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[3];
  47   /* GCC split stack support.  */
  48   void *__private_ss;
  49   void *__glibc_reserved2;
  50 } tcbhead_t;
  51
  52 /* morestack.S in libgcc uses offset 0x30 to access __private_ss,   */
  53 _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
  54                 "offset of __private_ss != 0x30");
  55
  56 # define TLS_MULTIPLE_THREADS_IN_TCB 1
  57
  58 #else /* __ASSEMBLER__ */
  59 # include <tcb-offsets.h>
  60 #endif
  61
  62
  63 /* Alignment requirement for the stack.  For IA-32 this is governed by
  64    the SSE memory functions.  */
  65 #define STACK_ALIGN     16
  66
  67 #ifndef __ASSEMBLER__
  68 /* Get system call information.  */
  69 # include <sysdep.h>
  70
  71 /* The old way: using LDT.  */
  72
  73 /* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
  74 struct user_desc
  75 {
  76   unsigned int entry_number;
  77   unsigned long int base_addr;
  78   unsigned int limit;
  79   unsigned int seg_32bit:1;
  80   unsigned int contents:2;
  81   unsigned int read_exec_only:1;
  82   unsigned int limit_in_pages:1;
  83   unsigned int seg_not_present:1;
  84   unsigned int useable:1;
  85   unsigned int empty:25;
  86 };
  87
  88 /* Initializing bit fields is slow.  We speed it up by using a union.  */
  89 union user_desc_init
  90 {
  91   struct user_desc desc;
  92   unsigned int vals[4];
  93 };
  94
  95
  96 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
  97    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
  98    struct pthread even when not linked with -lpthread.  */
  99 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
 100
 101 /* Alignment requirements for the initial TCB.  */
 102 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
 103
 104 /* This is the size of the TCB.  */
 105 # define TLS_TCB_SIZE sizeof (struct pthread)
 106
 107 /* Alignment requirements for the TCB.  */
 108 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 109
 110 /* The TCB can have any size and the memory following the address the
 111    thread pointer points to is unspecified.  Allocate the TCB there.  */
 112 # define TLS_TCB_AT_TP  1
 113 # define TLS_DTV_AT_TP  0
 114
 115 /* Get the thread descriptor definition.  */
 116 # include <nptl/descr.h>
 117
 118
 119 /* Install the dtv pointer.  The pointer passed is to the element with
 120    index -1 which contain the length.  */
 121 # define INSTALL_DTV(descr, dtvp) \
 122   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 123
 124 /* Install new dtv for current thread.  */
 125 # define INSTALL_NEW_DTV(dtvp) \
 126   ({ struct pthread *__pd;                                                    \
 127      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 128
 129 /* Return dtv of given thread descriptor.  */
 130 # define GET_DTV(descr) \
 131   (((tcbhead_t *) (descr))->dtv)
 132
 133 /* Macros to load from and store into segment registers.  */
 134 # ifndef TLS_GET_GS
 135 #  define TLS_GET_GS() \
 136   ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
 137 # endif
 138 # ifndef TLS_SET_GS
 139 #  define TLS_SET_GS(val) \
 140   __asm ("movw %w0, %%gs" :: "q" (val))
 141 # endif
 142
 143 #ifdef NEED_DL_SYSINFO
 144 # define INIT_SYSINFO \
 145   _head->sysinfo = GLRO(dl_sysinfo)
 146 # define SETUP_THREAD_SYSINFO(pd) \
 147   ((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 148 # define CHECK_THREAD_SYSINFO(pd) \
 149   assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 150 #else
 151 # define INIT_SYSINFO
 152 #endif
 153
 154 #ifndef LOCK_PREFIX
 155 # ifdef UP
 156 #  define LOCK_PREFIX  /* nothing */
 157 # else
 158 #  define LOCK_PREFIX "lock;"
 159 # endif
 160 #endif
 161
 162 static inline void __attribute__ ((unused, always_inline))
 163 tls_fill_user_desc (union user_desc_init *desc,
 164                     unsigned int entry_number,
 165                     void *pd)
 166 {
 167   desc->vals[0] = entry_number;
 168   /* The 'base_addr' field.  Pointer to the TCB.  */
 169   desc->vals[1] = (unsigned long int) pd;
