arch/x86/include/asm/segment.h

   1 #ifndef _ASM_X86_SEGMENT_H
   2 #define _ASM_X86_SEGMENT_H
   3
   4 #include <linux/const.h>
   5
   6 /* Constructor for a conventional segment GDT (or LDT) entry */
   7 /* This is a macro so it can be used in initializers */
   8 #define GDT_ENTRY(flags, base, limit)                   \
   9         ((((base)  & _AC(0xff000000,ULL)) << (56-24)) | \
  10          (((flags) & _AC(0x0000f0ff,ULL)) << 40) |      \
  11          (((limit) & _AC(0x000f0000,ULL)) << (48-16)) | \
  12          (((base)  & _AC(0x00ffffff,ULL)) << 16) |      \
  13          (((limit) & _AC(0x0000ffff,ULL))))
  14
  15 /* Simple and small GDT entries for booting only */
  16
  17 #define GDT_ENTRY_BOOT_CS       2
  18 #define __BOOT_CS               (GDT_ENTRY_BOOT_CS * 8)
  19
  20 #define GDT_ENTRY_BOOT_DS       (GDT_ENTRY_BOOT_CS + 1)
  21 #define __BOOT_DS               (GDT_ENTRY_BOOT_DS * 8)
  22
  23 #define GDT_ENTRY_BOOT_TSS      (GDT_ENTRY_BOOT_CS + 2)
  24 #define __BOOT_TSS              (GDT_ENTRY_BOOT_TSS * 8)
  25
  26 #ifdef CONFIG_X86_32
  27 /*
  28  * The layout of the per-CPU GDT under Linux:
  29  *
  30  *   0 - null
  31  *   1 - reserved
  32  *   2 - reserved
  33  *   3 - reserved
  34  *
  35  *   4 - unused                 <==== new cacheline
  36  *   5 - unused
  37  *
  38  *  ------- start of TLS (Thread-Local Storage) segments:
  39  *
  40  *   6 - TLS segment #1                 [ glibc's TLS segment ]
  41  *   7 - TLS segment #2                 [ Wine's %fs Win32 segment ]
  42  *   8 - TLS segment #3
  43  *   9 - reserved
  44  *  10 - reserved
  45  *  11 - reserved
  46  *
  47  *  ------- start of kernel segments:
  48  *
  49  *  12 - kernel code segment            <==== new cacheline
  50  *  13 - kernel data segment
  51  *  14 - default user CS
  52  *  15 - default user DS
  53  *  16 - TSS
  54  *  17 - LDT
  55  *  18 - PNPBIOS support (16->32 gate)
  56  *  19 - PNPBIOS support
  57  *  20 - PNPBIOS support
  58  *  21 - PNPBIOS support
  59  *  22 - PNPBIOS support
  60  *  23 - APM BIOS support
  61  *  24 - APM BIOS support
  62  *  25 - APM BIOS support
  63  *
  64  *  26 - ESPFIX small SS
  65  *  27 - per-cpu                        [ offset to per-cpu data area ]
  66  *  28 - stack_canary-20                [ for stack protector ]
  67  *  29 - unused
  68  *  30 - unused
  69  *  31 - TSS for double fault handler
  70  */
  71 #define GDT_ENTRY_TLS_MIN       6
  72 #define GDT_ENTRY_TLS_MAX       (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
  73
  74 #define GDT_ENTRY_DEFAULT_USER_CS       14
  75
  76 #define GDT_ENTRY_DEFAULT_USER_DS       15
  77
  78 #define GDT_ENTRY_KERNEL_BASE           (12)
  79
  80 #define GDT_ENTRY_KERNEL_CS             (GDT_ENTRY_KERNEL_BASE+0)
  81
  82 #define GDT_ENTRY_KERNEL_DS             (GDT_ENTRY_KERNEL_BASE+1)
  83
  84 #define GDT_ENTRY_TSS                   (GDT_ENTRY_KERNEL_BASE+4)
  85 #define GDT_ENTRY_LDT                   (GDT_ENTRY_KERNEL_BASE+5)
  86
  87 #define GDT_ENTRY_PNPBIOS_BASE          (GDT_ENTRY_KERNEL_BASE+6)
  88 #define GDT_ENTRY_APMBIOS_BASE          (GDT_ENTRY_KERNEL_BASE+11)
  89
  90 #define GDT_ENTRY_ESPFIX_SS             (GDT_ENTRY_KERNEL_BASE+14)
  91 #define __ESPFIX_SS                     (GDT_ENTRY_ESPFIX_SS*8)
  92
  93 #define GDT_ENTRY_PERCPU                (GDT_ENTRY_KERNEL_BASE+15)
  94 #ifdef CONFIG_SMP
  95 #define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8)
  96 #else
  97 #define __KERNEL_PERCPU 0
  98 #endif
  99
