sysdeps/i386/nptl/tls.h

   1 /* Definition for thread-local data handling.  nptl/i386 version.
   2    Copyright (C) 2002-2019 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   /* Bit 0: X86_FEATURE_1_IBT.
  45      Bit 1: X86_FEATURE_1_SHSTK.
  46    */
  47   unsigned int feature_1;
  48   /* Reservation of some values for the TM ABI.  */
  49   void *__private_tm[3];
  50   /* GCC split stack support.  */
  51   void *__private_ss;
  52   /* The lowest address of shadow stack,  */
  53   unsigned long ssp_base;
  54 } tcbhead_t;
  55
  56 /* morestack.S in libgcc uses offset 0x30 to access __private_ss,   */
  57 _Static_assert (offsetof (tcbhead_t, __private_ss) == 0x30,
  58                 "offset of __private_ss != 0x30");
  59
  60 # define TLS_MULTIPLE_THREADS_IN_TCB 1
  61
  62 #else /* __ASSEMBLER__ */
  63 # include <tcb-offsets.h>
  64 #endif
  65
  66
  67 /* Alignment requirement for the stack.  For IA-32 this is governed by
  68    the SSE memory functions.  */
  69 #define STACK_ALIGN     16
  70
  71 #ifndef __ASSEMBLER__
  72 /* Get system call information.  */
  73 # include <sysdep.h>
  74
  75 /* The old way: using LDT.  */
  76
  77 /* Structure passed to `modify_ldt', 'set_thread_area', and 'clone' calls.  */
  78 struct user_desc
  79 {
  80   unsigned int entry_number;
  81   unsigned long int base_addr;
  82   unsigned int limit;
  83   unsigned int seg_32bit:1;
  84   unsigned int contents:2;
  85   unsigned int read_exec_only:1;
  86   unsigned int limit_in_pages:1;
  87   unsigned int seg_not_present:1;
  88   unsigned int useable:1;
  89   unsigned int empty:25;
  90 };
  91
  92 /* Initializing bit fields is slow.  We speed it up by using a union.  */
  93 union user_desc_init
  94 {
  95   struct user_desc desc;
  96   unsigned int vals[4];
  97 };
  98
  99
 100 /* This is the size of the initial TCB.  Can't be just sizeof (tcbhead_t),
 101    because NPTL getpid, __libc_alloca_cutoff etc. need (almost) the whole
 102    struct pthread even when not linked with -lpthread.  */
 103 # define TLS_INIT_TCB_SIZE sizeof (struct pthread)
 104
 105 /* Alignment requirements for the initial TCB.  */
 106 # define TLS_INIT_TCB_ALIGN __alignof__ (struct pthread)
 107
 108 /* This is the size of the TCB.  */
 109 # define TLS_TCB_SIZE sizeof (struct pthread)
 110
 111 /* Alignment requirements for the TCB.  */
 112 # define TLS_TCB_ALIGN __alignof__ (struct pthread)
 113
 114 /* The TCB can have any size and the memory following the address the
 115    thread pointer points to is unspecified.  Allocate the TCB there.  */
 116 # define TLS_TCB_AT_TP  1
 117 # define TLS_DTV_AT_TP  0
 118
 119 /* Get the thread descriptor definition.  */
 120 # include <nptl/descr.h>
 121
 122
 123 /* Install the dtv pointer.  The pointer passed is to the element with
 124    index -1 which contain the length.  */
 125 # define INSTALL_DTV(descr, dtvp) \
 126   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 127
 128 /* Install new dtv for current thread.  */
 129 # define INSTALL_NEW_DTV(dtvp) \
 130   ({ struct pthread *__pd;                                                    \
 131      THREAD_SETMEM (__pd, header.dtv, (dtvp)); })
 132
 133 /* Return dtv of given thread descriptor.  */
 134 # define GET_DTV(descr) \
 135   (((tcbhead_t *) (descr))->dtv)
 136
 137 /* Macros to load from and store into segment registers.  */
 138 # ifndef TLS_GET_GS
 139 #  define TLS_GET_GS() \
 140   ({ int __seg; __asm ("movw %%gs, %w0" : "=q" (__seg)); __seg & 0xffff; })
 141 # endif
 142 # ifndef TLS_SET_GS
 143 #  define TLS_SET_GS(val) \
 144   __asm ("movw %w0, %%gs" :: "q" (val))
 145 # endif
 146
 147 #ifdef NEED_DL_SYSINFO
 148 # define INIT_SYSINFO \
 149   _head->sysinfo = GLRO(dl_sysinfo)
 150 # define SETUP_THREAD_SYSINFO(pd) \
 151   ((pd)->header.sysinfo = THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 152 # define CHECK_THREAD_SYSINFO(pd) \
 153   assert ((pd)->header.sysinfo == THREAD_GETMEM (THREAD_SELF, header.sysinfo))
 154 #else
 155 # define INIT_SYSINFO
 156 #endif
 157
 158 #ifndef LOCK_PREFIX
 159 # ifdef UP
 160 #  define LOCK_PREFIX  /* nothing */
 161 # else
 162 #  define LOCK_PREFIX "lock;"
 163 # endif
 164 #endif
 165
 166 static inline void __attribute__ ((unused, always_inline))
 167 tls_fill_user_desc (union user_desc_init *desc,
 168                     unsigned int entry_number,
