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.

gold/ChangeLog

@@ -1,3 +1,14 @@
+2016-12-27  Cary Coutant  <ccoutant@gmail.com>
+
+	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.
+
 2016-12-23  Cary Coutant  <ccoutant@gmail.com>
 
 	* NEWS: Add new features in 1.14.

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;
-    {
-      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);
-    }
 
-  Output_data_space* dynbss = this->dynbss_;
+  if (is_readonly)
+    {
+      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_;
+    }
 
   if (addralign > dynbss->addralign())
     dynbss->set_space_alignment(addralign);

gold/copy-relocs.h

@@ -54,7 +54,8 @@ class Copy_relocs
 
  public:
   Copy_relocs(unsigned int copy_reloc_type)
-    : entries_(), copy_reloc_type_(copy_reloc_type), dynbss_(NULL)
+    : entries_(), copy_reloc_type_(copy_reloc_type), dynbss_(NULL),
+      dynrelro_(NULL)
   { }
 
   // This is called while scanning relocs if we see a relocation
@@ -152,8 +153,11 @@ class Copy_relocs
   // The target specific relocation type of the COPY relocation.
   const unsigned int copy_reloc_type_;
   // The dynamic BSS data which goes into the .bss section.  This is
-  // where variables which require COPY relocations are placed.
+  // where writable variables which require COPY relocations are placed.
   Output_data_space* dynbss_;
+  // The dynamic read-only data, which goes into the .dynbss section.  This
+  // is where read-only variables which require COPY relocations are placed.
+  Output_data_space* dynrelro_;
 };
 
 } // End namespace gold.

gold/testsuite/Makefile.am

@@ -858,6 +858,16 @@ copy_test_2_pic.o: copy_test_2.cc
 copy_test_2.so: gcctestdir/ld copy_test_2_pic.o
 	$(CXXLINK) -Bgcctestdir/ -shared copy_test_2_pic.o
 
+check_PROGRAMS += copy_test_relro
+copy_test_relro_SOURCES = copy_test_relro.cc
+copy_test_relro_DEPENDENCIES = gcctestdir/ld copy_test_relro_1.so
+copy_test_relro_LDFLAGS = -Bgcctestdir/ -Wl,-R,. -Wl,-z,relro
+copy_test_relro_LDADD = copy_test_relro_1.so
+copy_test_relro_1_pic.o: copy_test_relro_1.cc
+	$(CXXCOMPILE) -c -fpic -o $@ $<
+copy_test_relro_1.so: gcctestdir/ld copy_test_relro_1_pic.o
+	$(CXXLINK) -Bgcctestdir/ -shared -Wl,-z,relro copy_test_relro_1_pic.o
+
 if !DEFAULT_TARGET_POWERPC
 check_SCRIPTS += copy_test_protected.sh
 check_DATA += copy_test_protected.err

