gold patch committed: Add FreeBSD support

[Ian Lance Taylor <iant at google dot com>]

FreeBSD requires that the EI_OSABI byte in the e_ident field in the ELF
header of an executable be set to ELFOSABI_FREEBSD (aka 9).  I committed
this patch to gold to implement that by adding a Target_freebsd class
which is the new parent class of Target_i386 and Target_x86_64.  This
makes it trivial to add FreeBSD support to any target.

Ian


2009-03-23  Ian Lance Taylor  <iant@google.com>

	* freebsd.h: New file.
	* i386.cc: Include "freebsd.h".
	(Target_i386): Derive from Target_freebsd rather than
	Sized_target.
	(Target_selector_i386): Derive from Target_selector_freebsd rather
	than Target_selector.
	* x86_64.cc: Include "freebsd.h".
	(Target_x86_64): Derive from Target_freebsd rather than
	Sized_target.
	(Target_selector_x86_64): Derive from Target_selector_freebsd
	rather than Target_selector.
	* target.h (class Target): Add adjust_elf_header and
	do_adjust_elf_header.
	* output.cc (Output_file_header:: do_sized_write): Call target
	adjust_elf_header routine.
	* configure.tgt: Set targ_osabi.
	* configure.ac: Define GOLD_DEFAULT_OSABI.
	* parameters.cc (Parameters::default_target): Pass
	GOLD_DEFAULT_OSABI to select_target.
	* target-select.h (class Target_selector): Make instantiate_target
	protected rather than private.
	* Makefile.am (HFILES): Add freebsd.h.
	* configure, Makefile.in, config.in: Rebuild.


Index: Makefile.am
===================================================================
RCS file: /cvs/src/src/gold/Makefile.am,v
retrieving revision 1.45
diff -p -u -r1.45 Makefile.am
--- Makefile.am	20 Mar 2009 23:37:51 -0000	1.45
+++ Makefile.am	24 Mar 2009 00:25:37 -0000
@@ -88,6 +88,7 @@ HFILES = \
 	ehframe.h \
 	errors.h \
 	fileread.h \
+	freebsd.h \
         gc.h \
 	gold.h \
 	gold-threads.h \
Index: configure.ac
===================================================================
RCS file: /cvs/src/src/gold/configure.ac,v
retrieving revision 1.38
diff -p -u -r1.38 configure.ac
--- configure.ac	17 Mar 2009 22:25:28 -0000	1.38
+++ configure.ac	24 Mar 2009 00:25:38 -0000
@@ -103,6 +103,7 @@ all_targets=
 default_machine=
 default_size=
 default_big_endian=
+default_osabi=ELFOSABI_NONE
 targ_32_little=
 targ_32_big=
 targ_64_little=
@@ -149,6 +150,7 @@ for targ in $target $canon_targets; do
         default_machine=$targ_machine
 	default_size=$targ_size
 	default_big_endian=$targ_big_endian
+	default_osabi=$targ_osabi
       fi
     fi
   fi
@@ -184,6 +186,8 @@ AC_DEFINE_UNQUOTED(GOLD_DEFAULT_SIZE, $d
 		   [Default size (32 or 64)])
 AC_DEFINE_UNQUOTED(GOLD_DEFAULT_BIG_ENDIAN, $default_big_endian,
 		   [Default big endian (true or false)])
+AC_DEFINE_UNQUOTED(GOLD_DEFAULT_OSABI, $default_osabi,
+		   [Default OSABI code])
 
 AC_PROG_CC
 AC_PROG_CXX
Index: configure.tgt
===================================================================
RCS file: /cvs/src/src/gold/configure.tgt,v
retrieving revision 1.5
diff -p -u -r1.5 configure.tgt
--- configure.tgt	19 Jan 2009 19:55:26 -0000	1.5
+++ configure.tgt	24 Mar 2009 00:25:38 -0000
@@ -36,6 +36,7 @@
 # targ_extra_size        extra targ_size setting for the target
 # targ_big_endian        whether the target is big-endian--true or false
 # targ_extra_big_endian  extra targ_big_endian setting for the target
+# targ_osabi		 EI_OSABI value
 
