sysdeps/i386/nptl/tls.h

   1 /* Definition for thread-local data handling.  nptl/i386 version.
   2    Copyright (C) 2002-2018 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-pointer-arith.h> /* For cast_to_integer. */
  30 # include <kernel-features.h>
  31 # include <dl-dtv.h>
  32
  33 typedef struct
  34 {
  35   void *tcb;            /* Pointer to the TCB.  Not necessarily the
  36                            thread descriptor used by libpthread.  */
  37   dtv_t *dtv;
  38   void *self;           /* Pointer to the thread descriptor.  */
  39   int multiple_threads;
  40   uintptr_t sysinfo;
  41   uintptr_t stack_guard;
  42   uintptr_t pointer_guard;
  43   int gscope_flag;
  44   int __glibc_reserved1;
  45   /* Reservation of some values for the TM ABI.  */
  46   void *__private_tm[4];
  47   /* GCC split stack support.  */
  48   void *__private_ss;
  49 } tcbhead_t;
  50
  51 # define TLS_MULTIPLE_THREADS_IN_TCB 1
  52
  53 #else /* __ASSEMBLER__ */
  54 # include <tcb-offsets.h>
  55 #endif
  56
  57
  58 /* Alignment requirement for the stack.  For IA-32 this is governed by
  59    the SSE memory functions.  */
  60 #define STACK_ALIGN     16
  61
  62 #ifndef __ASSEMBLER__
  63 /* Get system call information.  */
  64 # include <sysdep.h>
  65
  66 /* The old way: using LDT.  */
  67
  68 /* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
  69 struct user_desc
  70 {
  71   unsigned int entry_number;
  72   unsigned long int base_addr;
  73   unsigned int limit;
  74   unsigned int seg_32bit:1;
  75   unsigned int contents:2;
  76   unsigned int read_exec_only:1;
  77   unsigned int limit_in_pages:1;
  78   unsigned int seg_not_present:1;
  79   unsigned int useable:1;
  80   unsigned int empty:25;
  81 };
  82
  83 /* Initializing bit fields is slow.  We speed it up by using a union.  */
  84 union user_desc_init
  85 {
  86   struct user_desc desc;
  87   unsigned int vals[4];
  88 };
  89
  90
  91 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
  92    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
  93    struct pthread even when not linked with -lpthread.  */
  94 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
  95
  96 /* Alignment requirements for the initial TCB.  */
  97 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
  98
  99 /* This is the size of the TCB.  */
 100 # define TLS_TCB_SIZE sizeof (struct pthread)
 101
 102 /* Alignment requirements for the TCB.  */
 103 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 104
 105 /* The TCB can have any size and the memory following the address the
 106    thread pointer points to is unspecified.  Allocate the TCB there.  */
 107 # define TLS_TCB_AT_TP  1
 108 # define TLS_DTV_AT_TP  0
 109
 110 /* Get the thread descriptor definition.  */
 111 # include <nptl/descr.h>
 112
 113
 114 /* Install the dtv pointer.  The pointer passed is to the element with
 115    index -1 which contain the length.  */
 116 # define INSTALL_DTV(descr, dtvp) \
 117   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 118
 119 /* Install new dtv for current thread.  */
 120 # define INSTALL_NEW_DTV(dtvp) \
 121   ({ struct pthread *__pd;                                                    \
 122      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 123
 124 /* Return dtv of given thread descriptor.  */
 125 # define GET_DTV(descr) \
 126   (((tcbhead_t *) (descr))->dtv)
 127
 128 /* Macros to load from and store into segment registers.  */
 129 # ifndef TLS_GET_GS
 130 #  define TLS_GET_GS() \
 131   ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
 132 # endif
 133 # ifndef TLS_SET_GS
 134 #  define TLS_SET_GS(val) \
 135   __asm ("movw %w0, %%gs" :: "q" (val))
 136 # endif
 137
 138 #ifdef NEED_DL_SYSINFO
 139 # define INIT_SYSINFO \
 140   _head->sysinfo = GLRO(dl_sysinfo)
 141 # define SETUP_THREAD_SYSINFO(pd) \
 142   ((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 143 # define CHECK_THREAD_SYSINFO(pd) \
 144   assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 145 #else
 146 # define INIT_SYSINFO
 147 #endif
 148
 149 #ifndef LOCK_PREFIX
 150 # ifdef UP
 151 #  define LOCK_PREFIX  /* nothing */
 152 # else
 153 #  define LOCK_PREFIX "lock;"
 154 # endif
 155 #endif
 156
 157 static inline void __attribute__ ((unused, always_inline))
 158 tls_fill_user_desc (union user_desc_init *desc,
