linuxthreads/sysdeps/i386/tls.h

   1 /* Definition for thread-local data handling.  linuxthreads/i386 version.
   2    Copyright (C) 2002, 2003, 2004, 2005 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #ifndef _TLS_H
  21 #define _TLS_H
  22
  23 # include <dl-sysdep.h>
  24 # include <pt-machine.h>
  25
  26 #ifndef __ASSEMBLER__
  27 # include <stdbool.h>
  28 # include <stddef.h>
  29 # include <stdint.h>
  30
  31 /* Type for the dtv.  */
  32 typedef union dtv
  33 {
  34   size_t counter;
  35   struct
  36   {
  37     void *val;
  38     bool is_static;
  39   } pointer;
  40 } dtv_t;
  41
  42
  43 typedef struct
  44 {
  45   void *tcb;            /* Pointer to the TCB.  Not necessary the
  46                            thread descriptor used by libpthread.  */
  47   dtv_t *dtv;
  48   void *self;           /* Pointer to the thread descriptor.  */
  49   int multiple_threads;
  50 #ifdef NEED_DL_SYSINFO
  51   uintptr_t sysinfo;
  52 #endif
  53 } tcbhead_t;
  54
  55 #else /* __ASSEMBLER__ */
  56 # include <tcb-offsets.h>
  57 #endif
  58
  59 /* We can support TLS only if the floating-stack support is available.
  60    However, we want to compile in the support and test at runtime whether
  61    the running kernel can support it or not.  To avoid bothering with the
  62    TLS support code at all, use configure --without-tls.
  63
  64    We need USE_TLS to be consistently defined, for ldsodefs.h conditionals.
  65    But some of the code below can cause problems in building libpthread
  66    (e.g. useldt.h will defined FLOATING_STACKS when it shouldn't).  */
  67
  68 #if defined HAVE_TLS_SUPPORT \
  69     && (defined FLOATING_STACKS || !defined IS_IN_libpthread)
  70
  71 /* Signal that TLS support is available.  */
  72 # define USE_TLS        1
  73
  74 # ifndef __ASSEMBLER__
  75 /* Get system call information.  */
  76 #  include <sysdep.h>
  77
  78
  79 /* Get the thread descriptor definition.  */
  80 #  include <linuxthreads/descr.h>
  81
  82 /* This is the size of the initial TCB.  */
  83 #  define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
  84
  85 /* Alignment requirements for the initial TCB.  */
  86 #  define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
  87
  88 /* This is the size of the TCB.  */
  89 #  ifndef IS_IN_rtld
  90 #   define TLS_TCB_SIZE sizeof (struct _pthread_descr_struct)
  91 #  else
  92 #   include <nptl-struct-pthread.h>
  93 #   define TLS_TCB_SIZE \
  94   (sizeof (struct _pthread_descr_struct) > NPTL_STRUCT_PTHREAD_SIZE     \
  95    ? sizeof (struct _pthread_descr_struct) : NPTL_STRUCT_PTHREAD_SIZE)
  96 #  endif
  97
  98 /* Alignment requirements for the TCB.  */
  99 #  define TLS_TCB_ALIGN __alignof__ (struct _pthread_descr_struct)
 100
 101 /* The TCB can have any size and the memory following the address the
 102    thread pointer points to is unspecified.  Allocate the TCB there.  */
 103 #  define TLS_TCB_AT_TP 1
 104
 105
 106 /* Install the dtv pointer.  The pointer passed is to the element with
 107    index -1 which contain the length.  */
 108 #  define INSTALL_DTV(descr, dtvp) \
 109   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
 110
 111 /* Install new dtv for current thread.  */
 112 #  define INSTALL_NEW_DTV(dtv) \
 113   ({ struct _pthread_descr_struct *__descr;                                   \
 114      THREAD_SETMEM (__descr, p_header.data.dtvp, (dtv)); })
 115
 116 /* Return dtv of given thread descriptor.  */
 117 #  define GET_DTV(descr) \
 118   (((tcbhead_t *) (descr))->dtv)
 119
 120 #  ifdef __PIC__
 121 #   define TLS_EBX_ARG "r"
 122 #   define TLS_LOAD_EBX "xchgl %3, %%ebx\n\t"
 123 #  else
 124 #   define TLS_EBX_ARG "b"
 125 #   define TLS_LOAD_EBX
 126 #  endif
 127
 128 #  if !defined IS_IN_linuxthreads && !defined DO_MODIFY_LDT
 129 #   include "useldt.h"          /* For the structure.  */
 130 #  endif
 131 #  if __ASSUME_LDT_WORKS > 0
 132 #   define TLS_DO_MODIFY_LDT_KERNEL_CHECK(doit) (doit) /* Nothing to check.  */
 133 #  else
 134 #   define TLS_DO_MODIFY_LDT_KERNEL_CHECK(doit)                               \
 135   (__builtin_expect (GLRO(dl_osversion) < 131939, 0)                          \
 136    ? "kernel too old for thread-local storage support\n"                              \
 137    : (doit))
 138 #  endif
 139
 140 #  define TLS_DO_MODIFY_LDT(descr, nr)                                        \
 141 TLS_DO_MODIFY_LDT_KERNEL_CHECK(                                               \
 142 ({                                                                            \
 143   struct modify_ldt_ldt_s ldt_entry =                                         \
 144     { nr, (unsigned long int) (descr), 0xfffff /* 4GB in pages */,            \
 145       1, 0, 0, 1, 0, 1, 0 };                                                  \
 146   int result;                                                                 \
 147   asm volatile (TLS_LOAD_EBX                                                  \
 148                 "int $0x80\n\t"                                               \
 149                 TLS_LOAD_EBX                                                  \
 150                 : "=a" (result)                                               \
