/* Locate TLS data for a thread.
   Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include "thread_dbP.h"
#include <dl-tls.h>

/* Value used for dtv entries for which the allocation is delayed.  */
# define TLS_DTV_UNALLOCATED	((void *) -1l)

td_err_e
td_thr_tlsbase (const td_thrhandle_t *th,
		unsigned long int modid,
		psaddr_t *base)
{
  if (modid < 1)
    return TD_NOTLS;

#if USE_TLS
  union dtv pdtv, *dtvp;

  LOG ("td_thr_tlsbase");

  psaddr_t dtvpp = th->th_unique;
#if TLS_TCB_AT_TP
  dtvpp += offsetof (struct _pthread_descr_struct, p_header.data.dtvp);
#elif TLS_DTV_AT_TP && TLS_TP_OFFSET > 0
/* Special case hack.  Really this #if should be TLS_TCB_SIZE == 0, but
   when untrue it's a sizeof expression, and that wouldn't fly.  In this
   flavor (PowerPC), there is no TCB containing the DTV at the TP, but
   actually the TCB lies behind the TP, i.e. at the very end of the area
   covered by TLS_PRE_TCB_SIZE.  */
  dtvpp += TLS_PRE_TCB_SIZE - sizeof (tcbhead_t) + offsetof (tcbhead_t, dtv);
#elif TLS_DTV_AT_TP
  dtvpp += TLS_PRE_TCB_SIZE + offsetof (tcbhead_t, dtv);
#else
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined."
#endif

  /* Get the DTV pointer from the thread descriptor.  */
  if (ps_pdread (th->th_ta_p->ph, dtvpp, &dtvp, sizeof dtvp) != PS_OK)
    return TD_ERR;	/* XXX Other error value?  */

  /* Get the corresponding entry in the DTV.  */
  if (ps_pdread (th->th_ta_p->ph, dtvp + modid,
		 &pdtv, sizeof (union dtv)) != PS_OK)
    return TD_ERR;	/* XXX Other error value?  */

  /* It could be that the memory for this module is not allocated for
     the given thread.  */
  if (pdtv.pointer == TLS_DTV_UNALLOCATED)
    return TD_TLSDEFER;

  *base = (char *) pdtv.pointer;

  return TD_OK;
#else
  return TD_ERR;
#endif
}