l4/pkg/uclibc/lib/contrib/uclibc/libpthread/linuxthreads.old/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 <pt-machine.h>
  24
  25 #ifndef __ASSEMBLER__
  26 # include <stdbool.h>
  27 # include <stddef.h>
  28 # include <stdint.h>
  29
  30 /* Type for the dtv.  */
  31 typedef union dtv
  32 {
  33   size_t counter;
  34   void *pointer;
  35 } dtv_t;
  36
  37
  38 typedef struct
  39 {
  40   void *tcb;            /* Pointer to the TCB.  Not necessary the
  41                            thread descriptor used by libpthread.  */
  42   dtv_t *dtv;
  43   void *self;           /* Pointer to the thread descriptor.  */
  44 } tcbhead_t;
  45 #endif
  46
  47
  48 /* We can support TLS only if the floating-stack support is available.  */
  49 #if defined FLOATING_STACKS && defined HAVE_TLS_SUPPORT
  50
  51 /* Signal that TLS support is available.  */
  52 //# define USE_TLS      1
  53
  54 # ifndef __ASSEMBLER__
  55 /* Get system call information.  */
  56 #  include <sysdep.h>
  57
  58
  59 /* Get the thread descriptor definition.  */
  60 #  include <linuxthreads/descr.h>
  61
  62 /* This is the size of the initial TCB.  */
  63 #  define TLS_INIT_TCB_SIZE sizeof (tcbhead_t)
  64
  65 /* Alignment requirements for the initial TCB.  */
  66 #  define TLS_INIT_TCB_ALIGN __alignof__ (tcbhead_t)
  67
  68 /* This is the size of the TCB.  */
  69 #  define TLS_TCB_SIZE sizeof (struct _pthread_descr_struct)
  70
  71 /* Alignment requirements for the TCB.  */
  72 #  define TLS_TCB_ALIGN __alignof__ (struct _pthread_descr_struct)
  73
  74 /* The TCB can have any size and the memory following the address the
  75    thread pointer points to is unspecified.  Allocate the TCB there.  */
  76 #  define TLS_TCB_AT_TP 1
  77
  78
  79 /* Install the dtv pointer.  The pointer passed is to the element with
  80    index -1 which contain the length.  */
  81 #  define INSTALL_DTV(descr, dtvp) \
  82   ((tcbhead_t *) (descr))->dtv = (dtvp) + 1
  83
  84 /* Install new dtv for current thread.  */
  85 #  define INSTALL_NEW_DTV(dtv) \
  86   ({ struct _pthread_descr_struct *__descr;                                   \
  87      THREAD_SETMEM (__descr, p_header.data.dtvp, (dtv)); })
  88
  89 /* Return dtv of given thread descriptor.  */
  90 #  define GET_DTV(descr) \
  91   (((tcbhead_t *) (descr))->dtv)
  92
  93 #  ifdef __PIC__
  94 #   define TLS_EBX_ARG "r"
  95 #   define TLS_LOAD_EBX "xchgl %3, %%ebx\n\t"
  96 #  else
  97 #   define TLS_EBX_ARG "b"
  98 #   define TLS_LOAD_EBX
  99 #  endif
 100
 101 #  define TLS_DO_MODIFY_LDT(descr, nr)                                        \
 102 ({                                                                            \
 103   struct modify_ldt_ldt_s ldt_entry =                                         \
 104     { nr, (unsigned long int) (descr), 0xfffff /* 4GB in pages */,            \
 105       1, 0, 0, 1, 0, 1, 0 };                                                  \
 106   int result;                                                                 \
 107   __asm__ __volatile__ (TLS_LOAD_EBX                                                  \
 108                 "int $0x80\n\t"                                               \
 109                 TLS_LOAD_EBX                                                  \
 110                 : "=a" (result)                                               \
 111                 : "0" (__NR_modify_ldt),                                      \
 112                 /* The extra argument with the "m" constraint is necessary    \
 113                    to let the compiler know that we are accessing LDT_ENTRY   \
 114                    here.  */                                                  \
 115                 "m" (ldt_entry), TLS_EBX_ARG (1), "c" (&ldt_entry),           \
 116                 "d" (sizeof (ldt_entry)));                                    \
 117   __builtin_expect (result, 0) != 0 ? -1 : nr * 8 + 7;                        \
 118 })
 119
 120 #  define TLS_DO_SET_THREAD_AREA(descr, secondcall)                           \
 121 ({                                                                            \
