[v4,25/35,CHANGED] bfd, ld: add CTF section linking

Message ID 20190924135131.441906-26-nick.alcock@oracle.com
State New
Headers show
Series
  • CTF linking support
Related show

Commit Message

Nick Alcock Sept. 24, 2019, 1:51 p.m.
This is quite complicated because the CTF section's contents depend on
the final contents of the symtab and strtab, because it has two sections
whose contents are shuffled to be in 1:1 correspondence with the symtab,
and an internal strtab that gets deduplicated against the ELF strtab
(with offsets adjusted to point into the ELF strtab instead).  It is
also compressed if large enough, so its size depends on its contents!

So we cannot construct it as early as most sections: we cannot even
*begin* construction until after the symtab and strtab are finalized.
Thankfully there is already one section treated similarly: compressed
debugging sections: the only differences are that compressed debugging
sections have extra handling to deal with their changing name if
compressed (CTF sections are always called ".ctf" for now, though we
have reserved ".ctf.*" against future use), and that compressed
debugging sections have previously-uncompressed content which has to be
stashed away for later compression, while CTF sections have no content
at all until we generate it (very late).

BFD also cannot do the link itself: libctf knows how to do it, and BFD
cannot call libctf directly because libctf already depends on bfd for
file I/O.  So we have to use a pair of callbacks, one, examine_strtab,
which allows a caller to examine the symtab and strtab after
finalization (called from elf_link_swap_symbols_out(), right before the
symtabs are written, and after the strtab has been finalized), and one
which actually does the emission (called emit_ctf simply because it is
grouped with a bunch of section-specific late-emission function calls at
the bottom of bfd_elf_final_link, and a section-specific name seems best
for that).  emit_ctf is actually called *twice*: once from lang_process
if the emulation suggests that this bfd target does not examine the
symtab or strtab, and once via a bfd callback if it does.  (This means
that non-ELF targets still get CTF emitted, even though the late CTF
emission stage is never called for them).

v2: merged with non-ELF support patch: slight commit message
    adjustments.
v3: do not spend time merging CTF, or crash, if the CTF section is
    explicitly discarded.  Do not try to merge or compress CTF unless
    linking.
v4: add CTF_COMPRESSION_THRESHOLD.  Annul the freed input ctf_file_t's
    after writeout: set SEC_IN_MEMORY on the output contents so a future
    bfd enhancement knows it could free it.  Add SEC_LINKER_CREATED |
    SEC_KEEP to avoid having to add .ctf to the linker script.  Drop
    now-unnecessary ldlang.h-level elf-bfd.h include and hackery around
    it.  Adapt to elf32.em->elf.em and elf-generic.em->ldelf*.c
    changes.

        * Makefile.def (dependencies): all-ld depends on all-libctf.
        * Makefile.in: Regenerated.

include/
        * bfdlink.h (elf_strtab_hash): New forward.
        (elf_sym_strtab): Likewise.
        (struct bfd_link_callbacks <examine_strtab>): New.
        (struct bfd_link_callbacks <emit_ctf>): Likewise.

bfd/
	* elf-bfd.h (SECTION_IS_CTF): New macro.
	* elf.c (special_sections_c): Add ".ctf".
	(assign_file_positions_for_non_load_sections): Note that
	compressed debugging sections etc are not assigned here.  Treat
	CTF sections like SEC_ELF_COMPRESS sections when is_linker_output:
	sh_offset -1.
	(assign_file_positions_except_relocs): Likewise.
	(find_section_in_list): Note that debugging and CTF sections, as
	well as reloc sections, are assigned later.
	(_bfd_elf_assign_file_positions_for_non_load): CTF sections get
	their size and contents updated.
	(_bfd_elf_set_section_contents): Skip CTF sections: unlike
	compressed sections, they have no uncompressed content to copy at
	this stage.
	* elflink.c (elf_link_swap_symbols_out): Call the examine_strtab
	callback right before the strtab is written out.
	(bfd_elf_final_link): Don't cache the section contents of CTF
	sections: they are not populated yet.  Call the emit_ctf callback
	right at the end, after all the symbols and strings are flushed
	out.