 # If the target is not recognized targ_obj is set to "UNKNOWN".
 
@@ -45,12 +46,18 @@ targ_size=
 targ_extra_size=
 targ_big_endian=
 targ_extra_big_endian=
+targ_osabi=ELFOSABI_NONE
 case "$targ" in
 i?86-*)
   targ_obj=i386
   targ_machine=EM_386
   targ_size=32
   targ_big_endian=false
+  case "$targ" in
+  i?86-*-freebsd*)
+    targ_osabi=ELFOSABI_FREEBSD
+    ;;
+  esac
   ;;
 x86_64*)
   targ_obj=x86_64
@@ -59,6 +66,11 @@ x86_64*)
   targ_size=64
   targ_extra_size=32
   targ_big_endian=false
+  case "$targ" in
+  x86_64-*-freebsd*)
+    targ_osabi=ELFOSABI_FREEBSD
+    ;;
+  esac
   ;;
 sparc-*)
   targ_obj=sparc
Index: freebsd.h
===================================================================
RCS file: freebsd.h
diff -N freebsd.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ freebsd.h	24 Mar 2009 00:25:38 -0000
@@ -0,0 +1,168 @@
+// freebsd.h -- FreeBSD support for gold    -*- C++ -*-
+
+// Copyright 2009 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#include "target.h"
+#include "target-select.h"
+
+#ifndef GOLD_FREEBSD_H
+#define GOLD_FREEBSD_H
+
+namespace gold
+{
+
+// FreeBSD 4.1 and later wants the EI_OSABI field in the ELF header to
+// be set to ELFOSABI_FREEBSD.  This is a subclass of Sized_target
+// which supports that.  The real target would be a subclass of this
+// one.  We permit combining FreeBSD and non-FreeBSD object files.
+// The effect of this target is to set the code in the output file.
+
+template<int size, bool big_endian>
+class Target_freebsd : public Sized_target<size, big_endian>
+{
+ public:
+  // Set the value to use for the EI_OSABI field in the ELF header.
+  void
+  set_osabi(elfcpp::ELFOSABI osabi)
+  { this->osabi_ = osabi; }
+
+ protected:
+  Target_freebsd(const Target::Target_info* pti)
+    : Sized_target<size, big_endian>(pti),
+      osabi_(elfcpp::ELFOSABI_NONE)
+  { }
+
+  virtual void
+  do_adjust_elf_header(unsigned char* view, int len) const;
+
+ private:
+  // Value to store in the EI_OSABI field of the ELF file header.
+  elfcpp::ELFOSABI osabi_;
+};
+
+// Adjust the ELF file header by storing the requested value in the
+// OSABI field.  This is for FreeBSD support.
+
+template<int size, bool big_endian>
+inline void
+Target_freebsd<size, big_endian>::do_adjust_elf_header(unsigned char* view,
+						       int len) const
+{
+  if (this->osabi_ != elfcpp::ELFOSABI_NONE)
+    {
+      gold_assert(len == elfcpp::Elf_sizes<32>::ehdr_size);
+
+      elfcpp::Ehdr<32, false> ehdr(view);
+      unsigned char e_ident[elfcpp::EI_NIDENT];
+      memcpy(e_ident, ehdr.get_e_ident(), elfcpp::EI_NIDENT);
+
+      e_ident[elfcpp::EI_OSABI] = this->osabi_;
+
+      elfcpp::Ehdr_write<32, false> oehdr(view);
+      oehdr.put_e_ident(e_ident);
+    }
+}
+
+// A target selector for targets which permit combining both FreeBSD
+// and non-FreeBSD object files.
+
+class Target_selector_freebsd : public Target_selector
+{
+ public:
+  Target_selector_freebsd(int machine, int size, bool is_big_endian,
+			  const char* bfd_name,
+			  const char* freebsd_bfd_name)
+    : Target_selector(machine, size, is_big_endian, NULL),
+      bfd_name_(bfd_name), freebsd_bfd_name_(freebsd_bfd_name)
+  { }
+
+ protected:
+  // If we see a FreeBSD input file, mark the output file as using
+  // FreeBSD.
+  virtual Target*
+  do_recognize(int, int osabi, int)
+  {
+    Target* ret = this->instantiate_target();
+    if (osabi == elfcpp::ELFOSABI_FREEBSD)
+      this->set_osabi(ret);
+    return ret;
+  }
+  
+  // Recognize two names.
+  virtual Target*
+  do_recognize_by_name(const char* name)
+  {
+    if (strcmp(name, this->bfd_name_) == 0)
+      return this->instantiate_target();
+    else if (strcmp(name, this->freebsd_bfd_name_) == 0)
+      {
+	Target* ret = this->instantiate_target();
+	this->set_osabi(ret);
+	return ret;
+      }
+    else
+      return NULL;
+  }
+
+  // Print both names in --help output.
+  virtual void
+  do_supported_names(std::vector<const char*>* names)
+  {
+    names->push_back(this->bfd_name_);
+    names->push_back(this->freebsd_bfd_name_);
+  }
+
+ private:
+  // Set the OSABI field.  This is quite ugly.
+  void
+  set_osabi(Target* target)
+  {
+    if (this->get_size() == 32)
+      {
+	if (this->is_big_endian())
+	  static_cast<Target_freebsd<32, true>*>(target)->
+	    set_osabi(elfcpp::ELFOSABI_FREEBSD);
+	else
+	  static_cast<Target_freebsd<32, false>*>(target)->
+	    set_osabi(elfcpp::ELFOSABI_FREEBSD);
+      }
+    else if (this->get_size() == 64)
+      {
+	if (this->is_big_endian())
+	  static_cast<Target_freebsd<64, true>*>(target)->
+	    set_osabi(elfcpp::ELFOSABI_FREEBSD);
+	else
+	  static_cast<Target_freebsd<64, false>*>(target)->
+	    set_osabi(elfcpp::ELFOSABI_FREEBSD);
+      }
+    else
+      gold_unreachable();
+  }
+
+  // The BFD name for the non-Freebsd target.
+  const char* bfd_name_;
+  // The BFD name for the Freebsd target.
+  const char* freebsd_bfd_name_;
+};
+
+} // end namespace gold
+
+#endif // !defined(GOLD_FREEBSD_H)
Index: i386.cc
===================================================================
RCS file: /cvs/src/src/gold/i386.cc,v
retrieving revision 1.85
diff -p -u -r1.85 i386.cc
--- i386.cc	4 Mar 2009 06:46:27 -0000	1.85
+++ i386.cc	24 Mar 2009 00:25:38 -0000
@@ -37,6 +37,7 @@
 #include "target-reloc.h"
 #include "target-select.h"
 #include "tls.h"
+#include "freebsd.h"
 