 169                     void *pd)
 170 {
 171   desc->vals[0] = entry_number;
 172   /* The 'base_addr' field.  Pointer to the TCB.  */
 173   desc->vals[1] = (unsigned long int) pd;
 174   /* The 'limit' field.  We use 4GB which is 0xfffff pages.  */
 175   desc->vals[2] = 0xfffff;
 176   /* Collapsed value of the bitfield:
 177      .seg_32bit = 1
 178      .contents = 0
 179      .read_exec_only = 0
 180      .limit_in_pages = 1
 181      .seg_not_present = 0
 182      .useable = 1 */
 183   desc->vals[3] = 0x51;
 184 }
 185
 186 /* Code to initially initialize the thread pointer.  This might need
 187    special attention since 'errno' is not yet available and if the
 188    operation can cause a failure 'errno' must not be touched.  */
 189 # define TLS_INIT_TP(thrdescr) \
 190   ({ void *_thrdescr = (thrdescr);                                            \
 191      tcbhead_t *_head = _thrdescr;                                            \
 192      union user_desc_init _segdescr;                                          \
 193      int _result;                                                             \
 194                                                                               \
 195      _head->tcb = _thrdescr;                                                  \
 196      /* For now the thread descriptor is at the same address.  */             \
 197      _head->self = _thrdescr;                                                 \
 198      /* New syscall handling support.  */                                     \
 199      INIT_SYSINFO;                                                            \
 200                                                                               \
 201      /* Let the kernel pick a value for the 'entry_number' field.  */         \
 202      tls_fill_user_desc (&_segdescr, -1, _thrdescr);                          \
 203                                                                               \
 204      /* Install the TLS.  */                                                  \
 205      INTERNAL_SYSCALL_DECL (err);                                             \
 206      _result = INTERNAL_SYSCALL (set_thread_area, err, 1, &_segdescr.desc);   \
 207                                                                               \
 208      if (_result == 0)                                                        \
 209        /* We know the index in the GDT, now load the segment register.        \
 210           The use of the GDT is described by the value 3 in the lower         \
 211           three bits of the segment descriptor value.                         \
 212                                                                               \
 213           Note that we have to do this even if the numeric value of           \
 214           the descriptor does not change.  Loading the segment register       \
 215           causes the segment information from the GDT to be loaded            \
 216           which is necessary since we have changed it.   */                   \
 217        TLS_SET_GS (_segdescr.desc.entry_number * 8 + 3);                      \
 218                                                                               \
 219      _result == 0 ? NULL                                                      \
 220      : "set_thread_area failed when setting up thread-local storage\n"; })
 221
 222 # define TLS_DEFINE_INIT_TP(tp, pd)                                           \
 223   union user_desc_init _segdescr;                                             \
 224   /* Find the 'entry_number' field that the kernel selected in TLS_INIT_TP.   \
 225      The first three bits of the segment register value select the GDT,       \
 226      ignore them.  We get the index from the value of the %gs register in     \
 227      the current thread.  */                                                  \
 228   tls_fill_user_desc (&_segdescr, TLS_GET_GS () >> 3, pd);                    \
 229   const struct user_desc *tp = &_segdescr.desc
 230
 231
 232 /* Return the address of the dtv for the current thread.  */
 233 # define THREAD_DTV() \
 234   ({ struct pthread *__pd;                                                    \
 235      THREAD_GETMEM (__pd, header.dtv); })
 236
 237
 238 /* Return the thread descriptor for the current thread.
