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/** @file
Call into 16-bit BIOS code, Use AsmThunk16 function of BaseLib.
Copyright (c) 2006 - 2010, 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 "LegacyBiosInterface.h"
THUNK_CONTEXT mThunkContext;
/**
Thunk to 16-bit real mode and execute a software interrupt with a vector
of BiosInt. Regs will contain the 16-bit register context on entry and
exit.
@param This Protocol instance pointer.
@param BiosInt Processor interrupt vector to invoke
@param Regs Register contexted passed into (and returned) from thunk to
16-bit mode
@retval FALSE Thunk completed, and there were no BIOS errors in the target code.
See Regs for status.
@retval TRUE There was a BIOS erro in the target code.
**/
BOOLEAN
EFIAPI
LegacyBiosInt86 (
IN EFI_LEGACY_BIOS_PROTOCOL *This,
IN UINT8 BiosInt,
IN EFI_IA32_REGISTER_SET *Regs
)
{
Regs->X.Flags.Reserved1 = 1;
Regs->X.Flags.Reserved2 = 0;
Regs->X.Flags.Reserved3 = 0;
Regs->X.Flags.Reserved4 = 0;
Regs->X.Flags.IOPL = 3;
Regs->X.Flags.NT = 0;
Regs->X.Flags.IF = 0;
Regs->X.Flags.TF = 0;
Regs->X.Flags.CF = 0;
return InternalLegacyBiosFarCall (
This,
(UINT16) (((UINT32 *)NULL)[BiosInt] >> 16),
(UINT16) ((UINT32 *)NULL)[BiosInt],
Regs,
&Regs->X.Flags,
sizeof (Regs->X.Flags)
);
}
/**
Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the
16-bit register context on entry and exit. Arguments can be passed on
the Stack argument
@param This Protocol instance pointer.
@param Segment Segemnt of 16-bit mode call
@param Offset Offset of 16-bit mdoe call
@param Regs Register contexted passed into (and returned) from
thunk to 16-bit mode
@param Stack Caller allocated stack used to pass arguments
@param StackSize Size of Stack in bytes
@retval FALSE Thunk completed, and there were no BIOS errors in
the target code. See Regs for status.
@retval TRUE There was a BIOS erro in the target code.
**/
BOOLEAN
EFIAPI
LegacyBiosFarCall86 (
IN EFI_LEGACY_BIOS_PROTOCOL *This,
IN UINT16 Segment,
IN UINT16 Offset,
IN EFI_IA32_REGISTER_SET *Regs,
IN VOID *Stack,
IN UINTN StackSize
)
{
Regs->X.Flags.Reserved1 = 1;
Regs->X.Flags.Reserved2 = 0;
Regs->X.Flags.Reserved3 = 0;
Regs->X.Flags.Reserved4 = 0;
Regs->X.Flags.IOPL = 3;
Regs->X.Flags.NT = 0;
Regs->X.Flags.IF = 1;
Regs->X.Flags.TF = 0;
Regs->X.Flags.CF = 0;
return InternalLegacyBiosFarCall (This, Segment, Offset, Regs, Stack, StackSize);
}
/**
Thunk to 16-bit real mode and call Segment:Offset. Regs will contain the
16-bit register context on entry and exit. Arguments can be passed on
the Stack argument
@param This Protocol instance pointer.
@param Segment Segemnt of 16-bit mode call
@param Offset Offset of 16-bit mdoe call
@param Regs Register contexted passed into (and returned) from thunk to
16-bit mode
@param Stack Caller allocated stack used to pass arguments
@param StackSize Size of Stack in bytes
@retval FALSE Thunk completed, and there were no BIOS errors in the target code.
See Regs for status.
@retval TRUE There was a BIOS erro in the target code.
**/
BOOLEAN
EFIAPI
InternalLegacyBiosFarCall (
IN EFI_LEGACY_BIOS_PROTOCOL *This,
IN UINT16 Segment,
IN UINT16 Offset,
IN EFI_IA32_REGISTER_SET *Regs,
IN VOID *Stack,
IN UINTN StackSize
)
{
UINTN Status;
LEGACY_BIOS_INSTANCE *Private;
UINT16 *Stack16;
EFI_TPL OriginalTpl;
IA32_REGISTER_SET ThunkRegSet;
BOOLEAN InterruptState;
Private = LEGACY_BIOS_INSTANCE_FROM_THIS (This);
ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));
ThunkRegSet.X.DI = Regs->X.DI;
ThunkRegSet.X.SI = Regs->X.SI;
ThunkRegSet.X.BP = Regs->X.BP;
ThunkRegSet.X.BX = Regs->X.BX;
ThunkRegSet.X.DX = Regs->X.DX;
//
// Sometimes, ECX is used to pass in 32 bit data. For example, INT 1Ah, AX = B10Dh is
// "PCI BIOS v2.0c + Write Configuration DWORD" and ECX has the dword to write.
