elf/dl-debug.c

   1 /* Communicate dynamic linker state to the debugger at runtime.
   2    Copyright (C) 1996, 1998,2000,2002,2004,2005 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 #include <ldsodefs.h>
  21
  22 /* This structure communicates dl state to the debugger.  The debugger
  23    normally finds it via the DT_DEBUG entry in the dynamic section, but in
  24    a statically-linked program there is no dynamic section for the debugger
  25    to examine and it looks for this particular symbol name.  */
  26 struct r_debug _r_debug;
  27
  28
  29 /* Initialize _r_debug if it has not already been done.  The argument is
  30    the run-time load address of the dynamic linker, to be put in
  31    _r_debug.r_ldbase.  Returns the address of _r_debug.  */
  32
  33 struct r_debug *
  34 internal_function
  35 _dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
  36 {
  37   struct r_debug *r;
  38
  39   if (ns == LM_ID_BASE)
  40     r = &_r_debug;
  41   else
  42     r = &GL(dl_ns)[ns]._ns_debug;
  43
  44   if (r->r_brk == 0 || ldbase != 0)
  45     {
  46       /* Tell the debugger where to find the map of loaded objects.  */
  47       r->r_version = 1  /* R_DEBUG_VERSION XXX */;
  48       r->r_ldbase = ldbase ?: _r_debug.r_ldbase;
  49       r->r_map = GL(dl_ns)[ns]._ns_loaded;
  50       r->r_brk = (ElfW(Addr)) &_dl_debug_state;
  51     }
  52
  53   return r;
  54 }
  55
  56
  57 /* This function exists solely to have a breakpoint set on it by the
  58    debugger.  The debugger is supposed to find this function's address by
  59    examining the r_brk member of struct r_debug, but GDB 4.15 in fact looks
  60    for this particular symbol name in the PT_INTERP file.  */
  61 void
  62 _dl_debug_state (void)
  63 {
  64 }
  65 rtld_hidden_def (_dl_debug_state)