LXR linux/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__
 216extern 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)                                         \
 223do {                                                                    \
 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
 264static 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 */
 275