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Use __ehdr_start, if available, as fallback for AT_PHDR.

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This commit is contained in:
Roland McGrath 2013-03-28 16:15:48 -07:00
parent dc0a026385
commit 288f7d79fe
3 changed files with 38 additions and 8 deletions
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6
ChangeLog
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@ -1,5 +1,11 @@
2013-03-28 Roland McGrath <roland@hack.frob.com>
* csu/libc-start.c (__libc_start_main) [!SHARED]: If _dl_aux_init
didn't do it already, then set _dl_phdr and _dl_phnum based on the
magic __ehdr_start linker symbol if it's defined.
* sysdeps/mach/hurd/i386/init-first.c (init1) [!SHARED]: Don't set
them up here if it was already done.
* elf/dl-support.c (_dl_phdr): Make pointer to const.
(_dl_aux_init): Use const in cast when setting it.
* sysdeps/mach/hurd/i386/init-first.c (init1): Remove superfluous cast.

18
csu/libc-start.c
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@ -15,6 +15,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
@ -151,7 +152,24 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
}
# endif
_dl_aux_init (auxvec);
if (GL(dl_phdr) == NULL)
# endif
{
/* Starting from binutils-2.23, the linker will define the
magic symbol __ehdr_start to point to our own ELF header
if it is visible in a segment that also includes the phdrs.
So we can set up _dl_phdr and _dl_phnum even without any
information from auxv. */
extern const ElfW(Ehdr) __ehdr_start __attribute__ ((weak));
if (&__ehdr_start != NULL)
{
assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
GL(dl_phnum) = __ehdr_start.e_phnum;
}
}
# ifdef DL_SYSDEP_OSCHECK
if (!__libc_multiple_libcs)
{

6
sysdeps/mach/hurd/i386/init-first.c
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@ -117,6 +117,11 @@ init1 (int argc, char *arg0, ...)
if ((void *) d == argv[0])
{
#ifndef SHARED
/* With a new enough linker (binutils-2.23 or better),
the magic __ehdr_start symbol will be available and
__libc_start_main will have done this that way already. */
if (_dl_phdr == NULL)
{
/* 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. */
@ -125,6 +130,7 @@ init1 (int argc, char *arg0, ...)
_dl_phdr = (const void *) ehdr + ehdr->e_phoff;
_dl_phnum = ehdr->e_phnum;
assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
}
#endif
return;
}