 namespace
 {
@@ -50,13 +51,13 @@ class Output_data_plt_i386;
 //   http://people.redhat.com/drepper/tls.pdf
 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
 
-class Target_i386 : public Sized_target<32, false>
+class Target_i386 : public Target_freebsd<32, false>
 {
  public:
   typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
 
   Target_i386()
-    : Sized_target<32, false>(&i386_info),
+    : Target_freebsd<32, false>(&i386_info),
       got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
       copy_relocs_(elfcpp::R_386_COPY), dynbss_(NULL),
       got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
@@ -2659,11 +2660,12 @@ Target_i386::do_code_fill(section_size_t
 
 // The selector for i386 object files.
 
-class Target_selector_i386 : public Target_selector
+class Target_selector_i386 : public Target_selector_freebsd
 {
 public:
   Target_selector_i386()
-    : Target_selector(elfcpp::EM_386, 32, false, "elf32-i386")
+    : Target_selector_freebsd(elfcpp::EM_386, 32, false,
+			      "elf32-i386", "elf32-i386-freebsd")
   { }
 
   Target*
Index: output.cc
===================================================================
RCS file: /cvs/src/src/gold/output.cc,v
retrieving revision 1.87
diff -p -u -r1.87 output.cc
--- output.cc	17 Mar 2009 22:25:30 -0000	1.87
+++ output.cc	24 Mar 2009 00:25:39 -0000
@@ -432,7 +432,6 @@ Output_file_header::do_sized_write(Outpu
 			      ? elfcpp::ELFDATA2MSB
 			      : elfcpp::ELFDATA2LSB);
   e_ident[elfcpp::EI_VERSION] = elfcpp::EV_CURRENT;
-  // FIXME: Some targets may need to set EI_OSABI and EI_ABIVERSION.
   oehdr.put_e_ident(e_ident);
 
   elfcpp::ET e_type;
@@ -489,6 +488,10 @@ Output_file_header::do_sized_write(Outpu
   else
     oehdr.put_e_shstrndx(elfcpp::SHN_XINDEX);
 
+  // Let the target adjust the ELF header, e.g., to set EI_OSABI in
+  // the e_ident field.
+  parameters->target().adjust_elf_header(view, ehdr_size);
+
   of->write_output_view(0, ehdr_size, view);
 }
 
Index: parameters.cc
===================================================================
RCS file: /cvs/src/src/gold/parameters.cc,v
retrieving revision 1.26
diff -p -u -r1.26 parameters.cc
--- parameters.cc	14 Mar 2009 05:56:46 -0000	1.26
+++ parameters.cc	24 Mar 2009 00:25:39 -0000
@@ -92,7 +92,8 @@ Parameters::default_target() const
   const Target* target = select_target(elfcpp::GOLD_DEFAULT_MACHINE,
                                        GOLD_DEFAULT_SIZE,
                                        GOLD_DEFAULT_BIG_ENDIAN,
-                                       0, 0);
+				       elfcpp::GOLD_DEFAULT_OSABI,
+				       0);
   gold_assert(target != NULL);
   return *target;
 }
Index: target-select.h
===================================================================
RCS file: /cvs/src/src/gold/target-select.h,v
retrieving revision 1.7
diff -p -u -r1.7 target-select.h
--- target-select.h	25 Mar 2008 21:39:01 -0000	1.7
+++ target-select.h	24 Mar 2009 00:25:39 -0000
@@ -106,10 +106,10 @@ class Target_selector
   virtual Target*
   do_instantiate_target() = 0;
 
