1 #ifndef _ASM_X86_SEGMENT_H 2 #define _ASM_X86_SEGMENT_H 3 4 #include <linux/const.h> 5 6 /* 7 * Constructor for a conventional segment GDT (or LDT) entry. 8 * This is a macro so it can be used in initializers. 9 */ 10 #define GDT_ENTRY(flags, base, limit) \ 11 ((((base) & _AC(0xff000000,ULL)) << (56-24)) | \ 12 (((flags) & _AC(0x0000f0ff,ULL)) << 40) | \ 13 (((limit) & _AC(0x000f0000,ULL)) << (48-16)) | \ 14 (((base) & _AC(0x00ffffff,ULL)) << 16) | \ 15 (((limit) & _AC(0x0000ffff,ULL)))) 16 17 /* Simple and small GDT entries for booting only: */ 18 19 #define GDT_ENTRY_BOOT_CS 2 20 #define GDT_ENTRY_BOOT_DS 3 21 #define GDT_ENTRY_BOOT_TSS 4 22 #define __BOOT_CS (GDT_ENTRY_BOOT_CS*8) 23 #define __BOOT_DS (GDT_ENTRY_BOOT_DS*8) 24 #define __BOOT_TSS (GDT_ENTRY_BOOT_TSS*8) 25 26 /* 27 * Bottom two bits of selector give the ring 28 * privilege level 29 */ 30 #define SEGMENT_RPL_MASK 0x3 31 32 /* User mode is privilege level 3: */ 33 #define USER_RPL 0x3 34 35 /* Bit 2 is Table Indicator (TI): selects between LDT or GDT */ 36 #define SEGMENT_TI_MASK 0x4 37 /* LDT segment has TI set ... */ 38 #define SEGMENT_LDT 0x4 39 /* ... GDT has it cleared */ 40 #define SEGMENT_GDT 0x0 41 42 #ifdef CONFIG_X86_32 43 /* 44 * The layout of the per-CPU GDT under Linux: 45 * 46 * 0 - null <=== cacheline #1 47 * 1 - reserved 48 * 2 - reserved 49 * 3 - reserved 50 * 51 * 4 - unused <=== cacheline #2 52 * 5 - unused 53 * 54 * ------- start of TLS (Thread-Local Storage) segments: 55 * 56 * 6 - TLS segment #1 [ glibc's TLS segment ] 57 * 7 - TLS segment #2 [ Wine's %fs Win32 segment ] 58 * 8 - TLS segment #3 <=== cacheline #3 59 * 9 - reserved 60 * 10 - reserved 61 * 11 - reserved 62 * 63 * ------- start of kernel segments: 64 * 65 * 12 - kernel code segment <=== cacheline #4 66 * 13 - kernel data segment 67 * 14 - default user CS 68 * 15 - default user DS 69 * 16 - TSS <=== cacheline #5 70 * 17 - LDT 71 * 18 - PNPBIOS support (16->32 gate) 72 * 19 - PNPBIOS support 73 * 20 - PNPBIOS support <=== cacheline #6 74 * 21 - PNPBIOS support 75 * 22 - PNPBIOS support 76 * 23 - APM BIOS support 77 * 24 - APM BIOS support <=== cacheline #7 78 * 25 - APM BIOS support 79 * 80 * 26 - ESPFIX small SS 81 * 27 - per-cpu [ offset to per-cpu data area ] 82 * 28 - stack_canary-20 [ for stack protector ] <=== cacheline #8 83 * 29 - unused 84 * 30 - unused 85 * 31 - TSS for double fault handler 86 */ 87 #define GDT_ENTRY_TLS_MIN 6 88 #define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1) 89 90 #define GDT_ENTRY_KERNEL_CS 12 91 #define GDT_ENTRY_KERNEL_DS 13 92 #define GDT_ENTRY_DEFAULT_USER_CS 14 93 #define GDT_ENTRY_DEFAULT_USER_DS 15 94 #define GDT_ENTRY_TSS 16 95 #define GDT_ENTRY_LDT 17 96 #define GDT_ENTRY_PNPBIOS_CS32 18 97 #define GDT_ENTRY_PNPBIOS_CS16 19 98 #define GDT_ENTRY_PNPBIOS_DS 20 99 #define GDT_ENTRY_PNPBIOS_TS1 21 100 #define GDT_ENTRY_PNPBIOS_TS2 22 101 #define GDT_ENTRY_APMBIOS_BASE 23 102 103 #define GDT_ENTRY_ESPFIX_SS 26 104 #define GDT_ENTRY_PERCPU 27 105 #define GDT_ENTRY_STACK_CANARY 28 106 107 #define GDT_ENTRY_DOUBLEFAULT_TSS 31 108 109 /* 110 * Number of entries in the GDT table: 111 */ 112 #define GDT_ENTRIES 32 113 114 /* 115 * Segment selector values corresponding to the above entries: 116 */ 117 118 #define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) 119 #define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) 120 #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) 121 #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) 122 #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8) 123 124 /* segment for calling fn: */ 125 #define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32*8) 126 /* code segment for BIOS: */ 127 #define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16*8) 128 129 /* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */ 130 #define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == PNP_CS32) 131 132 /* data segment for BIOS: */ 133 #define PNP_DS (GDT_ENTRY_PNPBIOS_DS*8) 134 /* transfer data segment: */ 135 #define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1*8) 136 /* another data segment: */ 137 #define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2*8) 138 139 #ifdef CONFIG_SMP 140 # define __KERNEL_PERCPU (GDT_ENTRY_PERCPU*8) 141 #else 142 # define __KERNEL_PERCPU 0 143 #endif 144 145 #ifdef CONFIG_CC_STACKPROTECTOR 