Adjust for new NaCl startup ABI

elf/rtld.c

 /* Run time dynamic linker.
    Copyright (C) 1995-2006, 2007, 2008 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,
@@ skipping 532 matching lines @@
      therefore need not test whether we have to allocate the array
      for the relocation results (as done in dl-reloc.c).  */
 
   /* Now life is sane; we can call functions and access global data.
      Set up to use the operating system facilities, and find out from
      the operating system's program loader where to find the program
      header table in core.  Put the rest of _dl_start into a separate
      function, that way the compiler cannot put accesses to the GOT
      before ELF_DYNAMIC_RELOCATE.  */
 
-  struct process_args *ipc_args = argmsg_fetch ();
-  if (ipc_args != NULL)
-    {
-      /* Because code following the ELF ABI expects to find the argv
-         and env arrays on the stack, this is a little convoluted
-         because we have to allocate stack space here.  */
-      size_t size = argmsg_get_size_on_stack (ipc_args);
-      arg = alloca (size);
-      argmsg_move_to_stack (ipc_args, arg, size);
-    }
+  /* If we are getting arguments and environment from IPC rather from the
+     startup stack, this will replace ARG with a new mmap'd pointer.
+
+     Keeping _dl_starting_up set lets _dl_*printf calls work.  */
+  int starting = INTUSE(_dl_starting_up);
+  INTUSE(_dl_starting_up) = 1;
+  arg = argmsg_fetch(arg);
+  INTUSE(_dl_starting_up) = starting;
 
   {
 #ifdef DONT_USE_BOOTSTRAP_MAP
     ElfW(Addr) entry = _dl_start_final (arg);
 #else
     ElfW(Addr) entry = _dl_start_final (arg, &info);
 #endif
 
 #ifndef ELF_MACHINE_START_ADDRESS
 # define ELF_MACHINE_START_ADDRESS(map, start) (start)
 #endif
 
     struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
     uintptr_t entry_point = ELF_MACHINE_START_ADDRESS (main_map, entry);
 
-    if (ipc_args != NULL)
-      {
-        /* This copies the logic of _start in dl-machine.h, but in C
-           rather than assembly.  */
+    /* This roughly copies the logic of _start in dl-machine.h, but in C
+       rather than assembly.  We are adjusting the NaCl startup information
+       block rather than the traditional Unix/ELF stack setup.  */
+    uint32_t *arginfo = arg;
+    int envc = arginfo[1];
+    int argc = arginfo[2] - _dl_skip_args;
+    arginfo += _dl_skip_args;
+    arginfo[0] = (uintptr_t) &_dl_fini;
+    arginfo[1] = envc;
+    arginfo[2] = argc;
+    char **argv = (void *) &arginfo[3];
+    char **envp = &argv[argc + 1];
+    _dl_init (main_map, argc, argv, envp);
+    (*(void (*)(uint32_t *)) entry_point) (arginfo);
+    /*NOTREACHED*/
 
-        /* Adjust for skipped arguments.  */
-        int argc = *(argc_type *) arg;
-        argc -= _dl_skip_args;
-        arg = (char **) arg + _dl_skip_args;
-        *(argc_type *) arg = argc;
-
-        char **argv = (char **) ((argc_type *) arg + 1);
-        char **envp = argv + argc + 1;
-        _dl_init (main_map, argc, argv, envp);
-
-        jump_to_elf_start (arg, entry_point, (uintptr_t) _dl_fini);
-      }
-    else
-      return entry_point;
+    return entry_point;
   }
 }
 
 
 
 /* Now life is peachy; we can do all normal operations.
    On to the real work.  */
 
 /* Some helper functions.  */
 
@@ skipping 2258 matching lines @@
           *wp++ = '.';
           *wp++ = *cp++;
         }
       *wp = '\0';
       _dl_debug_printf ("\
            time needed to load objects: %s (%s%%)\n",
                                 buf, pbuf);
     }
 #endif
 }