mirror of
https://git.proxmox.com/git/mirror_edk2
synced 2025-10-31 22:30:33 +00:00
18c319ae39
2. Updated Thunk code to preserve EFLAGS/RFLAGS across real mode code invocation 3. Updated comments in x86Thunk.c git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@248 6f19259b-4bc3-4df7-8a09-765794883524
243 lines
7.7 KiB
C
243 lines
7.7 KiB
C
/** @file
|
|
Real Mode Thunk Functions for IA32 and X64.
|
|
|
|
Copyright (c) 2006, Intel Corporation<BR>
|
|
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
|
|
|
|
**/
|
|
|
|
//
|
|
// Byte packed structure for a segment descriptor in a GDT/LDT
|
|
//
|
|
typedef union {
|
|
struct {
|
|
UINT32 LimitLow:16;
|
|
UINT32 BaseLow:16;
|
|
UINT32 BaseMid:8;
|
|
UINT32 Type:4;
|
|
UINT32 S:1;
|
|
UINT32 DPL:2;
|
|
UINT32 P:1;
|
|
UINT32 LimitHigh:4;
|
|
UINT32 AVL:1;
|
|
UINT32 L:1;
|
|
UINT32 DB:1;
|
|
UINT32 G:1;
|
|
UINT32 BaseHigh:8;
|
|
} Bits;
|
|
UINT64 Uint64;
|
|
} IA32_SEGMENT_DESCRIPTOR;
|
|
|
|
extern CONST UINT8 m16Start;
|
|
extern CONST UINT16 m16Size;
|
|
extern CONST UINT16 mThunk16Attr;
|
|
extern CONST UINT16 m16Gdt;
|
|
extern CONST UINT16 m16GdtrBase;
|
|
extern CONST UINT16 mTransition;
|
|
|
|
/**
|
|
Invokes 16-bit code in big real mode and returns the updated register set.
|
|
|
|
This function transfers control to the 16-bit code specified by CS:EIP using
|
|
the stack specified by SS:ESP in RegisterSet. The updated registers are saved
|
|
on the real mode stack and the starting address of the save area is returned.
|
|
|
|
@param RegisterSet Values of registers before invocation of 16-bit code.
|
|
@param Transition Pointer to the transition code under 1MB.
|
|
|
|
@return The pointer to a IA32_REGISTER_SET structure containing the updated
|
|
register values.
|
|
|
|
**/
|
|
IA32_REGISTER_SET *
|
|
InternalAsmThunk16 (
|
|
IN IA32_REGISTER_SET *RegisterSet,
|
|
IN OUT VOID *Transition
|
|
);
|
|
|
|
/**
|
|
Retrieves the properties for 16-bit thunk functions.
|
|
|
|
Computes the size of the buffer and stack below 1MB required to use the
|
|
AsmPrepareThunk16(), AsmThunk16() and AsmPrepareAndThunk16() functions. This
|
|
buffer size is returned in RealModeBufferSize, and the stack size is returned
|
|
in ExtraStackSize. If parameters are passed to the 16-bit real mode code,
|
|
then the actual minimum stack size is ExtraStackSize plus the maximum number
|
|
of bytes that need to be passed to the 16-bit real mode code.
|
|
|
|
If RealModeBufferSize is NULL, then ASSERT().
|
|
If ExtraStackSize is NULL, then ASSERT().
|
|
|
|
@param RealModeBufferSize A pointer to the size of the buffer below 1MB
|
|
required to use the 16-bit thunk functions.
|
|
@param ExtraStackSize A pointer to the extra size of stack below 1MB
|
|
that the 16-bit thunk functions require for
|
|
temporary storage in the transition to and from
|
|
16-bit real mode.
|
|
|
|
**/
|
|
VOID
|
|
EFIAPI
|
|
AsmGetThunk16Properties (
|
|
OUT UINT32 *RealModeBufferSize,
|
|
OUT UINT32 *ExtraStackSize
|
|
)
|
|
{
|
|
ASSERT (RealModeBufferSize != NULL);
|
|
ASSERT (ExtraStackSize != NULL);
|
|
|
|
*RealModeBufferSize = m16Size;
|
|
|
|
//
|
|
// Extra 4 bytes for return address, and another 4 bytes for mode transition
|
|
//
|
|
*ExtraStackSize = sizeof (IA32_DWORD_REGS) + 8;
|
|
}
|
|
|
|
/**
|
|
Prepares all structures a code required to use AsmThunk16().
|
|
|
|
Prepares all structures and code required to use AsmThunk16().
|
|
|
|
If ThunkContext is NULL, then ASSERT().
|
|
|
|
@param ThunkContext A pointer to the context structure that describes the
|
|
16-bit real mode code to call.
