Interrupt Debug Service (0×2D), Boot loader, Vista 64bits (On the fly)
DebugPrint proc near
mov r9d, r8d
mov r8d, edx
mov dx, [rcx]
mov rcx, [rcx+8]
mov eax, 1
int 2Dh ; Internal routine for MSDOS (IRET)
int 3 ; Trap to Debugger
retn
DebugPrint endp
DebugPrompt proc near
mov r9w, [rdx+2]
mov r8, [rdx+8]
mov dx, [rcx]
mov rcx, [rcx+8]
mov eax, 2
int 2Dh ; Internal routine for MSDOS (IRET)
int 3 ; Trap to Debugger
retn
DebugPrompt endp
DebugService2 proc near
mov eax, r8d
int 2Dh ; Internal routine for MSDOS (IRET)
int 3 ; Trap to Debugger
retn
DebugService2 endp
BlBdStart+11C:
lea rdx, [rsp+78h+var_28]
lea rcx, [rsp+78h+var_58]
mov r8d, 3
call DebugService2
BlBdStop proc near
lea rdx, [rax-28h]
mov r8d, 4
xor ecx, ecx
[...]
call DebugService2
typedef enum _STATUS_DEBUG_SERVICE {
STATUS_PRINT = 1,
STATUS_PROMPT = 2,
STATUS_START = 3,
STATUS_STOP = 4
} STATUS_DEBUG_SERVICE;
Interrupts, Boot Loader, Vista 64bits (On the fly)
I’ve to do something to save me from idling while a software is rescuing my HDD.
That’s why I’m gonna write short post about the boot loader and the interrupts initialization.
By the way, I add a new category called “On the fly” for post like that which are more or less RCE Memento (interessting or not ::)).
If I had to explain it I’d answer “no blabla just code. don’t read but analyse.”
This article covers where the interrupts 0×1, 0×3, 0×6, 0xD, 0xE, 0×2C, 0×2D are initialized inside the bootloader.
For reminding, I’ve rewritten some things :
//
// 63 32 16 0
// +------------------------------+------------------------------+
// + OffsetLow + HighLow + HighHigh +
// +------------------------------+------------------------------+
//
typedef struct _KIDT_ENTRY { // (sizeof=0x10)
unsigned short wOffsetHighHigh; // +0x00
unsigned short Reserved02; // +0x02
unsigned short Reserved04; // +0x04
unsigned short wOffsetHighLow; // +0x06
unsigned long dwOffsetLow; // +0x08
unsigned long Reserved0C; // +0x0C
} KIDT_ENTRY;
typedef enum _INTERRUPT_ID{
NONE=-1,
DIVIDE_ERROR=0, // 0x00
SINGLE_STEP, // 0x01
NMI_INTERRUPT, // 0x02
BREAKPOINT, // 0x03
OVERFLOW, // 0x04
BOUND, // 0x05
INVALID_OPCODE, // 0x6
NPX_NOT_AVAILABLE, // 0x07
DOUBLE_FAULT, // 0x08
NPX_SEGMENT_OVERRUN, // 0x09
INVALID_TSS, // 0x0A
SEGMENT_NOT_PRESENT, // 0x0B
STACK, // 0x0C
GENERAL_PROTECTION, // 0x0D
PAGE, // 0x0E
RESERVED, // 0x0F
FLOATING_ERROR, // 0x10
ALIGNMENT, // 0x11
MACHINE_CHECK, // 0x12
XMM_EXCEPTION, // 0x13
//
// Other Critical Interrupts
//
APC=0x1F, // 0x1F
RAISE_ASSERTION=0x2C, // 0x2C
DEBUG_SERVICE=0x2D, // 0x2D
DPC=0x2F, // 0x2F
IPI=0xE1 // 0xE1
} INTERRUPT_ID;
Firstly, we have to know these to function inside the “.text” section.
Function : ArchGetIdtRegister
XREF: BdInstallTrapVectors, BlpArchInitialize
ArchGetIdtRegister proc near
sidt qword ptr [rcx]
retn
ArchGetIdtRegister endp
Function : ArchSetIdtRegister
XREF: BdInstallTrapVectors, BlpArchInitialize
ArchSetIdtRegister proc near
lidt qword ptr [rcx]
retn
ArchGetIdtRegister endp
Let’s look at the XREF’s functions.
