linuxthreads_db/td_thr_tlsbase.c

   1 /* Locate TLS data for a thread.
   2    Copyright (C) 2003, 2004 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 #include "thread_dbP.h"
  21 #include <dl-tls.h>
  22
  23 /* Value used for dtv entries for which the allocation is delayed.  */
  24 # define TLS_DTV_UNALLOCATED    ((void *) -1l)
  25
  26 td_err_e
  27 td_thr_tlsbase (const td_thrhandle_t *th,
  28                 unsigned long int modid,
  29                 psaddr_t *base)
  30 {
  31   if (modid < 1)
  32     return TD_NOTLS;
  33
  34 #if USE_TLS
  35   union dtv pdtv, *dtvp;
  36
  37   LOG ("td_thr_tlsbase");
  38
  39   psaddr_t dtvpp = th->th_unique;
  40 #if TLS_TCB_AT_TP
  41   dtvpp += offsetof (struct _pthread_descr_struct, p_header.data.dtvp);
  42 #elif TLS_DTV_AT_TP && TLS_TP_OFFSET > 0
  43 /* Special case hack.  Really this #if should be TLS_TCB_SIZE == 0, but
  44    when untrue it's a sizeof expression, and that wouldn't fly.  In this
  45    flavor (PowerPC), there is no TCB containing the DTV at the TP, but
  46    actually the TCB lies behind the TP, i.e. at the very end of the area
  47    covered by TLS_PRE_TCB_SIZE.  */
  48   dtvpp += TLS_PRE_TCB_SIZE - sizeof (tcbhead_t) + offsetof (tcbhead_t, dtv);
  49 #elif TLS_DTV_AT_TP
  50   dtvpp += TLS_PRE_TCB_SIZE + offsetof (tcbhead_t, dtv);
  51 #else
  52 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined."
  53 #endif
  54
  55   /* Get the DTV pointer from the thread descriptor.  */
  56   if (ps_pdread (th->th_ta_p->ph, dtvpp, &dtvp, sizeof dtvp) != PS_OK)
  57     return TD_ERR;      /* XXX Other error value?  */
  58
  59   /* Get the corresponding entry in the DTV.  */
  60   if (ps_pdread (th->th_ta_p->ph, dtvp + modid,
  61                  &pdtv, sizeof (union dtv)) != PS_OK)
  62     return TD_ERR;      /* XXX Other error value?  */
  63
  64   /* It could be that the memory for this module is not allocated for
  65      the given thread.  */
  66   if (pdtv.pointer == TLS_DTV_UNALLOCATED)
  67     return TD_TLSDEFER;
  68
  69   *base = (char *) pdtv.pointer;
  70
  71   return TD_OK;
  72 #else
  73   return TD_ERR;
  74 #endif
  75 }