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glibc  2.9
td_thr_tlsbase.c File Reference
#include "thread_dbP.h"

Go to the source code of this file.


td_err_e td_thr_tlsbase (const td_thrhandle_t *th, unsigned long int modid, psaddr_t *base)

Function Documentation

td_err_e td_thr_tlsbase ( const td_thrhandle_t th,
unsigned long int  modid,
psaddr_t base 

Definition at line 23 of file td_thr_tlsbase.c.

  td_err_e err;
  psaddr_t dtv, dtvslot, dtvptr;

  if (modid < 1)
    return TD_NOTLS;

  psaddr_t pd = th->th_unique;
  if (pd == 0)
      /* This is the fake handle for the main thread before libpthread
        initialization.  We are using 0 for its th_unique because we can't
        trust that its thread register has been initialized.  But we need
        a real pointer to have any TLS access work.  In case of dlopen'd
        libpthread, initialization might not be for quite some time.  So
        try looking up the thread register now.  Worst case, it's nonzero
        uninitialized garbage and we get bogus results for TLS access
        attempted too early.  Tough.  */

      td_thrhandle_t main_th;
      err = __td_ta_lookup_th_unique (th->th_ta_p, ps_getpid (th->th_ta_p->ph),
      if (err == 0)
       pd = main_th.th_unique;
      if (pd == 0)
       return TD_TLSDEFER;

  /* Get the DTV pointer from the thread descriptor.  */
  err = DB_GET_FIELD (dtv, th->th_ta_p, pd, pthread, dtvp, 0);
  if (err != TD_OK)
    return err;

  /* Find the corresponding entry in the DTV.  */
  err = DB_GET_FIELD_ADDRESS (dtvslot, th->th_ta_p, dtv, dtv, dtv, modid);
  if (err != TD_OK)
    return err;

  /* Extract the TLS block address from that DTV slot.  */
  err = DB_GET_FIELD (dtvptr, th->th_ta_p, dtvslot, dtv_t, pointer_val, 0);
  if (err != TD_OK)
    return err;

  /* It could be that the memory for this module is not allocated for
     the given thread.  */
  if ((uintptr_t) dtvptr & 1)
    return TD_TLSDEFER;

  *base = dtvptr;
  return TD_OK;

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