gold: Add put_ch_reserved to 64-bit Chdr_write

The 64-bit ELF compression header has a reserved field.  It should be
cleared to avoid random bits in it.

elfcpp/

	PR gold/21857
	* elfcpp.h (Chdr_write): Add put_ch_reserved.
	(Chdr_write<64, true>::put_ch_reserved): New.
	(Chdr_write<64, false>::put_ch_reserved): Likewise.

gold/

	PR gold/21857
	* compressed_output.cc (Output_compressed_section::set_final_data_size):
	Call put_ch_reserved to clear the reserved field for 64-bit ELF.

elfcpp/ChangeLog

@@ -1,3 +1,10 @@
+2017-07-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR gold/21857
+	* elfcpp.h (Chdr_write): Add put_ch_reserved.
+	(Chdr_write<64, true>::put_ch_reserved): New.
+	(Chdr_write<64, false>::put_ch_reserved): Likewise.
+
 2017-07-03  Alan Modra  <amodra@gmail.com>
 
 	* dwarf.h (DW_FIRST_IDX, DW_IDX, DW_IDX_DUP, DW_END_IDX): Define,

elfcpp/elfcpp.h

@@ -1351,10 +1351,27 @@ class Chdr_write
   put_ch_addralign(typename Elf_types<size>::Elf_WXword v)
   { this->p_->ch_addralign = Convert<size, big_endian>::convert_host(v); }
 
+  void
+  put_ch_reserved(Elf_Word);
+
  private:
   internal::Chdr_data<size>* p_;
 };
 
+template<>
+inline void
+elfcpp::Chdr_write<64, true>::put_ch_reserved(Elf_Word v)
+{
+  this->p_->ch_reserved = v;
+}
+
+template<>
+inline void
+elfcpp::Chdr_write<64, false>::put_ch_reserved(Elf_Word v)
+{
+  this->p_->ch_reserved = v;
+}
+
 // Accessor class for an ELF segment header.
 
 template<int size, bool big_endian>

gold/ChangeLog

@@ -1,3 +1,9 @@
+2017-07-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR gold/21857
+	* compressed_output.cc (Output_compressed_section::set_final_data_size):
+	Call put_ch_reserved to clear the reserved field for 64-bit ELF.
+
 2017-07-26  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* mips.cc (Mips_relocate_functions): Add "llu" suffix to

gold/compressed_output.cc

@@ -286,6 +286,8 @@ Output_compressed_section::set_final_data_size()
 		  chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB);
 		  chdr.put_ch_size(uncompressed_size);
 		  chdr.put_ch_addralign(addralign);
+		  // Clear the reserved field.
+		  chdr.put_ch_reserved(0);
 		}
 	      else
 		{
@@ -293,6 +295,8 @@ Output_compressed_section::set_final_data_size()
 		  chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB);
 		  chdr.put_ch_size(uncompressed_size);
 		  chdr.put_ch_addralign(addralign);
+		  // Clear the reserved field.
+		  chdr.put_ch_reserved(0);
 		}
 	    }
 	  else