lib/csu/common/crtbrand.c

   1 /*-
   2  * Copyright 1996, 1997, 1998, 2000 John D. Polstra.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/lib/csu/common/crtbrand.c SVN 232832 2012/03/11 kib $
  26  */
  27
  28 #include <sys/param.h>
  29 #include "notes.h"
  30
  31 /*
  32  * Special ".note" entry specifying the ABI version.  See
  33  * http://www.netbsd.org/Documentation/kernel/elf-notes.html
  34  * for more information.
  35  *
  36  * For all arches except sparc, gcc emits the section directive for the
  37  * following struct with a PROGBITS type.  However, newer versions of binutils
  38  * (after 2.16.90) require the section to be of NOTE type, to guarantee that the
  39  * .note.ABI-tag section correctly ends up in the first page of the final
  40  * executable.
  41  *
  42  * Unfortunately, there is no clean way to tell gcc to use another section type,
  43  * so this C file (or the C file that includes it) must be compiled in multiple
  44  * steps:
  45  *
  46  * - Compile the .c file to a .s file.
  47  * - Edit the .s file to change the 'progbits' type to 'note', for the section
  48  *   directive that defines the .note.ABI-tag section.
  49  * - Compile the .s file to an object file.
  50  *
  51  * These steps are done in the individual Makefiles for each applicable arch.
  52  */
  53 static const struct {
  54         int32_t namesz;
  55         int32_t descsz;
  56         int32_t type;
  57         char    name[sizeof(NOTE_VENDOR)];
  58         int32_t desc;
  59 } abitag __attribute__ ((section (NOTE_SECTION),
  60     aligned(4))) __attribute__ ((used)) = {
  61         .namesz = sizeof(NOTE_VENDOR),
  62         .descsz = sizeof(int32_t),
  63         .type = ABI_NOTETYPE,
  64         .name = NOTE_VENDOR,
  65         .desc = __DragonFly_version
  66 };