-  // Recognize an object file given a machine code, size, and
-  // endianness.  When this is called we already know that they match
-  // the machine_, size_, and is_big_endian_ fields.  The child class
-  // may implement a different version of this to do additional
+  // Recognize an object file given a machine code, OSABI code, and
+  // ELF version value.  When this is called we already know that they
+  // match the machine_, size_, and is_big_endian_ fields.  The child
+  // class may implement a different version of this to do additional
   // checks, or to check for multiple machine codes if the machine_
   // field is EM_NONE.
   virtual Target*
@@ -134,7 +134,6 @@ class Target_selector
     names->push_back(this->bfd_name_);
   }
 
- private:
   // Instantiate the target and return it.
   Target*
   instantiate_target()
@@ -144,6 +143,7 @@ class Target_selector
     return this->instantiated_target_;
   }
 
+ private:
   // ELF machine code.
   const int machine_;
   // Target size--32 or 64.
Index: target.h
===================================================================
RCS file: /cvs/src/src/gold/target.h,v
retrieving revision 1.31
diff -p -u -r1.31 target.h
--- target.h	28 Jan 2009 02:25:33 -0000	1.31
+++ target.h	24 Mar 2009 00:25:39 -0000
@@ -167,6 +167,12 @@ class Target
   is_defined_by_abi(const Symbol* sym) const
   { return this->do_is_defined_by_abi(sym); }
 
+  // Adjust the output file header before it is written out.  VIEW
+  // points to the header in external form.  LEN is the length.
+  void
+  adjust_elf_header(unsigned char* view, int len) const
+  { return this->do_adjust_elf_header(view, len); }
+
  protected:
   // This struct holds the constant information for a child class.  We
   // use a struct to avoid the overhead of virtual function calls for
@@ -225,6 +231,14 @@ class Target
   do_is_defined_by_abi(const Symbol*) const
   { return false; }
 
+  // Adjust the output file header before it is written out.  VIEW
+  // points to the header in external form.  LEN is the length, and
+  // will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size.
+  // By default, we do nothing.
+  virtual void
+  do_adjust_elf_header(unsigned char*, int) const
+  { }
+
  private:
   Target(const Target&);
   Target& operator=(const Target&);
Index: x86_64.cc
===================================================================
RCS file: /cvs/src/src/gold/x86_64.cc,v
retrieving revision 1.79
diff -p -u -r1.79 x86_64.cc
--- x86_64.cc	4 Mar 2009 06:46:27 -0000	1.79
+++ x86_64.cc	24 Mar 2009 00:25:39 -0000
@@ -37,6 +37,7 @@
 #include "target-reloc.h"
 #include "target-select.h"
 #include "tls.h"
+#include "freebsd.h"
 
 namespace
 {
@@ -52,7 +53,7 @@ class Output_data_plt_x86_64;
 //   http://people.redhat.com/drepper/tls.pdf
 //   http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
 
-class Target_x86_64 : public Sized_target<64, false>
+class Target_x86_64 : public Target_freebsd<64, false>
 {
  public:
   // In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
@@ -60,7 +61,7 @@ class Target_x86_64 : public Sized_targe
   typedef Output_data_reloc<elfcpp::SHT_RELA, true, 64, false> Reloc_section;
 
   Target_x86_64()
-    : Sized_target<64, false>(&x86_64_info),
+    : Target_freebsd<64, false>(&x86_64_info),
       got_(NULL), plt_(NULL), got_plt_(NULL), rela_dyn_(NULL),
       copy_relocs_(elfcpp::R_X86_64_COPY), dynbss_(NULL),
       got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
@@ -2648,16 +2649,18 @@ Target_x86_64::do_code_fill(section_size
 
 // The selector for x86_64 object files.
 
-class Target_selector_x86_64 : public Target_selector
+class Target_selector_x86_64 : public Target_selector_freebsd
 {
 public:
   Target_selector_x86_64()
-    : Target_selector(elfcpp::EM_X86_64, 64, false, "elf64-x86-64")
+    : Target_selector_freebsd(elfcpp::EM_X86_64, 64, false, "elf64-x86-64",
+			      "elf64-x86-64-freebsd")
   { }
 
   Target*
   do_instantiate_target()
   { return new Target_x86_64(); }
+
 };
 
 Target_selector_x86_64 target_selector_x86_64;