Place copy relocations in .dynbss when target is read-only.

gold/
	PR ld/20995
	* copy-relocs.cc (Copy_relocs::make_copy_reloc): Use .dynbss for
	read-only data when linking with -z relro.
	* copy-relocs.h (Copy_relocs::dynrelro_): New data member.
	* testsuite/Makefile.am (copy_test_relro): New test case.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/copy_test_relro.cc: New source file.
	* testsuite/copy_test_relro_1.cc: New source file.

1 files changed, 36 insertions, 8 deletions

diff --git a/gold/copy-relocs.cc b/gold/copy-relocs.cc
index ce019c4265e..4fe17e9dfd7 100644
--- a/gold/copy-relocs.cc
+++ b/gold/copy-relocs.cc
@@ -141,6 +141,7 @@ Copy_relocs<sh_type, size, big_endian>::make_copy_reloc(
   unsigned int shndx = sym->shndx(&is_ordinary);
   gold_assert(is_ordinary);
   typename elfcpp::Elf_types<size>::Elf_WXword addralign;
+  bool is_readonly = false;
 
   {
     // Lock the object so we can read from it.  This is only called
@@ -150,6 +151,17 @@ Copy_relocs<sh_type, size, big_endian>::make_copy_reloc(
     Object* obj = sym->object();
     Task_lock_obj<Object> tl(dummy_task, obj);
     addralign = obj->section_addralign(shndx);
+    if (parameters->options().relro())
+      {
+	if ((obj->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
+	  is_readonly = true;
+	else
+	  {
+	    // Symbols in .data.rel.ro should also be treated as read-only.
+	    if (obj->section_name(shndx) == ".data.rel.ro")
+	      is_readonly = true;
+	  }
+      }
   }
 
   typename Sized_symbol<size>::Value_type value = sym->value();
@@ -159,16 +171,32 @@ Copy_relocs<sh_type, size, big_endian>::make_copy_reloc(
   // Mark the dynamic object as needed for the --as-needed option.
   sym->object()->set_is_needed();
 
-  if (this->dynbss_ == NULL)
+  Output_data_space* dynbss;
+
+  if (is_readonly)
     {
-      this->dynbss_ = new Output_data_space(addralign, "** dynbss");
-      layout->add_output_section_data(".bss",
-				      elfcpp::SHT_NOBITS,
-				      elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
-				      this->dynbss_, ORDER_BSS, false);
+      if (this->dynrelro_ == NULL)
+	{
+	  this->dynrelro_ = new Output_data_space(addralign, "** dynrelro");
+	  layout->add_output_section_data(".data.rel.ro",
+					  elfcpp::SHT_PROGBITS,
+					  elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
+					  this->dynrelro_, ORDER_RELRO, false);
+	}
+      dynbss = this->dynrelro_;
+    }
+  else
+    {
+      if (this->dynbss_ == NULL)
+	{
+	  this->dynbss_ = new Output_data_space(addralign, "** dynbss");
+	  layout->add_output_section_data(".bss",
+					  elfcpp::SHT_NOBITS,
+					  elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
+					  this->dynbss_, ORDER_BSS, false);
+	}
+      dynbss = this->dynbss_;
     }
-
-  Output_data_space* dynbss = this->dynbss_;
 
   if (addralign > dynbss->addralign())
     dynbss->set_space_alignment(addralign);