ld/
	* ldlang.h (includes): Add ctf-api.h.
	(struct lang_input_statement_struct): Add the_ctf.
	(struct elf_sym_strtab): Add forward.
	(struct elf_strtab_hash): Likewise.
	(ldlang_ctf_apply_strsym): Declare.
	(ldlang_write_ctf_late): Likewise.
	* ldemul.h (ldemul_emit_ctf_early): New.
	(ldemul_examine_strtab_for_ctf): Likewise.
	(ld_emulation_xfer_type) <emit_ctf_early>: Likewise.
	(ld_emulation_xfer_type) <examine_strtab_for_ctf>: Likewise.
	* ldemul.c (ldemul_emit_ctf_early): New.
	(ldemul_examine_strtab_for_ctf): Likewise.
	* ldlang.c (includes): elf-bfd.h is now included by ldlang.h.
	Include elf/internal.h.
	(CTF_COMPRESSION_THRESHOLD): New.
	(ctf_output): New. Initialized in...
	(ldlang_open_ctf): ... this new function.  Open all the CTF
	sections in the input files: mark them non-loaded and empty
	so as not to copy their contents to the output, but linker-created
	so the section gets created in the target.
	(ldlang_merge_ctf): New, merge types via ctf_link_add_ctf and
	ctf_link.
	(ldlang_ctf_apply_strsym): New, an examine_strtab callback: wrap
	ldemul_examine_strtab_for_ctf.
	(lang_write_ctf): New, write out the CTF section.
	(ldlang_write_ctf_late): New, late call via bfd's emit_ctf hook.
	(lang_process): Call ldlang_open_ctf, ldlang_merge_ctf, and
	lang_write_ctf.
	* ldmain.c (link_callbacks): Add ldlang_ctf_apply_strsym,
	ldlang_write_ctf_late.

	* ldelfgen.c (ldelf_emit_ctf_early): New.
	(ldelf_examine_strtab_for_ctf): tell libctf about the symtab and
	strtab.
	(struct ctf_strsym_iter_cb_arg): New, state to do so.
	(ldelf_ctf_strtab_iter_cb): New: tell libctf about
	each string in the strtab in turn.
	(ldelf_ctf_symbols_iter_cb): New, tell libctf
	about each symbol in the symtab in turn.
	* ldelfgen.h (includes): Add sysdep.h, bfd.h, ctf-api.h.
	(struct elf_sym_strtab): Add forward.
	(struct elf_strtab_hash): Likewise.
	(ldelf_emit_ctf_early): Declare.
	(ldelf_examine_strtab_for_ctf): Likewise.
	* emultempl/elf-generic.em (LDEMUL_EMIT_CTF_EARLY): Set it.
	(LDEMUL_EXAMINE_STRTAB_FOR_CTF): Likewise.
	* emultempl/aix.em (ld_${EMULATION_NAME}_emulation): Add
	emit_ctf_early and examine_strtab_for_ctf, NULL by default.
	* emultempl/armcoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/beos.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/elf.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/generic.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/linux.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/msp430.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pe.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pep.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/ticoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/vanilla.em (ld_vanilla_emulation): Likewise.

	* Makefile.am: Pull in libctf (and zlib, a transitive requirement
	for compressed CTF section emission).  Pass it on to DejaGNU.
	* configure.ac: Add AM_ZLIB.
	* aclocal.m4: Added zlib.m4.
	* Makefile.in: Regenerated.
	* testsuite/ld-bootstrap/bootstrap.exp: Use it when relinking ld.
---
 ChangeLog                               |   5 +
 Makefile.def                            |   1 +
 Makefile.in                             |   7 +
 bfd/elf-bfd.h                           |   6 +-
 bfd/elf.c                               |  47 ++++--
 bfd/elflink.c                           |  25 ++-
 include/bfdlink.h                       |  15 ++
 ld/Makefile.am                          |  15 +-
 ld/Makefile.in                          |  23 ++-
 ld/aclocal.m4                           |   1 +
 ld/configure                            |  28 +++-
 ld/configure.ac                         |   4 +
 ld/emultempl/aix.em                     |   4 +-
 ld/emultempl/armcoff.em                 |   4 +-
 ld/emultempl/beos.em                    |   4 +-
 ld/emultempl/elf-generic.em             |   4 +
 ld/emultempl/elf.em                     |   4 +-
 ld/emultempl/generic.em                 |   4 +-
 ld/emultempl/linux.em                   |   4 +-
 ld/emultempl/msp430.em                  |   4 +-
 ld/emultempl/pe.em                      |   4 +-
 ld/emultempl/pep.em                     |   4 +-
 ld/emultempl/ticoff.em                  |   4 +-
 ld/emultempl/vanilla.em                 |   4 +-
 ld/ldelfgen.c                           | 110 +++++++++++++
 ld/ldelfgen.h                           |  11 ++
 ld/ldemul.c                             |  22 +++
 ld/ldemul.h                             |  21 +++
 ld/ldlang.c                             | 197 ++++++++++++++++++++++++
 ld/ldlang.h                             |  10 ++
 ld/ldmain.c                             |   4 +-
 ld/testsuite/ld-bootstrap/bootstrap.exp |   8 +-
 32 files changed, 560 insertions(+), 48 deletions(-)

