1 #ifndef _ASM_X86_SEGMENT_H 2 #define _ASM_X86_SEGMENT_H 3 4 #include <linux/const.h> 5 #include <asm/alternative.h> 6 7 /* 8 * Constructor for a conventional segment GDT (or LDT) entry. 9 * This is a macro so it can be used in initializers. 10 */ 11 #define GDT_ENTRY(flags, base, limit) \ 12 ((((base) & _AC(0xff000000,ULL)) << (56-24)) | \ 13 (((flags) & _AC(0x0000f0ff,ULL)) << 40) | \ 14 (((limit) & _AC(0x000f0000,ULL)) << (48-16)) | \ 15 (((base) & _AC(0x00ffffff,ULL)) << 16) | \ 16 (((limit) & _AC(0x0000ffff,ULL)))) 17 18 /* Simple and small GDT entries for booting only: */ 19 20 #define GDT_ENTRY_BOOT_CS 2 21 #define GDT_ENTRY_BOOT_DS 3 22 #define GDT_ENTRY_BOOT_TSS 4 23 #define __BOOT_CS (GDT_ENTRY_BOOT_CS*8) 24 #define __BOOT_DS (GDT_ENTRY_BOOT_DS*8) 25 #define __BOOT_TSS (GDT_ENTRY_BOOT_TSS*8) 26 27 /* 28 * Bottom two bits of selector give the ring 29 * privilege level 30 */ 31 #define SEGMENT_RPL_MASK 0x3 32 33 /* User mode is privilege level 3: */ 34 #define USER_RPL 0x3 35 36 /* Bit 2 is Table Indicator (TI): selects between LDT or GDT */ 37 #define SEGMENT_TI_MASK 0x4 38 /* LDT segment has TI set ... */ 39 #define SEGMENT_LDT 0x4 40 /* ... GDT has it cleared */ 41 #define SEGMENT_GDT 0x0 42 43 #define GDT_ENTRY_INVALID_SEG 0 44 45 #ifdef CONFIG_X86_32 46 /* 47 * The layout of the per-CPU GDT under Linux: 48 * 49 * 0 - null <=== cacheline #1 50 * 1 - reserved 51 * 2 - reserved 52 * 3 - reserved 53 * 54 * 4 - unused <=== cacheline #2 55 * 5 - unused 56 * 57 * ------- start of TLS (Thread-Local Storage) segments: 58 * 59 * 6 - TLS segment #1 [ glibc's TLS segment ] 60 * 7 - TLS segment #2 [ Wine's %fs Win32 segment ] 61 * 8 - TLS segment #3 <=== cacheline #3 62 * 9 - reserved 63 * 10 - reserved 64 * 11 - reserved 65 * 66 * ------- start of kernel segments: 67 * 68 * 12 - kernel code segment <=== cacheline #4 69 * 13 - kernel data segment 70 * 14 - default user CS 71 * 15 - default user DS 72 * 16 - TSS <=== cacheline #5 73 * 17 - LDT 74 * 18 - PNPBIOS support (16->32 gate) 75 * 19 - PNPBIOS support 76 * 20 - PNPBIOS support <=== cacheline #6 77 * 21 - PNPBIOS support 78 * 22 - PNPBIOS support 79 * 23 - APM BIOS support 80 * 24 - APM BIOS support <=== cacheline #7 81 * 25 - APM BIOS support 82 * 83 * 26 - ESPFIX small SS 84 * 27 - per-cpu [ offset to per-cpu data area ] 85 * 28 - stack_canary-20 [ for stack protector ] <=== cacheline #8 86 * 29 - unused 87 * 30 - unused 88 * 31 - TSS for double fault handler 89 */ 90 #define GDT_ENTRY_TLS_MIN 6 91 #define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1) 92 93 #define GDT_ENTRY_KERNEL_CS 12 94 #define GDT_ENTRY_KERNEL_DS 13 95 #define GDT_ENTRY_DEFAULT_USER_CS 14 96 #define GDT_ENTRY_DEFAULT_USER_DS 15 97 #define GDT_ENTRY_TSS 16 98 #define GDT_ENTRY_LDT 17 99 #define GDT_ENTRY_PNPBIOS_CS32 18 100 #define GDT_ENTRY_PNPBIOS_CS16 19 101 #define GDT_ENTRY_PNPBIOS_DS 20 102 #define GDT_ENTRY_PNPBIOS_TS1 21 103 #define GDT_ENTRY_PNPBIOS_TS2 22 104 #define GDT_ENTRY_APMBIOS_BASE 23 105 106 #define GDT_ENTRY_ESPFIX_SS 26 107 #define GDT_ENTRY_PERCPU 27 108 #define GDT_ENTRY_STACK_CANARY 28 109 110 #define GDT_ENTRY_DOUBLEFAULT_TSS 31 111 112 /* 113 * Number of entries in the GDT table: 114 */ 115 #define GDT_ENTRIES 32 116 117 /* 118 * Segment selector values corresponding to the above entries: 119 */ 120 121 #define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) 122 #define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) 123 #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) 124 #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) 125 #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS*8) 126 127 /* segment for calling fn: */ 128 #define PNP_CS32 (GDT_ENTRY_PNPBIOS_CS32*8) 129 /* code segment for BIOS: */ 130 #define PNP_CS16 (GDT_ENTRY_PNPBIOS_CS16*8) 131 132 /* "Is this PNP code selector (PNP_CS32 or PNP_CS16)?" */ 133 #define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == PNP_CS32) 134 135 /* data segment for BIOS: */ 136 #define PNP_DS (GDT_ENTRY_PNPBIOS_DS*8) 137 /* transfer data segment: */ 138 #define PNP_TS1 (GDT_ENTRY_PNPBIOS_TS1*8) 139 /* another data segment: */ 140 #define PNP_TS2 (GDT_ENTRY_PNPBIOS_TS2*8) 141 142 #ifdef CONFIG_SMP 143 # define __KERNEL_PERCPU (GDT_ENTRY_PERCPU*8) 144 #else 145 # define __KERNEL_PERCPU 0 146 #endif 147 148 #ifdef CONFIG_CC_STACKPROTECTOR 149 # define __KERNEL_STACK_CANARY (GDT_ENTRY_STACK_CANARY*8) 150 #else 151 # define __KERNEL_STACK_CANARY 0 152 #endif 153 154 #else /* 64-bit: */ 155 156 #include <asm/cache.h> 157 158 #define GDT_ENTRY_KERNEL32_CS 1 159 #define GDT_ENTRY_KERNEL_CS 2 160 #define GDT_ENTRY_KERNEL_DS 3 161 162 /* 163 * We cannot use the same code segment descriptor for user and kernel mode, 164 * not even in long flat mode, because of different DPL. 165 * 166 * GDT layout to get 64-bit SYSCALL/SYSRET support right. SYSRET hardcodes 167 * selectors: 168 * 169 * if returning to 32-bit userspace: cs = STAR.SYSRET_CS, 170 * if returning to 64-bit userspace: cs = STAR.SYSRET_CS+16, 171 * 172 * ss = STAR.SYSRET_CS+8 (in either case) 173 * 174 * thus USER_DS should be between 32-bit and 64-bit code selectors: 175 */ 176 #define GDT_ENTRY_DEFAULT_USER32_CS 4 177 #define GDT_ENTRY_DEFAULT_USER_DS 5 178 #define GDT_ENTRY_DEFAULT_USER_CS 6 179 180 /* Needs two entries */ 181 #define GDT_ENTRY_TSS 8 182 /* Needs two entries */ 183 #define GDT_ENTRY_LDT 10 184 185 #define GDT_ENTRY_TLS_MIN 12 186 #define GDT_ENTRY_TLS_MAX 14 187 188 /* Abused to load per CPU data from limit */ 189 #define GDT_ENTRY_PER_CPU 15 190 191 /* 192 * Number of entries in the GDT table: 193 */ 194 #define GDT_ENTRIES 16 195 196 /* 197 * Segment selector values corresponding to the above entries: 198 * 199 * Note, selectors also need to have a correct RPL, 200 * expressed with the +3 value for user-space selectors: 201 */ 202 #define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS*8) 203 #define __KERNEL_CS (GDT_ENTRY_KERNEL_CS*8) 204 #define __KERNEL_DS (GDT_ENTRY_KERNEL_DS*8) 205 #define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS*8 + 3) 206 #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS*8 + 3) 207 #define __USER32_DS __USER_DS 208 #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS*8 + 3) 209 #define __PER_CPU_SEG (GDT_ENTRY_PER_CPU*8 + 3) 210 211 #endif 212 213 #ifndef CONFIG_PARAVIRT 214 # define get_kernel_rpl() 0 215 #endif 216 217 #define IDT_ENTRIES 256 218 #define NUM_EXCEPTION_VECTORS 32 219 220 /* Bitmask of exception vectors which push an error code on the stack: */ 221 #define EXCEPTION_ERRCODE_MASK 0x00027d00 222 223 #define GDT_SIZE (GDT_ENTRIES*8) 224 #define GDT_ENTRY_TLS_ENTRIES 3 225 #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES* 8) 226 227 #ifdef __KERNEL__ 228 229 /* 230 * early_idt_handler_array is an array of entry points referenced in the 231 * early IDT. For simplicity, it's a real array with one entry point 232 * every nine bytes. That leaves room for an optional 'push $0' if the 233 * vector has no error code (two bytes), a 'push $vector_number' (two 234 * bytes), and a jump to the common entry code (up to five bytes). 