/** @file
Provide legacy thunk interface for accessing Bios Video Rom.
Copyright (c) 2006 - 2007, 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 "BiosVideo.h"
#define EFI_CPU_EFLAGS_IF 0x200
/**
Initialize legacy environment for BIOS INI caller.
@param ThunkContext the instance pointer of THUNK_CONTEXT
**/
VOID
InitializeBiosIntCaller (
THUNK_CONTEXT *ThunkContext
)
{
EFI_STATUS Status;
UINT32 RealModeBufferSize;
UINT32 ExtraStackSize;
EFI_PHYSICAL_ADDRESS LegacyRegionBase;
UINT32 LegacyRegionSize;
//
// Get LegacyRegion
//
AsmGetThunk16Properties (&RealModeBufferSize, &ExtraStackSize);
LegacyRegionSize = (((RealModeBufferSize + ExtraStackSize) / EFI_PAGE_SIZE) + 1) * EFI_PAGE_SIZE;
LegacyRegionBase = 0x100000;
Status = gBS->AllocatePages (
AllocateMaxAddress,
EfiACPIMemoryNVS,
EFI_SIZE_TO_PAGES(LegacyRegionSize),
&LegacyRegionBase
);
ASSERT_EFI_ERROR (Status);
ThunkContext->RealModeBuffer = (VOID*)(UINTN)LegacyRegionBase;
ThunkContext->RealModeBufferSize = LegacyRegionSize;
ThunkContext->ThunkAttributes = THUNK_ATTRIBUTE_BIG_REAL_MODE|THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;
AsmPrepareThunk16(ThunkContext);
}
/**
Initialize interrupt redirection code and entries, because
IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
Or the interrupt will lost when we do thunk.
NOTE: We do not reset 8259 vector base, because it will cause pending
interrupt lost.
@param Legacy8259 Instance pointer for EFI_LEGACY_8259_PROTOCOL.
**/
VOID
InitializeInterruptRedirection (
IN EFI_LEGACY_8259_PROTOCOL *Legacy8259
)
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS LegacyRegionBase;
UINTN LegacyRegionLength;
UINT32 *IdtArray;
UINTN Index;
UINT8 ProtectedModeBaseVector;
UINT32 InterruptRedirectionCode[] = {
0x90CF08CD, // INT8; IRET; NOP
0x90CF09CD, // INT9; IRET; NOP
0x90CF0ACD, // INTA; IRET; NOP
0x90CF0BCD, // INTB; IRET; NOP
0x90CF0CCD, // INTC; IRET; NOP
0x90CF0DCD, // INTD; IRET; NOP
0x90CF0ECD, // INTE; IRET; NOP
0x90CF0FCD // INTF; IRET; NOP
};
//
// Get LegacyRegion
//
LegacyRegionLength = sizeof(InterruptRedirectionCode);
LegacyRegionBase = 0x100000;
Status = gBS->AllocatePages (
AllocateMaxAddress,
EfiACPIMemoryNVS,
EFI_SIZE_TO_PAGES(LegacyRegionLength),
&LegacyRegionBase
);
ASSERT_EFI_ERROR (Status);
//
// Copy code to legacy region
//
CopyMem ((VOID *)(UINTN)LegacyRegionBase, InterruptRedirectionCode, sizeof (InterruptRedirectionCode));
//
// Get VectorBase, it should be 0x68
//
Status = Legacy8259->GetVector (Legacy8259, Efi8259Irq0, &ProtectedModeBaseVector);
ASSERT_EFI_ERROR (Status);
//
// Patch IVT 0x68 ~ 0x6f
//
IdtArray = (UINT32 *) 0;
for (Index = 0; Index < 8; Index++) {
IdtArray[ProtectedModeBaseVector + Index] = ((EFI_SEGMENT (LegacyRegionBase + Index * 4)) << 16) | (EFI_OFFSET (LegacyRegionBase + Index * 4));
}
return ;
}
/**
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 Reg Register contexted passed into (and returned) from thunk to 16-bit mode
@retval TRUE Thunk completed, and there were no BIOS errors in the target code.
See Regs for status.
@retval FALSE There was a BIOS erro in the target code.
**/
BOOLEAN
EFIAPI
LegacyBiosInt86 (
IN BIOS_VIDEO_DEV *BiosDev,
IN UINT8 BiosInt,
IN IA32_REGISTER_SET *Regs
)
{
UINTN Status;
IA32_REGISTER_SET ThunkRegSet;
BOOLEAN Ret;
UINT16 *Stack16;
BOOLEAN Enabled;
ZeroMem (&ThunkRegSet, sizeof (ThunkRegSet));
ThunkRegSet.E.EFLAGS.Bits.Reserved_0 = 1;
ThunkRegSet.E.EFLAGS.Bits.Reserved_1 = 0;
ThunkRegSet.E.EFLAGS.Bits.Reserved_2 = 0;
ThunkRegSet.E.EFLAGS.Bits.Reserved_3 = 0;
ThunkRegSet.E.EFLAGS.Bits.IOPL = 3;
ThunkRegSet.E.EFLAGS.Bits.NT = 0;
ThunkRegSet.E.EFLAGS.Bits.IF = 1;
ThunkRegSet.E.EFLAGS.Bits.TF = 0;
ThunkRegSet.E.EFLAGS.Bits.CF = 0;
ThunkRegSet.E.EDI = Regs->E.EDI;
ThunkRegSet.E.ESI = Regs->E.ESI;
ThunkRegSet.E.EBP = Regs->E.EBP;
ThunkRegSet.E.EBX = Regs->E.EBX;
ThunkRegSet.E.EDX = Regs->E.EDX;
ThunkRegSet.E.ECX = Regs->E.ECX;
ThunkRegSet.E.EAX = Regs->E.EAX;
ThunkRegSet.E.DS = Regs->E.DS;
ThunkRegSet.E.ES = Regs->E.ES;
//
// The call to Legacy16 is a critical section to EFI
//
Enabled = SaveAndDisableInterrupts();
//
// Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
//
Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259LegacyMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
Stack16 = (UINT16 *)((UINT8 *) BiosDev->ThunkContext->RealModeBuffer + BiosDev->ThunkContext->RealModeBufferSize - sizeof (UINT16));
ThunkRegSet.E.SS = (UINT16) (((UINTN) Stack16 >> 16) << 12);
ThunkRegSet.E.ESP = (UINT16) (UINTN) Stack16;
ThunkRegSet.E.Eip = (UINT16)((UINT32 *)NULL)[BiosInt];
ThunkRegSet.E.CS = (UINT16)(((UINT32 *)NULL)[BiosInt] >> 16);
BiosDev->ThunkContext->RealModeState = &ThunkRegSet;
AsmThunk16 (BiosDev->ThunkContext);
//
// Restore protected mode interrupt state
//
Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259ProtectedMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
//
// End critical section
//
SetInterruptState (Enabled);
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->E.SS = ThunkRegSet.E.SS;
Regs->E.CS = ThunkRegSet.E.CS;
Regs->E.DS = ThunkRegSet.E.DS;
Regs->E.ES = ThunkRegSet.E.ES;
CopyMem (&(Regs->E.EFLAGS), &(ThunkRegSet.E.EFLAGS), sizeof (UINT32));
Ret = (BOOLEAN) (Regs->E.EFLAGS.Bits.CF == 1);
return Ret;
}