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Re: __executable_start (was: [bug #17644] glibc: support for TLS)
From: |
Anatoly A. Kazantsev |
Subject: |
Re: __executable_start (was: [bug #17644] glibc: support for TLS) |
Date: |
Sun, 26 May 2013 22:11:51 +0400 |
On Sun, 26 May 2013 16:38:23 +0200
Thomas Schwinge <thomas@codesourcery.com> wrote:
> Hi!
>
> Re-submitting an oldie of Samuel's:
>
> On Sun, 24 Jun 2007 17:45:35 +0200, Samuel Thibault
> <samuel.thibault@ens-lyon.org> wrote:
> > - _start points on the first instruction, not on the elf header.
> > __executable_start does point on the elf header.
>
> > --- sysdeps/mach/hurd/i386/init-first.c.orig 2007-06-23
> > 19:27:14.000000000 +0000
> > +++ sysdeps/mach/hurd/i386/init-first.c 2007-06-23 21:41:40.000000000
> > +0000
> > @@ -116,14 +116,14 @@
> > /* We may need to see our own phdrs, e.g. for TLS setup.
> > Try the usual kludge to find the headers without help from
> > the exec server. */
> > - extern const void _start;
> > - const ElfW(Ehdr) *const ehdr = &_start;
> > + extern const void __executable_start;
> > + const ElfW(Ehdr) *const ehdr = &__executable_start;
> > _dl_phdr = (ElfW(Phdr) *) ((const void *) ehdr + ehdr->e_phoff);
> > _dl_phnum = ehdr->e_phnum;
> > assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
>
> This is, as far as I can tell, the only such usage of _start in glibc.
>
> OK to commit?
>
> * sysdeps/mach/hurd/i386/init-first.c (init1): Use
> __executable_start symbol intsead instead of _start.
>
> diff --git sysdeps/mach/hurd/i386/init-first.c
> sysdeps/mach/hurd/i386/init-first.c
> index fc3330c..7031ed4 100644
> --- sysdeps/mach/hurd/i386/init-first.c
> +++ sysdeps/mach/hurd/i386/init-first.c
> @@ -125,8 +125,8 @@ init1 (int argc, char *arg0, ...)
> /* We may need to see our own phdrs, e.g. for TLS setup.
> Try the usual kludge to find the headers without help from
> the exec server. */
> - extern const void _start;
> - const ElfW(Ehdr) *const ehdr = &_start;
> + extern const void __executable_start;
> + const ElfW(Ehdr) *const ehdr = &__executable_start;
> _dl_phdr = (const void *) ehdr + ehdr->e_phoff;
> _dl_phnum = ehdr->e_phnum;
> assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
>
>
> Grüße,
> Thomas
--
Regards,
Anatoly
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