 159                     unsigned int entry_number,
 160                     void *pd)
 161 {
 162   desc->vals[0] = entry_number;
 163   /* The 'base_addr' field.  Pointer to the TCB.  */
 164   desc->vals[1] = (unsigned long int) pd;
 165   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */
 166   desc->vals[2] = 0xfffff;
 167   /* Collapsed value of the bitfield:
 168      .seg_32bit = 1
 169      .contents = 0
 170      .read_exec_only = 0
 171      .limit_in_pages = 1
 172      .seg_not_present = 0
 173      .useable = 1 */
 174   desc->vals[3] = 0x51;
 175 }
 176
 177 /* Code to initially initialize the thread pointer.  This might need
 178    special attention since 'errno' is not yet available and if the
 179    operation can cause a failure 'errno' must not be touched.  */
 180 # define TLS_INIT_TP(thrdescr) \
 181   ({ void *_thrdescr = (thrdescr);                                            \
 182      tcbhead_t *_head = _thrdescr;                                            \
 183      union user_desc_init _segdescr;                                          \
 184      int _result;                                                             \
 185                                                                               \
 186      _head->tcb = _thrdescr;                                                  \
 187      /* For now the thread descriptor is at the same address.  */             \
 188      _head->self = _thrdescr;                                                 \
 189      /* New syscall handling support.  */                                     \
 190      INIT_SYSINFO;                                                            \
 191                                                                               \
 192      /* Let the kernel pick a value for the 'entry_number' field.  */         \
 193      tls_fill_user_desc (&_segdescr, -1, _thrdescr);                          \
 194                                                                               \
 195      /* Install the TLS.  */                                                  \
 196      INTERNAL_SYSCALL_DECL (err);                                             \
 197      _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 198                                                                               \
 199      if (_result == 0)                                                        \
 200        /* We know the index in the GDT, now load the segment register.        \
 201           The use of the GDT is described by the value 3 in the lower         \
 202           three bits of the segment descriptor value.                         \
 203                                                                               \
 204           Note that we have to do this even if the numeric value of           \
 205           the descriptor does not change.  Loading the segment register       \
 206           causes the segment information from the GDT to be loaded            \
 207           which is necessary since we have changed it.   */                   \
 208        TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                      \
 209                                                                               \
 210      _result == 0 ? NULL                                                      \
 211      : "set_thread_area failed when setting up thread-local storage\n"; })
 212
 213 # define TLS_DEFINE_INIT_TP(tp, pd)                                           \
 214   union user_desc_init _segdescr;                                             \
 215   /* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP.   \
 216      The first three bits of the segment register value select the GDT,       \
 217      ignore them.  We get the index from the value of the %gs register in     \
 218      the current thread.  */                                                  \
 219   tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd);                    \
 220   const struct user_desc *tp = &_segdescr.desc
 221
 222
 223 /* Return the address of the dtv for the current thread.  */
 224 # define THREAD_DTV() \
 225   ({ struct pthread *__pd;                                                    \
 226      THREAD_GETMEM (__pd, header.dtv); })
 227
 228
 229 /* Return the thread descriptor for the current thread.