-- 
2.23.0.239.g28aa4420fd

Patch

diff --git a/ChangeLog b/ChangeLog
index 5d1dfee8dd6..daa456380b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@ 
+2019-07-13  Nick Alcock  <nick.alcock@oracle.com>
+
+	* Makefile.def (dependencies): all-ld depends on all-libctf.
+	* Makefile.in: Regenerated.
+
 2019-09-09  Phil Blundell  <pb@pbcl.net>
 
 	binutils 2.33 branch created
diff --git a/Makefile.def b/Makefile.def
index 28bf61d7715..e887f498f4b 100644
--- a/Makefile.def
+++ b/Makefile.def
@@ -432,6 +432,7 @@  dependencies = { module=all-binutils; on=all-build-bison; };
 dependencies = { module=all-binutils; on=all-intl; };
 dependencies = { module=all-binutils; on=all-gas; };
 dependencies = { module=all-binutils; on=all-libctf; };
+dependencies = { module=all-ld; on=all-libctf; };
 
 // We put install-opcodes before install-binutils because the installed
 // binutils might be on PATH, and they might need the shared opcodes
diff --git a/Makefile.in b/Makefile.in
index 7a6700af964..eeba51e8297 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -51159,6 +51159,13 @@  all-stage3-binutils: maybe-all-stage3-libctf
 all-stage4-binutils: maybe-all-stage4-libctf
 all-stageprofile-binutils: maybe-all-stageprofile-libctf
 all-stagefeedback-binutils: maybe-all-stagefeedback-libctf
+all-ld: maybe-all-libctf
+all-stage1-ld: maybe-all-stage1-libctf
+all-stage2-ld: maybe-all-stage2-libctf
+all-stage3-ld: maybe-all-stage3-libctf
+all-stage4-ld: maybe-all-stage4-libctf
+all-stageprofile-ld: maybe-all-stageprofile-libctf
+all-stagefeedback-ld: maybe-all-stagefeedback-libctf
 install-binutils: maybe-install-opcodes
 install-strip-binutils: maybe-install-strip-opcodes
 install-opcodes: maybe-install-bfd
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 4240d97a429..2b18db08c3c 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -2257,7 +2257,7 @@  extern bfd_size_type _bfd_elf_strtab_len
 extern bfd_size_type _bfd_elf_strtab_offset
   (struct elf_strtab_hash *, size_t);
 extern const char * _bfd_elf_strtab_str
-  (struct elf_strtab_hash *, size_t idx, size_t *offset);
+  (struct elf_strtab_hash *, size_t idx, bfd_size_type *offset);
 extern bfd_boolean _bfd_elf_strtab_emit
   (bfd *, struct elf_strtab_hash *);
 extern void _bfd_elf_strtab_finalize
@@ -2965,6 +2965,10 @@  extern asection _bfd_elf_large_com_section;
 	 || (H)->start_stop \
 	 || ((INFO)->dynamic && !(H)->dynamic)))
 
+/* Determine if a section contains CTF data, using its name.  */
+#define SECTION_IS_CTF(name) \
+	(strcmp ((name), ".ctf") == 0 || strncmp ((name), ".ctf.", 5) == 0)
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/bfd/elf.c b/bfd/elf.c
index bb994b5aaa3..c15ba056026 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -2671,6 +2671,7 @@  static const struct bfd_elf_special_section special_sections_b[] =
 static const struct bfd_elf_special_section special_sections_c[] =
 {
   { STRING_COMMA_LEN (".comment"), 0, SHT_PROGBITS, 0 },
+  { STRING_COMMA_LEN (".ctf"),	0, SHT_PROGBITS,    0 },
   { NULL,			0, 0, 0,	    0 }
 };
 
