* x86_64.cc (Target_x86_64::saw_tls_block_reloc_): Remove member.
[binutils-gdb.git] / gold / x86_64.cc
index bfa494c33dcd92adb5400d2db58ad146be7d0ba7..1396fb39283eaf3f47930dc149851fc8df38efa5 100644 (file)
@@ -46,7 +46,115 @@ namespace
 
 using namespace gold;
 
-class Output_data_plt_x86_64;
+// A class to handle the PLT data.
+
+class Output_data_plt_x86_64 : public Output_section_data
+{
+ public:
+  typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
+
+  Output_data_plt_x86_64(Symbol_table*, Layout*, Output_data_got<64, false>*,
+                         Output_data_space*);
+
+  // Add an entry to the PLT.
+  void
+  add_entry(Symbol* gsym);
+
+  // Add an entry to the PLT for a local STT_GNU_IFUNC symbol.
+  unsigned int
+  add_local_ifunc_entry(Sized_relobj<64, false>* relobj,
+                       unsigned int local_sym_index);
+
+  // Add the reserved TLSDESC_PLT entry to the PLT.
+  void
+  reserve_tlsdesc_entry(unsigned int got_offset)
+  { this->tlsdesc_got_offset_ = got_offset; }
+
+  // Return true if a TLSDESC_PLT entry has been reserved.
+  bool
+  has_tlsdesc_entry() const
+  { return this->tlsdesc_got_offset_ != -1U; }
+
+  // Return the GOT offset for the reserved TLSDESC_PLT entry.
+  unsigned int
+  get_tlsdesc_got_offset() const
+  { return this->tlsdesc_got_offset_; }
+
+  // Return the offset of the reserved TLSDESC_PLT entry.
+  unsigned int
+  get_tlsdesc_plt_offset() const
+  { return (this->count_ + 1) * plt_entry_size; }
+
+  // Return the .rela.plt section data.
+  Reloc_section*
+  rela_plt()
+  { return this->rel_; }
+
+  // Return where the TLSDESC relocations should go.
+  Reloc_section*
+  rela_tlsdesc(Layout*);
+
+  // Return the number of PLT entries.
+  unsigned int
+  entry_count() const
+  { return this->count_; }
+
+  // Return the offset of the first non-reserved PLT entry.
+  static unsigned int
+  first_plt_entry_offset()
+  { return plt_entry_size; }
+
+  // Return the size of a PLT entry.
+  static unsigned int
+  get_plt_entry_size()
+  { return plt_entry_size; }
+
+ protected:
+  void
+  do_adjust_output_section(Output_section* os);
+
+  // Write to a map file.
+  void
+  do_print_to_mapfile(Mapfile* mapfile) const
+  { mapfile->print_output_data(this, _("** PLT")); }
+
+ private:
+  // The size of an entry in the PLT.
+  static const int plt_entry_size = 16;
+
+  // The first entry in the PLT.
+  // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
+  // procedure linkage table for both programs and shared objects."
+  static unsigned char first_plt_entry[plt_entry_size];
+
+  // Other entries in the PLT for an executable.
+  static unsigned char plt_entry[plt_entry_size];
+
+  // The reserved TLSDESC entry in the PLT for an executable.
+  static unsigned char tlsdesc_plt_entry[plt_entry_size];
+
+  // Set the final size.
+  void
+  set_final_data_size();
+
+  // Write out the PLT data.
+  void
+  do_write(Output_file*);
+
+  // The reloc section.
+  Reloc_section* rel_;
+  // The TLSDESC relocs, if necessary.  These must follow the regular
+  // PLT relocs.
+  Reloc_section* tlsdesc_rel_;
+  // The .got section.
+  Output_data_got<64, false>* got_;
+  // The .got.plt section.
+  Output_data_space* got_plt_;
+  // The number of PLT entries.
+  unsigned int count_;
+  // Offset of the reserved TLSDESC_GOT entry when needed.
+  unsigned int tlsdesc_got_offset_;
+};
 
 // The x86_64 target class.
 // See the ABI at
@@ -188,6 +296,15 @@ class Target_x86_64 : public Target_freebsd<64, false>
   uint64_t
   do_reloc_addend(void* arg, unsigned int r_type, uint64_t addend) const;
 
+  // Return the PLT section.
+  Output_data*
+  do_plt_section_for_global(const Symbol*) const
+  { return this->plt_section(); }
+
+  Output_data*
+  do_plt_section_for_local(const Relobj*, unsigned int) const
+  { return this->plt_section(); }
+
   // Adjust -fstack-split code which calls non-stack-split code.
   void
   do_calls_non_split(Relobj* object, unsigned int shndx,
@@ -197,12 +314,33 @@ class Target_x86_64 : public Target_freebsd<64, false>
 
