address 0 than
|
|
ValueSize permits, then ASSERT().
|
|
|
|
@param[in] PatchValue The constant to write to the immediate operand.
|
|
The caller is responsible for ensuring that
|
|
PatchValue can be represented in the byte, word,
|
|
dword or qword operand (as indicated through
|
|
ValueSize); otherwise ASSERT().
|
|
|
|
@param[in] ValueSize The size of the operand in bytes; must be 1, 2,
|
|
4, or 8. ASSERT() otherwise.
|
|
**/
|
|
VOID
|
|
EFIAPI
|
|
PatchInstructionX86 (
|
|
OUT X86_ASSEMBLY_PATCH_LABEL *InstructionEnd,
|
|
IN UINT64 PatchValue,
|
|
IN UINTN ValueSize
|
|
)
|
|
{
|
|
//
|
|
// The equality ((UINTN)InstructionEnd == ValueSize) would assume a zero-size
|
|
// instruction at address 0; forbid it.
|
|
//
|
|
ASSERT ((UINTN)InstructionEnd > ValueSize);
|
|
|
|
switch (ValueSize) {
|
|
case 1:
|
|
ASSERT (PatchValue <= MAX_UINT8);
|
|
*((UINT8 *)(UINTN)InstructionEnd - 1) = (UINT8)PatchValue;
|
|
break;
|
|
|
|
case 2:
|
|
ASSERT (PatchValue <= MAX_UINT16);
|
|
WriteUnaligned16 ((UINT16 *)(UINTN)InstructionEnd - 1, (UINT16)PatchValue);
|
|
break;
|
|
|
|
case 4:
|
|
ASSERT (PatchValue <= MAX_UINT32);
|
|
WriteUnaligned32 ((UINT32 *)(UINTN)InstructionEnd - 1, (UINT32)PatchValue);
|
|
break;
|
|
|
|
case 8:
|
|
WriteUnaligned64 ((UINT64 *)(UINTN)InstructionEnd - 1, PatchValue);
|
|
break;
|
|
|
|
default:
|
|
ASSERT (FALSE);
|
|
}
|
|
}
|