Edit: /usr/include/asm/ldt.h (1306B)
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* ldt.h
*
* Definitions of structures used with the modify_ldt system call.
*/
#ifndef _ASM_X86_LDT_H
#define _ASM_X86_LDT_H
/* Maximum number of LDT entries supported. */
#define LDT_ENTRIES 8192
/* The size of each LDT entry. */
#define LDT_ENTRY_SIZE 8
#ifndef __ASSEMBLY__
/*
* Note on 64bit base and limit is ignored and you cannot set DS/ES/CS
* not to the default values if you still want to do syscalls. This
* call is more for 32bit mode therefore.
*/
struct user_desc {
unsigned int entry_number;
unsigned int base_addr;
unsigned int limit;
unsigned int seg_32bit:1;
unsigned int contents:2;
unsigned int read_exec_only:1;
unsigned int limit_in_pages:1;
unsigned int seg_not_present:1;
unsigned int useable:1;
#ifdef __x86_64__
/*
* Because this bit is not present in 32-bit user code, user
* programs can pass uninitialized values here. Therefore, in
* any context in which a user_desc comes from a 32-bit program,
* the kernel must act as though lm == 0, regardless of the
* actual value.
*/
unsigned int lm:1;
#endif
};
#define MODIFY_LDT_CONTENTS_DATA 0
#define MODIFY_LDT_CONTENTS_STACK 1
#define MODIFY_LDT_CONTENTS_CODE 2
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_LDT_H */