   // Return the size of the GOT section.
   section_size_type
-  got_size()
+  got_size() const
   {
     gold_assert(this->got_ != NULL);
     return this->got_->data_size();
   }
 
+  // Return the number of entries in the GOT.
+  unsigned int
+  got_entry_count() const
+  {
+    if (this->got_ == NULL)
+      return 0;
+    return this->got_size() / 8;
+  }
+
+  // Return the number of entries in the PLT.
+  unsigned int
+  plt_entry_count() const;
+
+  // Return the offset of the first non-reserved PLT entry.
+  unsigned int
+  first_plt_entry_offset() const;
+
+  // Return the size of each PLT entry.
+  unsigned int
+  plt_entry_size() const;
+
   // Add a new reloc argument, returning the index in the vector.
   size_t
   add_tlsdesc_info(Sized_relobj<64, false>* object, unsigned int r_sym)
@@ -270,6 +408,9 @@ class Target_x86_64 : public Target_freebsd<64, false>
     inline bool
     possible_function_pointer_reloc(unsigned int r_type);
 
+    bool
+    reloc_needs_plt_for_ifunc(Sized_relobj<64, false>*, unsigned int r_type);
+
     // Whether we have issued an error about a non-PIC compilation.
     bool issued_non_pic_error_;
   };
@@ -279,7 +420,7 @@ class Target_x86_64 : public Target_freebsd<64, false>
   {
    public:
     Relocate()
-      : skip_call_tls_get_addr_(false), saw_tls_block_reloc_(false)
+      : skip_call_tls_get_addr_(false)
     { }
 
     ~Relocate()
@@ -370,12 +511,6 @@ class Target_x86_64 : public Target_freebsd<64, false>
     // This is set if we should skip the next reloc, which should be a
     // PLT32 reloc against ___tls_get_addr.
     bool skip_call_tls_get_addr_;
-
-    // This is set if we see a relocation which could load the address
-    // of the TLS block.  Whether we see such a relocation determines
-    // how we handle the R_X86_64_DTPOFF32 relocation, which is used
-    // in debugging sections.
-    bool saw_tls_block_reloc_;
   };
 
   // A class which returns the size required for a relocation type,
@@ -420,6 +555,12 @@ class Target_x86_64 : public Target_freebsd<64, false>
   void
   make_plt_entry(Symbol_table*, Layout*, Symbol*);
 
+  // Create a PLT entry for a local STT_GNU_IFUNC symbol.
+  void
+  make_local_ifunc_plt_entry(Symbol_table*, Layout*,
+                            Sized_relobj<64, false>* relobj,
+                            unsigned int local_sym_index);
+
   // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
   void
   define_tls_base_symbol(Symbol_table*, Layout*);
@@ -466,6 +607,10 @@ class Target_x86_64 : public Target_freebsd<64, false>
   // general Target structure.
   static const Target::Target_info x86_64_info;
 
+  // The types of GOT entries needed for this platform.
+  // These values are exposed to the ABI in an incremental link.
+  // Do not renumber existing values without changing the version
+  // number of the .gnu_incremental_inputs section.
   enum Got_type
   {
     GOT_TYPE_STANDARD = 0,      // GOT entry for a regular symbol
@@ -541,7 +686,7 @@ const Target::Target_info Target_x86_64::x86_64_info =
 // we handle the SHF_X86_64_LARGE.
 
 void
-Target_x86_64::do_new_output_section(Output_section *os) const
+Target_x86_64::do_new_output_section(Output_sectionos) const
 {
   if ((os->flags() & elfcpp::SHF_X86_64_LARGE) != 0)
     os->set_is_large_section();
@@ -616,101 +761,12 @@ Target_x86_64::rela_dyn_section(Layout* layout)
   return this->rela_dyn_;
 }
 
