[GOLD][PATCH] Set SHF_LINK_ORDER flags of ARM EXIDX sections.

["Doug Kwan (關振德)" <dougkwan@google.com>]

Hi

    This patch changes code writing output section headers so that the
SHF_LINK_ORDER flag of a section of type SHT_ARM_EXIDX is always set.
The flag is required to be set for such a section by the ARM EHABI.
The existing code drops the SHF_LINK_ORDER flag and that confuses
other tools.  Gold does not handle SHF_LINK_ORDER in general but the
ARM back-end can handle the EXIDX sections.

-Doug


2010-10-19  Doug Kwan  <dougkwan@google.com>

        * output.cc(Output_section::write_header): Set SHF_LINK_ORDER flags of
        ARM EXIDX sections.

Index: gold/output.cc
===================================================================
RCS file: /cvs/src/src/gold/output.cc,v
retrieving revision 1.136
diff -u -u -p -r1.136 output.cc
--- gold/output.cc	18 Oct 2010 05:39:23 -0000	1.136
+++ gold/output.cc	19 Oct 2010 08:09:15 -0000
@@ -3091,6 +3091,10 @@ Output_section::write_header(const Layou
   elfcpp::Elf_Xword flags = this->flags_;
   if (this->info_section_ != NULL && this->info_uses_section_index_)
     flags |= elfcpp::SHF_INFO_LINK;
+  // ARM EHABI requires a SHT_ARM_EXIDX section to have the SHF_LINK_ORDER
+  // flag set.
+  if (this->type_ == elfcpp::SHT_ARM_EXIDX)
+    flags |= elfcpp::SHF_LINK_ORDER;
   oshdr->put_sh_flags(flags);

   oshdr->put_sh_addr(this->address());