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OpenCorePkg/Library/OcLegacyThunkLib/OcLegacyThunkLib.c
John Davis bb44e89add
Implement legacy OS booting support (#482)
2023-09-07 20:00:30 -05:00

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/** @file
This file implements thunking to legacy 16-bit environment.
Copyright (c) 2023, Goldfish64. All rights reserved.<BR>
Copyright (c) 2006 - 2007, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause
**/
#include <Uefi.h>
#include <IndustryStandard/Pci.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/OcDeviceMiscLib.h>
#include <Library/OcLegacyThunkLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Protocol/PciIo.h>
#include <Protocol/Timer.h>
//
// 8254 Timer registers
//
#define TIMER0_COUNT_PORT 0x40
#define TIMER1_COUNT_PORT 0x41
#define TIMER2_COUNT_PORT 0x42
#define TIMER_CONTROL_PORT 0x43
#define TIMER0_CONTROL_WORD 0x36
//
// Vector base definitions
//
//
// 8259 Hardware definitions
//
#define LEGACY_MODE_BASE_VECTOR_MASTER 0x08
#define LEGACY_MODE_BASE_VECTOR_SLAVE 0x70
//
// The original PC used INT8-F for master PIC. Since these mapped over
// processor exceptions TIANO moved the master PIC to INT68-6F.
//
// The vector base for slave PIC is set as 0x70 for PC-AT compatibility.
//
#define PROTECTED_MODE_BASE_VECTOR_MASTER 0x68
#define PROTECTED_MODE_BASE_VECTOR_SLAVE 0x70
/**
Initialize legacy environment for BIOS INI caller.
@param ThunkContext The instance pointer of THUNK_CONTEXT.
**/
EFI_STATUS
OcLegacyThunkInitializeBiosIntCaller (
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 = LEGACY_REGION_BASE;
Status = gBS->AllocatePages (
AllocateMaxAddress,
EfiACPIMemoryNVS,
EFI_SIZE_TO_PAGES (LegacyRegionSize),
&LegacyRegionBase
);
if (EFI_ERROR (Status)) {
return Status;
}
ZeroMem ((VOID *)(UINTN)LegacyRegionBase, LegacyRegionSize);
ThunkContext->RealModeBuffer = (VOID *)(UINTN)LegacyRegionBase;
ThunkContext->RealModeBufferSize = LegacyRegionSize;
ThunkContext->ThunkAttributes = THUNK_ATTRIBUTE_BIG_REAL_MODE|THUNK_ATTRIBUTE_DISABLE_A20_MASK_INT_15;
AsmPrepareThunk16 (ThunkContext);
return Status;
}
/**
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.
**/
EFI_STATUS
OcLegacyThunkInitializeInterruptRedirection (
IN EFI_LEGACY_8259_PROTOCOL *Legacy8259
)
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS LegacyRegionBase;
UINTN LegacyRegionLength;
volatile UINT32 *IdtArray;
UINTN Index;
UINT8 ProtectedModeBaseVector;
STATIC CONST 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 = LEGACY_REGION_BASE;
Status = gBS->AllocatePages (
AllocateMaxAddress,
EfiACPIMemoryNVS,
EFI_SIZE_TO_PAGES (LegacyRegionLength),
&LegacyRegionBase
);
if (EFI_ERROR (Status)) {
return 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 Status;
}
/**
Disconnect all EFI graphics device handles in preparation for calling to legacy mode.
**/
VOID
OcLegacyThunkDisconnectEfiGraphics (
VOID
)
{
EFI_STATUS Status;
UINTN HandleCount;
EFI_HANDLE *HandleBuffer;
UINTN Index;
EFI_PCI_IO_PROTOCOL *PciIo;
PCI_CLASSCODE ClassCode;
Status = gBS->LocateHandleBuffer (
ByProtocol,
&gEfiPciIoProtocolGuid,
NULL,
&HandleCount,
&HandleBuffer
);
if (EFI_ERROR (Status)) {
return;
}
for (Index = 0; Index < HandleCount; ++Index) {
Status = gBS->HandleProtocol (
HandleBuffer[Index],
&gEfiPciIoProtocolGuid,
(VOID **)&PciIo
);
if (EFI_ERROR (Status)) {
continue;
}
Status = PciIo->Pci.Read (
PciIo,
EfiPciIoWidthUint8,
PCI_CLASSCODE_OFFSET,
sizeof (PCI_CLASSCODE) / sizeof (UINT8),
&ClassCode
);
if (EFI_ERROR (Status)) {
continue;
}
if ((ClassCode.BaseCode == PCI_CLASS_DISPLAY) && (ClassCode.SubClassCode == PCI_CLASS_DISPLAY_VGA)) {
Status = gBS->DisconnectController (
HandleBuffer[Index],
NULL,
NULL
);
DEBUG ((DEBUG_INFO, "OCLT: Disconnected graphics controller - %r\n", Status));
}
}
FreePool (HandleBuffer);
}
/**
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 ThunkContext The instance pointer of THUNK_CONTEXT.