-// A class to handle the PLT data.
-
-class Output_data_plt_x86_64 : public Output_section_data
-{
- public:
-  typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
-
-  Output_data_plt_x86_64(Layout*, Output_data_got<64, false>*,
-                         Output_data_space*);
-
-  // Add an entry to the PLT.
-  void
-  add_entry(Symbol* gsym);
-
-  // Add the reserved TLSDESC_PLT entry to the PLT.
-  void
-  reserve_tlsdesc_entry(unsigned int got_offset)
-  { this->tlsdesc_got_offset_ = got_offset; }
-
-  // Return true if a TLSDESC_PLT entry has been reserved.
-  bool
-  has_tlsdesc_entry() const
-  { return this->tlsdesc_got_offset_ != -1U; }
-
-  // Return the GOT offset for the reserved TLSDESC_PLT entry.
-  unsigned int
-  get_tlsdesc_got_offset() const
-  { return this->tlsdesc_got_offset_; }
-
-  // Return the offset of the reserved TLSDESC_PLT entry.
-  unsigned int
-  get_tlsdesc_plt_offset() const
-  { return (this->count_ + 1) * plt_entry_size; }
-
-  // Return the .rela.plt section data.
-  const Reloc_section*
-  rela_plt() const
-  { return this->rel_; }
-
-  // Return where the TLSDESC relocations should go.
-  Reloc_section*
-  rela_tlsdesc(Layout*);
-
- protected:
-  void
-  do_adjust_output_section(Output_section* os);
-
-  // Write to a map file.
-  void
-  do_print_to_mapfile(Mapfile* mapfile) const
-  { mapfile->print_output_data(this, _("** PLT")); }
-
- private:
-  // The size of an entry in the PLT.
-  static const int plt_entry_size = 16;
-
-  // The first entry in the PLT.
-  // From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
-  // procedure linkage table for both programs and shared objects."
-  static unsigned char first_plt_entry[plt_entry_size];
-
-  // Other entries in the PLT for an executable.
-  static unsigned char plt_entry[plt_entry_size];
-
-  // The reserved TLSDESC entry in the PLT for an executable.
-  static unsigned char tlsdesc_plt_entry[plt_entry_size];
-
-  // Set the final size.
-  void
-  set_final_data_size();
-
-  // Write out the PLT data.
-  void
-  do_write(Output_file*);
-
-  // The reloc section.
-  Reloc_section* rel_;
-  // The TLSDESC relocs, if necessary.  These must follow the regular
-  // PLT relocs.
-  Reloc_section* tlsdesc_rel_;
-  // The .got section.
-  Output_data_got<64, false>* got_;
-  // The .got.plt section.
-  Output_data_space* got_plt_;
-  // The number of PLT entries.
-  unsigned int count_;
-  // Offset of the reserved TLSDESC_GOT entry when needed.
-  unsigned int tlsdesc_got_offset_;
-};
-
 // Create the PLT section.  The ordinary .got section is an argument,
 // since we need to refer to the start.  We also create our own .got
 // section just for PLT entries.
 
-Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
+Output_data_plt_x86_64::Output_data_plt_x86_64(Symbol_table* symtab,
+                                              Layout* layout,
                                                Output_data_got<64, false>* got,
                                                Output_data_space* got_plt)
   : Output_section_data(8), tlsdesc_rel_(NULL), got_(got), got_plt_(got_plt),
@@ -720,6 +776,24 @@ Output_data_plt_x86_64::Output_data_plt_x86_64(Layout* layout,
   layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
                                  elfcpp::SHF_ALLOC, this->rel_,
                                  ORDER_DYNAMIC_PLT_RELOCS, false);
+
+  if (parameters->doing_static_link())
+    {
+      // A statically linked executable will only have a .rela.plt
+      // section to hold R_X86_64_IRELATIVE relocs for STT_GNU_IFUNC
+      // symbols.  The library will use these symbols to locate the
+      // IRELATIVE relocs at program startup time.
+      symtab->define_in_output_data("__rela_iplt_start", NULL,
+                                   Symbol_table::PREDEFINED,
+                                   this->rel_, 0, 0, elfcpp::STT_NOTYPE,
+                                   elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN,
+                                   0, false, true);
+      symtab->define_in_output_data("__rela_iplt_end", NULL,
+                                   Symbol_table::PREDEFINED,
+                                   this->rel_, 0, 0, elfcpp::STT_NOTYPE,
+                                   elfcpp::STB_GLOBAL, elfcpp::STV_HIDDEN,
+                                   0, true, true);
+    }
 }
 
 void
@@ -749,15 +823,46 @@ Output_data_plt_x86_64::add_entry(Symbol* gsym)
   this->got_plt_->set_current_data_size(got_offset + 8);
 
   // Every PLT entry needs a reloc.
-  gsym->set_needs_dynsym_entry();
-  this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
-                        got_offset, 0);
+  if (gsym->type() == elfcpp::STT_GNU_IFUNC
+      && gsym->can_use_relative_reloc(false))
+    this->rel_->add_symbolless_global_addend(gsym, elfcpp::R_X86_64_IRELATIVE,
+                                            this->got_plt_, got_offset, 0);
+  else
+    {
+      gsym->set_needs_dynsym_entry();
+      this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
+                            got_offset, 0);
+    }
 
