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