@@ -5893,7 +5894,8 @@  is_debuginfo_file (bfd *abfd)
   return TRUE;
 }
 
-/* Assign file positions for the other sections.  */
+/* Assign file positions for the other sections, except for compressed debugging
+   and other sections assigned in _bfd_elf_assign_file_positions_for_non_load().  */
 
 static bfd_boolean
 assign_file_positions_for_non_load_sections (bfd *abfd,
@@ -5953,8 +5955,11 @@  assign_file_positions_for_non_load_sections (bfd *abfd,
       else if (((hdr->sh_type == SHT_REL || hdr->sh_type == SHT_RELA)
 		&& hdr->bfd_section == NULL)
 	       || (hdr->bfd_section != NULL
-		   && (hdr->bfd_section->flags & SEC_ELF_COMPRESS))
-		   /* Compress DWARF debug sections.  */
+		   && (hdr->bfd_section->flags & SEC_ELF_COMPRESS
+		       || (SECTION_IS_CTF (hdr->bfd_section->name)
+			   && abfd->is_linker_output)))
+		   /* We don't know the offset of these sections yet: their size
+                      has not been decided.  */
 	       || hdr == i_shdrpp[elf_onesymtab (abfd)]
 	       || (elf_symtab_shndx_list (abfd) != NULL
 		   && hdr == i_shdrpp[elf_symtab_shndx_list (abfd)->ndx])
@@ -6222,11 +6227,12 @@  find_section_in_list (unsigned int i, elf_section_list * list)
    VMAs must be known before this is called.
 
    Reloc sections come in two flavours: Those processed specially as
-   "side-channel" data attached to a section to which they apply, and
-   those that bfd doesn't process as relocations.  The latter sort are
-   stored in a normal bfd section by bfd_section_from_shdr.   We don't
-   consider the former sort here, unless they form part of the loadable
-   image.  Reloc sections not assigned here will be handled later by
+   "side-channel" data attached to a section to which they apply, and those that
+   bfd doesn't process as relocations.  The latter sort are stored in a normal
+   bfd section by bfd_section_from_shdr.  We don't consider the former sort
+   here, unless they form part of the loadable image.  Reloc sections not
+   assigned here (and compressed debugging sections and CTF sections which
+   nothing else in the file can rely upon) will be handled later by
    assign_file_positions_for_relocs.
 
    We also don't set the positions of the .symtab and .strtab here.  */
@@ -6262,8 +6268,11 @@  assign_file_positions_except_relocs (bfd *abfd,
 	  if (((hdr->sh_type == SHT_REL || hdr->sh_type == SHT_RELA)
 	       && hdr->bfd_section == NULL)
 	      || (hdr->bfd_section != NULL
-		  && (hdr->bfd_section->flags & SEC_ELF_COMPRESS))
-		  /* Compress DWARF debug sections.  */
+		  && (hdr->bfd_section->flags & SEC_ELF_COMPRESS
+		      || (SECTION_IS_CTF (hdr->bfd_section->name)
+			  && abfd->is_linker_output)))
+              /* Do not assign offsets for these sections yet: we don't know
+                 their sizes.  */
 	      || i == elf_onesymtab (abfd)
 	      || (elf_symtab_shndx_list (abfd) != NULL
 		  && hdr == i_shdrpp[elf_symtab_shndx_list (abfd)->ndx])
@@ -6471,12 +6480,14 @@  _bfd_elf_assign_file_positions_for_non_load (bfd *abfd)
 	  asection *sec = shdrp->bfd_section;
 	  bfd_boolean is_rel = (shdrp->sh_type == SHT_REL
 				|| shdrp->sh_type == SHT_RELA);
+          bfd_boolean is_ctf = sec && SECTION_IS_CTF (sec->name);
 	  if (is_rel
+              || is_ctf
 	      || (sec != NULL && (sec->flags & SEC_ELF_COMPRESS)))
 	    {
-	      if (!is_rel)
+	      if (!is_rel && !is_ctf)
 		{
-		  const char *name = sec->name;
+                  const char *name = sec->name;
 		  struct bfd_elf_section_data *d;
 