   // Note that we don't need to save the symbol.  The contents of the
   // PLT are independent of which symbols are used.  The symbols only
   // appear in the relocations.
 }
 
+// Add an entry to the PLT for a local STT_GNU_IFUNC symbol.  Return
+// the PLT offset.
+
+unsigned int
+Output_data_plt_x86_64::add_local_ifunc_entry(Sized_relobj<64, false>* relobj,
+                                             unsigned int local_sym_index)
+{
+  unsigned int plt_offset = (this->count_ + 1) * plt_entry_size;
+  ++this->count_;
+
+  section_offset_type got_offset = this->got_plt_->current_data_size();
+
+  // Every PLT entry needs a GOT entry which points back to the PLT
+  // entry.
+  this->got_plt_->set_current_data_size(got_offset + 8);
+
+  // Every PLT entry needs a reloc.
+  this->rel_->add_symbolless_local_addend(relobj, local_sym_index,
+                                         elfcpp::R_X86_64_IRELATIVE,
+                                         this->got_plt_, got_offset, 0);
+
+  return plt_offset;
+}
+
 // Return where the TLSDESC relocations should go, creating it if
 // necessary.  These follow the JUMP_SLOT relocations.
 
@@ -928,12 +1033,16 @@ Target_x86_64::make_plt_section(Symbol_table* symtab, Layout* layout)
       // Create the GOT sections first.
       this->got_section(symtab, layout);
 
-      this->plt_ = new Output_data_plt_x86_64(layout, this->got_,
+      this->plt_ = new Output_data_plt_x86_64(symtab, layout, this->got_,
                                               this->got_plt_);
       layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
                                      (elfcpp::SHF_ALLOC
                                       | elfcpp::SHF_EXECINSTR),
                                      this->plt_, ORDER_PLT, false);
+
+      // Make the sh_info field of .rela.plt point to .plt.
+      Output_section* rela_plt_os = this->plt_->rela_plt()->output_section();
+      rela_plt_os->set_info_section(this->plt_->output_section());
     }
 }
 
@@ -960,6 +1069,48 @@ Target_x86_64::make_plt_entry(Symbol_table* symtab, Layout* layout,
   this->plt_->add_entry(gsym);
 }
 
+// Make a PLT entry for a local STT_GNU_IFUNC symbol.
+
+void
+Target_x86_64::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout,
+                                         Sized_relobj<64, false>* relobj,
+                                         unsigned int local_sym_index)
+{
+  if (relobj->local_has_plt_offset(local_sym_index))
+    return;
+  if (this->plt_ == NULL)
+    this->make_plt_section(symtab, layout);
+  unsigned int plt_offset = this->plt_->add_local_ifunc_entry(relobj,
+                                                             local_sym_index);
+  relobj->set_local_plt_offset(local_sym_index, plt_offset);
+}
+
+// Return the number of entries in the PLT.
+
+unsigned int
+Target_x86_64::plt_entry_count() const
+{
+  if (this->plt_ == NULL)
+    return 0;
+  return this->plt_->entry_count();
+}
+
+// Return the offset of the first non-reserved PLT entry.
+
+unsigned int
+Target_x86_64::first_plt_entry_offset() const
+{
+  return Output_data_plt_x86_64::first_plt_entry_offset();
+}
+
+// Return the size of each PLT entry.
+
+unsigned int
+Target_x86_64::plt_entry_size() const
+{
+  return Output_data_plt_x86_64::get_plt_entry_size();
+}
+
 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
 
 void
@@ -1106,6 +1257,7 @@ Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type)
     {
       // These are the relocation types supported by glibc for x86_64.
     case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
     case elfcpp::R_X86_64_GLOB_DAT:
     case elfcpp::R_X86_64_JUMP_SLOT:
     case elfcpp::R_X86_64_DTPMOD64:
@@ -1134,6 +1286,72 @@ Target_x86_64::Scan::check_non_pic(Relobj* object, unsigned int r_type)
     }
 }
 