BdInstallTrapVectors
BdInstallTrapVectors proc near ; CODE XREF: BlBdInitialize+20D
var_18 = qword ptr -18h
sub rsp, 38h
lea rcx, [rsp+38h+var_18]
call ArchGetIdtRegister
mov r11, [rsp+38h+var_18+2]
mov r9w, 10h
mov [r11+12h], r9w
mov r8w, 8E00h
lea rax, BdTrap01
mov [r11+10h], ax ; 0x10/(16 = sizeof(_KIDT_ENTRY)) = 0x1
mov [r11+14h], r8w
mov rcx, rax
shr rcx, 10h
shr rax, 20h
mov [r11+16h], cx
mov [r11+18h], eax
mov rdx, [rsp+38h+var_18+2]
mov [rdx+32h], r9w
mov [rdx+34h], r8w
lea rax, BdTrap03
mov [rdx+30h], ax ; 0x30/(16 = sizeof(_KIDT_ENTRY)) = 0x3
mov rcx, rax
shr rax, 20h
mov [rdx+38h], eax
shr rcx, 10h
lea rax, BdTrap0d
mov [rdx+36h], cx
mov rdx, [rsp+38h+var_18+2]
mov rcx, rax
mov [rdx+0D0h], ax ; 0x0D/(16 = sizeof(_KIDT_ENTRY)) = 0x0D
mov [rdx+0D2h], r9w
mov [rdx+0D4h], r8w
shr rcx, 10h
shr rax, 20h
mov [rdx+0D6h], cx
mov [rdx+0D8h], eax
mov rdx, [rsp+38h+var_18+2]
mov [rdx+0E2h], r9w
mov [rdx+0E4h], r8w
lea rax, BdTrap0e
mov [rdx+0E0h], ax ; 0xE0/(16 = sizeof(_KIDT_ENTRY)) = 0x0E
mov rcx, rax
shr rax, 20h
mov [rdx+0E8h], eax
shr rcx, 10h
lea rax, BdTrap2c
mov [rdx+0E6h], cx
mov rdx, [rsp+38h+var_18+2]
mov rcx, rax
mov [rdx+2C0h], ax ; 0x2C0/(16 = sizeof(_KIDT_ENTRY)) = 0x2C
mov [rdx+2C2h], r9w
mov [rdx+2C4h], r8w
shr rcx, 10h
shr rax, 20h
mov [rdx+2C6h], cx
mov [rdx+2C8h], eax
mov rdx, [rsp+38h+var_18+2]
lea rax, BdTrap2d
mov [rdx+2D2h], r9w
mov [rdx+2D4h], r8w
mov rcx, rax
mov [rdx+2D0h], ax ; 0x2D0/(16 = sizeof(_KIDT_ENTRY)) = 0x2D
shr rax, 20h
shr rcx, 10h
mov [rdx+2D8h], eax
mov [rdx+2D6h], cx
lea rcx, [rsp+38h+var_18]
call ArchSetIdtRegister
add rsp, 38h
retn
BdInstallTrapVectors endp
InitializeLibrary
BlpArchInitialize proc near ; CODE XREF: InitializeLibrary+12A
IdtEntry = qword ptr -18h
sub rsp, 38h
cmp ecx, 1
jnz _exit
lea rcx, [rsp+38h+IdtEntry]
call ArchGetIdtRegister
mov r11, [rsp+38h+IdtEntry+2]
lea rax, ArchTrapNoProcess
mov [r11+30h], ax ; 0x30/(16 = sizeof(_KIDT_ENTRY)) = 0x3
mov word ptr [r11+32h], 10h
mov word ptr [r11+34h], 8E00h
mov r8, rax
mov rdx, rax
shr r8, 10h
shr rdx, 20h
mov [r11+36h], r8w
mov [r11+38h], edx
mov rcx, [rsp+38h+IdtEntry+2]
mov [rcx+2C0h], ax ; 0x2C0/(16 = sizeof(_KIDT_ENTRY)) = 0x2C
mov [rcx+2C6h], r8w
mov [rcx+2C8h], edx
mov word ptr [rcx+2C2h], 10h
mov word ptr [rcx+2C4h], 8E00h
mov rcx, [rsp+38h+IdtEntry+2]
mov [rcx+2D0h], ax ; 0x2D0/(16 = sizeof(_KIDT_ENTRY)) = 0x2D
mov [rcx+2D6h], r8w
mov [rcx+2D8h], edx
mov word ptr [rcx+2D2h], 10h
mov word ptr [rcx+2D4h], 8E00h
lea rcx, [rsp+38h+IdtEntry]
call ArchSetIdtRegister
_exit:
xor eax, eax
add rsp, 38h
retn
BlpArchInitialize endp