//
ThunkRegSet.E.ECX = Regs->E.ECX;
ThunkRegSet.X.AX = Regs->X.AX;
ThunkRegSet.E.DS = Regs->X.DS;
ThunkRegSet.E.ES = Regs->X.ES;
CopyMem (&(ThunkRegSet.E.EFLAGS.UintN), &(Regs->X.Flags), sizeof (Regs->X.Flags));
//
// Clear the error flag; thunk code may set it. Stack16 should be the high address
// Make Statk16 address the low 16 bit must be not zero.
//
Stack16 = (UINT16 *)((UINT8 *) mThunkContext.RealModeBuffer + mThunkContext.RealModeBufferSize - sizeof (UINT16));
//
// Save and disable interrutp of debug timer
//
InterruptState = SaveAndSetDebugTimerInterrupt (FALSE);
//
// The call to Legacy16 is a critical section to EFI
//
OriginalTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);
if (Stack != NULL && StackSize != 0) {
//
// Copy Stack to low memory stack
//
Stack16 -= StackSize / sizeof (UINT16);
CopyMem (Stack16, Stack, StackSize);
}
ThunkRegSet.E.SS = (UINT16) (((UINTN) Stack16 >> 16) << 12);
ThunkRegSet.E.ESP = (UINT16) (UINTN) Stack16;
ThunkRegSet.E.CS = Segment;
ThunkRegSet.E.Eip = Offset;
mThunkContext.RealModeState = &ThunkRegSet;
//
// Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
//
Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259LegacyMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
AsmThunk16 (&mThunkContext);
//
// OPROM may allocate EBDA range by itself and change EBDA base and EBDA size.
// Get the current EBDA base address, and compared with pre-allocate minimum
// EBDA base address, if the current EBDA base address is smaller, it indicates
// PcdEbdaReservedMemorySize should be adjusted to larger for more OPROMs.
//
DEBUG_CODE (
{
UINTN EbdaBaseAddress;
UINTN ReservedEbdaBaseAddress;
EbdaBaseAddress = (*(UINT16 *) (UINTN) 0x40E) << 4;
ReservedEbdaBaseAddress = CONVENTIONAL_MEMORY_TOP - PcdGet32 (PcdEbdaReservedMemorySize);
ASSERT (ReservedEbdaBaseAddress <= EbdaBaseAddress);
}
);
if (Stack != NULL && StackSize != 0) {
//
// Copy low memory stack to Stack
//
CopyMem (Stack, Stack16, StackSize);
}
//
// Restore protected mode interrupt state
//
Status = Private->Legacy8259->SetMode (Private->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
mThunkContext.RealModeState = NULL;
//
// End critical section
//
gBS->RestoreTPL (OriginalTpl);
//
// Restore interrutp of debug timer
//
SaveAndSetDebugTimerInterrupt (InterruptState);
Regs->E.EDI = ThunkRegSet.E.EDI;
Regs->E.ESI = ThunkRegSet.E.ESI;
Regs->E.EBP = ThunkRegSet.E.EBP;
Regs->E.EBX = ThunkRegSet.E.EBX;
Regs->E.EDX = ThunkRegSet.E.EDX;
Regs->E.ECX = ThunkRegSet.E.ECX;
Regs->E.EAX = ThunkRegSet.E.EAX;
Regs->X.SS = ThunkRegSet.E.SS;
Regs->X.CS = ThunkRegSet.E.CS;
Regs->X.DS = ThunkRegSet.E.DS;
Regs->X.ES = ThunkRegSet.E.ES;
CopyMem (&(Regs->X.Flags), &(ThunkRegSet.E.EFLAGS.UintN), sizeof (Regs->X.Flags));
return (BOOLEAN) (Regs->X.Flags.CF == 1);
}
/**
Allocate memory < 1 MB and copy the thunker code into low memory. Se up
all the descriptors.
@param Private Private context for Legacy BIOS
@retval EFI_SUCCESS Should only pass.
**/
EFI_STATUS
LegacyBiosInitializeThunk (
IN LEGACY_BIOS_INSTANCE *Private
)
{
EFI_PHYSICAL_ADDRESS MemoryAddress;
MemoryAddress = (EFI_PHYSICAL_ADDRESS) (UINTN) Private->IntThunk;
mThunkContext.RealModeBuffer = (VOID *) (UINTN) (MemoryAddress + ((sizeof (LOW_MEMORY_THUNK) / EFI_PAGE_SIZE) + 1) * EFI_PAGE_SIZE);
mThunkContext.RealModeBufferSize = EFI_PAGE_SIZE;
mThunkContext.ThunkAttributes = THUNK_ATTRIBUTE_BIG_REAL_MODE | THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;
AsmPrepareThunk16 (&mThunkContext);
return EFI_SUCCESS;
}
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