+// Return whether we need to make a PLT entry for a relocation of the
+// given type against a STT_GNU_IFUNC symbol.
+
+bool
+Target_x86_64::Scan::reloc_needs_plt_for_ifunc(Sized_relobj<64, false>* object,
+                                              unsigned int r_type)
+{
+  switch (r_type)
+    {
+    case elfcpp::R_X86_64_NONE:
+    case elfcpp::R_X86_64_GNU_VTINHERIT:
+    case elfcpp::R_X86_64_GNU_VTENTRY:
+      return false;
+
+    case elfcpp::R_X86_64_64:
+    case elfcpp::R_X86_64_32:
+    case elfcpp::R_X86_64_32S:
+    case elfcpp::R_X86_64_16:
+    case elfcpp::R_X86_64_8:
+    case elfcpp::R_X86_64_PC64:
+    case elfcpp::R_X86_64_PC32:
+    case elfcpp::R_X86_64_PC16:
+    case elfcpp::R_X86_64_PC8:
+    case elfcpp::R_X86_64_PLT32:
+    case elfcpp::R_X86_64_GOTPC32:
+    case elfcpp::R_X86_64_GOTOFF64:
+    case elfcpp::R_X86_64_GOTPC64:
+    case elfcpp::R_X86_64_PLTOFF64:
+    case elfcpp::R_X86_64_GOT64:
+    case elfcpp::R_X86_64_GOT32:
+    case elfcpp::R_X86_64_GOTPCREL64:
+    case elfcpp::R_X86_64_GOTPCREL:
+    case elfcpp::R_X86_64_GOTPLT64:
+      return true;
+
+    case elfcpp::R_X86_64_COPY:
+    case elfcpp::R_X86_64_GLOB_DAT:
+    case elfcpp::R_X86_64_JUMP_SLOT:
+    case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
+    case elfcpp::R_X86_64_TPOFF64:
+    case elfcpp::R_X86_64_DTPMOD64:
+    case elfcpp::R_X86_64_TLSDESC:
+      // We will give an error later.
+      return false;
+
+    case elfcpp::R_X86_64_TLSGD:
+    case elfcpp::R_X86_64_GOTPC32_TLSDESC:
+    case elfcpp::R_X86_64_TLSDESC_CALL:
+    case elfcpp::R_X86_64_TLSLD:
+    case elfcpp::R_X86_64_DTPOFF32:
+    case elfcpp::R_X86_64_DTPOFF64:
+    case elfcpp::R_X86_64_GOTTPOFF:
+    case elfcpp::R_X86_64_TPOFF32:
+      gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"),
+                object->name().c_str(), r_type);
+      return false;
+
+    case elfcpp::R_X86_64_SIZE32:
+    case elfcpp::R_X86_64_SIZE64:
+    default:
+      // We will give an error later.
+      return false;
+    }
+}
+
 // Scan a relocation for a local symbol.
 
 inline void
@@ -1147,6 +1365,14 @@ Target_x86_64::Scan::local(Symbol_table* symtab,
                            unsigned int r_type,
                            const elfcpp::Sym<64, false>& lsym)
 {
+  // A local STT_GNU_IFUNC symbol may require a PLT entry.
+  if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
+      && this->reloc_needs_plt_for_ifunc(object, r_type))
+    {
+      unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
+      target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
+    }
+
   switch (r_type)
     {
     case elfcpp::R_X86_64_NONE:
@@ -1165,11 +1391,11 @@ Target_x86_64::Scan::local(Symbol_table* symtab,
         {
           unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
           Reloc_section* rela_dyn = target->rela_dyn_section(layout);
-          rela_dyn->add_local_relative(object, r_sym,
-                                       elfcpp::R_X86_64_RELATIVE,
-                                       output_section, data_shndx,
-                                       reloc.get_r_offset(),
-                                       reloc.get_r_addend());
+         rela_dyn->add_local_relative(object, r_sym,
+                                      elfcpp::R_X86_64_RELATIVE,
+                                      output_section, data_shndx,
+                                      reloc.get_r_offset(),
+                                      reloc.get_r_addend());
         }
       break;
 
