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/*++
Copyright (c) 2006, Intel Corporation
All rights reserved. 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.
Module Name:
x86Thunk.c
Abstract:
Real Mode Thunk Functions
--*/
#include "Thunk16Lib.h"
#include "EfiCommonLib.h"
extern CONST UINTN mCode16Size;
extern
IA32_REGISTER_SET *
EFIAPI
_Thunk16 (
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 ThunkFlags,
IN UINT32 RealModeCs
);
extern
VOID
EFIAPI
_Code16Addr (
VOID
);
VOID
EFIAPI
AsmFxRestore (
IN CONST IA32_FX_BUFFER *Buffer
);
VOID
EFIAPI
AsmFxSave (
OUT IA32_FX_BUFFER *Buffer
);
//
// Implementation
//
STATIC
IA32_REGISTER_SET *
AsmThunk16 (
IN THUNK_CONTEXT *ThunkContext,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 ThunkFlags
)
/*++
Routine Description:
Do the 16-bit thunk code.
NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts
disabled because of GDTR and IDTR manipulations.
This function must be placed in identity mapped pages.
Arguments:
ThunkContext - Thunk context to use.
RegisterSet - CPU registers would be set to the values contained in this
structure before making the far call. Then CPU registers are
copied back to this structure.
SS:ESP points to the real mode stack if THUNK_USER_STACK is
set on input, otherwise ignored.
EFlages is ignored on input.
On output, values of CS, EIP, SS and ESP should be ignored.
ThunkFlags - 2 flags have currently been defined, THUNK_SAVE_FP_STATE and
THUNK_USER_STACK.
THUNK_SAVE_FP_STATE - FPU state would be saved/restored
before/after calling real mode code.
THUNK_USER_STACK - The stack specified by SS:ESP would be
used instead of the default stack.
Returns:
RegisterSet is returned.
--*/
{
IA32_FX_BUFFER *FpSavedState;
UINT8 FpBuffer[sizeof (*FpSavedState) + 0x10];
FpSavedState = (IA32_FX_BUFFER*)(((UINTN)FpBuffer + 0xf) & ~0xf);
if (!(ThunkFlags & THUNK_USER_STACK)) {
RegisterSet->E.ESP = (UINT16)ThunkContext->DefaultStack;
RegisterSet->E.SS = (UINT16)((ThunkContext->DefaultStack >> 4) & 0xf000);
}
if (ThunkFlags & THUNK_SAVE_FP_STATE) {
AsmFxSave (FpSavedState);
}
EfiCommonLibCopyMem (
RegisterSet,
_Thunk16 (
RegisterSet,
(UINT16)(ThunkFlags >> 16),
ThunkContext->RealModeBuffer >> 4
),
sizeof (*RegisterSet)
);
if (ThunkFlags & THUNK_SAVE_FP_STATE) {
AsmFxRestore (FpSavedState);
}
return RegisterSet;
}
UINTN
EFIAPI
AsmThunk16GetProperties (
OUT UINTN *MinimumStackSize
)
/*++
Routine Description:
Returns the properties of this real mode thunk implementation. Currently
there are 2 properties has been defined, the minimum real mode buffer size
and the minimum stack size.
Arguments:
MinimumStackSize - The minimum size required for a 16-bit stack.
Returns:
The minimum size of the real mode buffer needed by this thunk implementation
is returned.
--*/
{
//
// This size should be large enough to hold the register set as well as saved
// CPU contexts including GDTR, CR0 and CR4
//
if (MinimumStackSize) {
*MinimumStackSize = sizeof (IA32_REGISTER_SET) + 0x200;
}
return mCode16Size;
}
THUNK_CONTEXT *
EFIAPI
AsmThunk16SetProperties (
OUT THUNK_CONTEXT *ThunkContext,
IN VOID *RealModeBuffer,
IN UINTN BufferSize
)
/*++
Routine Description:
Tell this real mode thunk implementation the address and size of the real
mode buffer needed.
Arguments:
ThunkContext - The thunk context whose properties to set.
