sysdeps/nacl/dl-sysdep.c

   1 /* Operating system support for run-time dynamic linker.  NaCl version.
   2    Copyright (C) 2015 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifdef SHARED
  20
  21 # include <assert.h>
  22 # include <ldsodefs.h>
  23 # include <stdint.h>
  24 # include <nacl-interfaces.h>
  25
  26 /* NaCl's elf32.h is incompatible with the real <elf.h>.  */
  27 # define NATIVE_CLIENT_SRC_INCLUDE_ELF32_H_
  28 # include <native_client/src/untrusted/nacl/nacl_startup.h>
  29
  30 /* The RTLD_START code sets up the pointer that gets to these
  31    macros as COOKIE to point to two words:
  32    [0] the argument to the entry point from the system (see nacl_startup.h)
  33    [1] the stack base
  34 */
  35
  36 # define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp) \
  37   do {                                                          \
  38     uint32_t *_info = ((void **) (cookie))[0];                  \
  39     (argc) = nacl_startup_argc (_info);                         \
  40     (argv) = nacl_startup_argv (_info);                         \
  41     (envp) = nacl_startup_envp (_info);                         \
  42     (auxp) = nacl_startup_auxv (_info);                         \
  43   } while (0)
  44
  45 # define DL_STACK_END(cookie)   (((void **) (cookie))[1])
  46
  47 /* This is called from the entry point (_start), defined by the RTLD_START
  48    macro in the machine-specific dl-machine.h file.  At this point, dynamic
  49    linking has been completed and the first argument is the application's
  50    entry point.  */
  51 attribute_hidden internal_function __attribute__ ((noreturn))
  52 void
  53 _dl_start_user (void (*user_entry) (uint32_t info[]), uint32_t info[])
  54 {
  55   if (_dl_skip_args > 0)
  56     {
  57       /* There are some arguments that the user program should not see.
  58          Just slide up the INFO pointer so its NACL_STARTUP_ARGV points
  59          to what should now be argv[0], and copy back the earlier fields.  */
  60       assert (nacl_startup_argc (info) >= _dl_skip_args);
  61       assert (NACL_STARTUP_ARGV == 3);
  62       uint32_t envc = info[NACL_STARTUP_ENVC];
  63       uint32_t argc = info[NACL_STARTUP_ARGC];
  64       info += _dl_skip_args;
  65       info[NACL_STARTUP_ENVC] = envc;
  66       info[NACL_STARTUP_ARGC] = argc - _dl_skip_args;
  67     }
  68
  69   /* Pass our finalizer function to the user.  */
  70   info[NACL_STARTUP_FINI] = (uintptr_t) &_dl_fini;
  71
  72   /* Run initializers.  */
  73   _dl_init (GL(dl_ns)[0]._ns_loaded,
  74             nacl_startup_argc (info),
  75             nacl_startup_argv (info),
  76             nacl_startup_envp (info));
  77
  78   /* Call the user's entry point.  This should never return.  */
  79   (*user_entry) (info);
  80
  81   /* Fail clearly just in case it did return.  */
  82   __builtin_trap ();
  83 }
  84
  85 # define DL_SYSDEP_INIT __nacl_initialize_interfaces ()
  86
  87 #endif  /* SHARED */
  88
  89 #include <elf/dl-sysdep.c>