235 */ 236 #define EARLY_IDT_HANDLER_SIZE 9 237 238 #ifndef __ASSEMBLY__ 239 240 extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE]; 241 #ifdef CONFIG_TRACING 242 # define trace_early_idt_handler_array early_idt_handler_array 243 #endif 244 245 /* 246 * Load a segment. Fall back on loading the zero segment if something goes 247 * wrong. This variant assumes that loading zero fully clears the segment. 248 * This is always the case on Intel CPUs and, even on 64-bit AMD CPUs, any 249 * failure to fully clear the cached descriptor is only observable for 250 * FS and GS. 251 */ 252 #define __loadsegment_simple(seg, value) \ 253 do { \ 254 unsigned short __val = (value); \ 255 \ 256 asm volatile(" \n" \ 257 "1: movl %k0,%%" #seg " \n" \ 258 \ 259 ".section .fixup,\"ax\" \n" \ 260 "2: xorl %k0,%k0 \n" \ 261 " jmp 1b \n" \ 262 ".previous \n" \ 263 \ 264 _ASM_EXTABLE(1b, 2b) \ 265 \ 266 : "+r" (__val) : : "memory"); \ 267 } while (0) 268 269 #define __loadsegment_ss(value) __loadsegment_simple(ss, (value)) 270 #define __loadsegment_ds(value) __loadsegment_simple(ds, (value)) 271 #define __loadsegment_es(value) __loadsegment_simple(es, (value)) 272 273 #ifdef CONFIG_X86_32 274 275 /* 276 * On 32-bit systems, the hidden parts of FS and GS are unobservable if 277 * the selector is NULL, so there's no funny business here. 278 */ 279 #define __loadsegment_fs(value) __loadsegment_simple(fs, (value)) 280 #define __loadsegment_gs(value) __loadsegment_simple(gs, (value)) 281 282 #else 283 284 static inline void __loadsegment_fs(unsigned short value) 285 { 286 asm volatile(" \n" 287 "1: movw %0, %%fs \n" 288 "2: \n" 289 290 _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_clear_fs) 291 292 : : "rm" (value) : "memory"); 293 } 294 295 /* __loadsegment_gs is intentionally undefined. Use load_gs_index instead. */ 296 297 #endif 298 299 #define loadsegment(seg, value) __loadsegment_ ## seg (value) 300 301 /* 302 * Save a segment register away: 303 */ 304 #define savesegment(seg, value) \ 305 asm("mov %%" #seg ",%0":"=r" (value) : : "memory") 306 307 /* 308 * x86-32 user GS accessors: 309 */ 310 #ifdef CONFIG_X86_32 311 # ifdef CONFIG_X86_32_LAZY_GS 312 # define get_user_gs(regs) (u16)({ unsigned long v; savesegment(gs, v); v; }) 313 # define set_user_gs(regs, v) loadsegment(gs, (unsigned long)(v)) 314 # define task_user_gs(tsk) ((tsk)->thread.gs) 315 # define lazy_save_gs(v) savesegment(gs, (v)) 316 # define lazy_load_gs(v) loadsegment(gs, (v)) 317 # else /* X86_32_LAZY_GS */ 318 # define get_user_gs(regs) (u16)((regs)->gs) 319 # define set_user_gs(regs, v) do { (regs)->gs = (v); } while (0) 320 # define task_user_gs(tsk) (task_pt_regs(tsk)->gs) 321 # define lazy_save_gs(v) do { } while (0) 322 # define lazy_load_gs(v) do { } while (0) 323 # endif /* X86_32_LAZY_GS */ 324 #endif /* X86_32 */ 325 326 #endif /* !__ASSEMBLY__ */ 327 #endif /* __KERNEL__ */ 328 329 #endif /* _ASM_X86_SEGMENT_H */ 330