@@ -1240,7 +1466,16 @@ Target_x86_64::Scan::local(Symbol_table* symtab,
         // The symbol requires a GOT entry.
         Output_data_got<64, false>* got = target->got_section(symtab, layout);
         unsigned int r_sym = elfcpp::elf_r_sym<64>(reloc.get_r_info());
-        if (got->add_local(object, r_sym, GOT_TYPE_STANDARD))
+
+       // For a STT_GNU_IFUNC symbol we want the PLT offset.  That
+       // lets function pointers compare correctly with shared
+       // libraries.  Otherwise we would need an IRELATIVE reloc.
+       bool is_new;
+       if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC)
+         is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD);
+       else
+         is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD);
+        if (is_new)
           {
             // If we are generating a shared object, we need to add a
             // dynamic relocation for this symbol's GOT entry.
@@ -1249,9 +1484,13 @@ Target_x86_64::Scan::local(Symbol_table* symtab,
                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
                // R_X86_64_RELATIVE assumes a 64-bit relocation.
                if (r_type != elfcpp::R_X86_64_GOT32)
-                  rela_dyn->add_local_relative(
-                      object, r_sym, elfcpp::R_X86_64_RELATIVE, got,
-                      object->local_got_offset(r_sym, GOT_TYPE_STANDARD), 0);
+                 {
+                   unsigned int got_offset =
+                     object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
+                   rela_dyn->add_local_relative(object, r_sym,
+                                                elfcpp::R_X86_64_RELATIVE,
+                                                got, got_offset, 0);
+                 }
                 else
                   {
                     this->check_non_pic(object, r_type);
@@ -1272,6 +1511,7 @@ Target_x86_64::Scan::local(Symbol_table* symtab,
     case elfcpp::R_X86_64_GLOB_DAT:
     case elfcpp::R_X86_64_JUMP_SLOT:
     case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
       // These are outstanding tls relocs, which are unexpected when linking
     case elfcpp::R_X86_64_TPOFF64:
     case elfcpp::R_X86_64_DTPMOD64:
@@ -1505,6 +1745,11 @@ Target_x86_64::Scan::global(Symbol_table* symtab,
                             unsigned int r_type,
                             Symbol* gsym)
 {
+  // A STT_GNU_IFUNC symbol may require a PLT entry.
+  if (gsym->type() == elfcpp::STT_GNU_IFUNC
+      && this->reloc_needs_plt_for_ifunc(object, r_type))
+    target->make_plt_entry(symtab, layout, gsym);
+
   switch (r_type)
     {
     case elfcpp::R_X86_64_NONE:
@@ -1537,14 +1782,34 @@ Target_x86_64::Scan::global(Symbol_table* symtab,
                 target->copy_reloc(symtab, layout, object,
                                    data_shndx, output_section, gsym, reloc);
               }
+           else if (r_type == elfcpp::R_X86_64_64
+                    && gsym->type() == elfcpp::STT_GNU_IFUNC
+                    && gsym->can_use_relative_reloc(false)
+                    && !gsym->is_from_dynobj()
+                    && !gsym->is_undefined()
+                    && !gsym->is_preemptible())
+             {
+               // Use an IRELATIVE reloc for a locally defined
+               // STT_GNU_IFUNC symbol.  This makes a function
+               // address in a PIE executable match the address in a
+               // shared library that it links against.
+               Reloc_section* rela_dyn = target->rela_dyn_section(layout);
+               unsigned int r_type = elfcpp::R_X86_64_IRELATIVE;
+               rela_dyn->add_symbolless_global_addend(gsym, r_type,
+                                                      output_section, object,
+                                                      data_shndx,
+                                                      reloc.get_r_offset(),
+                                                      reloc.get_r_addend());
+             }
             else if (r_type == elfcpp::R_X86_64_64
                      && gsym->can_use_relative_reloc(false))
               {
                 Reloc_section* rela_dyn = target->rela_dyn_section(layout);
-                rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE,
-                                              output_section, object,
-                                              data_shndx, reloc.get_r_offset(),
-                                              reloc.get_r_addend());
+               rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE,
+                                             output_section, object,
+                                             data_shndx,
+                                             reloc.get_r_offset(),
+                                             reloc.get_r_addend());
               }
             else
               {
@@ -1598,23 +1863,49 @@ Target_x86_64::Scan::global(Symbol_table* symtab,
         // The symbol requires a GOT entry.
         Output_data_got<64, false>* got = target->got_section(symtab, layout);
         if (gsym->final_value_is_known())
-          got->add_global(gsym, GOT_TYPE_STANDARD);
+         {
+           // For a STT_GNU_IFUNC symbol we want the PLT address.
+           if (gsym->type() == elfcpp::STT_GNU_IFUNC)
+             got->add_global_plt(gsym, GOT_TYPE_STANDARD);
+           else
+             got->add_global(gsym, GOT_TYPE_STANDARD);
+         }
         else
           {
             // If this symbol is not fully resolved, we need to add a
             // dynamic relocation for it.
             Reloc_section* rela_dyn = target->rela_dyn_section(layout);
-            if (gsym->is_from_dynobj()
-                || gsym->is_undefined()
-                || gsym->is_preemptible())
+           if (gsym->is_from_dynobj()
+               || gsym->is_undefined()
+               || gsym->is_preemptible()
+               || (gsym->type() == elfcpp::STT_GNU_IFUNC
+                   && parameters->options().output_is_position_independent()))
               got->add_global_with_rela(gsym, GOT_TYPE_STANDARD, rela_dyn,
                                         elfcpp::R_X86_64_GLOB_DAT);
             else
               {
-                if (got->add_global(gsym, GOT_TYPE_STANDARD))
-                  rela_dyn->add_global_relative(
-                      gsym, elfcpp::R_X86_64_RELATIVE, got,
-                      gsym->got_offset(GOT_TYPE_STANDARD), 0);
+               // For a STT_GNU_IFUNC symbol we want to write the PLT
+               // offset into the GOT, so that function pointer
+               // comparisons work correctly.
+               bool is_new;
+               if (gsym->type() != elfcpp::STT_GNU_IFUNC)
+                 is_new = got->add_global(gsym, GOT_TYPE_STANDARD);
+               else
+                 {
+                   is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD);
+                   // Tell the dynamic linker to use the PLT address
+                   // when resolving relocations.
+                   if (gsym->is_from_dynobj()
+                       && !parameters->options().shared())
+                     gsym->set_needs_dynsym_value();
+                 }
+                if (is_new)
+                 {
+                   unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD);
+                   rela_dyn->add_global_relative(gsym,
+                                                 elfcpp::R_X86_64_RELATIVE,
+                                                 got, got_off, 0);
+                 }
               }
           }
         // For GOTPLT64, we also need a PLT entry (but only if the
@@ -1657,6 +1948,7 @@ Target_x86_64::Scan::global(Symbol_table* symtab,
     case elfcpp::R_X86_64_GLOB_DAT:
     case elfcpp::R_X86_64_JUMP_SLOT:
     case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
       // These are outstanding tls relocs, which are unexpected when linking
     case elfcpp::R_X86_64_TPOFF64:
     case elfcpp::R_X86_64_DTPMOD64:
@@ -1719,7 +2011,7 @@ Target_x86_64::Scan::global(Symbol_table* symtab,
                // the section has been created.
                target->got_section(symtab, layout);
                 Output_data_got<64, false>* got = target->got_tlsdesc_section();
-               Reloc_section *rt = target->rela_tlsdesc_section(layout);
+               Reloc_sectionrt = target->rela_tlsdesc_section(layout);
                 got->add_global_pair_with_rela(gsym, GOT_TYPE_TLS_DESC, rt,
                                                elfcpp::R_X86_64_TLSDESC, 0);
              }
@@ -1941,7 +2233,9 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
        }
     }
 
