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.

1 files changed, 32 insertions, 1 deletions

diff --git a/include/plugin-api.h b/include/plugin-api.h
index 3220142..af60419 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -318,6 +318,33 @@ typedef
 enum ld_plugin_status
 (*ld_plugin_allow_section_ordering) (void);
 
+/* The linker's interface for specifying that a subset of sections is
+   to be mapped to a unique segment.  If the plugin wants to call
+   unique_segment_for_sections, it must call this function from a
+   claim_file_handler or when it is first loaded.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_allow_unique_segment_for_sections) (void);
+
+/* The linker's interface for specifying that a specific set of sections
+   must be mapped to a unique segment.  ELF segments do not have names
+   and the NAME is used as the name of the newly created output section
+   that is then placed in the unique PT_LOAD segment.  FLAGS is used to
+   specify if any additional segment flags need to be set.  For instance,
+   a specific segment flag can be set to identify this segment.  Unsetting
+   segment flags that would be set by default is not possible.  The
+   parameter SEGMENT_ALIGNMENT when non-zero will override the default.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_unique_segment_for_sections) (
+    const char* segment_name,
+    uint64_t segment_flags,
+    uint64_t segment_alignment,
+    const struct ld_plugin_section * section_list,
+    unsigned int num_sections);
+
 enum ld_plugin_level
 {
   LDPL_INFO,
@@ -355,7 +382,9 @@ enum ld_plugin_tag
   LDPT_GET_INPUT_SECTION_CONTENTS,
   LDPT_UPDATE_SECTION_ORDER,
   LDPT_ALLOW_SECTION_ORDERING,
-  LDPT_GET_SYMBOLS_V2
+  LDPT_GET_SYMBOLS_V2,
+  LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS,
+  LDPT_UNIQUE_SEGMENT_FOR_SECTIONS
 };
 
 /* The plugin transfer vector.  */
@@ -385,6 +414,8 @@ struct ld_plugin_tv
     ld_plugin_get_input_section_contents tv_get_input_section_contents;
     ld_plugin_update_section_order tv_update_section_order;
     ld_plugin_allow_section_ordering tv_allow_section_ordering;
+    ld_plugin_allow_unique_segment_for_sections tv_allow_unique_segment_for_sections; 
+    ld_plugin_unique_segment_for_sections tv_unique_segment_for_sections;
   } tv_u;
 };