linuxthreads/sysdeps/powerpc/tls.h

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