/* 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 */