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[HAL/x64] Fix x86BiosCall

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Use an INT call stub and exit on the address after the stub instead or using iret (some BIOS code uses int / iret internally). This fixes the messed up display when trying to switch modes.
This commit is contained in:
Timo Kreuzer 2022-08-14 14:41:53 +02:00
parent 38fc6e1274
commit 3381bf39db
1 changed files with 20 additions and 21 deletions
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41
hal/halx86/amd64/x86bios.c
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@ -412,12 +412,8 @@ x86BiosCall(
_In_ ULONG InterruptNumber,
_Inout_ PX86_BIOS_REGISTERS Registers)
{
const ULONG StackBase = 0x2000;
FAST486_STATE EmulatorContext;
struct
{
USHORT Ip;
USHORT SegCs;
} *Ivt;
ULONG FlatIp;
PUCHAR InstructionPointer;
@ -432,8 +428,6 @@ x86BiosCall(
NULL, // FpuCallback,
NULL); // Tlb
//RegisterBop(BOP_UNSIMULATE, CpuUnsimulateBop);
/* Copy the registers */
EmulatorContext.GeneralRegs[FAST486_REG_EAX].Long = Registers->Eax;
EmulatorContext.GeneralRegs[FAST486_REG_EBX].Long = Registers->Ebx;
@ -449,36 +443,41 @@ x86BiosCall(
EmulatorContext.Flags.AlwaysSet = 1;
EmulatorContext.Flags.If = 1;
/* Set the stack pointer */
Fast486SetStack(&EmulatorContext, 0, 0x2000 - 2); // FIXME
/* Set up the INT stub */
FlatIp = StackBase - 4;
InstructionPointer = x86BiosMemoryMapping + FlatIp;
InstructionPointer[0] = 0xCD; // INT instruction
InstructionPointer[1] = (UCHAR)InterruptNumber;
InstructionPointer[2] = 0x90; // NOP. We will stop at this address.
/* Set CS:EIP from the IVT entry */
Ivt = (PVOID)x86BiosMemoryMapping;
Fast486ExecuteAt(&EmulatorContext,
Ivt[InterruptNumber].SegCs,
Ivt[InterruptNumber].Ip);
/* Set the stack pointer */
Fast486SetStack(&EmulatorContext, 0, StackBase - 8);
/* Start execution at the INT stub */
Fast486ExecuteAt(&EmulatorContext, 0x00, FlatIp);
while (TRUE)
{
/* Step one instruction */
Fast486StepInto(&EmulatorContext);
/* Check for iret */
/* Get the current flat IP */
FlatIp = (EmulatorContext.SegmentRegs[FAST486_REG_CS].Selector << 4) +
EmulatorContext.InstPtr.Long;
/* Make sure we haven't left the allowed memory range */
if (FlatIp >= 0x100000)
{
DPRINT1("x86BiosCall: invalid IP (0x%lx) during BIOS execution", FlatIp);
return FALSE;
}
/* Read the next instruction and check if it's IRET */
InstructionPointer = x86BiosMemoryMapping + FlatIp;
if (*InstructionPointer == 0xCF)
/* Check if we returned from our int stub */
if (FlatIp == (StackBase - 2))
{
/* We are done! */
break;
}
/* Emulate one instruction */
Fast486StepInto(&EmulatorContext);
}
/* Copy the registers back */