Patch adds support to allow plugins to map selected subset of sections to unique

segments.


2012-08-24  Sriraman Tallam  <tmsriram@google.com>

	* gold.cc (queue_middle_tasks): Call layout again when unique
	segments for sections is desired.
	* layout.cc (Layout::Layout): Initialize new members.
	(Layout::get_output_section_flags): New function.
	(Layout::choose_output_section): Call get_output_section_flags.
	(Layout::layout): Make output section for mapping to a unique segment.
	(Layout::insert_section_segment_map): New function.
	(Layout::attach_allocated_section_to_segment): Make unique segment for
	output sections marked so.
	(Layout::segment_precedes): Check for unique segments when sorting.
	* layout.h (Layout::Unique_segment_info): New struct.
	(Layout::Section_segment_map): New typedef.
	(Layout::insert_section_segment_map): New function.
	(Layout::get_output_section_flags): New function.
	(Layout::is_unique_segment_for_sections_specified): New function.
	(Layout::set_unique_segment_for_sections_specified): New function.
	(Layout::unique_segment_for_sections_specified_): New member.
	(Layout::section_segment_map_): New member.
	* object.cc (Sized_relobj_file<size, big_endian>::do_layout):
	Rename is_gc_pass_one to is_pass_one.
	Rename is_gc_pass_two to is_pass_two.
	Rename is_gc_or_icf to is_two_pass.
	Check for which pass based on whether symbols data is present.
	Make it two pass when unique segments for sections is desired.
	* output.cc (Output_section::Output_section): Initialize new
	members.
	* output.h (Output_section::is_unique_segment): New function.
	(Output_section::set_is_unique_segment): New function.
	(Output_section::is_unique_segment_): New member.
	(Output_section::extra_segment_flags): New function.
	(Output_section::set_extra_segment_flags): New function.
	(Output_section::extra_segment_flags_): New member.
	(Output_section::segment_alignment): New function.
	(Output_section::set_segment_alignment): New function.
	(Output_section::segment_alignment_): New member.
	(Output_segment::Output_segment): Initialize is_unique_segment_.
	(Output_segment::is_unique_segment): New function.
	(Output_segment::set_is_unique_segment): New function.
	(Output_segment::is_unique_segment_): New member.
	* plugin.cc (allow_unique_segment_for_sections): New function.
	(unique_segment_for_sections): New function.
	(Plugin::load): Add new functions to transfer vector.
	* Makefile.am (plugin_final_layout.readelf.stdout): Add readelf output.
	* Makefile.in: Regenerate.
	* testsuite/plugin_final_layout.sh: Check if unique segment
	functionality works.
	* testsuite/plugin_section_order.c (onload): Check if new interfaces
	are available.
	(allow_unique_segment_for_sections): New global.
	(unique_segment_for_sections): New global.
	(claim_file_hook): Call allow_unique_segment_for_sections.
	(all_symbols_read_hook): Call unique_segment_for_sections.


2012-08-24  Sriraman Tallam  <tmsriram@google.com>

	* plugin-api.h (ld_plugin_allow_unique_segment_for_sections):
	New interface.
	(ld_plugin_unique_segment_for_sections): New interface.
	(LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS): New enum val.
	(LDPT_UNIQUE_SEGMENT_FOR_SECTIONS): New enum val.
	(tv_allow_unique_segment_for_sections): New member.
	(tv_unique_segment_for_sections): New member.

