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authorH.J. Lu <hjl.tools@gmail.com>2017-09-28 15:28:00 -0700
committerH.J. Lu <hjl.tools@gmail.com>2017-09-28 15:28:12 -0700
commit4088d8dd29ce0629eeaa7cceca02414c85d98e05 (patch)
tree0b807276e1826b3c4522721d076aa81c23c5da8b /sysdeps/x86_64
parent4d3693ec1cb7d247a217dc1eb7121c658f818dca (diff)
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x86: Allow undefined _DYNAMIC in static executable
When --enable-static-pie is used to build static PIE, _DYNAMIC is used
to compute the load address of static PIE.  But _DYNAMIC is undefined
when creating static executable.  This patch makes _DYNAMIC weak in PIE
libc.a so that it can be undefined.

	* sysdeps/i386/dl-machine.h (elf_machine_load_address): Allow
	undefined _DYNAMIC in PIE libc.a.
	* sysdeps/x86_64/dl-machine.h (elf_machine_load_address):
	Likewse.
Diffstat (limited to 'sysdeps/x86_64')
-rw-r--r--sysdeps/x86_64/dl-machine.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index 6a04cbcdc9..a79e5ca2f9 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -55,8 +55,15 @@ elf_machine_load_address (void)
   /* Compute the difference between the runtime address of _DYNAMIC as seen
      by an IP-relative reference, and the link-time address found in the
      special unrelocated first GOT entry.  */
-  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
-  return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic ();
+#ifndef SHARED
+  extern ElfW(Dyn) _DYNAMIC[] __attribute__((weak, visibility ("hidden")));
+  if (!_DYNAMIC)
+    return 0;
+#endif
+  /* The address of dynamic must be taken as non-weak to avoid dynamic
+     relocation.  */
+  extern ElfW(Dyn) dynamic[] asm ("_DYNAMIC") attribute_hidden;
+  return (ElfW(Addr)) &dynamic - elf_machine_dynamic ();
 }
 
 /* Set up the loaded object described by L so its unrelocated PLT