Include file for GDT configuration. More...

#include <stdint.h>
#include "maldefines.h"

Data Structures
struct	segment_descriptor_s
	Meant to be written inside the GDT. Provides the processor with the size and location of a segment, as well as access control and status information. More...

struct	callgate_descriptor_s
	A callgate descriptor for the GDT/LDT Intel 64 and IA-32 Architectures Software Developer's Manual - Vol. 3a - Sec. 5.8.3 and Fig. 5.8. More...

struct	tss_descriptor_s

union	gdt_entry

struct	gdt_ptr
	Pointer to the GDT. More...

struct	tss_s
	Task State Segment structure . More...

Macros
#define	GRANULARITY_1 0

#define	GRANULARITY_4096 1

#define	SEG_DATA_READONLY_EXPANDUP_TYPE 0b0000

#define	SEG_DATA_READWRITE_EXPANDUP_TYPE 0b0010

#define	SEG_DATA_READONLY_EXPANDDOWN_TYPE 0b0100

#define	SEG_DATA_READWRITE_EXPANDDOWN_TYPE 0b0110

#define	SEG_CODE_EXECONLY_NONCONFORMING_TYPE 0b1000

#define	SEG_CODE_EXECREAD_NONCONFORMING_TYPE 0b1010

#define	SEG_CODE_EXECONLY_CONFORMING_TYPE 0b1100

#define	SEG_CODE_EXECREAD_CONFORMING_TYPE 0b1110

#define	GDT_CALLGATE_TYPE 0b1100

#define	GDT_TSS_INACTIVE_TYPE 0b1001

#define	GDT_TSS_BUSY_TYPE 0b1011

Typedefs
typedef struct segment_descriptor_s	segment_descriptor_t

typedef struct callgate_descriptor_s	callgate_descriptor_t

typedef struct tss_descriptor_s	tss_descriptor_t

typedef union gdt_entry	gdt_entry_t

typedef struct tss_s	tss_t

Functions
struct gdt_ptr	__attribute__ ((packed))

void	gdt_init ()
	Installs the GDT into the CPU. More...

void	setKernelStack (uint32_t stack)
	Updates the kernel stack address into the TSS. More...

Variables
unsigned short	limit
	Address limit. More...

unsigned int	base
	Base address. More...

unsigned	prev_tss
	Pointer to the previous TSS entry (updated on a task switch) More...

unsigned	reserved0

unsigned	esp0
	Kernel-mode ESP (static) More...

unsigned	ss0
	Kernel-mode stack segment (static) More...

unsigned	reserved1

unsigned	esp1
	Ring-1 ESP (static) More...

unsigned	ss1
	Ring-1 stack segment (static) More...

unsigned	reserved2

unsigned	esp2
	Ring-2 ESP (static) More...

unsigned	ss2
	Ring-2 stack segment (static) More...

unsigned	reserved3

unsigned	cr3
	Page directory address (static) More...

unsigned	eip
	Execution pointer (prior to task switch) More...

unsigned	eflags
	CPU flags (prior to task switch) More...

unsigned	eax
	General register EAX (prior to task switch) More...

unsigned	ecx
	General register ECX (prior to task switch) More...

unsigned	edx
	General register EDX (prior to task switch) More...

unsigned	ebx
	General register EBX (prior to task switch) More...

unsigned	esp
	User-mode ESP (prior to task switch) More...

unsigned	ebp
	User-mode EBP (prior to task switch) More...

unsigned	esi
	General register ESI (prior to task switch) More...

unsigned	edi
	General register EDI (prior to task switch) More...

unsigned	es
	Segment selector ES (prior to task switch) More...

unsigned	reserved4

unsigned	cs
	Segment selector CS (prior to task switch) More...

unsigned	reserved5

unsigned	ss
	Segment selector SS (prior to task switch) More...

unsigned	reserved6

unsigned	ds
	Segment selector DS (prior to task switch) More...

unsigned	reserved7

unsigned	fs
	Segment selector FS (prior to task switch) More...

unsigned	reserved8

unsigned	gs
	Segment selector GS (prior to task switch) More...

unsigned	reserved9

unsigned	ldt
	Pointer to the LDT (static) More...

unsigned	reserved10

unsigned	trap
	Flag to raise an exception when a task switch to this task occurs (static) More...

unsigned	reserved11

unsigned	iomap_base
	IOMMU base. More...

tss_t	tss
	Generic TSS for userland-to-kernel switch. More...

Detailed Description

Include file for GDT configuration.