gold/testsuite/Makefile.in

@@ -205,7 +205,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
 @FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_16 = weak_undef_nonpic_test
 @FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_17 = alt/weak_undef_lib_nonpic.so
 @GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_18 = weak_alias_test weak_plt \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test copy_test_relro
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_19 = copy_test_protected.sh
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_20 = copy_test_protected.err
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_21 = copy_test_protected.err
@@ -1085,7 +1085,8 @@ libgoldtest_a_OBJECTS = $(am_libgoldtest_a_OBJECTS)
 @GCC_TRUE@@NATIVE_LINKER_TRUE@am__EXEEXT_14 =  \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@	weak_alias_test$(EXEEXT) \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@	weak_plt$(EXEEXT) \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test$(EXEEXT)
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test$(EXEEXT) \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test_relro$(EXEEXT)
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@am__EXEEXT_15 =  \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@	tls_test$(EXEEXT) \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@	tls_pic_test$(EXEEXT) \
@@ -1298,6 +1299,11 @@ constructor_test_LINK = $(CXXLD) $(AM_CXXFLAGS) $(CXXFLAGS) \
 copy_test_OBJECTS = $(am_copy_test_OBJECTS)
 copy_test_LINK = $(CXXLD) $(AM_CXXFLAGS) $(CXXFLAGS) \
 	$(copy_test_LDFLAGS) $(LDFLAGS) -o $@
+@GCC_TRUE@@NATIVE_LINKER_TRUE@am_copy_test_relro_OBJECTS =  \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	copy_test_relro.$(OBJEXT)
+copy_test_relro_OBJECTS = $(am_copy_test_relro_OBJECTS)
+copy_test_relro_LINK = $(CXXLD) $(AM_CXXFLAGS) $(CXXFLAGS) \
+	$(copy_test_relro_LDFLAGS) $(LDFLAGS) -o $@
 @GCC_TRUE@@NATIVE_LINKER_TRUE@am_discard_locals_test_OBJECTS =  \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@	discard_locals_test.$(OBJEXT)
 discard_locals_test_OBJECTS = $(am_discard_locals_test_OBJECTS)
@@ -2357,10 +2363,11 @@ SOURCES = $(libgoldtest_a_SOURCES) basic_pic_test.c basic_pie_test.c \
 	$(binary_test_SOURCES) $(binary_unittest_SOURCES) \
 	$(common_test_1_SOURCES) $(common_test_2_SOURCES) \
 	$(constructor_static_test_SOURCES) $(constructor_test_SOURCES) \
-	$(copy_test_SOURCES) $(discard_locals_test_SOURCES) \
+	$(copy_test_SOURCES) $(copy_test_relro_SOURCES) \
-	$(dynamic_list_2_SOURCES) eh_test.c \
+	$(discard_locals_test_SOURCES) $(dynamic_list_2_SOURCES) \
-	$(ehdr_start_test_1_SOURCES) $(ehdr_start_test_2_SOURCES) \
+	eh_test.c $(ehdr_start_test_1_SOURCES) \
-	$(ehdr_start_test_3_SOURCES) $(ehdr_start_test_5_SOURCES) \
+	$(ehdr_start_test_2_SOURCES) $(ehdr_start_test_3_SOURCES) \
+	$(ehdr_start_test_5_SOURCES) \
 	$(exception_same_shared_test_SOURCES) \
 	$(exception_separate_shared_12_test_SOURCES) \
 	$(exception_separate_shared_21_test_SOURCES) \
@@ -3051,6 +3058,10 @@ LDADD = libgoldtest.a ../libgold.a ../../libiberty/libiberty.a $(LIBINTL) \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_DEPENDENCIES = gcctestdir/ld copy_test_1.so copy_test_2.so
 @GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_LDFLAGS = -Bgcctestdir/ -Wl,-R,.
 @GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_LDADD = copy_test_1.so copy_test_2.so
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_SOURCES = copy_test_relro.cc
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_DEPENDENCIES = gcctestdir/ld copy_test_relro_1.so
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_LDFLAGS = -Bgcctestdir/ -Wl,-R,. -Wl,-z,relro
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_LDADD = copy_test_relro_1.so
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@tls_test_SOURCES = tls_test.cc tls_test_file2.cc tls_test_main.cc tls_test.h
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@tls_test_DEPENDENCIES = gcctestdir/ld tls_test_c.o
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@TLS_TRUE@tls_test_LDFLAGS = -Bgcctestdir/
@@ -3468,6 +3479,9 @@ constructor_test$(EXEEXT): $(constructor_test_OBJECTS) $(constructor_test_DEPEND
 copy_test$(EXEEXT): $(copy_test_OBJECTS) $(copy_test_DEPENDENCIES) $(EXTRA_copy_test_DEPENDENCIES) 
 	@rm -f copy_test$(EXEEXT)
 	$(copy_test_LINK) $(copy_test_OBJECTS) $(copy_test_LDADD) $(LIBS)
+copy_test_relro$(EXEEXT): $(copy_test_relro_OBJECTS) $(copy_test_relro_DEPENDENCIES) $(EXTRA_copy_test_relro_DEPENDENCIES) 
+	@rm -f copy_test_relro$(EXEEXT)
+	$(copy_test_relro_LINK) $(copy_test_relro_OBJECTS) $(copy_test_relro_LDADD) $(LIBS)
 discard_locals_test$(EXEEXT): $(discard_locals_test_OBJECTS) $(discard_locals_test_DEPENDENCIES) $(EXTRA_discard_locals_test_DEPENDENCIES) 
 	@rm -f discard_locals_test$(EXEEXT)
 	$(discard_locals_test_LINK) $(discard_locals_test_OBJECTS) $(discard_locals_test_LDADD) $(LIBS)
@@ -4343,6 +4357,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/common_test_1.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/constructor_test.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/copy_test.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/copy_test_relro.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/discard_locals_test.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/dynamic_list_2.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/eh_test.Po@am__quote@
@@ -5396,6 +5411,8 @@ weak_plt.log: weak_plt$(EXEEXT)
 	@p='weak_plt$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 copy_test.log: copy_test$(EXEEXT)
 	@p='copy_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
+copy_test_relro.log: copy_test_relro$(EXEEXT)
+	@p='copy_test_relro$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 tls_test.log: tls_test$(EXEEXT)
 	@p='tls_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 tls_pic_test.log: tls_pic_test$(EXEEXT)
@@ -6115,6 +6132,10 @@ uninstall-am:
 @GCC_TRUE@@NATIVE_LINKER_TRUE@	$(CXXCOMPILE) -c -fpic -o $@ $<
 @GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_2.so: gcctestdir/ld copy_test_2_pic.o
 @GCC_TRUE@@NATIVE_LINKER_TRUE@	$(CXXLINK) -Bgcctestdir/ -shared copy_test_2_pic.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_1_pic.o: copy_test_relro_1.cc
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(CXXCOMPILE) -c -fpic -o $@ $<
+@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_relro_1.so: gcctestdir/ld copy_test_relro_1_pic.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(CXXLINK) -Bgcctestdir/ -shared -Wl,-z,relro copy_test_relro_1_pic.o
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@copy_test_protected.err: copy_test_protected.o copy_test_2.so gcctestdir/ld
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@echo $(CXXLINK) -Bgcctestdir/ -o copy_test_protected copy_test_protected.o copy_test_2.so -Wl,-R,. "2>$@"
 @DEFAULT_TARGET_POWERPC_FALSE@@GCC_TRUE@@NATIVE_LINKER_TRUE@	@if $(CXXLINK) -Bgcctestdir/ -o copy_test_protected copy_test_protected.o copy_test_2.so -Wl,-R,. 2>$@; \