 151                 : "0" (__NR_modify_ldt),                                      \
 152                 /* The extra argument with the "m" constraint is necessary    \
 153                    to let the compiler know that we are accessing LDT_ENTRY   \
 154                    here.  */                                                  \
 155                 "m" (ldt_entry), TLS_EBX_ARG (1), "c" (&ldt_entry),           \
 156                 "d" (sizeof (ldt_entry)));                                    \
 157   __builtin_expect (result, 0) == 0                                           \
 158   ? ({ asm ("movw %w0, %%gs" : : "q" ((nr) * 8 + 7)); NULL; })                \
 159   : "cannot set up LDT for thread-local storage\n";                           \
 160 }))
 161
 162 #  define TLS_DO_SET_THREAD_AREA(descr, secondcall)                           \
 163 ({                                                                            \
 164   struct modify_ldt_ldt_s ldt_entry =                                         \
 165     { -1, (unsigned long int) (descr), 0xfffff /* 4GB in pages */,            \
 166       1, 0, 0, 1, 0, 1, 0 };                                                  \
 167   int result;                                                                 \
 168   if (secondcall)                                                             \
 169     ldt_entry.entry_number = ({ int _gs;                                      \
 170                                 asm ("movw %%gs, %w0" : "=q" (_gs));          \
 171                                 (_gs & 0xffff) >> 3; });                      \
 172   asm volatile (TLS_LOAD_EBX                                                  \
 173                 "int $0x80\n\t"                                               \
 174                 TLS_LOAD_EBX                                                  \
 175                 : "=a" (result), "=m" (ldt_entry.entry_number)                \
 176                 : "0" (__NR_set_thread_area),                                 \
 177                 /* The extra argument with the "m" constraint is necessary    \
 178                    to let the compiler know that we are accessing LDT_ENTRY   \
 179                    here.  */                                                  \
 180                 TLS_EBX_ARG (&ldt_entry), "m" (ldt_entry));                   \
 181   if (__builtin_expect (result, 0) == 0)                                      \
 182     asm ("movw %w0, %%gs" : : "q" (ldt_entry.entry_number * 8 + 3));          \
 183   result;                                                                     \
 184 })
 185
 186 #  ifdef __ASSUME_SET_THREAD_AREA_SYSCALL
 187 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall)                            \
 188   (TLS_DO_SET_THREAD_AREA (descr, secondcall)                                 \
 189    ? "set_thread_area failed when setting up thread-local storage\n" : NULL)
 190 #  elif defined __NR_set_thread_area
 191 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall) \
 192   (TLS_DO_SET_THREAD_AREA (descr, secondcall)                                 \
 193    ? TLS_DO_MODIFY_LDT (descr, 0) : NULL)
 194 #  else
 195 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall) \
 196   TLS_DO_MODIFY_LDT ((descr), 0)
 197 #  endif
 198
 199 #if defined NEED_DL_SYSINFO
 200 # define INIT_SYSINFO \
 201   head->sysinfo = GLRO(dl_sysinfo)
 202 #else
 203 # define INIT_SYSINFO
 204 #endif
 205
 206 /* Code to initially initialize the thread pointer.  This might need
 207    special attention since 'errno' is not yet available and if the
 208    operation can cause a failure 'errno' must not be touched.
 209
 210    The value of this macro is null if successful, or an error string.  */
 211 #  define TLS_INIT_TP(descr, secondcall)                                      \
 212   ({                                                                          \
 213     void *_descr = (descr);                                                   \
 214     tcbhead_t *head = _descr;                                                 \
 215                                                                               \
 216     head->tcb = _descr;                                                       \
 217     /* For now the thread descriptor is at the same address.  */              \
 218     head->self = _descr;                                                      \
 219                                                                               \
 220     INIT_SYSINFO;                                                             \
 221     TLS_SETUP_GS_SEGMENT (_descr, secondcall);                                \
 222   })
 223
 224 /* Indicate that dynamic linker shouldn't try to initialize TLS even
 225    when no PT_TLS segments are found in the program and libraries
 226    it is linked against.  */
 227 #  define TLS_INIT_TP_EXPENSIVE 1
 228
 229 /* Return the address of the dtv for the current thread.  */
 230 #  define THREAD_DTV() \
 231   ({ struct _pthread_descr_struct *__descr;                                   \
 232      THREAD_GETMEM (__descr, p_header.data.dtvp); })
 233
 234 # endif /* HAVE_TLS_SUPPORT && (FLOATING_STACKS || !IS_IN_libpthread) */
 235 #endif /* __ASSEMBLER__ */
 236
 237 #endif  /* tls.h */