 122   struct modify_ldt_ldt_s ldt_entry =                                         \
 123     { -1, (unsigned long int) (descr), 0xfffff /* 4GB in pages */,            \
 124       1, 0, 0, 1, 0, 1, 0 };                                                  \
 125   int result;                                                                 \
 126   if (secondcall)                                                             \
 127     ldt_entry.entry_number = ({ int _gs;                                      \
 128                                 __asm__ ("movw %%gs, %w0" : "=q" (_gs));              \
 129                                 (_gs & 0xffff) >> 3; });                      \
 130   __asm__ __volatile__ (TLS_LOAD_EBX                                                  \
 131                 "int $0x80\n\t"                                               \
 132                 TLS_LOAD_EBX                                                  \
 133                 : "=a" (result), "=m" (ldt_entry.entry_number)                \
 134                 : "0" (__NR_set_thread_area),                                 \
 135                 /* The extra argument with the "m" constraint is necessary    \
 136                    to let the compiler know that we are accessing LDT_ENTRY   \
 137                    here.  */                                                  \
 138                 TLS_EBX_ARG (&ldt_entry), "m" (ldt_entry));                   \
 139     __builtin_expect (result, 0) == 0 ? ldt_entry.entry_number * 8 + 3 : -1;  \
 140 })
 141
 142 #  ifdef __ASSUME_SET_THREAD_AREA_SYSCALL
 143 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall) \
 144   TLS_DO_SET_THREAD_AREA (descr, firstcall)
 145 #  elif defined __NR_set_thread_area
 146 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall) \
 147   ({ int __seg = TLS_DO_SET_THREAD_AREA (descr, secondcall); \
 148      __seg == -1 ? TLS_DO_MODIFY_LDT (descr, 0) : __seg; })
 149 #  else
 150 #   define TLS_SETUP_GS_SEGMENT(descr, secondcall) \
 151   TLS_DO_MODIFY_LDT ((descr), 0)
 152 #  endif
 153
 154 /* Code to initially initialize the thread pointer.  This might need
 155    special attention since 'errno' is not yet available and if the
 156    operation can cause a failure 'errno' must not be touched.  */
 157 #  define TLS_INIT_TP(descr, secondcall)                                      \
 158   ({                                                                          \
 159     void *_descr = (descr);                                                   \
 160     tcbhead_t *head = _descr;                                                 \
 161     int __gs;                                                                 \
 162                                                                               \
 163     head->tcb = _descr;                                                       \
 164     /* For now the thread descriptor is at the same address.  */              \
 165     head->self = _descr;                                                      \
 166                                                                               \
 167     __gs = TLS_SETUP_GS_SEGMENT (_descr, secondcall);                         \
 168     if (__builtin_expect (__gs, 7) != -1)                                     \
 169       {                                                                       \
 170         __asm__ ("movw %w0, %%gs" : : "q" (__gs));                                    \
 171         __gs = 0;                                                             \
 172       }                                                                       \
 173     __gs;                                                                     \
 174   })
 175
 176
 177 /* Return the address of the dtv for the current thread.  */
 178 #  define THREAD_DTV() \
 179   ({ struct _pthread_descr_struct *__descr;                                   \
 180      THREAD_GETMEM (__descr, p_header.data.dtvp); })
 181
 182 # endif /* FLOATING_STACKS && HAVE_TLS_SUPPORT */
 183 #endif /* __ASSEMBLER__ */
 184
 185 #endif  /* tls.h */