@param Legacy8259 Instance pointer for EFI_LEGACY_8259_PROTOCOL.
@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 error in the target code.
**/
BOOLEAN
EFIAPI
OcLegacyThunkBiosInt86 (
IN THUNK_CONTEXT *ThunkContext,
IN EFI_LEGACY_8259_PROTOCOL *Legacy8259,
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 = Legacy8259->SetMode (Legacy8259, Efi8259LegacyMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
Stack16 = (UINT16 *)((UINT8 *)ThunkContext->RealModeBuffer + ThunkContext->RealModeBufferSize - sizeof (UINT16));
ThunkRegSet.E.SS = (UINT16)(((UINTN)Stack16 >> 16) << 12);
ThunkRegSet.E.ESP = (UINT16)(UINTN)Stack16;
ThunkRegSet.E.Eip = (UINT16)((volatile UINT32 *)NULL)[BiosInt];
ThunkRegSet.E.CS = (UINT16)(((volatile UINT32 *)NULL)[BiosInt] >> 16);
ThunkContext->RealModeState = &ThunkRegSet;
AsmThunk16 (ThunkContext);
//
// Restore protected mode interrupt state
//
Status = Legacy8259->SetMode (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;
}
BOOLEAN
EFIAPI
OcLegacyThunkFarCall86 (
IN THUNK_CONTEXT *ThunkContext,
IN EFI_LEGACY_8259_PROTOCOL *Legacy8259,
IN UINT16 Segment,
IN UINT16 Offset,
IN IA32_REGISTER_SET *Regs,
IN VOID *Stack,
IN UINTN StackSize
)
{
UINTN Status;
UINT16 *Stack16;
IA32_REGISTER_SET ThunkRegSet;
BOOLEAN Ret;
UINT64 TimerPeriod;
BOOLEAN Enabled;
EFI_TIMER_ARCH_PROTOCOL *TimerProtocol;
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 ();
//
// Save current rate of DXE timer and disable it
// while executing in real mode.
//
Status = gBS->LocateProtocol (
&gEfiTimerArchProtocolGuid,
NULL,
(VOID **)&TimerProtocol
);
if (!EFI_ERROR (Status)) {
TimerProtocol->GetTimerPeriod (TimerProtocol, &TimerPeriod);
TimerProtocol->SetTimerPeriod (TimerProtocol, 0);
} else {
TimerProtocol = NULL;
}
//
// Reset timer to default legacy rate of 54.9254.
//
IoWrite8 (TIMER_CONTROL_PORT, TIMER0_CONTROL_WORD);
IoWrite8 (TIMER0_COUNT_PORT, 0x00);
IoWrite8 (TIMER0_COUNT_PORT, 0x00);
//
// Put the 8259 into its legacy mode by reprogramming the vector bases
//
Status = Legacy8259->SetVectorBase (Legacy8259, LEGACY_MODE_BASE_VECTOR_MASTER, LEGACY_MODE_BASE_VECTOR_SLAVE);
ASSERT_EFI_ERROR (Status);
//
// Set Legacy16 state. 0x08, 0x70 is legacy 8259 vector bases.
//
Status = Legacy8259->SetMode (Legacy8259, Efi8259LegacyMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
//
// Clear the error flag; thunk code may set it. Stack16 should be the high address.
// Make Stack16 address the low 16 bit must be not zero.
//
Stack16 = (UINT16 *)((UINT8 *)ThunkContext->RealModeBuffer + ThunkContext->RealModeBufferSize - sizeof (UINT16));
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;
ThunkContext->RealModeState = &ThunkRegSet;
AsmThunk16 (ThunkContext);
//
// EFI is likely trashed if we get here, but attempt to restore state.
//
if ((Stack != NULL) && (StackSize != 0)) {
//
// Copy low memory stack to Stack
//
CopyMem (Stack, Stack16, StackSize);
}
//
// Restore protected mode interrupt state
//
Status = Legacy8259->SetMode (Legacy8259, Efi8259ProtectedMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
ThunkContext->RealModeState = NULL;
//
// Enable and restore rate of DXE Timer
//
if (TimerProtocol != NULL) {
TimerProtocol->SetTimerPeriod (TimerProtocol, TimerPeriod);
}
//
// 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;
}
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