|
|
|
|
**/
|
|
VOID
|
|
EFIAPI
|
|
AsmPrepareThunk16 (
|
|
OUT THUNK_CONTEXT *ThunkContext
|
|
)
|
|
{
|
|
IA32_SEGMENT_DESCRIPTOR *RealModeGdt;
|
|
|
|
ASSERT (ThunkContext != NULL);
|
|
ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);
|
|
ASSERT (ThunkContext->RealModeBufferSize >= m16Size);
|
|
ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);
|
|
|
|
CopyMem (ThunkContext->RealModeBuffer, &m16Start, m16Size);
|
|
|
|
//
|
|
// Point RealModeGdt to the GDT to be used in transition
|
|
//
|
|
// RealModeGdt[0]: Reserved as NULL descriptor
|
|
// RealModeGdt[1]: Code Segment
|
|
// RealModeGdt[2]: Data Segment
|
|
// RealModeGdt[3]: Call Gate
|
|
//
|
|
RealModeGdt = (IA32_SEGMENT_DESCRIPTOR*)(
|
|
(UINTN)ThunkContext->RealModeBuffer + m16Gdt);
|
|
|
|
//
|
|
// Update Code & Data Segment Descriptor
|
|
//
|
|
RealModeGdt[1].Bits.BaseLow =
|
|
(UINT32)(UINTN)ThunkContext->RealModeBuffer & ~0xf;
|
|
RealModeGdt[1].Bits.BaseMid =
|
|
(UINT32)(UINTN)ThunkContext->RealModeBuffer >> 16;
|
|
|
|
//
|
|
// Update transition code entry point offset
|
|
//
|
|
*(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mTransition) +=
|
|
(UINT32)(UINTN)ThunkContext->RealModeBuffer & 0xf;
|
|
|
|
//
|
|
// Update Segment Limits for both Code and Data Segment Descriptors
|
|
//
|
|
if ((ThunkContext->ThunkAttributes & THUNK_ATTRIBUTE_BIG_REAL_MODE) == 0) {
|
|
//
|
|
// Set segment limits to 64KB
|
|
//
|
|
RealModeGdt[1].Bits.LimitHigh = 0;
|
|
RealModeGdt[1].Bits.G = 0;
|
|
RealModeGdt[2].Bits.LimitHigh = 0;
|
|
RealModeGdt[2].Bits.G = 0;
|
|
}
|
|
|
|
//
|
|
// Update GDTBASE for this thunk context
|
|
//
|
|
*(VOID**)((UINTN)ThunkContext->RealModeBuffer + m16GdtrBase) = RealModeGdt;
|
|
|
|
//
|
|
// Update Thunk Attributes
|
|
//
|
|
*(UINT32*)((UINTN)ThunkContext->RealModeBuffer + mThunk16Attr) =
|
|
ThunkContext->ThunkAttributes;
|
|
}
|
|
|
|
/**
|
|
Transfers control to a 16-bit real mode entry point and returns the results.
|
|
|
|
Transfers control to a 16-bit real mode entry point and returns the results.
|
|
AsmPrepareThunk16() must be called with ThunkContext before this function is
|
|
used. This function must be called with interrupts disabled.
|
|
|
|
If ThunkContext is NULL, then ASSERT().
|
|
If AsmPrepareThunk16() was not previously called with ThunkContext, then ASSERT().
|
|
|
|
@param ThunkContext A pointer to the context structure that describes the
|
|
16-bit real mode code to call.
|
|
|
|
**/
|
|
VOID
|
|
EFIAPI
|
|
AsmThunk16 (
|
|
IN OUT THUNK_CONTEXT *ThunkContext
|
|
)
|
|
{
|
|
IA32_REGISTER_SET *UpdatedRegs;
|
|
|
|
ASSERT (ThunkContext != NULL);
|
|
ASSERT ((UINTN)ThunkContext->RealModeBuffer < 0x100000);
|
|
ASSERT (ThunkContext->RealModeBufferSize >= m16Size);
|
|
ASSERT ((UINTN)ThunkContext->RealModeBuffer + m16Size <= 0x100000);
|
|
|
|
UpdatedRegs = InternalAsmThunk16 (
|
|
ThunkContext->RealModeState,
|
|
ThunkContext->RealModeBuffer
|
|
);
|
|
|
|
CopyMem (ThunkContext->RealModeState, UpdatedRegs, sizeof (*UpdatedRegs));
|
|
}
|
|
|
|
/**
|
|
Prepares all structures and code for a 16-bit real mode thunk, transfers
|
|
control to a 16-bit real mode entry point, and returns the results.
|
|
|
|
Prepares all structures and code for a 16-bit real mode thunk, transfers
|
|
control to a 16-bit real mode entry point, and returns the results. If the
|
|
caller only need to perform a single 16-bit real mode thunk, then this
|
|
service should be used. If the caller intends to make more than one 16-bit
|
|
real mode thunk, then it is more efficient if AsmPrepareThunk16() is called
|
|
once and AsmThunk16() can be called for each 16-bit real mode thunk. This
|
|
function must be called with interrupts disabled.
|
|
|
|
If ThunkContext is NULL, then ASSERT().
|
|
|
|
@param ThunkContext A pointer to the context structure that describes the
|
|
16-bit real mode code to call.
|
|
|
|
**/
|
|
VOID
|
|
EFIAPI
|
|
AsmPrepareAndThunk16 (
|
|
IN OUT THUNK_CONTEXT *ThunkContext
|
|
)
|
|
{
|
|
AsmPrepareThunk16 (ThunkContext);
|
|
AsmThunk16 (ThunkContext);
|
|
}
|