1  /* Special .init and .fini section support.
       2     Copyright (C) 1997-2023 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     In addition to the permissions in the GNU Lesser General Public
      11     License, the Free Software Foundation gives you unlimited
      12     permission to link the compiled version of this file with other
      13     programs, and to distribute those programs without any restriction
      14     coming from the use of this file.  (The Lesser General Public
      15     License restrictions do apply in other respects; for example, they
      16     cover modification of the file, and distribution when not linked
      17     into another program.)
      18  
      19     The GNU C Library is distributed in the hope that it will be useful,
      20     but WITHOUT ANY WARRANTY; without even the implied warranty of
      21     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      22     Lesser General Public License for more details.
      23  
      24     You should have received a copy of the GNU Lesser General Public
      25     License along with the GNU C Library; if not, see
      26     <https://www.gnu.org/licenses/>.  */
      27  
      28  /* Define an ELF note identifying the operating-system ABI that the
      29     executable was created for.  The ELF note information identifies a
      30     particular OS or coordinated development effort within which the
      31     ELF header's e_machine value plus (for dynamically linked programs)
      32     the PT_INTERP dynamic linker name and DT_NEEDED shared library
      33     names fully identify the runtime environment required by an
      34     executable.
      35  
      36     The general format of ELF notes is as follows.
      37     Offsets and lengths are bytes or (parenthetical references) to the
      38     values in other fields.
      39  
      40  offset	length	contents
      41  0	4	length of name
      42  4	4	length of data
      43  8	4	note type
      44  12	(0)	vendor name
      45  		- null-terminated ASCII string, padded to 4-byte alignment
      46  12+(0)	(4)	note data,
      47  
      48     The GNU project and cooperating development efforts (including the
      49     Linux community) use note type 1 and a vendor name string of "GNU"
      50     for a note descriptor that indicates ABI requirements.  The note data
      51     is four 32-bit words.  The first of these is an operating system
      52     number (0=Linux, 1=Hurd, 2=Solaris, ...) and the remaining three
      53     identify the earliest release of that OS that supports this ABI.
      54     See abi-tags (top level) for details. */
      55  
      56  #include <link.h>
      57  #include <stdint.h>
      58  #include <config.h>
      59  #include <abi-tag.h>		/* OS-specific ABI tag value */
      60  
      61  /* The linker (GNU ld 2.8 and later) recognizes an allocated section whose
      62     name begins with `.note' and creates a PT_NOTE program header entry
      63     pointing at it. */
      64  
      65  __attribute__ ((used, aligned (4), section (".note.ABI-tag")))
      66  static const struct
      67  {
      68    ElfW(Nhdr) nhdr;
      69    char name[4];
      70    int32_t desc[4];
      71  } __abi_tag = {
      72    { .n_namesz = sizeof __abi_tag.name,
      73      .n_descsz = sizeof __abi_tag.desc,
      74      .n_type = 1 },
      75    "GNU",
      76    { __ABI_TAG_OS, __ABI_TAG_VERSION }
      77  };