| 1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
| 2 | /* |
| 3 | * ldt.h |
| 4 | * |
| 5 | * Definitions of structures used with the modify_ldt system call. |
| 6 | */ |
| 7 | #ifndef _ASM_X86_LDT_H |
| 8 | #define _ASM_X86_LDT_H |
| 9 | |
| 10 | /* Maximum number of LDT entries supported. */ |
| 11 | #define LDT_ENTRIES 8192 |
| 12 | /* The size of each LDT entry. */ |
| 13 | #define LDT_ENTRY_SIZE 8 |
| 14 | |
| 15 | #ifndef __ASSEMBLER__ |
| 16 | /* |
| 17 | * Note on 64bit base and limit is ignored and you cannot set DS/ES/CS |
| 18 | * not to the default values if you still want to do syscalls. This |
| 19 | * call is more for 32bit mode therefore. |
| 20 | */ |
| 21 | struct user_desc { |
| 22 | unsigned int entry_number; |
| 23 | unsigned int base_addr; |
| 24 | unsigned int limit; |
| 25 | unsigned int seg_32bit:1; |
| 26 | unsigned int contents:2; |
| 27 | unsigned int read_exec_only:1; |
| 28 | unsigned int limit_in_pages:1; |
| 29 | unsigned int seg_not_present:1; |
| 30 | unsigned int useable:1; |
| 31 | #ifdef __x86_64__ |
| 32 | /* |
| 33 | * Because this bit is not present in 32-bit user code, user |
| 34 | * programs can pass uninitialized values here. Therefore, in |
| 35 | * any context in which a user_desc comes from a 32-bit program, |
| 36 | * the kernel must act as though lm == 0, regardless of the |
| 37 | * actual value. |
| 38 | */ |
| 39 | unsigned int lm:1; |
| 40 | #endif |
| 41 | }; |
| 42 | |
| 43 | #define MODIFY_LDT_CONTENTS_DATA 0 |
| 44 | #define MODIFY_LDT_CONTENTS_STACK 1 |
| 45 | #define MODIFY_LDT_CONTENTS_CODE 2 |
| 46 | |
| 47 | #endif /* !__ASSEMBLER__ */ |
| 48 | #endif /* _ASM_X86_LDT_H */ |