Fix "overflow in PLT unwind data" warning

When linking statically, it's possible to hit this warning with IFUNC
or very large executables, due to .glink being unused.

	* powerpc.cc (do_plt_fde_location): Handle zero length .glink.
	Compare FDE contents with DW_CFA_nop rather than 0.

2 files changed, 52 insertions, 33 deletions

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 6d1c14b..f0ee1f7 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,8 @@
+2014-05-15  Alan Modra  <amodra@gmail.com>
+
+	* powerpc.cc (do_plt_fde_location): Handle zero length .glink.
+	Compare FDE contents with DW_CFA_nop rather than 0.
+
 2014-05-13  Sriraman Tallam  <tmsriram@google.com>
 
 	* symtab.h (may_need_copy_reloc): Remove check for position independent
@@ -15,7 +20,7 @@
 	* testsuite/pie_copyrelocs_test.cc: New file.
 	* testsuite/pie_copyrelocs_shared_test.cc: New file.
 	* Makefile.am (pie_copyrelocs_test): New test.
-	* Makefile.in: Regenerate.  
+	* Makefile.in: Regenerate.
 
 2014-05-08  Martin Liška  <mliska@suse.cz>
 
@@ -45,37 +50,37 @@
 	class.
 
 2014-05-05  Cary Coutant  <ccoutant@google.com>
-        
+
 	* gdb-index.cc (Gdb_index_info_reader): Don't complain about language
 	if we have pubnames/pubtypes.
 
 2014-05-02  Cary Coutant  <ccoutant@google.com>
 
-    	* defstd.cc (in_segment): Define __ehdr_start here...
-    	* layout.cc (Layout::finalize): ...Instead of here.  Set the
-    	output segment when known.
-    	* resolve.cc (Symbol::override_base_with_special): Remember
-    	the original binding.
-    	* symtab.cc (Symbol::set_output_segment): New function.
-    	(Symbol::set_undefined): New function.
-    	* symtab.h (Symbol::is_weak_undefined): Check original undef
-    	binding.
-    	(Symbol::is_strong_undefined): New function.
-    	(Symbol::set_output_segment): New function.
-    	(Symbol::set_undefined): New function.
-    	* target-reloc.h (is_strong_undefined): Remove.
-    	(issue_undefined_symbol_error): Call Symbol::is_weak_undefined.
-    	Check for hidden undefs.
-    	(relocate_section): Call Symbol::is_strong_undefined.
-    
-    	* testsuite/Makefile.am (ehdr_start_test_1)
-    	(ehdr_start_test_2, ehdr_start_test_3)
-    	(ehdr_start_test_4, ehdr_start_test_5): New test cases.
-    	* testsuite/Makefile.in: Regenerate.
-    	* testsuite/ehdr_start_def.cc: New source file.
-    	* testsuite/ehdr_start_test.cc: New source file.
-    	* testsuite/ehdr_start_test.t: New linker script.
-    	* testsuite/ehdr_start_test_4.sh: New shell script.
+	* defstd.cc (in_segment): Define __ehdr_start here...
+	* layout.cc (Layout::finalize): ...Instead of here.  Set the
+	output segment when known.
+	* resolve.cc (Symbol::override_base_with_special): Remember
+	the original binding.
+	* symtab.cc (Symbol::set_output_segment): New function.
+	(Symbol::set_undefined): New function.
+	* symtab.h (Symbol::is_weak_undefined): Check original undef
+	binding.
+	(Symbol::is_strong_undefined): New function.
+	(Symbol::set_output_segment): New function.
+	(Symbol::set_undefined): New function.
+	* target-reloc.h (is_strong_undefined): Remove.
+	(issue_undefined_symbol_error): Call Symbol::is_weak_undefined.
+	Check for hidden undefs.
+	(relocate_section): Call Symbol::is_strong_undefined.
+
+	* testsuite/Makefile.am (ehdr_start_test_1)
+	(ehdr_start_test_2, ehdr_start_test_3)
+	(ehdr_start_test_4, ehdr_start_test_5): New test cases.
+	* testsuite/Makefile.in: Regenerate.
+	* testsuite/ehdr_start_def.cc: New source file.
+	* testsuite/ehdr_start_test.cc: New source file.
+	* testsuite/ehdr_start_test.t: New linker script.
+	* testsuite/ehdr_start_test_4.sh: New shell script.
 
 2014-04-23  Cary Coutant  <ccoutant@google.com>
 
@@ -135,7 +140,7 @@
 	(Target::do_adjust_dyn_symbol): New function.
 
 2014-03-10  Sasa Stankovic  <Sasa.Stankovic@imgtec.com>
-  
+
 	* output.cc (Output_data_dynamic::Dynamic_entry::write):
 	Get the value of DYNAMIC_CUSTOM dynamic entry.
 	* output.h (Output_data_dynamic::add_custom): New function.
@@ -208,7 +213,7 @@
 	Check for is_strong_undefined.
 
 2014-02-05  Cary Coutant  <ccoutant@google.com>
-    
+
 	Fix problems with the --dynamic-list option.
 
 	PR gold/13577
@@ -221,11 +226,11 @@
 	(General_options::have_dynamic_list_): New data member.
 	* symtab.h (Symbol::is_preemptible): Handle --dynamic-list
 	correctly.
-   
+
 	PR gold/16530
 	* symtab.cc (Symbol_table::add_from_relobj): If symbol is named
 	in --dynamic-list, mark it.
-   
+
 	* testsuite/Makefile.am (gc_dynamic_list_test.sh): New test case.
 	(dynamic_list_2): New test case.
 	* testsuite/Makefile.in: Regenerate.
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index b9ee86e..e59c319 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -2851,7 +2851,21 @@ Target_powerpc<size, big_endian>::do_plt_fde_location(const Output_data* plt,
   if (plt == this->glink_)
     {
       // See Output_data_glink::do_write() for glink contents.
-      if (size == 64)
+      if (len == 0)
+	{
+	  gold_assert(parameters->doing_static_link());
+	  // Static linking may need stubs, to support ifunc and long
+	  // branches.  We need to create an output section for
+	  // .eh_frame early in the link process, to have a place to
+	  // attach stub .eh_frame info.  We also need to have
+	  // registered a CIE that matches the stub CIE.  Both of
+	  // these requirements are satisfied by creating an FDE and
+	  // CIE for .glink, even though static linking will leave
+	  // .glink zero length.
+	  // ??? Hopefully generating an FDE with a zero address range
+	  // won't confuse anything that consumes .eh_frame info.
+	}
+      else if (size == 64)
 	{
 	  // There is one word before __glink_PLTresolve
 	  address += 8;
@@ -2863,7 +2877,7 @@ Target_powerpc<size, big_endian>::do_plt_fde_location(const Output_data* plt,
 	  // The first covers the branch table, the second
 	  // __glink_PLTresolve at the end of glink.
 	  off_t resolve_size = this->glink_->pltresolve_size;
-	  if (oview[9] == 0)
+	  if (oview[9] == elfcpp::DW_CFA_nop)
 	    len -= resolve_size;
 	  else
 	    {