 239
 240    The contained asm must *not* be marked volatile since otherwise
 241    assignments like
 242         pthread_descr self = thread_self();
 243    do not get optimized away.  */
 244 # define THREAD_SELF \
 245   ({ struct pthread *__self;                                                  \
 246      asm ("movl %%gs:%c1,%0" : "=r" (__self)                                  \
 247           : "i" (offsetof (struct pthread, header.self)));                    \
 248      __self;})
 249
 250 /* Magic for libthread_db to know how to do THREAD_SELF.  */
 251 # define DB_THREAD_SELF \
 252   REGISTER_THREAD_AREA (32, offsetof (struct user_regs_struct, xgs), 3) \
 253   REGISTER_THREAD_AREA (64, 26 * 8, 3) /* x86-64's user_regs_struct->gs */
 254
 255
 256 /* Read member of the thread descriptor directly.  */
 257 # define THREAD_GETMEM(descr, member) \
 258   ({ __typeof (descr->member) __value;                                        \
 259      if (sizeof (__value) == 1)                                               \
 260        asm volatile ("movb %%gs:%P2,%b0"                                      \
 261                      : "=q" (__value)                                         \
 262                      : "0" (0), "i" (offsetof (struct pthread, member)));     \
 263      else if (sizeof (__value) == 4)                                          \
 264        asm volatile ("movl %%gs:%P1,%0"                                       \
 265                      : "=r" (__value)                                         \
 266                      : "i" (offsetof (struct pthread, member)));              \
 267      else                                                                     \
 268        {                                                                      \
 269          if (sizeof (__value) != 8)                                           \
 270            /* There should not be any value with a size other than 1,         \
 271               4 or 8.  */                                                     \
 272            abort ();                                                          \
 273                                                                               \
 274          asm volatile ("movl %%gs:%P1,%%eax\n\t"                              \
 275                        "movl %%gs:%P2,%%edx"                                  \
 276                        : "=A" (__value)                                       \
 277                        : "i" (offsetof (struct pthread, member)),             \
 278                          "i" (offsetof (struct pthread, member) + 4));        \
 279        }                                                                      \
 280      __value; })
 281
 282
 283 /* Same as THREAD_GETMEM, but the member offset can be non-constant.  */
 284 # define THREAD_GETMEM_NC(descr, member, idx) \
 285   ({ __typeof (descr->member[0]) __value;                                     \
 286      if (sizeof (__value) == 1)                                               \
 287        asm volatile ("movb %%gs:%P2(%3),%b0"                                  \
 288                      : "=q" (__value)                                         \
 289                      : "0" (0), "i" (offsetof (struct pthread, member[0])),   \
 290                      "r" (idx));                                              \
 291      else if (sizeof (__value) == 4)                                          \
 292        asm volatile ("movl %%gs:%P1(,%2,4),%0"                                \
 293                      : "=r" (__value)                                         \
 294                      : "i" (offsetof (struct pthread, member[0])),            \
 295                        "r" (idx));                                            \
 296      else                                                                     \
 297        {                                                                      \
 298          if (sizeof (__value) != 8)                                           \
 299            /* There should not be any value with a size other than 1,         \
 300               4 or 8.  */                                                     \
 301            abort ();                                                          \
 302                                                                               \
 303          asm volatile  ("movl %%gs:%P1(,%2,8),%%eax\n\t"                      \
 304                         "movl %%gs:4+%P1(,%2,8),%%edx"                        \
 305                         : "=&A" (__value)                                     \
 306                         : "i" (offsetof (struct pthread, member[0])),         \
 307                           "r" (idx));                                         \
 308        }                                                                      \
 309      __value; })
 310
 311
 312
 313 /* Set member of the thread descriptor directly.  */
 314 # define THREAD_SETMEM(descr, member, value) \
 315   ({ if (sizeof (descr->member) == 1)                                         \
 316        asm volatile ("movb %b0,%%gs:%P1" :                                    \
 317                      : "iq" (value),                                          \
 318                        "i" (offsetof (struct pthread, member)));              \
 319      else if (sizeof (descr->member) == 4)                                    \
 320        asm volatile ("movl %0,%%gs:%P1" :                                     \
 321                      : "ir" (value),                                          \
 322                        "i" (offsetof (struct pthread, member)));              \
 323      else                                                                     \
 324        {                                                                      \
 325          if (sizeof (descr->member) != 8)                                     \
 326            /* There should not be any value with a size other than 1,         \
 327               4 or 8.  */                                                     \
 328            abort ();                                                          \
 329                                                                               \
 330          asm volatile ("movl %%eax,%%gs:%P1\n\t"                              \
 331                        "movl %%edx,%%gs:%P2" :                                \
 332                        : "A" ((uint64_t) cast_to_integer (value)),            \