 170   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */
 171   desc->vals[2] = 0xfffff;
 172   /* Collapsed value of the bitfield:
 173      .seg_32bit = 1
 174      .contents = 0
 175      .read_exec_only = 0
 176      .limit_in_pages = 1
 177      .seg_not_present = 0
 178      .useable = 1 */
 179   desc->vals[3] = 0x51;
 180 }
 181
 182 /* Code to initially initialize the thread pointer.  This might need
 183    special attention since 'errno' is not yet available and if the
 184    operation can cause a failure 'errno' must not be touched.  */
 185 # define TLS_INIT_TP(thrdescr) \
 186   ({ void *_thrdescr = (thrdescr);                                            \
 187      tcbhead_t *_head = _thrdescr;                                            \
 188      union user_desc_init _segdescr;                                          \
 189      int _result;                                                             \
 190                                                                               \
 191      _head->tcb = _thrdescr;                                                  \
 192      /* For now the thread descriptor is at the same address.  */             \
 193      _head->self = _thrdescr;                                                 \
 194      /* New syscall handling support.  */                                     \
 195      INIT_SYSINFO;                                                            \
 196                                                                               \
 197      /* Let the kernel pick a value for the 'entry_number' field.  */         \
 198      tls_fill_user_desc (&_segdescr, -1, _thrdescr);                          \
 199                                                                               \
 200      /* Install the TLS.  */                                                  \
 201      INTERNAL_SYSCALL_DECL (err);                                             \
 202      _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 203                                                                               \
 204      if (_result == 0)                                                        \
 205        /* We know the index in the GDT, now load the segment register.        \
 206           The use of the GDT is described by the value 3 in the lower         \
 207           three bits of the segment descriptor value.                         \
 208                                                                               \
 209           Note that we have to do this even if the numeric value of           \
 210           the descriptor does not change.  Loading the segment register       \
 211           causes the segment information from the GDT to be loaded            \
 212           which is necessary since we have changed it.   */                   \
 213        TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                      \
 214                                                                               \
 215      _result == 0 ? NULL                                                      \
 216      : "set_thread_area failed when setting up thread-local storage\n"; })
 217
 218 # define TLS_DEFINE_INIT_TP(tp, pd)                                           \
 219   union user_desc_init _segdescr;                                             \
 220   /* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP.   \
 221      The first three bits of the segment register value select the GDT,       \
 222      ignore them.  We get the index from the value of the %gs register in     \
 223      the current thread.  */                                                  \
 224   tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd);                    \
 225   const struct user_desc *tp = &_segdescr.desc
 226
 227
 228 /* Return the address of the dtv for the current thread.  */
 229 # define THREAD_DTV() \
 230   ({ struct pthread *__pd;                                                    \
 231      THREAD_GETMEM (__pd, header.dtv); })
 232
 233
 234 /* Return the thread descriptor for the current thread.