 		  /* Compress DWARF debug sections.  */
@@ -6520,6 +6531,13 @@  _bfd_elf_assign_file_positions_for_non_load (bfd *abfd)
 		  shdrp->contents = sec->contents;
 		  shdrp->bfd_section->contents = NULL;
 		}
+              else if (is_ctf)
+                {
+		  /* Update section size and contents.  */
+		  shdrp->sh_size = sec->size;
+		  shdrp->contents = sec->contents;
+                }
+
 	      off = _bfd_elf_assign_file_position_for_section (shdrp,
 							       off,
 							       TRUE);
@@ -9099,6 +9117,11 @@  _bfd_elf_set_section_contents (bfd *abfd,
   hdr = &elf_section_data (section)->this_hdr;
   if (hdr->sh_offset == (file_ptr) -1)
     {
+      if (SECTION_IS_CTF (section->name))
+        /* Nothing to do with this section: the contents are generated
+           later.  */
+        return TRUE;
+
       /* We must compress this section.  Write output to the buffer.  */
       unsigned char *contents = hdr->contents;
       if ((offset + count) > hdr->sh_size
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 2169e2b40cb..3e3266b91f6 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -9539,6 +9539,15 @@  elf_link_swap_symbols_out (struct elf_final_link_info *flinfo)
 				+ elfsym->destshndx_index));
     }
 
+  /* Allow the linker to examine the strtab and symtab now they are
+     populated.  */
+
+  if (flinfo->info->callbacks->examine_strtab)
+    flinfo->info->callbacks->examine_strtab (hash_table->strtab,
+                                             hash_table->strtabcount,
+                                             flinfo->symstrtab);
+
+
   hdr = &elf_tdata (flinfo->output_bfd)->symtab_hdr;
   pos = hdr->sh_offset + hdr->sh_size;
   amt = hash_table->strtabcount * bed->s->sizeof_sym;
@@ -11810,7 +11819,7 @@  bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* The object attributes have been merged.  Remove the input
      sections from the link, and set the contents of the output
-     secton.  */
+     section.  */
   std_attrs_section = get_elf_backend_data (abfd)->obj_attrs_section;
   for (o = abfd->sections; o != NULL; o = o->next)
     {
@@ -12032,7 +12041,8 @@  bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       esdo->rel.count = 0;
       esdo->rela.count = 0;
 
-      if (esdo->this_hdr.sh_offset == (file_ptr) -1)
+      if ((esdo->this_hdr.sh_offset == (file_ptr) -1)
+          && !SECTION_IS_CTF (o->name))
 	{
 	  /* Cache the section contents so that they can be compressed
 	     later.  Use bfd_malloc since it will be freed by
@@ -12048,10 +12058,10 @@  bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	}
     }
 
-  /* We have now assigned file positions for all the sections except
-     .symtab, .strtab, and non-loaded reloc sections.  We start the
-     .symtab section at the current file position, and write directly
-     to it.  We build the .strtab section in memory.  */
+  /* We have now assigned file positions for all the sections except .symtab,
+     .strtab, and non-loaded reloc and compressed debugging sections.  We start
+     the .symtab section at the current file position, and write directly to it.
+     We build the .strtab section in memory.  */
   abfd->symcount = 0;
   symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
   /* sh_name is set in prep_headers.  */
@@ -12837,6 +12847,9 @@  bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   if (! _bfd_elf_write_section_eh_frame_hdr (abfd, info))
     goto error_return;
 
+  if (info->callbacks->emit_ctf)
+      info->callbacks->emit_ctf ();
+
   elf_final_link_free (abfd, &flinfo);
 
   if (attr_section)
diff --git a/include/bfdlink.h b/include/bfdlink.h
index 68fc17f55e8..76355a3b953 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -636,6 +636,11 @@  struct bfd_link_info
   struct bfd_elf_version_tree *version_info;
 };
 
+/* Some forward-definitions used by some callbacks.  */
+
+struct elf_strtab_hash;
+struct elf_sym_strtab;
+
 /* This structures holds a set of callback functions.  These are called
    by the BFD linker routines.  */
 
@@ -757,6 +762,16 @@  struct bfd_link_callbacks
     (struct bfd_link_info *, bfd * abfd,
      asection * current_section, asection * previous_section,
      bfd_boolean new_segment);
+  /* This callback provides a chance for callers of the BFD to examine the
+     ELF string table and symbol table once they are complete and indexes and
+     offsets assigned.  */
+  void (*examine_strtab)
+    (struct elf_sym_strtab *syms, bfd_size_type symcount,
+     struct elf_strtab_hash *symstrtab);
+  /* This callback should emit the CTF section into a non-loadable section in
+     the output BFD named .ctf or a name beginning with ".ctf.".  */
+  void (*emit_ctf)
+    (void);
 };
 