 230
 231    The contained asm must *not* be marked volatile since otherwise
 232    assignments like
 233         pthread_descr self = thread_self();
 234    do not get optimized away.  */
 235 # define THREAD_SELF \
 236   ({ struct pthread *__self;                                                  \
 237      asm ("movl %%gs:%c1,%0" : "=r" (__self)                                  \
 238           : "i" (offsetof (struct pthread, header.self)));                    \
 239      __self;})
 240
 241 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 242 # define DB_THREAD_SELF \
 243   REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
 244   REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
 245
 246
 247 /* Read member of the thread descriptor directly.  */
 248 # define THREAD_GETMEM(descr, member) \
 249   ({ __typeof (descr->member) __value;                                        \
 250      if (sizeof (__value) == 1)                                               \
 251        asm volatile ("movb %%gs:%P2,%b0"                                      \
 252                      : "=q" (__value)                                         \
 253                      : "0" (0), "i" (offsetof (struct pthread, member)));     \
 254      else if (sizeof (__value) == 4)                                          \
 255        asm volatile ("movl %%gs:%P1,%0"                                       \
 256                      : "=r" (__value)                                         \
 257                      : "i" (offsetof (struct pthread, member)));              \
 258      else                                                                     \
 259        {                                                                      \
 260          if (sizeof (__value) != 8)                                           \
 261            /* There should not be any value with a size other than 1,         \
 262               4 or 8.  */                                                     \
 263            abort ();                                                          \
 264                                                                               \
 265          asm volatile ("movl %%gs:%P1,%%eax\n\t"                              \
 266                        "movl %%gs:%P2,%%edx"                                  \
 267                        : "=A" (__value)                                       \
 268                        : "i" (offsetof (struct pthread, member)),             \
 269                          "i" (offsetof (struct pthread, member) + 4));        \
 270        }                                                                      \
 271      __value; })
 272
 273
 274 /* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
 275 # define THREAD_GETMEM_NC(descr, member, idx) \
 276   ({ __typeof (descr->member[0]) __value;                                     \
 277      if (sizeof (__value) == 1)                                               \
 278        asm volatile ("movb %%gs:%P2(%3),%b0"                                  \
 279                      : "=q" (__value)                                         \
 280                      : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
 281                      "r" (idx));                                              \
 282      else if (sizeof (__value) == 4)                                          \
 283        asm volatile ("movl %%gs:%P1(,%2,4),%0"                                \
 284                      : "=r" (__value)                                         \
 285                      : "i" (offsetof (struct pthread, member[0])),            \
 286                        "r" (idx));                                            \
 287      else                                                                     \
 288        {                                                                      \
 289          if (sizeof (__value) != 8)                                           \
 290            /* There should not be any value with a size other than 1,         \
 291               4 or 8.  */                                                     \
 292            abort ();                                                          \
 293                                                                               \
 294          asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                      \
 295                         "movl %%gs:4+%P1(,%2,8),%%edx"                        \
 296                         : "=&A" (__value)                                     \
 297                         : "i" (offsetof (struct pthread, member[0])),         \
 298                           "r" (idx));                                         \
 299        }                                                                      \
 300      __value; })
 301
 302
 303
 304 /* Set member of the thread descriptor directly.  */
 305 # define THREAD_SETMEM(descr, member, value) \
 306   ({ if (sizeof (descr->member) == 1)                                         \
 307        asm volatile ("movb %b0,%%gs:%P1" :                                    \
 308                      : "iq" (value),                                          \
 309                        "i" (offsetof (struct pthread, member)));              \
 310      else if (sizeof (descr->member) == 4)                                    \
 311        asm volatile ("movl %0,%%gs:%P1" :                                     \
 312                      : "ir" (value),                                          \
 313                        "i" (offsetof (struct pthread, member)));              \
 314      else                                                                     \
 315        {                                                                      \
 316          if (sizeof (descr->member) != 8)                                     \
 317            /* There should not be any value with a size other than 1,         \
 318               4 or 8.  */                                                     \
 319            abort ();                                                          \
 320                                                                               \
 321          asm volatile ("movl %%eax,%%gs:%P1\n\t"                              \
 322                        "movl %%edx,%%gs:%P2" :                                \
