linuxthreads/sysdeps/powerpc/tls.h

   1 /* Definitions for thread-local data handling.  linuxthreads/PPC version.
   2    Copyright (C) 2003, 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 #ifndef __ASSEMBLER__
  24
  25 # include <pt-machine.h>
  26 # include <stdbool.h>
  27 # include <stddef.h>
  28
  29 /* Type for the dtv.  */
  30 typedef union dtv
  31 {
  32   size_t counter;
  33   struct
  34   {
  35     void *val;
  36     bool is_static;
  37   } pointer;
  38 } dtv_t;
  39
  40 #else /* __ASSEMBLER__ */
  41 # include <tcb-offsets.h>
  42 #endif /* __ASSEMBLER__ */
  43
  44 #ifdef HAVE_TLS_SUPPORT
  45
  46 /* Signal that TLS support is available.  */
  47 # define USE_TLS        1
  48
  49 # ifndef __ASSEMBLER__
  50
  51 /* This layout is actually wholly private and not affected by the ABI.
  52    Nor does it overlap the pthread data structure, so we need nothing
  53    extra here at all.  */
  54 typedef struct
  55 {
  56   dtv_t *dtv;
  57 } tcbhead_t;
  58
  59 /* This is the size of the initial TCB.  */
  60 #  define TLS_INIT_TCB_SIZE     0
  61
  62 /* Alignment requirements for the initial TCB.  */
  63 #  define TLS_INIT_TCB_ALIGN    __alignof__ (struct _pthread_descr_struct)
  64
  65 /* This is the size of the TCB.  */
  66 #  define TLS_TCB_SIZE          0
  67
  68 /* Alignment requirements for the TCB.  */
  69 #  define TLS_TCB_ALIGN         __alignof__ (struct _pthread_descr_struct)
  70
  71 /* This is the size we need before TCB.  */
  72 #  ifndef IS_IN_rtld
  73 #   define TLS_PRE_TCB_SIZE \
  74   (sizeof (struct _pthread_descr_struct)                                      \
  75    + ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
  76 #  else
  77 #   include <nptl-struct-pthread.h>
  78 #   define TLS_PRE_TCB_SIZE \
  79   ((sizeof (struct _pthread_descr_struct) > NPTL_STRUCT_PTHREAD_SIZE          \
  80     ? sizeof (struct _pthread_descr_struct) : NPTL_STRUCT_PTHREAD_SIZE)       \
  81    + ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
  82 #  endif
  83
  84 /* The following assumes that TP (R2 or R13) points to the end of the
  85    TCB + 0x7000 (per the ABI).  This implies that TCB address is
  86    TP - 0x7000.  As we define TLS_DTV_AT_TP we can
  87    assume that the pthread_descr is allocated immediately ahead of the
  88    TCB.  This implies that the pthread_descr address is
  89    TP - (TLS_PRE_TCB_SIZE + 0x7000).  */
  90 #define TLS_TCB_OFFSET          0x7000
  91
  92 /* The DTV is allocated at the TP; the TCB is placed elsewhere.  */
  93 /* This is not really true for powerpc64.  We are following alpha
  94    where the DTV pointer is first doubleword in the TCB.  */
  95 #  define TLS_DTV_AT_TP 1
  96
  97 /* Install the dtv pointer.  The pointer passed is to the element with
  98    index -1 which contain the length.  */
  99 #  define INSTALL_DTV(TCBP, DTVP) \
 100   (((tcbhead_t *) (TCBP))[-1].dtv = (DTVP) + 1)
 101
 102 /* Install new dtv for current thread.  */
 103 #  define INSTALL_NEW_DTV(DTV) (THREAD_DTV() = (DTV))
 104
 105 /* Return dtv of given thread descriptor.  */
 106 #  define GET_DTV(TCBP) (((tcbhead_t *) (TCBP))[-1].dtv)
 107
 108 /* We still need this define so that tcb-offsets.sym can override it and
 109    use THREAD_SELF to generate MULTIPLE_THREADS_OFFSET.  */
 110 #  define __thread_register ((void *) __thread_self)
 111
 112 /* Code to initially initialize the thread pointer.  This might need
 113    special attention since 'errno' is not yet available and if the
 114    operation can cause a failure 'errno' must not be touched.
 115
 116    The global register variable is declared in pt-machine.h with the
 117    wrong type, so we need some extra casts to get the desired result.
 118    This avoids a lvalue cast that gcc-3.4 does not like.  */
 119 # define TLS_INIT_TP(TCBP, SECONDCALL) \
 120     (__thread_self = (struct _pthread_descr_struct *) \
 121         ((void *) (TCBP) + TLS_TCB_OFFSET), NULL)
 122
 123 /* Return the address of the dtv for the current thread.  */
 124 #  define THREAD_DTV() \
 125      (((tcbhead_t *) ((void *) __thread_self - TLS_TCB_OFFSET))[-1].dtv)
 126
 127 /* Return the thread descriptor for the current thread.  */
 128 #  undef THREAD_SELF
 129 #  define THREAD_SELF \
 130     ((pthread_descr) (__thread_register \
 131                       - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
 132
 133 #  undef INIT_THREAD_SELF
 134 #  define INIT_THREAD_SELF(DESCR, NR) \
 135      (__thread_self = (struct _pthread_descr_struct *)((void *) (DESCR) \
 136                            + TLS_TCB_OFFSET + TLS_PRE_TCB_SIZE))
 137
 138 /* Make sure we have the p_multiple_threads member in the thread structure.
 139    See below.  */
 140 #  define TLS_MULTIPLE_THREADS_IN_TCB 1
 141
 142 /* Get the thread descriptor definition.  */
 143 #  include <linuxthreads/descr.h>
 144
 145 /* l_tls_offset == 0 is perfectly valid on PPC, so we have to use some
 146    different value to mean unset l_tls_offset.  */
 147 #  define NO_TLS_OFFSET -1
 148
 149 # endif /* __ASSEMBLER__ */
 150
 151 #elif !defined __ASSEMBLER__
 152
 153 /* This overlaps the start of the pthread_descr.  System calls
 154    and such use this to find the multiple_threads flag and need
 155    to use the same offset relative to the thread register in both
 156    single-threaded and multi-threaded code.  */
 157 typedef struct
 158 {
 159   void *tcb;                    /* Never used.  */
 160   dtv_t *dtv;                   /* Never used.  */
 161   void *self;                   /* Used only if multithreaded, and rarely.  */
 162   int multiple_threads;         /* Only this member is really used.  */
 163 } tcbhead_t;
 164
 165 #define NONTLS_INIT_TP                                                  \
 166   do {                                                                  \
 167     static const tcbhead_t nontls_init_tp = { .multiple_threads = 0 };  \
 168     __thread_self = (__typeof (__thread_self)) &nontls_init_tp;         \
 169   } while (0)
 170
 171 #endif /* HAVE_TLS_SUPPORT */
 172
 173 #endif  /* tls.h */