 /* The linker builds link_order structures which tell the code how to
diff --git a/ld/Makefile.am b/ld/Makefile.am
index c56559dbfa2..00a2dc946c8 100644
--- a/ld/Makefile.am
+++ b/ld/Makefile.am
@@ -34,6 +34,12 @@  LEX = `if [ -f ../flex/flex ]; then echo ../flex/flex; else echo @LEX@; fi`
 am__skiplex =
 am__skipyacc =
 
+# This is where we get zlib from.  zlibdir is -L../zlib and zlibinc is
+# -I../zlib, unless we were configured with --with-system-zlib, in which
+# case both are empty.
+ZLIB = @zlibdir@ -lz
+ZLIBINC = @zlibinc@
+
 ELF_CLFAGS=-DELF_LIST_OPTIONS=@elf_list_options@ \
 	   -DELF_SHLIB_LIST_OPTIONS=@elf_shlib_list_options@ \
 	   -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
@@ -145,12 +151,13 @@  AM_MAKEINFOFLAGS = -I $(srcdir) -I $(BFDDIR)/doc -I ../bfd/doc \
 TEXI2DVI = texi2dvi -I $(srcdir) -I $(BFDDIR)/doc -I ../bfd/doc \
 		    -I $(top_srcdir)/../libiberty
 
-AM_CPPFLAGS = -I. -I$(srcdir) -I../bfd -I$(BFDDIR) -I$(INCDIR) \
+AM_CPPFLAGS = -I. -I$(srcdir) -I../bfd -I$(BFDDIR) -I$(INCDIR) @zlibinc@ \
 	@INCINTL@ $(HDEFINES) $(CFLAGS) $(PLUGIN_CFLAGS) \
 	-DLOCALEDIR="\"$(datadir)/locale\""
 
 BFDLIB = ../bfd/libbfd.la
 LIBIBERTY = ../libiberty/libiberty.a
+LIBCTF = ../libctf/libctf.a
 
 # These all start with e so 'make clean' can find them.
 ALL_EMULATION_SOURCES = \
@@ -959,8 +966,8 @@  ld_new_SOURCES = ldgram.y ldlex-wrapper.c lexsup.c ldlang.c mri.c ldctor.c ldmai
 	ldwrite.c ldexp.c ldemul.c ldver.c ldmisc.c ldfile.c ldcref.c $(PLUGIN_C) \
 	ldbuildid.c
 ld_new_DEPENDENCIES = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) \
-		      $(BFDLIB) $(LIBIBERTY) $(LIBINTL_DEP)
-ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBIBERTY) $(LIBINTL)
+		      $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL_DEP)
+ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL) $(ZLIB)
 