4 files changed, 65 insertions, 9 deletions

diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
index 0e98e6a..146c7e0 100644
--- a/gold/testsuite/Makefile.am
+++ b/gold/testsuite/Makefile.am
@@ -1529,13 +1529,15 @@ unused.c:
 	@cp /dev/null $@
 
 check_SCRIPTS += plugin_final_layout.sh
-check_DATA += plugin_final_layout.stdout
+check_DATA += plugin_final_layout.stdout plugin_final_layout_readelf.stdout
 plugin_final_layout.o: plugin_final_layout.cc
 	$(CXXCOMPILE) -O0 -c -ffunction-sections  -fdata-sections -g -o $@ $<
 plugin_final_layout: plugin_final_layout.o plugin_section_order.so gcctestdir/ld
 	$(CXXLINK) -Bgcctestdir/ -Wl,--plugin,"./plugin_section_order.so" plugin_final_layout.o
 plugin_final_layout.stdout: plugin_final_layout
 	$(TEST_NM) -n plugin_final_layout > plugin_final_layout.stdout
+plugin_final_layout_readelf.stdout: plugin_final_layout
+	$(TEST_READELF) -Wl plugin_final_layout > plugin_final_layout_readelf.stdout
 
 plugin_section_order.so: plugin_section_order.o
 	$(LINK) -Bgcctestdir/ -shared plugin_section_order.o
diff --git a/gold/testsuite/Makefile.in b/gold/testsuite/Makefile.in
index a3a4506..b937ff0 100644
--- a/gold/testsuite/Makefile.in
+++ b/gold/testsuite/Makefile.in
@@ -329,7 +329,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_test_7.err \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_test_7.syms \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_test_9.err \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_final_layout.stdout
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_final_layout.stdout \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_final_layout.readelf.stdout
 # Make a copy of two_file_test_1.o, which does not define the symbol _Z4t16av.
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@am__append_36 =  \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	plugin_test_1.err \
@@ -4875,6 +4876,8 @@ uninstall-am:
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	$(CXXLINK) -Bgcctestdir/ -Wl,--plugin,"./plugin_section_order.so" plugin_final_layout.o
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_final_layout.stdout: plugin_final_layout
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	$(TEST_NM) -n plugin_final_layout > plugin_final_layout.stdout
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_final_layout.readelf.stdout: plugin_final_layout
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	$(TEST_READELF) -Wl plugin_final_layout > plugin_final_layout_readelf.stdout
 
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_section_order.so: plugin_section_order.o
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@	$(LINK) -Bgcctestdir/ -shared plugin_section_order.o
diff --git a/gold/testsuite/plugin_final_layout.sh b/gold/testsuite/plugin_final_layout.sh
index 600f8e2..75a40d3 100755
--- a/gold/testsuite/plugin_final_layout.sh
+++ b/gold/testsuite/plugin_final_layout.sh
@@ -56,5 +56,35 @@ END {
     }" $1
 }
 
+# With readelf -l, an ELF Section to Segment mapping is printed as :
+##############################################
+#  Section to Segment mapping:
+#  Segment Sections...
+#  ...
+#     0x     .text.plugin_created_unique
+#  ...
+##############################################
+# Check of .text.plugin_created_unique is the only section in the segment.
+check_unique_segment()
+{
+    awk "
+BEGIN { saw_section = 0; saw_unique = 0; }
+/$2/ { saw_section = 1; }
+/[ ]*0[0-9][ ]*$2[ ]*\$/ { saw_unique = 1; }
+END {
+      if (!saw_section)
+	{
+	  printf \"Section $2 not seen in output\\n\";
+	  exit 1;
+	}
+      else if (!saw_unique)
+	{
+	  printf \"Unique segment not seen for: $2\\n\";
+	  exit 1;
+	}
+    }" $1
+}
+
 check plugin_final_layout.stdout "_Z3foov" "_Z3barv"
 check plugin_final_layout.stdout "_Z3barv" "_Z3bazv"
+check_unique_segment plugin_final_layout_readelf.stdout ".text.plugin_created_unique"
diff --git a/gold/testsuite/plugin_section_order.c b/gold/testsuite/plugin_section_order.c
index 0e2079b..fdc6fe4 100644
--- a/gold/testsuite/plugin_section_order.c
+++ b/gold/testsuite/plugin_section_order.c
@@ -36,6 +36,9 @@ static ld_plugin_get_input_section_name get_input_section_name = NULL;
 static ld_plugin_get_input_section_contents get_input_section_contents = NULL;
 static ld_plugin_update_section_order update_section_order = NULL;
 static ld_plugin_allow_section_ordering allow_section_ordering = NULL;
+static ld_plugin_allow_unique_segment_for_sections 
+    allow_unique_segment_for_sections = NULL;
+static ld_plugin_unique_segment_for_sections unique_segment_for_sections = NULL;
 
