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authorRoland McGrath <roland@hack.frob.com>2013-03-28 16:15:48 -0700
committerRoland McGrath <roland@hack.frob.com>2013-03-28 16:15:48 -0700
commit288f7d79fe2dcc8e62c539f57b25d7662a2cd5ff (patch)
tree01fbd48750047a5246b6bcc6d6551eb18bbdd4e3
parentdc0a02638583d8e7f7e1cc72643d1b26ec6042fd (diff)
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Use __ehdr_start, if available, as fallback for AT_PHDR.
-rw-r--r--ChangeLog6
-rw-r--r--csu/libc-start.c18
-rw-r--r--sysdeps/mach/hurd/i386/init-first.c22
3 files changed, 38 insertions, 8 deletions
diff --git a/ChangeLog b/ChangeLog
index de20ebb..876b577 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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.
diff --git a/csu/libc-start.c b/csu/libc-start.c
index 9c4c01d..fa9085c 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -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)
{
diff --git a/sysdeps/mach/hurd/i386/init-first.c b/sysdeps/mach/hurd/i386/init-first.c
index 59253db..fc3330c 100644
--- a/sysdeps/mach/hurd/i386/init-first.c
+++ b/sysdeps/mach/hurd/i386/init-first.c
@@ -117,14 +117,20 @@ init1 (int argc, char *arg0, ...)
if ((void *) d == argv[0])
{
#ifndef SHARED
- /* 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;
- _dl_phdr = (const void *) ehdr + ehdr->e_phoff;
- _dl_phnum = ehdr->e_phnum;
- assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
+ /* 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. */
+ extern const void _start;
+ const ElfW(Ehdr) *const ehdr = &_start;
+ _dl_phdr = (const void *) ehdr + ehdr->e_phoff;
+ _dl_phnum = ehdr->e_phnum;
+ assert (ehdr->e_phentsize == sizeof (ElfW(Phdr)));
+ }
#endif
return;
}