Adjust for new NaCl startup ABI

sysdeps/x86_64/dl-machine.h

 /* Machine-dependent ELF dynamic relocation inline functions.  x86-64 version.
    Copyright (C) 2001-2005, 2006 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Andreas Jaeger <aj@suse.de>.
 
    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.
 
@@ skipping 134 matching lines @@
       = (Elf64_Addr) &_dl_tlsdesc_resolve_rela;
 
   return lazy;
 }
 
 /* Initial entry point code for the dynamic linker.
    The C function `_dl_start' is the real entry point;
    its return value is the user program's entry point.  */
 
 #ifdef __native_client__
-#define ARGV_ENTRY_SIZE_STR "4"
-#define ARGC_SIZE_PLUS_ARGV_ENTRY_SIZE_STR "12"
-#define ADJUST_SP \
-    "leaq (%rsp,%rax,"ARGV_ENTRY_SIZE_STR"), %r13\n" \
-    "naclrestsp %r13d, %r15"
-#define CLEAR_BP "naclrestbp $0, %r15"
-#define MOV_R13_SP "naclrestsp %r13d, %r15"
-#define JMP_R12 "nacljmp %r12d, %r15"
+
+/* We're started with the normal C ABI for a one-argument function.
+   Our version of _dl_start runs the user's entry point directly, rather
+   than returning it.  Since the NaCl trusted runtime starts us up with
+   the registers set up for a normal C function call of one argument,
+   we can just go directly into _dl_start with no adjustment.  */
+
+#define RTLD_START asm("\n\
+.globl _start\n\
+.set _start, _dl_start\n\
+");
 
 #else
-#define ARGV_ENTRY_SIZE_STR "8"
-#define ARGC_SIZE_PLUS_ARGV_ENTRY_SIZE_STR "16"
-#define ADJUST_SP \
-    "leaq (%rsp,%rax,"ARGV_ENTRY_SIZE_STR"), %rsp"
-#define CLEAR_BP "xorl %ebp, %ebp"
-#define MOV_R13_SP "movq %r13, %rsp"
-#define JMP_R12 "jmp *%r12"
-#endif
 
 #define RTLD_START asm ("\n\
 .text\n\
         .align 16\n\
 .globl _start\n\
 .globl _dl_start_user\n\
 _start:\n\
         movq %rsp, %rdi\n\
         call _dl_start\n\
 _dl_start_user:\n\
@@ skipping 29 matching lines @@
         call _dl_init_internal@PLT\n\
         # Pass our finalizer function to the user in %rdx, as per ELF ABI.\n\
         leaq _dl_fini(%rip), %rdx\n\
         # And make sure %rsp points to argc stored on the stack.\n\
         "MOV_R13_SP"\n\
         # Jump to the user's entry point.\n\
         "JMP_R12"\n\
 .previous\n\
 ");
 
+#endif
+
 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
    TLS variable, so undefined references should not be allowed to
    define the value.
    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
    of the main executable's symbols, as for a COPY reloc.  */
 #if !defined RTLD_BOOTSTRAP || USE___THREAD
 # define elf_machine_type_class(type)                                         \
   ((((type) == R_X86_64_JUMP_SLOT                                             \
      || (type) == R_X86_64_DTPMOD64                                           \
      || (type) == R_X86_64_DTPOFF64                                           \
@@ skipping 285 matching lines @@
 
       td->arg = (void*)reloc;
       td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)])
                           + map->l_addr);
     }
   else
     _dl_reloc_bad_type (map, r_type, 1);
 }
 
 #endif /* RESOLVE_MAP */