-  // Pick the value to use for symbols defined in shared objects.
+  const Sized_relobj<64, false>* object = relinfo->object;
+
+  // Pick the value to use for symbols defined in the PLT.
   Symbol_value<64> symval;
   if (gsym != NULL
       && gsym->use_plt_offset(r_type == elfcpp::R_X86_64_PC64
@@ -1953,8 +2247,17 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
                              + gsym->plt_offset());
       psymval = &symval;
     }
+  else if (gsym == NULL && psymval->is_ifunc_symbol())
+    {
+      unsigned int r_sym = elfcpp::elf_r_sym<64>(rela.get_r_info());
+      if (object->local_has_plt_offset(r_sym))
+       {
+         symval.set_output_value(target->plt_section()->address()
+                                 + object->local_plt_offset(r_sym));
+         psymval = &symval;
+       }
+    }
 
-  const Sized_relobj<64, false>* object = relinfo->object;
   const elfcpp::Elf_Xword addend = rela.get_r_addend();
 
   // Get the GOT offset if needed.
@@ -2130,6 +2433,7 @@ Target_x86_64::Relocate::relocate(const Relocate_info<64, false>* relinfo,
     case elfcpp::R_X86_64_GLOB_DAT:
     case elfcpp::R_X86_64_JUMP_SLOT:
     case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
       // These are outstanding tls relocs, which are unexpected when linking
     case elfcpp::R_X86_64_TPOFF64:
     case elfcpp::R_X86_64_DTPMOD64:
@@ -2182,18 +2486,29 @@ Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
 
   const Sized_relobj<64, false>* object = relinfo->object;
   const elfcpp::Elf_Xword addend = rela.get_r_addend();
+  elfcpp::Shdr<64, false> data_shdr(relinfo->data_shdr);
+  bool is_executable = (data_shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0;
 
   elfcpp::Elf_types<64>::Elf_Addr value = psymval->value(relinfo->object, 0);
 
