PR30217, dynamic relocations using local dynamic symbols

glibc's ld.so ignores local dynamic symbols.  It's been that way
forever.  We therefore can't use them on dynamic relocations.  Fixing
that problem uncovered another problem in sorting of dynamic relocs,
caused no doubt by copying make_iplt_section (where we don't want
reloc sorting by the generic gold function, we want iplt relocs last)
to make_lplt_section (where we do want sorting).

	PR 30217
	* powerpc.cc (branch_needs_plt_entry): New function.
	(Target_powerpc::plt_off): Use it here..
	(Target_powerpc::Scan::global): ..and here to correct PLT16 reloc
	handling for forced-local global symbols.
	(Output_data_plt_powerpc::add_entry): Rename "stash"
	parameter "is_local".  Emit relative relocs for globals that
	are forced local, and don't set_needs_dynsym_entry.
	(Target_powerpc::make_lplt_section): Don't create a separate
	reloc section, use rela_dyn.
	(Target_powerpc::make_brlt_section): Likewise.

Author: amodra

gold/powerpc.cc

@@ -636,6 +636,24 @@ enum Got_type
     GOT_TYPE_SMALL_TPREL = 7
   };
 
+// gsym->needs_plt_entry purpose is to decide whether a non-branch
+// reloc should reference a plt entry.  It can't be used to decide
+// whether branches need a plt entry.  In fact the call to
+// needs_plt_entry here is not needed;  All cases where it might
+// return true ought to be covered already.  However, since this
+// function is used to decide between plt_ and lplt_ sections in
+// plt_off, make certain that every case where make_plt_entry puts
+// entries in plt_ is covered here.
+static bool
+branch_needs_plt_entry(const Symbol* gsym)
+{
+  return (((!gsym->is_defined()
+	    || gsym->is_from_dynobj()
+	    || gsym->is_preemptible())
+	   && !gsym->final_value_is_known())
+	  || gsym->needs_plt_entry());
+}
+
 template<int size, bool big_endian>
 class Target_powerpc : public Sized_target<size, big_endian>
 {
@@ -927,7 +945,7 @@ class Target_powerpc : public Sized_target<size, big_endian>
     if (gsym->type() == elfcpp::STT_GNU_IFUNC
 	&& gsym->can_use_relative_reloc(false))
       *sec = this->iplt_section();
-    else if (!parameters->doing_static_link())
+    else if (branch_needs_plt_entry(gsym))
       *sec = this->plt_section();
     else
       *sec = this->lplt_section();
@@ -4133,7 +4151,7 @@ class Output_data_plt_powerpc : public Output_section_data_build
 template<int size, bool big_endian>
 void
 Output_data_plt_powerpc<size, big_endian>::add_entry(Symbol* gsym,
-						     bool stash)
+						     bool is_local)
 {
   if (!gsym->has_plt_offset())
     {
@@ -4143,13 +4161,24 @@ Output_data_plt_powerpc<size, big_endian>::add_entry(Symbol* gsym,
       gsym->set_plt_offset(off);
       if (this->rel_)
 	{
-	  gsym->set_needs_dynsym_entry();
-	  unsigned int dynrel = elfcpp::R_POWERPC_JMP_SLOT;
-	  this->rel_->add_global(gsym, dynrel, this, off, 0);
+	  if (is_local)
+	    {
+	      unsigned int dynrel = elfcpp::R_POWERPC_RELATIVE;
+	      if (size == 64 && this->targ_->abiversion() < 2)
+		dynrel = elfcpp::R_POWERPC_JMP_SLOT;
+	      this->rel_->add_symbolless_global_addend(gsym, dynrel,
+						       this, off, 0);
+	    }
+	  else
+	    {
+	      gsym->set_needs_dynsym_entry();
+	      unsigned int dynrel = elfcpp::R_POWERPC_JMP_SLOT;
+	      this->rel_->add_global(gsym, dynrel, this, off, 0);
+	    }
 	}
       off += this->plt_entry_size();
       this->set_current_data_size(off);
-      if (stash)
+      if (is_local)
 	{
 	  Local_plt_ent sym(gsym);
 	  this->sym_ents_.push_back(sym);
@@ -4493,13 +4522,7 @@ Target_powerpc<size, big_endian>::make_lplt_section(Symbol_table* symtab,
     {
       Reloc_section* lplt_rel = NULL;
       if (parameters->options().output_is_position_independent())
-	{
-	  lplt_rel = new Reloc_section(false);
-	  this->rela_dyn_section(layout);
-	  if (this->rela_dyn_->output_section())
-	    this->rela_dyn_->output_section()
-	      ->add_output_section_data(lplt_rel);
-	}
+	lplt_rel = this->rela_dyn_section(layout);
       this->lplt_
 	= new Output_data_plt_powerpc<size, big_endian>(this, symtab, lplt_rel,
 							"** LPLT");
@@ -4609,11 +4632,7 @@ Target_powerpc<size, big_endian>::make_brlt_section(Layout* layout)
 	{
 	  // When PIC we can't fill in .branch_lt but must initialise at
 	  // runtime via dynamic relocations.
-	  this->rela_dyn_section(layout);
-	  brlt_rel = new Reloc_section(false);
-	  if (this->rela_dyn_->output_section())
-	    this->rela_dyn_->output_section()
-	      ->add_output_section_data(brlt_rel);
+	  brlt_rel = this->rela_dyn_section(layout);
 	}
       this->brlt_section_
 	= new Output_data_brlt_powerpc<size, big_endian>(this, brlt_rel);
@@ -9009,7 +9028,7 @@ Target_powerpc<size, big_endian>::Scan::global(
     case elfcpp::R_PPC64_PLT16_LO_DS:
       if (!pushed_ifunc)
 	{
-	  if (!parameters->doing_static_link())
+	  if (branch_needs_plt_entry(gsym))
 	    target->make_plt_entry(symtab, layout, gsym);
 	  else
 	    target->make_local_plt_entry(symtab, layout, gsym);
@@ -9028,11 +9047,7 @@ Target_powerpc<size, big_endian>::Scan::global(
 	  unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
 	  target->push_branch(ppc_object, data_shndx, reloc.get_r_offset(),
 			      r_type, r_sym, reloc.get_r_addend());
-	  if (gsym->needs_plt_entry()
-	      || (!gsym->final_value_is_known()
-		  && (gsym->is_undefined()
-		      || gsym->is_from_dynobj()
-		      || gsym->is_preemptible())))
+	  if (branch_needs_plt_entry(gsym))
 	    target->make_plt_entry(symtab, layout, gsym);
 	}
       // Fall through.