 235
 236    The contained asm must *not* be marked volatile since otherwise
 237    assignments like
 238         pthread_descr self = thread_self();
 239    do not get optimized away.  */
 240 # define THREAD_SELF \
 241   ({ struct pthread *__self;                                                  \
 242      asm ("movl %%gs:%c1,%0" : "=r" (__self)                                  \
 243           : "i" (offsetof (struct pthread, header.self)));                    \
 244      __self;})
 245
 246 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 247 # define DB_THREAD_SELF \
 248   REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
 249   REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
 250
 251
 252 /* Read member of the thread descriptor directly.  */
 253 # define THREAD_GETMEM(descr, member) \
 254   ({ __typeof (descr->member) __value;                                        \
 255      if (sizeof (__value) == 1)                                               \
 256        asm volatile ("movb %%gs:%P2,%b0"                                      \
 257                      : "=q" (__value)                                         \
 258                      : "0" (0), "i" (offsetof (struct pthread, member)));     \
 259      else if (sizeof (__value) == 4)                                          \
 260        asm volatile ("movl %%gs:%P1,%0"                                       \
 261                      : "=r" (__value)                                         \
 262                      : "i" (offsetof (struct pthread, member)));              \
 263      else                                                                     \
 264        {                                                                      \
 265          if (sizeof (__value) != 8)                                           \
 266            /* There should not be any value with a size other than 1,         \
 267               4 or 8.  */                                                     \
 268            abort ();                                                          \
 269                                                                               \
 270          asm volatile ("movl %%gs:%P1,%%eax\n\t"                              \
 271                        "movl %%gs:%P2,%%edx"                                  \
 272                        : "=A" (__value)                                       \
 273                        : "i" (offsetof (struct pthread, member)),             \
 274                          "i" (offsetof (struct pthread, member) + 4));        \
 275        }                                                                      \
 276      __value; })
 277
 278
 279 /* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
 280 # define THREAD_GETMEM_NC(descr, member, idx) \
 281   ({ __typeof (descr->member[0]) __value;                                     \
 282      if (sizeof (__value) == 1)                                               \
 283        asm volatile ("movb %%gs:%P2(%3),%b0"                                  \
 284                      : "=q" (__value)                                         \
 285                      : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
 286                      "r" (idx));                                              \
 287      else if (sizeof (__value) == 4)                                          \
 288        asm volatile ("movl %%gs:%P1(,%2,4),%0"                                \
 289                      : "=r" (__value)                                         \
 290                      : "i" (offsetof (struct pthread, member[0])),            \
 291                        "r" (idx));                                            \
 292      else                                                                     \
 293        {                                                                      \
 294          if (sizeof (__value) != 8)                                           \
 295            /* There should not be any value with a size other than 1,         \
 296               4 or 8.  */                                                     \
 297            abort ();                                                          \
 298                                                                               \
 299          asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                      \
 300                         "movl %%gs:4+%P1(,%2,8),%%edx"                        \
 301                         : "=&A" (__value)                                     \
 302                         : "i" (offsetof (struct pthread, member[0])),         \
 303                           "r" (idx));                                         \
 304        }                                                                      \
 305      __value; })
 306
 307
 308
 309 /* Set member of the thread descriptor directly.  */
 310 # define THREAD_SETMEM(descr, member, value) \
 311   ({ if (sizeof (descr->member) == 1)                                         \
 312        asm volatile ("movb %b0,%%gs:%P1" :                                    \
 313                      : "iq" (value),                                          \
 314                        "i" (offsetof (struct pthread, member)));              \
 315      else if (sizeof (descr->member) == 4)                                    \
 316        asm volatile ("movl %0,%%gs:%P1" :                                     \
 317                      : "ir" (value),                                          \
 318                        "i" (offsetof (struct pthread, member)));              \
 319      else                                                                     \
 320        {                                                                      \
 321          if (sizeof (descr->member) != 8)                                     \
 322            /* There should not be any value with a size other than 1,         \
 323               4 or 8.  */                                                     \
 324            abort ();                                                          \
 325                                                                               \
 326          asm volatile ("movl %%eax,%%gs:%P1\n\t"                              \
 327                        "movl %%edx,%%gs:%P2" :                                \
