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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 /csu
parentdc0a02638583d8e7f7e1cc72643d1b26ec6042fd (diff)
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Use __ehdr_start, if available, as fallback for AT_PHDR.
Diffstat (limited to 'csu')
-rw-r--r--csu/libc-start.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/csu/libc-start.c b/csu/libc-start.c
index 9c4c01d9fd..fa9085cf55 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)
     {