Don't add DT_DEBUG to MIPS shared libraries

[Richard Sandiford]

Sergey Rogozhkin <rogozhkin@niisi.msk.ru> writes:
>> best to just be consistent with other targets.  This patch therefore
>> removes DT_DEBUG tags from shared libraries and makes sure that the
>> PIEs do indeed get DT_DEBUG and DT_MIPS_RLD_MAP tags.
>
> It seems this patch broke PIE startup on linux-mips. bfd/elfxx-mips.c
> code creates DT_MIPS_RLD_MAP entry for pie but doesn't set its value
> (leave it equal to 0). On pie startup, dynamic linker tries to save
> debug structure address to the place pointed by DT_MIPS_RLD_MAP tag
> value. So now it doesn't work even if pie load address is equal to its
> link address. Maybe I miss something or my configuration is wrong?
> I use glibc-2.3.6 and binutils-2.17.50.0.12.

Sorry for the breakage, and for the long time it has taken me to reply.

All the other .rld_map code is indeed guarded with !info->shared rather
than info->executable, and I don't really have time to look at whether
that should change or not.  I don't use PIEs myself, but it sounds
like you do, and that they worked OK before the patch.  I'd therefore
like to restore the original !info->shared check for the RTLD_MAP code
while keeping the new info->executable check for the DT_DEBUG code.

Tested on mips64-linux-gnu.  OK to install?

Richard


bfd/
	* elfxx-mips.c (_bfd_mips_elf_size_dynamic_sections): Don't add
	DT_MIPS_RTLD_MAP for PIEs.

Index: bfd/elfxx-mips.c
===================================================================
RCS file: /cvs/src/src/bfd/elfxx-mips.c,v
retrieving revision 1.198
diff -u -p -r1.198 elfxx-mips.c
--- bfd/elfxx-mips.c	26 Mar 2007 10:29:35 -0000	1.198
+++ bfd/elfxx-mips.c	12 Apr 2007 15:32:50 -0000
@@ -7575,18 +7575,16 @@ _bfd_mips_elf_size_dynamic_sections (bfd
 	 must add the entries now so that we get the correct size for
 	 the .dynamic section.  The DT_DEBUG entry is filled in by the
 	 dynamic linker and used by the debugger.  */
-      if (info->executable)
-	{
-	  /* SGI object has the equivalence of DT_DEBUG in the
-	     DT_MIPS_RLD_MAP entry.  */
-	  if (!MIPS_ELF_ADD_DYNAMIC_ENTRY (info, DT_MIPS_RLD_MAP, 0))
-	    return FALSE;
-	  if (!SGI_COMPAT (output_bfd))
-	    {
-	      if (!MIPS_ELF_ADD_DYNAMIC_ENTRY (info, DT_DEBUG, 0))
-		return FALSE;
-	    }
-	}
+      if (info->executable
+	  && !SGI_COMPAT (output_bfd)
+	  && !MIPS_ELF_ADD_DYNAMIC_ENTRY (info, DT_DEBUG, 0))
+	return FALSE;
+
+      /* SGI object has the equivalence of DT_DEBUG in the
+	 DT_MIPS_RLD_MAP entry.  */
+      if (!info->shared
+	  && !MIPS_ELF_ADD_DYNAMIC_ENTRY (info, DT_MIPS_RLD_MAP, 0))
+	return FALSE;
 
       if (reltext && (SGI_COMPAT (output_bfd) || htab->is_vxworks))
 	info->flags |= DF_TEXTREL;