 328                        : "A" ((uint64_t) cast_to_integer (value)),            \
 329                          "i" (offsetof (struct pthread, member)),             \
 330                          "i" (offsetof (struct pthread, member) + 4));        \
 331        }})
 332
 333
 334 /* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
 335 # define THREAD_SETMEM_NC(descr, member, idx, value) \
 336   ({ if (sizeof (descr->member[0]) == 1)                                      \
 337        asm volatile ("movb %b0,%%gs:%P1(%2)" :                                \
 338                      : "iq" (value),                                          \
 339                        "i" (offsetof (struct pthread, member)),               \
 340                        "r" (idx));                                            \
 341      else if (sizeof (descr->member[0]) == 4)                                 \
 342        asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                              \
 343                      : "ir" (value),                                          \
 344                        "i" (offsetof (struct pthread, member)),               \
 345                        "r" (idx));                                            \
 346      else                                                                     \
 347        {                                                                      \
 348          if (sizeof (descr->member[0]) != 8)                                  \
 349            /* There should not be any value with a size other than 1,         \
 350               4 or 8.  */                                                     \
 351            abort ();                                                          \
 352                                                                               \
 353          asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                       \
 354                        "movl %%edx,%%gs:4+%P1(,%2,8)" :                       \
 355                        : "A" ((uint64_t) cast_to_integer (value)),            \
 356                          "i" (offsetof (struct pthread, member)),             \
 357                          "r" (idx));                                          \
 358        }})
 359
 360
 361 /* Atomic compare and exchange on TLS, returning old value.  */
 362 #define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
 363   ({ __typeof (descr->member) __ret;                                          \
 364      __typeof (oldval) __old = (oldval);                                      \
 365      if (sizeof (descr->member) == 4)                                         \
 366        asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                      \
 367                      : "=a" (__ret)                                           \
 368                      : "0" (__old), "r" (newval),                             \
 369                        "i" (offsetof (struct pthread, member)));              \
 370      else                                                                     \
 371        /* Not necessary for other sizes in the moment.  */                    \
 372        abort ();                                                              \
 373      __ret; })
 374
 375
 376 /* Atomic logical and.  */
 377 #define THREAD_ATOMIC_AND(descr, member, val) \
 378   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 379               asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0"                   \
 380                             :: "i" (offsetof (struct pthread, member)),       \
 381                                "ir" (val));                                   \
 382             else                                                              \
 383               /* Not necessary for other sizes in the moment.  */             \
 384               abort (); })
 385
 386
 387 /* Atomic set bit.  */
 388 #define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
 389   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 390               asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                    \
 391                             :: "i" (offsetof (struct pthread, member)),       \
 392                                "ir" (1 << (bit)));                            \
 393             else                                                              \
 394               /* Not necessary for other sizes in the moment.  */             \
 395               abort (); })
 396
 397
 398 /* Set the stack guard field in TCB head.  */
 399 #define THREAD_SET_STACK_GUARD(value) \
 400   THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 401 #define THREAD_COPY_STACK_GUARD(descr) \
 402   ((descr)->header.stack_guard                                                \
 403    = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 404
 405
 406 /* Set the pointer guard field in the TCB head.  */
 407 #define THREAD_SET_POINTER_GUARD(value) \
 408   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 409 #define THREAD_COPY_POINTER_GUARD(descr) \
 410   ((descr)->header.pointer_guard                                              \
 411    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 412
 413
 414 /* Get and set the global scope generation counter in the TCB head.  */
 415 #define THREAD_GSCOPE_IN_TCB      1
 416 #define THREAD_GSCOPE_FLAG_UNUSED 0
 417 #define THREAD_GSCOPE_FLAG_USED   1
 418 #define THREAD_GSCOPE_FLAG_WAIT   2
 419 #define THREAD_GSCOPE_RESET_FLAG() \
 420   do                                                                          \
 421     { int __res;                                                              \
 422       asm volatile ("xchgl %0, %%gs:%P1"                                      \
 423                     : "=r" (__res)                                            \
 424                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 425                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 426       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 427         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 428     }                                                                         \
 429   while (0)
 430 #define THREAD_GSCOPE_SET_FLAG() \
 431   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 432 #define THREAD_GSCOPE_WAIT() \
 433   GL(dl_wait_lookup_done) ()
 434
 435 #endif /* __ASSEMBLER__ */
 436
 437 #endif  /* tls.h */