 100 #define GDT_ENTRY_STACK_CANARY          (GDT_ENTRY_KERNEL_BASE+16)
 101 #ifdef CONFIG_CC_STACKPROTECTOR
 102 #define __KERNEL_STACK_CANARY           (GDT_ENTRY_STACK_CANARY*8)
 103 #else
 104 #define __KERNEL_STACK_CANARY           0
 105 #endif
 106
 107 #define GDT_ENTRY_DOUBLEFAULT_TSS       31
 108
 109 /*
 110  * The GDT has 32 entries
 111  */
 112 #define GDT_ENTRIES 32
 113
 114 /* The PnP BIOS entries in the GDT */
 115 #define GDT_ENTRY_PNPBIOS_CS32          (GDT_ENTRY_PNPBIOS_BASE + 0)
 116 #define GDT_ENTRY_PNPBIOS_CS16          (GDT_ENTRY_PNPBIOS_BASE + 1)
 117 #define GDT_ENTRY_PNPBIOS_DS            (GDT_ENTRY_PNPBIOS_BASE + 2)
 118 #define GDT_ENTRY_PNPBIOS_TS1           (GDT_ENTRY_PNPBIOS_BASE + 3)
 119 #define GDT_ENTRY_PNPBIOS_TS2           (GDT_ENTRY_PNPBIOS_BASE + 4)
 120
 121 /* The PnP BIOS selectors */
 122 #define PNP_CS32   (GDT_ENTRY_PNPBIOS_CS32 * 8) /* segment for calling fn */
 123 #define PNP_CS16   (GDT_ENTRY_PNPBIOS_CS16 * 8) /* code segment for BIOS */
 124 #define PNP_DS     (GDT_ENTRY_PNPBIOS_DS * 8)   /* data segment for BIOS */
 125 #define PNP_TS1    (GDT_ENTRY_PNPBIOS_TS1 * 8)  /* transfer data segment */
 126 #define PNP_TS2    (GDT_ENTRY_PNPBIOS_TS2 * 8)  /* another data segment */
 127
 128 /* Bottom two bits of selector give the ring privilege level */
 129 #define SEGMENT_RPL_MASK        0x3
 130 /* Bit 2 is table indicator (LDT/GDT) */
 131 #define SEGMENT_TI_MASK         0x4
 132
 133 /* User mode is privilege level 3 */
 134 #define USER_RPL                0x3
 135 /* LDT segment has TI set, GDT has it cleared */
 136 #define SEGMENT_LDT             0x4
 137 #define SEGMENT_GDT             0x0
 138
 139 /*
 140  * Matching rules for certain types of segments.
 141  */
 142
 143 /* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
 144 #define SEGMENT_IS_PNP_CODE(x)   (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
 145
 146
 147 #else
 148 #include <asm/cache.h>
 149
 150 #define GDT_ENTRY_KERNEL32_CS 1
 151 #define GDT_ENTRY_KERNEL_CS 2
 152 #define GDT_ENTRY_KERNEL_DS 3
 153
 154 #define __KERNEL32_CS   (GDT_ENTRY_KERNEL32_CS * 8)
 155
 156 /*
 157  * we cannot use the same code segment descriptor for user and kernel
 158  * -- not even in the long flat mode, because of different DPL /kkeil
 159  * The segment offset needs to contain a RPL. Grr. -AK
 160  * GDT layout to get 64bit syscall right (sysret hardcodes gdt offsets)
 161  */
 162 #define GDT_ENTRY_DEFAULT_USER32_CS 4
 163 #define GDT_ENTRY_DEFAULT_USER_DS 5
 164 #define GDT_ENTRY_DEFAULT_USER_CS 6
 165 #define __USER32_CS   (GDT_ENTRY_DEFAULT_USER32_CS*8+3)
 166 #define __USER32_DS     __USER_DS
 167
 168 #define GDT_ENTRY_TSS 8 /* needs two entries */
 169 #define GDT_ENTRY_LDT 10 /* needs two entries */
 170 #define GDT_ENTRY_TLS_MIN 12
 171 #define GDT_ENTRY_TLS_MAX 14
 172
 173 #define GDT_ENTRY_PER_CPU 15    /* Abused to load per CPU data from limit */
 174 #define __PER_CPU_SEG   (GDT_ENTRY_PER_CPU * 8 + 3)
 175
 176 /* TLS indexes for 64bit - hardcoded in arch_prctl */
 177 #define FS_TLS 0
 178 #define GS_TLS 1
 179
 180 #define GS_TLS_SEL ((GDT_ENTRY_TLS_MIN+GS_TLS)*8 + 3)
 181 #define FS_TLS_SEL ((GDT_ENTRY_TLS_MIN+FS_TLS)*8 + 3)
 182
 183 #define GDT_ENTRIES 16
 184
 185 #endif
 186
 187 #define __KERNEL_CS     (GDT_ENTRY_KERNEL_CS*8)
 188 #define __KERNEL_DS     (GDT_ENTRY_KERNEL_DS*8)
 189 #define __USER_DS       (GDT_ENTRY_DEFAULT_USER_DS*8+3)
 190 #define __USER_CS       (GDT_ENTRY_DEFAULT_USER_CS*8+3)
 191 #ifndef CONFIG_PARAVIRT
 192 #define get_kernel_rpl()  0
 193 #endif