 333                          "i" (offsetof (struct pthread, member)),             \
 334                          "i" (offsetof (struct pthread, member) + 4));        \
 335        }})
 336
 337
 338 /* Same as THREAD_SETMEM, but the member offset can be non-constant.  */
 339 # define THREAD_SETMEM_NC(descr, member, idx, value) \
 340   ({ if (sizeof (descr->member[0]) == 1)                                      \
 341        asm volatile ("movb %b0,%%gs:%P1(%2)" :                                \
 342                      : "iq" (value),                                          \
 343                        "i" (offsetof (struct pthread, member)),               \
 344                        "r" (idx));                                            \
 345      else if (sizeof (descr->member[0]) == 4)                                 \
 346        asm volatile ("movl %0,%%gs:%P1(,%2,4)" :                              \
 347                      : "ir" (value),                                          \
 348                        "i" (offsetof (struct pthread, member)),               \
 349                        "r" (idx));                                            \
 350      else                                                                     \
 351        {                                                                      \
 352          if (sizeof (descr->member[0]) != 8)                                  \
 353            /* There should not be any value with a size other than 1,         \
 354               4 or 8.  */                                                     \
 355            abort ();                                                          \
 356                                                                               \
 357          asm volatile ("movl %%eax,%%gs:%P1(,%2,8)\n\t"                       \
 358                        "movl %%edx,%%gs:4+%P1(,%2,8)" :                       \
 359                        : "A" ((uint64_t) cast_to_integer (value)),            \
 360                          "i" (offsetof (struct pthread, member)),             \
 361                          "r" (idx));                                          \
 362        }})
 363
 364
 365 /* Atomic compare and exchange on TLS, returning old value.  */
 366 #define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
 367   ({ __typeof (descr->member) __ret;                                          \
 368      __typeof (oldval) __old = (oldval);                                      \
 369      if (sizeof (descr->member) == 4)                                         \
 370        asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3"                      \
 371                      : "=a" (__ret)                                           \
 372                      : "0" (__old), "r" (newval),                             \
 373                        "i" (offsetof (struct pthread, member)));              \
 374      else                                                                     \
 375        /* Not necessary for other sizes in the moment.  */                    \
 376        abort ();                                                              \
 377      __ret; })
 378
 379
 380 /* Atomic logical and.  */
 381 #define THREAD_ATOMIC_AND(descr, member, val) \
 382   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 383               asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0"                   \
 384                             :: "i" (offsetof (struct pthread, member)),       \
 385                                "ir" (val));                                   \
 386             else                                                              \
 387               /* Not necessary for other sizes in the moment.  */             \
 388               abort (); })
 389
 390
 391 /* Atomic set bit.  */
 392 #define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
 393   (void) ({ if (sizeof ((descr)->member) == 4)                                \
 394               asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0"                    \
 395                             :: "i" (offsetof (struct pthread, member)),       \
 396                                "ir" (1 << (bit)));                            \
 397             else                                                              \
 398               /* Not necessary for other sizes in the moment.  */             \
 399               abort (); })
 400
 401
 402 /* Set the stack guard field in TCB head.  */
 403 #define THREAD_SET_STACK_GUARD(value) \
 404   THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)
 405 #define THREAD_COPY_STACK_GUARD(descr) \
 406   ((descr)->header.stack_guard                                                \
 407    = THREAD_GETMEM (THREAD_SELF, header.stack_guard))
 408
 409
 410 /* Set the pointer guard field in the TCB head.  */
 411 #define THREAD_SET_POINTER_GUARD(value) \
 412   THREAD_SETMEM (THREAD_SELF, header.pointer_guard, value)
 413 #define THREAD_COPY_POINTER_GUARD(descr) \
 414   ((descr)->header.pointer_guard                                              \
 415    = THREAD_GETMEM (THREAD_SELF, header.pointer_guard))
 416
 417
 418 /* Get and set the global scope generation counter in the TCB head.  */
 419 #define THREAD_GSCOPE_IN_TCB      1
 420 #define THREAD_GSCOPE_FLAG_UNUSED 0
 421 #define THREAD_GSCOPE_FLAG_USED   1
 422 #define THREAD_GSCOPE_FLAG_WAIT   2
 423 #define THREAD_GSCOPE_RESET_FLAG() \
 424   do                                                                          \
 425     { int __res;                                                              \
 426       asm volatile ("xchgl %0, %%gs:%P1"                                      \
 427                     : "=r" (__res)                                            \
 428                     : "i" (offsetof (struct pthread, header.gscope_flag)),    \
 429                       "0" (THREAD_GSCOPE_FLAG_UNUSED));                       \
 430       if (__res == THREAD_GSCOPE_FLAG_WAIT)                                   \
 431         lll_futex_wake (&THREAD_SELF->header.gscope_flag, 1, LLL_PRIVATE);    \
 432     }                                                                         \
 433   while (0)
 434 #define THREAD_GSCOPE_SET_FLAG() \
 435   THREAD_SETMEM (THREAD_SELF, header.gscope_flag, THREAD_GSCOPE_FLAG_USED)
 436 #define THREAD_GSCOPE_WAIT() \
 437   GL(dl_wait_lookup_done) ()
 438
 439 #endif /* __ASSEMBLER__ */
 440
 441 #endif  /* tls.h */