 enum ld_plugin_status onload(struct ld_plugin_tv *tv);
 enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file,
@@ -52,11 +55,13 @@ onload(struct ld_plugin_tv *tv)
       switch (entry->tv_tag)
         {
         case LDPT_REGISTER_CLAIM_FILE_HOOK:
-          assert((*entry->tv_u.tv_register_claim_file) (claim_file_hook) == LDPS_OK);
+          assert((*entry->tv_u.tv_register_claim_file) (claim_file_hook)
+		 == LDPS_OK);
           break;
 	case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
-          assert((*entry->tv_u.tv_register_all_symbols_read) (all_symbols_read_hook)
-		  == LDPS_OK);
+          assert((*entry->tv_u.tv_register_all_symbols_read)
+		     (all_symbols_read_hook)
+		 == LDPS_OK);
           break;
         case LDPT_GET_INPUT_SECTION_COUNT:
           get_input_section_count = *entry->tv_u.tv_get_input_section_count;
@@ -68,7 +73,8 @@ onload(struct ld_plugin_tv *tv)
           get_input_section_name = *entry->tv_u.tv_get_input_section_name;
           break;
         case LDPT_GET_INPUT_SECTION_CONTENTS:
-          get_input_section_contents = *entry->tv_u.tv_get_input_section_contents;
+          get_input_section_contents
+	      = *entry->tv_u.tv_get_input_section_contents;
           break;
 	case LDPT_UPDATE_SECTION_ORDER:
 	  update_section_order = *entry->tv_u.tv_update_section_order;
@@ -76,6 +82,13 @@ onload(struct ld_plugin_tv *tv)
 	case LDPT_ALLOW_SECTION_ORDERING:
 	  allow_section_ordering = *entry->tv_u.tv_allow_section_ordering;
 	  break;
+	case LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS:
+	  allow_unique_segment_for_sections
+	      = *entry->tv_u.tv_allow_unique_segment_for_sections;
+	case LDPT_UNIQUE_SEGMENT_FOR_SECTIONS:
+	  unique_segment_for_sections
+	      = *entry->tv_u.tv_unique_segment_for_sections;
+	  break;
         default:
           break;
         }
@@ -86,7 +99,9 @@ onload(struct ld_plugin_tv *tv)
       || get_input_section_name == NULL
       || get_input_section_contents == NULL
       || update_section_order == NULL
-      || allow_section_ordering == NULL)
+      || allow_section_ordering == NULL
+      || allow_unique_segment_for_sections == NULL
+      || unique_segment_for_sections == NULL)
     {
       fprintf(stderr, "Some interfaces are missing\n");
       return LDPS_ERR;
@@ -117,6 +132,9 @@ claim_file_hook(const struct ld_plugin_input_file *file, int *claimed)
     {
       /* Inform the linker to prepare for section reordering.  */
       (*allow_section_ordering)();
+      /* Inform the linker to prepare to map some sections to unique
+	 segments.  */
+      (*allow_unique_segment_for_sections)(); 
       is_ordering_specified = 1;
     }
 
@@ -160,8 +178,11 @@ enum ld_plugin_status
 all_symbols_read_hook(void)
 {
   if (num_entries == 3)
-    update_section_order(section_list, num_entries);
+    { 
+      update_section_order(section_list, num_entries);
+      unique_segment_for_sections (".text.plugin_created_unique", 0, 0x1000,
+				   section_list, num_entries);
+    }
 
   return LDPS_OK;
 }
-