 323                        : "A" ((uint64_t) cast_to_integer (value)),            \
 324                          "i" (offsetof (struct pthread, member)),             \
 325                          "i" (offsetof (struct pthread, member) + 4));        \
 326        }})
 327
 328
 329 /* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
 330 # define THREAD_SETMEM_NC(descr, member, idx, value) \
 331   ({ if (sizeof (descr->member[0]) == 1)                                      \
 332        asm volatile ("movb %b0,%%gs:%P1(%2)" :                                \
 333                      : "iq" (value),                                          \
 334                        "i" (offsetof (struct pthread, member)),               \
 335                        "r" (idx));                                            \
 336      else if (sizeof (descr->member[0]) == 4)                                 \
 337        asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                              \
 338                      : "ir" (value),                                          \
 339                        "i" (offsetof (struct pthread, member)),               \
 340                        "r" (idx));                                            \
 341      else                                                                     \
 342        {                                                                      \
 343          if (sizeof (descr->member[0]) != 8)                                  \
 344            /* There should not be any value with a size other than 1,         \
 345               4 or 8.  */                                                     \
 346            abort ();                                                          \
 347                                                                               \
 348          asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                       \
 349                        "movl %%edx,%%gs:4+%P1(,%2,8)" :                       \
 350                        : "A" ((uint64_t) cast_to_integer (value)),            \
 351                          "i" (offsetof (struct pthread, member)),             \
 352                          "r" (idx));                                          \
 353        }})
 354
 355
 356 /* Atomic compare and exchange on TLS, returning old value.  */
 357 #define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
 358   ({ __typeof (descr->member) __ret;                                          \
 359      __typeof (oldval) __old = (oldval);                                      \
 360      if (sizeof (descr->member) == 4)                                         \
 361        asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                      \
 362                      : "=a" (__ret)                                           \
 363                      : "0" (__old), "r" (newval),                             \
 364                        "i" (offsetof (struct pthread, member)));              \
 365      else                                                                     \
 366        /* Not necessary for other sizes in the moment.  */                    \
 367        abort ();                                                              \
 368      __ret; })
 369
 370
 371 /* Atomic logical and.  */
 372 #define THREAD_ATOMIC_AND(descr, member, val) \
 373   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 374               asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0"                   \
 375                             :: "i" (offsetof (struct pthread, member)),       \
 376                                "ir" (val));                                   \
 377             else                                                              \
 378               /* Not necessary for other sizes in the moment.  */             \
 379               abort (); })
 380
 381
 382 /* Atomic set bit.  */
 383 #define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
 384   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 385               asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                    \
 386                             :: "i" (offsetof (struct pthread, member)),       \
 387                                "ir" (1 << (bit)));                            \
 388             else                                                              \
 389               /* Not necessary for other sizes in the moment.  */             \
 390               abort (); })
 391
 392
 393 /* Set the stack guard field in TCB head.  */
 394 #define THREAD_SET_STACK_GUARD(value) \
 395   THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 396 #define THREAD_COPY_STACK_GUARD(descr) \
 397   ((descr)->header.stack_guard                                                \
 398    = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 399
 400
 401 /* Set the pointer guard field in the TCB head.  */
 402 #define THREAD_SET_POINTER_GUARD(value) \
 403   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 404 #define THREAD_COPY_POINTER_GUARD(descr) \
 405   ((descr)->header.pointer_guard                                              \
 406    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 407
 408
 409 /* Get and set the global scope generation counter in the TCB head.  */
 410 #define THREAD_GSCOPE_IN_TCB      1
 411 #define THREAD_GSCOPE_FLAG_UNUSED 0
 412 #define THREAD_GSCOPE_FLAG_USED   1
 413 #define THREAD_GSCOPE_FLAG_WAIT   2
 414 #define THREAD_GSCOPE_RESET_FLAG() \
 415   do                                                                          \
 416     { int __res;                                                              \
 417       asm volatile ("xchgl %0, %%gs:%P1"                                      \
 418                     : "=r" (__res)                                            \
 419                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 420                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 421       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 422         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 423     }                                                                         \
 424   while (0)
 425 #define THREAD_GSCOPE_SET_FLAG() \
 426   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 427 #define THREAD_GSCOPE_WAIT() \
 428   GL(dl_wait_lookup_done) ()
 429
 430 #endif /* __ASSEMBLER__ */
 431
 432 #endif  /* tls.h */