gold/testsuite/copy_test_relro.cc

@@ -0,0 +1,45 @@
+// copy_test_relro.cc -- test copy relocs against read-only and relro symbols.
+
+// Copyright (C) 2016 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@gmail.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#include <cassert>
+#include <stdint.h>
+
+extern char* _etext;
+extern char* __data_start;
+extern char* _edata;
+extern char* _end;
+
+extern int* const p;
+extern const int b[];
+int a = 123;
+
+int main()
+{
+  assert(*p == 123);
+  assert(b[0] == 100);
+  assert(b[1] == 200);
+  assert(b[2] == 300);
+  assert(b[3] == 400);
+  assert(reinterpret_cast<const void*>(&p) < reinterpret_cast<void*>(&__data_start));
+  assert(reinterpret_cast<const void*>(b) < reinterpret_cast<void*>(&__data_start));
+  return 0;
+}

gold/testsuite/copy_test_relro_1.cc

@@ -0,0 +1,26 @@
+// copy_test_relro_1.cc -- test copy relocs variables for gold
+
+// Copyright (C) 2016 Free Software Foundation, Inc.
+// Written by Cary Coutant <ccoutant@gmail.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+extern int a;
+extern int* const p = &a;
+
+extern const int b[] = { 100, 200, 300, 400 };