   const bool is_final = (gsym == NULL
                         ? !parameters->options().shared()
                         : gsym->final_value_is_known());
-  const tls::Tls_optimization optimized_type
+  tls::Tls_optimization optimized_type
       = Target_x86_64::optimize_tls_reloc(is_final, r_type);
   switch (r_type)
     {
     case elfcpp::R_X86_64_TLSGD:            // Global-dynamic
-      this->saw_tls_block_reloc_ = true;
+      if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
+       {
+         // If this code sequence is used in a non-executable section,
+         // we will not optimize the R_X86_64_DTPOFF32/64 relocation,
+         // on the assumption that it's being used by itself in a debug
+         // section.  Therefore, in the unlikely event that the code
+         // sequence appears in a non-executable section, we simply
+         // leave it unoptimized.
+         optimized_type = tls::TLSOPT_NONE;
+       }
       if (optimized_type == tls::TLSOPT_TO_LE)
        {
          gold_assert(tls_segment != NULL);
@@ -2244,7 +2559,11 @@ Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
 
     case elfcpp::R_X86_64_GOTPC32_TLSDESC:  // Global-dynamic (from ~oliva url)
     case elfcpp::R_X86_64_TLSDESC_CALL:
-      this->saw_tls_block_reloc_ = true;
+      if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
+       {
+         // See above comment for R_X86_64_TLSGD.
+         optimized_type = tls::TLSOPT_NONE;
+       }
       if (optimized_type == tls::TLSOPT_TO_LE)
        {
          gold_assert(tls_segment != NULL);
@@ -2307,7 +2626,11 @@ Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
       break;
 
     case elfcpp::R_X86_64_TLSLD:            // Local-dynamic
-      this->saw_tls_block_reloc_ = true;
+      if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
+       {
+         // See above comment for R_X86_64_TLSGD.
+         optimized_type = tls::TLSOPT_NONE;
+       }
       if (optimized_type == tls::TLSOPT_TO_LE)
         {
           gold_assert(tls_segment != NULL);
@@ -2332,31 +2655,27 @@ Target_x86_64::Relocate::relocate_tls(const Relocate_info<64, false>* relinfo,
       break;
 
     case elfcpp::R_X86_64_DTPOFF32:
-      if (optimized_type == tls::TLSOPT_TO_LE)
-        {
-          // This relocation type is used in debugging information.
-          // In that case we need to not optimize the value.  If we
-          // haven't seen a TLSLD reloc, then we assume we should not
-          // optimize this reloc.
-          if (this->saw_tls_block_reloc_)
-           {
-              gold_assert(tls_segment != NULL);
-              value -= tls_segment->memsz();
-           }
-        }
+      // This relocation type is used in debugging information.
+      // In that case we need to not optimize the value.  If the
+      // section is not executable, then we assume we should not
+      // optimize this reloc.  See comments above for R_X86_64_TLSGD,
+      // R_X86_64_GOTPC32_TLSDESC, R_X86_64_TLSDESC_CALL, and
+      // R_X86_64_TLSLD.
+      if (optimized_type == tls::TLSOPT_TO_LE && is_executable)
+       {
+         gold_assert(tls_segment != NULL);
+         value -= tls_segment->memsz();
+       }
       Relocate_functions<64, false>::rela32(view, value, addend);
       break;
 
     case elfcpp::R_X86_64_DTPOFF64:
-      if (optimized_type == tls::TLSOPT_TO_LE)
-        {
-          // See R_X86_64_DTPOFF32, just above, for why we test this.
-          if (this->saw_tls_block_reloc_)
-           {
-             gold_assert(tls_segment != NULL);
-             value -= tls_segment->memsz();
-           }
-        }
+      // See R_X86_64_DTPOFF32, just above, for why we check for is_executable.
+      if (optimized_type == tls::TLSOPT_TO_LE && is_executable)
+       {
+         gold_assert(tls_segment != NULL);
+         value -= tls_segment->memsz();
+       }
       Relocate_functions<64, false>::rela64(view, value, addend);
       break;
 
@@ -2723,6 +3042,7 @@ Target_x86_64::Relocatable_size_for_reloc::get_size_for_reloc(
     case elfcpp::R_X86_64_GLOB_DAT:
     case elfcpp::R_X86_64_JUMP_SLOT:
     case elfcpp::R_X86_64_RELATIVE:
+    case elfcpp::R_X86_64_IRELATIVE:
       // These are outstanding tls relocs, which are unexpected when linking
     case elfcpp::R_X86_64_TPOFF64:
     case elfcpp::R_X86_64_DTPMOD64: