sysdeps/i386/nptl/tls.h

   1 /* Definition for thread-local data handling.  nptl/i386 version.
   2    Copyright (C) 2002-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _TLS_H
  20 #define _TLS_H  1
  21
  22 #include <dl-sysdep.h>
  23 #ifndef __ASSEMBLER__
  24 # include <stdbool.h>
  25 # include <stddef.h>
  26 # include <stdint.h>
  27 # include <stdlib.h>
  28 # include <sysdep.h>
  29 # include <libc-internal.h>
  30 # include <kernel-features.h>
  31
  32
  33 /* Type for the dtv.  */
  34 typedef union dtv
  35 {
  36   size_t counter;
  37   struct
  38   {
  39     void *val;
  40     bool is_static;
  41   } pointer;
  42 } dtv_t;
  43
  44
  45 typedef struct
  46 {
  47   void *tcb;            /* Pointer to the TCB.  Not necessarily the
  48                            thread descriptor used by libpthread.  */
  49   dtv_t *dtv;
  50   void *self;           /* Pointer to the thread descriptor.  */
  51   int multiple_threads;
  52   uintptr_t sysinfo;
  53   uintptr_t stack_guard;
  54   uintptr_t pointer_guard;
  55   int gscope_flag;
  56 #ifndef __ASSUME_PRIVATE_FUTEX
  57   int private_futex;
  58 #else
  59   int __glibc_reserved1;
  60 #endif
  61   /* Reservation of some values for the TM ABI.  */
  62   void *__private_tm[4];
  63   /* GCC split stack support.  */
  64   void *__private_ss;
  65 } tcbhead_t;
  66
  67 # define TLS_MULTIPLE_THREADS_IN_TCB 1
  68
  69 #else /* __ASSEMBLER__ */
  70 # include <tcb-offsets.h>
  71 #endif
  72
  73
  74 /* Alignment requirement for the stack.  For IA-32 this is governed by
  75    the SSE memory functions.  */
  76 #define STACK_ALIGN     16
  77
  78 #ifndef __ASSEMBLER__
  79 /* Get system call information.  */
  80 # include <sysdep.h>
  81
  82 /* The old way: using LDT.  */
  83
  84 /* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
  85 struct user_desc
  86 {
  87   unsigned int entry_number;
  88   unsigned long int base_addr;
  89   unsigned int limit;
  90   unsigned int seg_32bit:1;
  91   unsigned int contents:2;
  92   unsigned int read_exec_only:1;
  93   unsigned int limit_in_pages:1;
  94   unsigned int seg_not_present:1;
  95   unsigned int useable:1;
  96   unsigned int empty:25;
  97 };
  98
  99 /* Initializing bit fields is slow.  We speed it up by using a union.  */
 100 union user_desc_init
 101 {
 102   struct user_desc desc;
 103   unsigned int vals[4];
 104 };
 105
 106
 107 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
 108    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
 109    struct pthread even when not linked with -lpthread.  */
 110 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
 111
 112 /* Alignment requirements for the initial TCB.  */
 113 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
 114
 115 /* This is the size of the TCB.  */
 116 # define TLS_TCB_SIZE sizeof (struct pthread)
 117
 118 /* Alignment requirements for the TCB.  */
 119 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 120
 121 /* The TCB can have any size and the memory following the address the
 122    thread pointer points to is unspecified.  Allocate the TCB there.  */
 123 # define TLS_TCB_AT_TP  1
 124 # define TLS_DTV_AT_TP  0
 125
 126 /* Get the thread descriptor definition.  */
 127 # include <nptl/descr.h>
 128
 129
 130 /* Install the dtv pointer.  The pointer passed is to the element with
 131    index -1 which contain the length.  */
 132 # define INSTALL_DTV(descr, dtvp) \
 133   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 134
 135 /* Install new dtv for current thread.  */
 136 # define INSTALL_NEW_DTV(dtvp) \
 137   ({ struct pthread *__pd;                                                    \
 138      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 139
 140 /* Return dtv of given thread descriptor.  */
 141 # define GET_DTV(descr) \
 142   (((tcbhead_t *) (descr))->dtv)
 143
 144 /* Macros to load from and store into segment registers.  */
 145 # ifndef TLS_GET_GS
 146 #  define TLS_GET_GS() \
 147   ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
 148 # endif
 149 # ifndef TLS_SET_GS
 150 #  define TLS_SET_GS(val) \
 151   __asm ("movw %w0, %%gs" :: "q" (val))
 152 # endif
 153
 154 #ifdef NEED_DL_SYSINFO
 155 # define INIT_SYSINFO \
 156   _head->sysinfo = GLRO(dl_sysinfo)
 157 # define SETUP_THREAD_SYSINFO(pd) \
 158   ((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 159 # define CHECK_THREAD_SYSINFO(pd) \
 160   assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 161 #else
 162 # define INIT_SYSINFO
 163 #endif
 164
 165 #ifndef LOCK_PREFIX
 166 # ifdef UP
 167 #  define LOCK_PREFIX  /* nothing */
 168 # else
 169 #  define LOCK_PREFIX "lock;"
 170 # endif
 171 #endif
 172
 173 static inline void __attribute__ ((unused, always_inline))
 174 tls_fill_user_desc (union user_desc_init *desc,
 175                     unsigned int entry_number,
 176                     void *pd)
 177 {
 178   desc->vals[0] = entry_number;
 179   /* The 'base_addr' field.  Pointer to the TCB.  */
 180   desc->vals[1] = (unsigned long int) pd;
 181   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */
 182   desc->vals[2] = 0xfffff;
 183   /* Collapsed value of the bitfield:
 184      .seg_32bit = 1
 185      .contents = 0
 186      .read_exec_only = 0
 187      .limit_in_pages = 1
 188      .seg_not_present = 0
 189      .useable = 1 */
 190   desc->vals[3] = 0x51;
 191 }
 192
 193 /* Code to initially initialize the thread pointer.  This might need
 194    special attention since 'errno' is not yet available and if the
 195    operation can cause a failure 'errno' must not be touched.  */
 196 # define TLS_INIT_TP(thrdescr) \
 197   ({ void *_thrdescr = (thrdescr);                                            \
 198      tcbhead_t *_head = _thrdescr;                                            \
 199      union user_desc_init _segdescr;                                          \
 200      int _result;                                                             \
 201                                                                               \
 202      _head->tcb = _thrdescr;                                                  \
 203      /* For now the thread descriptor is at the same address.  */             \
 204      _head->self = _thrdescr;                                                 \
 205      /* New syscall handling support.  */                                     \
 206      INIT_SYSINFO;                                                            \
 207                                                                               \
 208      /* Let the kernel pick a value for the 'entry_number' field.  */         \
 209      tls_fill_user_desc (&_segdescr, -1, _thrdescr);                          \
 210                                                                               \
 211      /* Install the TLS.  */                                                  \
 212      INTERNAL_SYSCALL_DECL (err);                                             \
 213      _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 214                                                                               \
 215      if (_result == 0)                                                        \
 216        /* We know the index in the GDT, now load the segment register.        \
 217           The use of the GDT is described by the value 3 in the lower         \
 218           three bits of the segment descriptor value.                         \
 219                                                                               \
 220           Note that we have to do this even if the numeric value of           \
 221           the descriptor does not change.  Loading the segment register       \
 222           causes the segment information from the GDT to be loaded            \
 223           which is necessary since we have changed it.   */                   \
 224        TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                      \
 225                                                                               \
 226      _result == 0 ? NULL                                                      \
 227      : "set_thread_area failed when setting up thread-local storage\n"; })
 228
 229 # define TLS_DEFINE_INIT_TP(tp, pd)                                           \
 230   union user_desc_init _segdescr;                                             \
 231   /* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP.   \
 232      The first three bits of the segment register value select the GDT,       \
 233      ignore them.  We get the index from the value of the %gs register in     \
 234      the current thread.  */                                                  \
 235   tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd);                    \
 236   const struct user_desc *tp = &_segdescr.desc
 237
 238
 239 /* Return the address of the dtv for the current thread.  */
 240 # define THREAD_DTV() \
 241   ({ struct pthread *__pd;                                                    \
 242      THREAD_GETMEM (__pd, header.dtv); })
 243
 244
 245 /* Return the thread descriptor for the current thread.
 246
 247    The contained asm must *not* be marked volatile since otherwise
 248    assignments like
 249         pthread_descr self = thread_self();
 250    do not get optimized away.  */
 251 # define THREAD_SELF \
 252   ({ struct pthread *__self;                                                  \
 253      asm ("movl %%gs:%c1,%0" : "=r" (__self)                                  \
 254           : "i" (offsetof (struct pthread, header.self)));                    \
 255      __self;})
 256
 257 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 258 # define DB_THREAD_SELF \
 259   REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
 260   REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
 261
 262
 263 /* Read member of the thread descriptor directly.  */
 264 # define THREAD_GETMEM(descr, member) \
 265   ({ __typeof (descr->member) __value;                                        \
 266      if (sizeof (__value) == 1)                                               \
 267        asm volatile ("movb %%gs:%P2,%b0"                                      \
 268                      : "=q" (__value)                                         \
 269                      : "0" (0), "i" (offsetof (struct pthread, member)));     \
 270      else if (sizeof (__value) == 4)                                          \
 271        asm volatile ("movl %%gs:%P1,%0"                                       \
 272                      : "=r" (__value)                                         \
 273                      : "i" (offsetof (struct pthread, member)));              \
 274      else                                                                     \
 275        {                                                                      \
 276          if (sizeof (__value) != 8)                                           \
 277            /* There should not be any value with a size other than 1,         \
 278               4 or 8.  */                                                     \
 279            abort ();                                                          \
 280                                                                               \
 281          asm volatile ("movl %%gs:%P1,%%eax\n\t"                              \
 282                        "movl %%gs:%P2,%%edx"                                  \
 283                        : "=A" (__value)                                       \
 284                        : "i" (offsetof (struct pthread, member)),             \
 285                          "i" (offsetof (struct pthread, member) + 4));        \
 286        }                                                                      \
 287      __value; })
 288
 289
 290 /* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
 291 # define THREAD_GETMEM_NC(descr, member, idx) \
 292   ({ __typeof (descr->member[0]) __value;                                     \
 293      if (sizeof (__value) == 1)                                               \
 294        asm volatile ("movb %%gs:%P2(%3),%b0"                                  \
 295                      : "=q" (__value)                                         \
 296                      : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
 297                      "r" (idx));                                              \
 298      else if (sizeof (__value) == 4)                                          \
 299        asm volatile ("movl %%gs:%P1(,%2,4),%0"                                \
 300                      : "=r" (__value)                                         \
 301                      : "i" (offsetof (struct pthread, member[0])),            \
 302                        "r" (idx));                                            \
 303      else                                                                     \
 304        {                                                                      \
 305          if (sizeof (__value) != 8)                                           \
 306            /* There should not be any value with a size other than 1,         \
 307               4 or 8.  */                                                     \
 308            abort ();                                                          \
 309                                                                               \
 310          asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                      \
 311                         "movl %%gs:4+%P1(,%2,8),%%edx"                        \
 312                         : "=&A" (__value)                                     \
 313                         : "i" (offsetof (struct pthread, member[0])),         \
 314                           "r" (idx));                                         \
 315        }                                                                      \
 316      __value; })
 317
 318
 319 /* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
 320 # define THREAD_SETMEM(descr, member, value) \
 321   ({ if (sizeof (descr->member) == 1)                                         \
 322        asm volatile ("movb %b0,%%gs:%P1" :                                    \
 323                      : "iq" (value),                                          \
 324                        "i" (offsetof (struct pthread, member)));              \
 325      else if (sizeof (descr->member) == 4)                                    \
 326        asm volatile ("movl %0,%%gs:%P1" :                                     \
 327                      : "ir" (value),                                          \
 328                        "i" (offsetof (struct pthread, member)));              \
 329      else                                                                     \
 330        {                                                                      \
 331          if (sizeof (descr->member) != 8)                                     \
 332            /* There should not be any value with a size other than 1,         \
 333               4 or 8.  */                                                     \
 334            abort ();                                                          \
 335                                                                               \
 336          asm volatile ("movl %%eax,%%gs:%P1\n\t"                              \
 337                        "movl %%edx,%%gs:%P2" :                                \
 338                        : "A" ((uint64_t) cast_to_integer (value)),            \
 339                          "i" (offsetof (struct pthread, member)),             \
 340                          "i" (offsetof (struct pthread, member) + 4));        \
 341        }})
 342
 343
 344 /* Set member of the thread descriptor directly.  */
 345 # define THREAD_SETMEM_NC(descr, member, idx, value) \
 346   ({ if (sizeof (descr->member[0]) == 1)                                      \
 347        asm volatile ("movb %b0,%%gs:%P1(%2)" :                                \
 348                      : "iq" (value),                                          \
 349                        "i" (offsetof (struct pthread, member)),               \
 350                        "r" (idx));                                            \
 351      else if (sizeof (descr->member[0]) == 4)                                 \
 352        asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                              \
 353                      : "ir" (value),                                          \
 354                        "i" (offsetof (struct pthread, member)),               \
 355                        "r" (idx));                                            \
 356      else                                                                     \
 357        {                                                                      \
 358          if (sizeof (descr->member[0]) != 8)                                  \
 359            /* There should not be any value with a size other than 1,         \
 360               4 or 8.  */                                                     \
 361            abort ();                                                          \
 362                                                                               \
 363          asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                       \
 364                        "movl %%edx,%%gs:4+%P1(,%2,8)" :                       \
 365                        : "A" ((uint64_t) cast_to_integer (value)),            \
 366                          "i" (offsetof (struct pthread, member)),             \
 367                          "r" (idx));                                          \
 368        }})
 369
 370
 371 /* Atomic compare and exchange on TLS, returning old value.  */
 372 #define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
 373   ({ __typeof (descr->member) __ret;                                          \
 374      __typeof (oldval) __old = (oldval);                                      \
 375      if (sizeof (descr->member) == 4)                                         \
 376        asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                      \
 377                      : "=a" (__ret)                                           \
 378                      : "0" (__old), "r" (newval),                             \
 379                        "i" (offsetof (struct pthread, member)));              \
 380      else                                                                     \
 381        /* Not necessary for other sizes in the moment.  */                    \
 382        abort ();                                                              \
 383      __ret; })
 384
 385
 386 /* Atomic logical and.  */
 387 #define THREAD_ATOMIC_AND(descr, member, val) \
 388   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 389               asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0"                   \
 390                             :: "i" (offsetof (struct pthread, member)),       \
 391                                "ir" (val));                                   \
 392             else                                                              \
 393               /* Not necessary for other sizes in the moment.  */             \
 394               abort (); })
 395
 396
 397 /* Atomic set bit.  */
 398 #define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
 399   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 400               asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                    \
 401                             :: "i" (offsetof (struct pthread, member)),       \
 402                                "ir" (1 << (bit)));                            \
 403             else                                                              \
 404               /* Not necessary for other sizes in the moment.  */             \
 405               abort (); })
 406
 407
 408 /* Call the user-provided thread function.  */
 409 #define CALL_THREAD_FCT(descr) \
 410   ({ void *__res;                                                             \
 411      int __ignore1, __ignore2;                                                \
 412      asm volatile ("pushl %%eax\n\t"                                          \
 413                    "pushl %%eax\n\t"                                          \
 414                    "pushl %%eax\n\t"                                          \
 415                    "pushl %%gs:%P4\n\t"                                       \
 416                    "call *%%gs:%P3\n\t"                                       \
 417                    "addl $16, %%esp"                                          \
 418                    : "=a" (__res), "=c" (__ignore1), "=d" (__ignore2)         \
 419                    : "i" (offsetof (struct pthread, start_routine)),          \
 420                      "i" (offsetof (struct pthread, arg)));                   \
 421      __res; })
 422
 423
 424 /* Set the stack guard field in TCB head.  */
 425 #define THREAD_SET_STACK_GUARD(value) \
 426   THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 427 #define THREAD_COPY_STACK_GUARD(descr) \
 428   ((descr)->header.stack_guard                                                \
 429    = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 430
 431
 432 /* Set the pointer guard field in the TCB head.  */
 433 #define THREAD_SET_POINTER_GUARD(value) \
 434   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 435 #define THREAD_COPY_POINTER_GUARD(descr) \
 436   ((descr)->header.pointer_guard                                              \
 437    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 438
 439
 440 /* Get and set the global scope generation counter in the TCB head.  */
 441 #define THREAD_GSCOPE_FLAG_UNUSED 0
 442 #define THREAD_GSCOPE_FLAG_USED   1
 443 #define THREAD_GSCOPE_FLAG_WAIT   2
 444 #define THREAD_GSCOPE_RESET_FLAG() \
 445   do                                                                          \
 446     { int __res;                                                              \
 447       asm volatile ("xchgl %0, %%gs:%P1"                                      \
 448                     : "=r" (__res)                                            \
 449                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 450                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 451       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 452         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 453     }                                                                         \
 454   while (0)
 455 #define THREAD_GSCOPE_SET_FLAG() \
 456   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 457 #define THREAD_GSCOPE_WAIT() \
 458   GL(dl_wait_lookup_done) ()
 459
 460 #endif /* __ASSEMBLER__ */
 461
 462 #endif  /* tls.h */