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/** @file
Real Mode Thunk Functions for IA32 and X64
@copyright
Copyright (c) 1999 - 2012 Intel Corporation. All rights reserved
This software and associated documentation (if any) is furnished
under a license and may only be used or copied in accordance
with the terms of the license. Except as permitted by such
license, no part of this software or documentation may be
reproduced, stored in a retrieval system, or transmitted in any
form or by any means without the express written consent of
Intel Corporation.
This file contains an 'Intel Peripheral Driver' and is
licensed for Intel CPUs and chipsets under the terms of your
license agreement with Intel or your vendor. This file may
be modified by the user, subject to additional terms of the
license agreement
**/
#if !defined(EDK_RELEASE_VERSION) || (EDK_RELEASE_VERSION < 0x00020000)
#include "EdkIIGlueDxe.h"
#include "ThunkLib.h"
#define _THUNK_INTERRUPT 0x10000
#endif
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
);
/**
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.
@param[in] MinimumStackSize - The minimum size required for a 16-bit stack.
@retval The minimum size of the real mode buffer needed by this thunk implementation
@retval is returned.
**/
UINTN
EFIAPI
R8AsmThunk16GetProperties (
OUT UINTN *MinimumStackSize
)
{
///
/// 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;
}
/**
Tell this real mode thunk implementation the address and size of the real
mode buffer needed.
@param[in] ThunkContext - The thunk context whose properties to set.
@param[in] 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.
@param[in] BufferSize - The size of RealModeBuffer. Must be larger than the minimum
size required as returned by R8AsmThunk16GetProperties().
**/
THUNK16_CONTEXT *
EFIAPI
R8AsmThunk16SetProperties (
OUT THUNK16_CONTEXT *ThunkContext,
IN VOID *RealModeBuffer,
IN UINTN BufferSize
)
{
BufferSize &= ~3;
ASSERT ((UINTN) RealModeBuffer < 0x100000);
ASSERT (((UINTN) RealModeBuffer & 0xf) == 0);
ASSERT (BufferSize >= mCode16Size);
ThunkContext->RealModeBuffer = (UINT32) ((UINTN) RealModeBuffer);
ThunkContext->DefaultStack = (UINT32) (ThunkContext->RealModeBuffer + BufferSize);
CopyMem (RealModeBuffer, (VOID *) (UINTN) _Code16Addr, mCode16Size);
return ThunkContext;
}
/**
Reset all internal states to their initial values. The caller should not
release the real mode buffer until after a call to this function.
@param[in] ThunkContext - The thunk context to destroy.
**/
VOID
EFIAPI
R8AsmThunk16Destroy (
IN OUT THUNK16_CONTEXT *ThunkContext
)
{
ThunkContext->RealModeBuffer = 0;
}
/**
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.
@param[in] ThunkContext - Thunk context to use.
@param[in] 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.
@param[in] 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.
@retval RegisterSet is returned.
**/
static
IA32_REGISTER_SET *
EFIAPI
R8AsmThunk16 (
IN THUNK16_CONTEXT *ThunkContext,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 ThunkFlags
)
{
ASSERT (ThunkContext->RealModeBuffer != 0);
ASSERT ((ThunkContext->RealModeBuffer & 0xf) == 0);
if (!(ThunkFlags & THUNK_USER_STACK)) {
RegisterSet->E.ESP = (UINT16) ThunkContext->DefaultStack;
RegisterSet->E.SS = (UINT16) ((ThunkContext->DefaultStack >> 4) & 0xf000);
}
ASSERT ((RegisterSet->E.ESP >> 16) == 0);
CopyMem (
RegisterSet,
_Thunk16 (RegisterSet,
(UINT16) (ThunkFlags >> 16),
ThunkContext->RealModeBuffer >> 4),
sizeof (IA32_REGISTER_SET)
);
return RegisterSet;
}
/**
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.
@param[in] ThunkContext - Thunk context to use.
@param[in] 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.
@param[in] Flags - 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.
@retval RegisterSet is returned.
**/
IA32_REGISTER_SET *
EFIAPI
R8AsmThunk16FarCall86 (
IN THUNK16_CONTEXT *ThunkContext,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 Flags
)
{
return R8AsmThunk16 (ThunkContext, RegisterSet, Flags);
}
/**
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.
@param[in] ThunkContext - Thunk context to use.
@param[in] IntNumber - The ordinal of the interrupt handler ranging from 0 to 255.
@param[in] 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.
@param[in] Flags - 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.
@retval RegisterSet is returned.
**/
IA32_REGISTER_SET *
EFIAPI
R8AsmThunk16Int86 (
IN THUNK16_CONTEXT *ThunkContext,
IN UINT8 IntNumber,
IN OUT IA32_REGISTER_SET *RegisterSet,
IN UINT32 Flags
)
{
RegisterSet->E.Eip = (UINT16) ((UINT32 *) NULL)[IntNumber];
RegisterSet->E.CS = (UINT16) (((UINT32 *) NULL)[IntNumber] >> 16);
return R8AsmThunk16 (ThunkContext, RegisterSet, Flags | _THUNK_INTERRUPT);
}
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