146 # define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY*8) 147 #else 148 # define __KERNEL_STACK_CANARY 0 149 #endif 150 151 #else /* 64-bit: */ 152 153 #include <asm/cache.h> 154 155 #define GDT_ENTRY_KERNEL32_CS 1 156 #define GDT_ENTRY_KERNEL_CS 2 157 #define GDT_ENTRY_KERNEL_DS 3 158 159 /* 160 * We cannot use the same code segment descriptor for user and kernel mode, 161 * not even in long flat mode, because of different DPL. 162 * 163 * GDT layout to get 64-bit SYSCALL/SYSRET support right. SYSRET hardcodes 164 * selectors: 165 * 166 * if returning to 32-bit userspace: cs = STAR.SYSRET_CS, 167 * if returning to 64-bit userspace: cs = STAR.SYSRET_CS+16, 168 * 169 * ss = STAR.SYSRET_CS+8 (in either case) 170 * 171 * thus USER_DS should be between 32-bit and 64-bit code selectors: 172 */ 173 #define GDT_ENTRY_DEFAULT_USER32_CS 4 174 #define GDT_ENTRY_DEFAULT_USER_DS 5 175 #define GDT_ENTRY_DEFAULT_USER_CS 6 176 177 /* Needs two entries */ 178 #define GDT_ENTRY_TSS 8 179 /* Needs two entries */ 180 #define GDT_ENTRY_LDT 10 181 182 #define GDT_ENTRY_TLS_MIN 12 183 #define GDT_ENTRY_TLS_MAX 14 184 185 /* Abused to load per CPU data from limit */ 186 #define GDT_ENTRY_PER_CPU 15 187 188 /* 189 * Number of entries in the GDT table: 190 */ 191 #define GDT_ENTRIES 16 192 193 /* 194 * Segment selector values corresponding to the above entries: 195 * 196 * Note, selectors also need to have a correct RPL, 197 * expressed with the +3 value for user-space selectors: 198 */ 199 #define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS*8) 200 #define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) 201 #define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) 202 #define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS*8 + 3) 203 #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) 204 #define __USER32_DS __USER_DS 205 #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) 206 #define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3) 207 208 /* TLS indexes for 64-bit - hardcoded in arch_prctl(): */ 209 #define FS_TLS 0 210 #define GS_TLS 1 211 212 #define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3) 213 #define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3) 214 215 #endif 216 217 #ifndef CONFIG_PARAVIRT 218 # define get_kernel_rpl() 0 219 #endif 220 221 #define IDT_ENTRIES 256 222 #define NUM_EXCEPTION_VECTORS 32 223 224 /* Bitmask of exception vectors which push an error code on the stack: */ 225 #define EXCEPTION_ERRCODE_MASK 0x00027d00 226 227 #define GDT_SIZE (GDT_ENTRIES*8) 228 #define GDT_ENTRY_TLS_ENTRIES 3 229 #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) 230 231 #ifdef __KERNEL__ 232 #ifndef __ASSEMBLY__ 233 234 extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5]; 235 #ifdef CONFIG_TRACING 236 # define trace_early_idt_handlers early_idt_handlers 237 #endif 238 239 /* 240 * Load a segment. Fall back on loading the zero 241 * segment if something goes wrong.. 242 */ 243 #define loadsegment(seg, value) \ 244 do { \ 245 unsigned short __val = (value); \ 246 \ 247 asm volatile(" \n" \ 248 "1: movl %k0,%%" #seg " \n" \ 249 \ 250 ".section .fixup,\"ax\" \n" \ 251 "2: xorl %k0,%k0 \n" \ 252 " jmp 1b \n" \ 253 ".previous \n" \ 254 \ 255 _ASM_EXTABLE(1b, 2b) \ 256 \ 257 : "+r" (__val) : : "memory"); \ 258 } while (0) 259 260 /* 261 * Save a segment register away: 262 */ 263 #define savesegment(seg, value) \ 264 asm("mov %%" #seg ",%0":"=r" (value) : : "memory") 265 266 /* 267 * x86-32 user GS accessors: 268 */ 269 #ifdef CONFIG_X86_32 270 # ifdef CONFIG_X86_32_LAZY_GS 271 # define get_user_gs(regs) (u16)({ unsigned long v; savesegment(gs, v); v; }) 272 # define set_user_gs(regs, v) loadsegment(gs, (unsigned long)(v)) 273 # define task_user_gs(tsk) ((tsk)->thread.gs) 274 # define lazy_save_gs(v) savesegment(gs, (v)) 275 # define lazy_load_gs(v) loadsegment(gs, (v)) 276 # else /* X86_32_LAZY_GS */ 277 # define get_user_gs(regs) (u16)((regs)->gs) 278 # define set_user_gs(regs, v) do { (regs)->gs = (v); } while (0) 279 # define task_user_gs(tsk) (task_pt_regs(tsk)->gs) 280 # define lazy_save_gs(v) do { } while (0) 281 # define lazy_load_gs(v) do { } while (0) 282 # endif /* X86_32_LAZY_GS */ 283 #endif /* X86_32 */ 284 285 #endif /* !__ASSEMBLY__ */ 286 #endif /* __KERNEL__ */ 287 288 #endif /* _ASM_X86_SEGMENT_H */ 289