[Bug dynamic-link/18422] elf/tst-audit tests fail without PLT entries

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https://sourceware.org/bugzilla/show_bug.cgi?id=18422

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=58007e9e68913290b1f4f73afc1055f779a8ed5d

commit 58007e9e68913290b1f4f73afc1055f779a8ed5d
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu May 28 05:06:27 2015 -0700

    Make sure that calloc is called at least once

    PLT relocations aren't required when -z now used.  Linker on master with:

    commit 25070364b0ce33eed46aa5d78ebebbec6accec7e
    Author: H.J. Lu <hjl.tools@gmail.com>
    Date:   Sat May 16 07:00:21 2015 -0700

        Don't generate PLT relocations for now binding

        There is no need for PLT relocations with -z now. We can use GOT
        relocations, which take less space, instead and replace 16-byte .plt
        entres with 8-byte .plt.got entries.

        bfd/

          * elf32-i386.c (elf_i386_check_relocs): Create .plt.got section
          for now binding.
          (elf_i386_allocate_dynrelocs): Use .plt.got section for now
          binding.
          * elf64-x86-64.c (elf_x86_64_check_relocs): Create .plt.got
          section for now binding.
          (elf_x86_64_allocate_dynrelocs): Use .plt.got section for now
          binding.

    won't generate PLT relocations with -z now.  elf/tst-audit2.c expect
    certain order of execution in ld.so. ïWith PLT relocations, the GOTPLT
    entry of calloc is update to calloc defined in tst-audit2:

    (gdb) bt
    ï ï skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,
    ï ï version=<optimized out>, sym=<optimized out>, map=<optimized out>)
    ï ï at ../sysdeps/i386/dl-machine.h:329
    out>,
    ï ï nrelative=<optimized out>, relsize=<optimized out>,
    ï ï reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137
    reloc_mode=reloc_mode@entry=0,
    ï ï consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258
    ï ï user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133
    ï ï start_argptr=start_argptr@entry=0xffffcfb0,
    ï ï dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at
    ../elf/dl-sysdep.c:249
    ï ïfrom /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so
    (gdb)

    and then calloc is called:

    (gdb) c
    Continuing.

    Breakpoint 4, calloc (n=n@entry=20, m=4) at tst-audit2.c:18
    18 {
    (gdb) bt
    ï ï reloc_mode=reloc_mode@entry=0, consider_profiling=1,
    ï ï consider_profiling@entry=0) at dl-reloc.c:272
    ï ï user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133
    ï ï start_argptr=start_argptr@entry=0xffffcfb0,
    ï ï dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at
    ../elf/dl-sysdep.c:249
    ï ïfrom /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so
    (gdb)

    With GOT relocation, calloc in ld.so is called first:

    (gdb) bt
    ï ï consider_profiling=1) at dl-reloc.c:272
    ï ï user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2074
    ï ï start_argptr=start_argptr@entry=0xffffcfa0,
    ï ï dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at
    ../elf/dl-sysdep.c:249
    ï ïfrom /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so
    (gdb)

    and then the GOT entry of calloc is updated:

    (gdb) bt
    ï ï skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,
    ï ï version=<optimized out>, sym=<optimized out>, map=<optimized out>)
    ï ï at ../sysdeps/i386/dl-machine.h:329
    out>,
    ï ï nrelative=<optimized out>, relsize=<optimized out>,
    ï ï reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137
    reloc_mode=reloc_mode@entry=0,
    ï ï consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258
    ï ï user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2133
    ï ï start_argptr=start_argptr@entry=0xffffcfa0,
    ï ï dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at
    ../elf/dl-sysdep.c:249
    ï ïfrom /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so
    (gdb)

    After that, since calloc isn't called from ld.so nor any other modules,
    magic in tst-audit2 isn't updated. ïBoth orders are correct.  This patch
    makes sure that calloc in tst-audit2.c is called at least once from ld.so.

        [BZ #18422]
        * Makefile ($(objpfx)tst-audit2): Depend on $(libdl).
        ($(objpfx)tst-audit2.out): Also depend on
        $(objpfx)tst-auditmod9b.so.
        * elf/tst-audit2.c: Include <dlfcn.h>.
        (calloc_called): New.
        (calloc): Allow to be called more than once.
        (do_test): dllopen/dlclose $ORIGIN/tst-auditmod9b.so.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog        |   11 +++++++++++
 NEWS             |    2 +-
 elf/Makefile     |    3 ++-
 elf/tst-audit2.c |   26 ++++++++++++++++++++------
 4 files changed, 34 insertions(+), 8 deletions(-)

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