RealModeBuffer - The address of the buffer allocated by caller. It should be
aligned on a 16-byte boundary.
This buffer must be in identity mapped pages.
BufferSize - The size of RealModeBuffer. Must be larger than the minimum
size required as returned by AsmThunk16GetProperties().
Returns:
None
--*/
{
BufferSize &= ~3;
ThunkContext->RealModeBuffer = (UINT32)(UINTN)RealModeBuffer;
ThunkContext->DefaultStack = (UINT32)(ThunkContext->RealModeBuffer + BufferSize);
EfiCommonLibCopyMem (RealModeBuffer, (VOID*)(UINTN)_Code16Addr, mCode16Size);
return ThunkContext;
}
VOID
EFIAPI
AsmThunk16Destroy (
IN OUT THUNK_CONTEXT *ThunkContext
)
/*++
Routine Description:
Reset all internal states to their initial values. The caller should not
release the real mode buffer until after a call to this function.
Arguments:
ThunkContext - The thunk context to destroy.
Returns:
None
--*/
{
ThunkContext->RealModeBuffer = 0;
}
IA32_REGISTER_SET *
EFIAPI
AsmThunk16FarCall86 (
IN THUNK_CONTEXT *ThunkContext,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 Flags
)
/*++
Routine Description:
Make a far call to 16-bit code.
NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts
disabled because of GDTR and IDTR manipulations.
This function must be placed in identity mapped pages.
Arguments:
ThunkContext - Thunk context to use.
RegisterSet - CPU registers would be set to the values contained in this
structure before making the far call. Then CPU registers are
copied back to this structure.
CS:EIP points to the real mode code being called on input.
SS:ESP points to the real mode stack if THUNK_USER_STACK is
set on input, otherwise ignored.
EFlages is ignored on input.
On output, values of CS, EIP, SS and ESP should be ignored.
ThunkFlags - 2 flags have currently been defined, THUNK_SAVE_FP_STATE and
THUNK_USER_STACK.
THUNK_SAVE_FP_STATE - FPU state would be saved/restored
before/after calling real mode code.
THUNK_USER_STACK - The stack specified by SS:ESP would be
used instead of the default stack.
Returns:
RegisterSet is returned.
--*/
{
return AsmThunk16 (ThunkContext, RegisterSet, Flags);
}
IA32_REGISTER_SET *
EFIAPI
AsmThunk16Int86 (
IN THUNK_CONTEXT *ThunkContext,
IN UINT8 IntNumber,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 Flags
)
/*++
Routine Description:
Invoke a 16-bit interrupt handler.
NOTE: This function must be called on TPL_HIGH_LEVEL or with interrupts
disabled because of GDTR and IDTR manipulations.
This function must be placed in identity mapped pages.
Arguments:
ThunkContext - Thunk context to use.
IntNumber - The ordinal of the interrupt handler ranging from 0 to 255.
RegisterSet - CPU registers would be set to the values contained in this
structure before making the far call. Then CPU registers are
copied back to this structure.
SS:ESP points to the real mode stack if THUNK_USER_STACK is
set on input, otherwise ignored.
EFlages is ignored on input.
On output, values of CS, EIP, SS and ESP should be ignored.
ThunkFlags - 2 flags have currently been defined, THUNK_SAVE_FP_STATE and
THUNK_USER_STACK.
THUNK_SAVE_FP_STATE - FPU state would be saved/restored
before/after calling real mode code.
THUNK_USER_STACK - The stack specified by SS:ESP would be
used instead of the default stack.
Returns:
RegisterSet is returned.
--*/
{
UINT32 *VectorBase;
//
// The base address of legacy interrupt vector table is 0.
// We use this base address to get the legacy interrupt handler.
//
VectorBase = 0;
RegisterSet->E.EIP = (UINT16)(VectorBase)[IntNumber];
RegisterSet->E.CS = (UINT16)((VectorBase)[IntNumber] >> 16);
return AsmThunk16 (ThunkContext, RegisterSet, Flags | THUNK_INTERRUPT);
}
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