From: H.J. Lu <hjl.tools@gmail.com>
Date: Wed, 4 Oct 2017 00:48:55 +0000 (-0700)
Subject: Revert x86: Allow undefined _DYNAMIC in static executable
X-Git-Tag: glibc-2.27~752
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=02d2d8927d2fd3815a9f3c5c767aa71a8a33408e;p=glibc.git

Revert x86: Allow undefined _DYNAMIC in static executable

This code is used in non-PIE static executable and static PIE.  It checks
if _DYNAMIC is undefined before using it to compute load address.  But
not all targets can convert access _DYNAMIC via GOT, which needs dynamic
relocation, to PC-relative at link-time.

	* sysdeps/i386/dl-machine.h (elf_machine_load_address): Don't
	allow undefined _DYNAMIC in PIE libc.a.
	* sysdeps/x86_64/dl-machine.h (elf_machine_load_address):
	Likewse.
---

diff --git a/ChangeLog b/ChangeLog
index 581a926106..01517c5514 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-10-03  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* sysdeps/i386/dl-machine.h (elf_machine_load_address): Don't
+	allow undefined _DYNAMIC in PIE libc.a.
+	* sysdeps/x86_64/dl-machine.h (elf_machine_load_address):
+	Likewse.
+
 2017-10-03  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* sysdeps/mips/dl-machine.h (elf_machine_load_address): Don't
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 242c692c17..2e17eba5c0 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -54,15 +54,8 @@ elf_machine_load_address (void)
   /* Compute the difference between the runtime address of _DYNAMIC as seen
      by a GOTOFF reference, and the link-time address found in the special
      unrelocated first GOT entry.  */
-#ifndef SHARED
-  extern Elf32_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 Elf32_Dyn dynamic[] asm ("_DYNAMIC") attribute_hidden;
-  return (Elf32_Addr) &dynamic - elf_machine_dynamic ();
+  extern Elf32_Dyn bygotoff[] asm ("_DYNAMIC") attribute_hidden;
+  return (Elf32_Addr) &bygotoff - elf_machine_dynamic ();
 }
 
 /* Set up the loaded object described by L so its unrelocated PLT
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index a79e5ca2f9..6a04cbcdc9 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -55,15 +55,8 @@ 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.  */
-#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 ();
+  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
+  return (ElfW(Addr)) &_DYNAMIC - elf_machine_dynamic ();
 }
 
 /* Set up the loaded object described by L so its unrelocated PLT