Macro Definition Documentation

◆ GDT_CALLGATE_TYPE

#define GDT_CALLGATE_TYPE 0b1100

◆ GDT_TSS_BUSY_TYPE

#define GDT_TSS_BUSY_TYPE 0b1011

◆ GDT_TSS_INACTIVE_TYPE

#define GDT_TSS_INACTIVE_TYPE 0b1001

◆ GRANULARITY_1

#define GRANULARITY_1 0

◆ GRANULARITY_4096

#define GRANULARITY_4096 1

◆ SEG_CODE_EXECONLY_CONFORMING_TYPE

#define SEG_CODE_EXECONLY_CONFORMING_TYPE 0b1100

◆ SEG_CODE_EXECONLY_NONCONFORMING_TYPE

#define SEG_CODE_EXECONLY_NONCONFORMING_TYPE 0b1000

◆ SEG_CODE_EXECREAD_CONFORMING_TYPE

#define SEG_CODE_EXECREAD_CONFORMING_TYPE 0b1110

◆ SEG_CODE_EXECREAD_NONCONFORMING_TYPE

#define SEG_CODE_EXECREAD_NONCONFORMING_TYPE 0b1010

◆ SEG_DATA_READONLY_EXPANDDOWN_TYPE

#define SEG_DATA_READONLY_EXPANDDOWN_TYPE 0b0100

◆ SEG_DATA_READONLY_EXPANDUP_TYPE

#define SEG_DATA_READONLY_EXPANDUP_TYPE 0b0000

All the different types of segments entries Last bit of the type is written every time the segment is accessed, and can be cleared for debug purposes and virtual memory management (according to Intel's doc).

Intel 64 and IA-32 Architectures Software Developer's Manual - Vol. 3a - Sec. 3.5 and Fig. 3-8

◆ SEG_DATA_READWRITE_EXPANDDOWN_TYPE

#define SEG_DATA_READWRITE_EXPANDDOWN_TYPE 0b0110

◆ SEG_DATA_READWRITE_EXPANDUP_TYPE

#define SEG_DATA_READWRITE_EXPANDUP_TYPE 0b0010

Typedef Documentation

◆ callgate_descriptor_t

typedef struct callgate_descriptor_s callgate_descriptor_t

◆ gdt_entry_t

typedef union gdt_entry gdt_entry_t

◆ segment_descriptor_t

typedef struct segment_descriptor_s segment_descriptor_t

◆ tss_descriptor_t

typedef struct tss_descriptor_s tss_descriptor_t

◆ tss_t

typedef struct tss_s tss_t

Function Documentation

◆ attribute()

struct gdt_ptr __attribute__ ( (packed) )

◆ gdt_init()

void gdt_init ( )

Installs the GDT into the CPU.

Callgate setup (Syscalls)

◆ setKernelStack()

void setKernelStack ( uint32_t stack )

Updates the kernel stack address into the TSS.

Parameters

stack The stack address

Variable Documentation

◆ base

unsigned int base

Base address.

◆ cr3

unsigned cr3

Page directory address (static)

◆ cs

unsigned cs

Segment selector CS (prior to task switch)

◆ ds

unsigned ds

Segment selector DS (prior to task switch)

◆ eax

unsigned eax

General register EAX (prior to task switch)

◆ ebp

unsigned ebp

User-mode EBP (prior to task switch)

◆ ebx

unsigned ebx

General register EBX (prior to task switch)

◆ ecx

unsigned ecx

General register ECX (prior to task switch)

◆ edi

unsigned edi

General register EDI (prior to task switch)

◆ edx

unsigned edx

General register EDX (prior to task switch)

◆ eflags

unsigned eflags

CPU flags (prior to task switch)

◆ eip

unsigned eip

Execution pointer (prior to task switch)

◆ es

unsigned es

Segment selector ES (prior to task switch)

◆ esi

unsigned esi

General register ESI (prior to task switch)

◆ esp

unsigned esp

User-mode ESP (prior to task switch)

◆ esp0

unsigned esp0

Kernel-mode ESP (static)

◆ esp1

unsigned esp1

Ring-1 ESP (static)

◆ esp2

unsigned esp2

Ring-2 ESP (static)

◆ fs

unsigned fs

Segment selector FS (prior to task switch)

◆ gs

unsigned gs

Segment selector GS (prior to task switch)

◆ iomap_base

unsigned iomap_base

IOMMU base.

◆ ldt

unsigned ldt

Pointer to the LDT (static)

◆ limit

unsigned short limit

Address limit.

◆ prev_tss

unsigned prev_tss

Pointer to the previous TSS entry (updated on a task switch)

◆ reserved0

unsigned reserved0

◆ reserved1

unsigned reserved1

◆ reserved10

unsigned reserved10

◆ reserved11

unsigned reserved11

◆ reserved2

unsigned reserved2

◆ reserved3

unsigned reserved3

◆ reserved4

unsigned reserved4

◆ reserved5

unsigned reserved5

◆ reserved6

unsigned reserved6

◆ reserved7

unsigned reserved7

◆ reserved8

unsigned reserved8

◆ reserved9

unsigned reserved9

◆ ss

unsigned ss

Segment selector SS (prior to task switch)

◆ ss0

unsigned ss0

Kernel-mode stack segment (static)

◆ ss1

unsigned ss1

Ring-1 stack segment (static)

◆ ss2

unsigned ss2

Ring-2 stack segment (static)

◆ trap

unsigned trap

Flag to raise an exception when a task switch to this task occurs (static)

◆ tss

tss_t tss

Generic TSS for userland-to-kernel switch.

Data Structures

Macros

Typedefs

Functions

Variables