 194
 195 /* User mode is privilege level 3 */
 196 #define USER_RPL                0x3
 197 /* LDT segment has TI set, GDT has it cleared */
 198 #define SEGMENT_LDT             0x4
 199 #define SEGMENT_GDT             0x0
 200
 201 /* Bottom two bits of selector give the ring privilege level */
 202 #define SEGMENT_RPL_MASK        0x3
 203 /* Bit 2 is table indicator (LDT/GDT) */
 204 #define SEGMENT_TI_MASK         0x4
 205
 206 #define IDT_ENTRIES 256
 207 #define NUM_EXCEPTION_VECTORS 32
 208 /* Bitmask of exception vectors which push an error code on the stack */
 209 #define EXCEPTION_ERRCODE_MASK  0x00027d00
 210 #define GDT_SIZE (GDT_ENTRIES * 8)
 211 #define GDT_ENTRY_TLS_ENTRIES 3
 212 #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES * 8)
 213
 214 #ifdef __KERNEL__
 215 #ifndef __ASSEMBLY__
 216 extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5];
 217
 218 /*
 219  * Load a segment. Fall back on loading the zero
 220  * segment if something goes wrong..
 221  */
 222 #define loadsegment(seg, value)                                         \
 223 do {                                                                    \
 224         unsigned short __val = (value);                                 \
 225                                                                         \
 226         asm volatile("                                          \n"     \
 227                      "1:        movl %k0,%%" #seg "             \n"     \
 228                                                                         \
 229                      ".section .fixup,\"ax\"                    \n"     \
 230                      "2:        xorl %k0,%k0                    \n"     \
 231                      "          jmp 1b                          \n"     \
 232                      ".previous                                 \n"     \
 233                                                                         \
 234                      _ASM_EXTABLE(1b, 2b)                               \
 235                                                                         \
 236                      : "+r" (__val) : : "memory");                      \
 237 } while (0)
 238
 239 /*
 240  * Save a segment register away
 241  */
 242 #define savesegment(seg, value)                         \
 243         asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
 244
 245 /*
 246  * x86_32 user gs accessors.
 247  */
 248 #ifdef CONFIG_X86_32
 249 #ifdef CONFIG_X86_32_LAZY_GS
 250 #define get_user_gs(regs)       (u16)({unsigned long v; savesegment(gs, v); v;})
 251 #define set_user_gs(regs, v)    loadsegment(gs, (unsigned long)(v))
 252 #define task_user_gs(tsk)       ((tsk)->thread.gs)
 253 #define lazy_save_gs(v)         savesegment(gs, (v))
 254 #define lazy_load_gs(v)         loadsegment(gs, (v))
 255 #else   /* X86_32_LAZY_GS */
 256 #define get_user_gs(regs)       (u16)((regs)->gs)
 257 #define set_user_gs(regs, v)    do { (regs)->gs = (v); } while (0)
 258 #define task_user_gs(tsk)       (task_pt_regs(tsk)->gs)
 259 #define lazy_save_gs(v)         do { } while (0)
 260 #define lazy_load_gs(v)         do { } while (0)
 261 #endif  /* X86_32_LAZY_GS */
 262 #endif  /* X86_32 */
 263
 264 static inline unsigned long get_limit(unsigned long segment)
 265 {
 266         unsigned long __limit;
 267         asm("lsll %1,%0" : "=r" (__limit) : "r" (segment));
 268         return __limit + 1;
 269 }
 270
 271 #endif /* !__ASSEMBLY__ */
 272 #endif /* __KERNEL__ */
 273
 274 #endif /* _ASM_X86_SEGMENT_H */