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