 # Dependency tracking for the generated emulation files.
 EXTRA_ld_new_SOURCES += $(ALL_EMULATION_SOURCES) $(ALL_64_EMULATION_SOURCES)
@@ -979,7 +986,7 @@  check-DEJAGNU: site.exp
 		CC="$(CC_FOR_TARGET)" CFLAGS="$(CFLAGS_FOR_TARGET)" \
 		CXX="$(CXX_FOR_TARGET)" CXXFLAGS="$(CXXFLAGS_FOR_TARGET)" \
 		CC_FOR_HOST="$(CC)" CFLAGS_FOR_HOST="$(CFLAGS)" \
-		OFILES="$(OFILES)" BFDLIB="$(TESTBFDLIB)" \
+		OFILES="$(OFILES)" BFDLIB="$(TESTBFDLIB)" CTFLIB="$(LIBCTF) $(ZLIB)" \
 		LIBIBERTY="$(LIBIBERTY) $(LIBINTL)" LIBS="$(LIBS)" \
 		DO_COMPARE="`echo '$(do_compare)' | sed -e 's,\\$$,,g'`" \
 		$(RUNTESTFLAGS); \
diff --git a/ld/Makefile.in b/ld/Makefile.in
index d509f62bd25..8b4753b808b 100644
--- a/ld/Makefile.in
+++ b/ld/Makefile.in
@@ -122,9 +122,9 @@  am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
 	$(top_srcdir)/../config/plugins.m4 \
 	$(top_srcdir)/../config/po.m4 \
 	$(top_srcdir)/../config/progtest.m4 \
-	$(top_srcdir)/../libtool.m4 $(top_srcdir)/../ltoptions.m4 \
-	$(top_srcdir)/../ltsugar.m4 $(top_srcdir)/../ltversion.m4 \
-	$(top_srcdir)/../lt~obsolete.m4 \
+	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
+	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
+	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
 	$(top_srcdir)/../bfd/version.m4 $(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
@@ -534,6 +534,8 @@  top_build_prefix = @top_build_prefix@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 use_sysroot = @use_sysroot@
+zlibdir = @zlibdir@
+zlibinc = @zlibinc@
 AUTOMAKE_OPTIONS = dejagnu no-texinfo.tex no-dist foreign info-in-builddir
 ACLOCAL_AMFLAGS = -I .. -I ../config -I ../bfd
 TEXINFO_TEX = ../texinfo/texinfo.tex
@@ -544,6 +546,12 @@  tooldir = $(exec_prefix)/$(target_alias)
 # maintainer mode is disabled.  Avoid this.
 am__skiplex = 
 am__skipyacc = 
+
+# This is where we get zlib from.  zlibdir is -L../zlib and zlibinc is
+# -I../zlib, unless we were configured with --with-system-zlib, in which
+# case both are empty.
+ZLIB = @zlibdir@ -lz
+ZLIBINC = @zlibinc@
 ELF_CLFAGS = -DELF_LIST_OPTIONS=@elf_list_options@ \
 	   -DELF_SHLIB_LIST_OPTIONS=@elf_shlib_list_options@ \
 	   -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
@@ -632,12 +640,13 @@  AM_MAKEINFOFLAGS = -I $(srcdir) -I $(BFDDIR)/doc -I ../bfd/doc \
 TEXI2DVI = texi2dvi -I $(srcdir) -I $(BFDDIR)/doc -I ../bfd/doc \
 		    -I $(top_srcdir)/../libiberty
 
-AM_CPPFLAGS = -I. -I$(srcdir) -I../bfd -I$(BFDDIR) -I$(INCDIR) \
+AM_CPPFLAGS = -I. -I$(srcdir) -I../bfd -I$(BFDDIR) -I$(INCDIR) @zlibinc@ \
 	@INCINTL@ $(HDEFINES) $(CFLAGS) $(PLUGIN_CFLAGS) \
 	-DLOCALEDIR="\"$(datadir)/locale\""
 
 BFDLIB = ../bfd/libbfd.la
 LIBIBERTY = ../libiberty/libiberty.a
+LIBCTF = ../libctf/libctf.a
 
 # These all start with e so 'make clean' can find them.
 ALL_EMULATION_SOURCES = \
@@ -1001,9 +1010,9 @@  ld_new_SOURCES = ldgram.y ldlex-wrapper.c lexsup.c ldlang.c mri.c ldctor.c ldmai
 	ldbuildid.c
 
 ld_new_DEPENDENCIES = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) \
-		      $(BFDLIB) $(LIBIBERTY) $(LIBINTL_DEP)
+		      $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL_DEP)
 
-ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBIBERTY) $(LIBINTL)
+ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL) $(ZLIB)
 #
 #
 # Build a dummy plugin using libtool.
@@ -2565,7 +2574,7 @@  check-DEJAGNU: site.exp
 		CC="$(CC_FOR_TARGET)" CFLAGS="$(CFLAGS_FOR_TARGET)" \
 		CXX="$(CXX_FOR_TARGET)" CXXFLAGS="$(CXXFLAGS_FOR_TARGET)" \
 		CC_FOR_HOST="$(CC)" CFLAGS_FOR_HOST="$(CFLAGS)" \
-		OFILES="$(OFILES)" BFDLIB="$(TESTBFDLIB)" \
+		OFILES="$(OFILES)" BFDLIB="$(TESTBFDLIB)" CTFLIB="$(LIBCTF) $(ZLIB)" \
 		LIBIBERTY="$(LIBIBERTY) $(LIBINTL)" LIBS="$(LIBS)" \
 		DO_COMPARE="`echo '$(do_compare)' | sed -e 's,\\$$,,g'`" \
 		$(RUNTESTFLAGS); \
diff --git a/ld/aclocal.m4 b/ld/aclocal.m4
index 4408082888b..7df8bf68f19 100644
--- a/ld/aclocal.m4
+++ b/ld/aclocal.m4
@@ -1198,6 +1198,7 @@  m4_include([../config/override.m4])
 m4_include([../config/plugins.m4])
 m4_include([../config/po.m4])
 m4_include([../config/progtest.m4])
+m4_include([../config/zlib.m4])
 m4_include([../libtool.m4])
 m4_include([../ltoptions.m4])
 m4_include([../ltsugar.m4])
diff --git a/ld/configure b/ld/configure
index 2d6ca5c0445..9ae333f03ea 100755
--- a/ld/configure
+++ b/ld/configure
@@ -645,6 +645,8 @@  elf_plt_unwind_list_options
 elf_shlib_list_options
 elf_list_options
 STRINGIFY
+zlibinc
+zlibdir
 enable_initfini_array
 ENABLE_PLUGINS_FALSE
 ENABLE_PLUGINS_TRUE
@@ -834,6 +836,7 @@  enable_werror
 enable_build_warnings
 enable_nls
 enable_initfini_array
+with_system_zlib
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1510,6 +1513,7 @@  Optional Packages:
   --with-gnu-ld           assume the C compiler uses GNU ld [default=no]
   --with-lib-path=dir1:dir2...  set default LIB_PATH
   --with-sysroot=DIR Search for usr/lib et al within DIR.
+  --with-system-zlib      use installed libz
 
 Some influential environment variables:
   CC          C compiler command
@@ -12027,7 +12031,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12030 "configure"
+#line 12034 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12133,7 +12137,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12136 "configure"
+#line 12140 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -17385,6 +17389,26 @@  cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+# Link in zlib if we can.  This allows us to read and write
+# compressed CTF sections.
+
+  # Use the system's zlib library.
+  zlibdir="-L\$(top_builddir)/../zlib"
+  zlibinc="-I\$(top_srcdir)/../zlib"
+
+# Check whether --with-system-zlib was given.
+if test "${with_system_zlib+set}" = set; then :
+  withval=$with_system_zlib; if test x$with_system_zlib = xyes ; then
+    zlibdir=
+    zlibinc=
+  fi
+
+fi
+
+
+
+
+
 # When converting linker scripts into strings for use in emulation
 # files, use astring.sed if the compiler supports ANSI string
 # concatenation, or ostring.sed otherwise.  This is to support the
diff --git a/ld/configure.ac b/ld/configure.ac
index 41a51bbb7e9..200d9d4fe91 100644
--- a/ld/configure.ac
+++ b/ld/configure.ac
@@ -293,6 +293,10 @@  BFD_BINARY_FOPEN
 
 AC_CHECK_DECLS([strstr, free, sbrk, getenv, environ])
 
+# Link in zlib if we can.  This allows us to read and write
+# compressed CTF sections.
+AM_ZLIB
+
 # When converting linker scripts into strings for use in emulation
 # files, use astring.sed if the compiler supports ANSI string
 # concatenation, or ostring.sed otherwise.  This is to support the
diff --git a/ld/emultempl/aix.em b/ld/emultempl/aix.em
index 96e84f9e62b..5f94b6c5a7a 100644
--- a/ld/emultempl/aix.em
+++ b/ld/emultempl/aix.em
@@ -1560,6 +1560,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation = {
   NULL,				/* recognized_file */
   NULL,				/* find potential_libraries */
   NULL,				/* new_vers_pattern */
-  NULL				/* extra_map_file_text */
+  NULL,				/* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/armcoff.em b/ld/emultempl/armcoff.em
index 180e1faa27c..a8f0b0ac09a 100644
--- a/ld/emultempl/armcoff.em
+++ b/ld/emultempl/armcoff.em
@@ -282,6 +282,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   NULL,	/* recognized file */
   NULL,	/* find_potential_libraries */
   NULL,	/* new_vers_pattern */
-  NULL	/* extra_map_file_text */
+  NULL,	/* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/beos.em b/ld/emultempl/beos.em
index 3ec285ba34b..141c4368f63 100644
--- a/ld/emultempl/beos.em
+++ b/ld/emultempl/beos.em
@@ -782,6 +782,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   NULL,	/* recognized file */
   NULL,	/* find_potential_libraries */
   NULL,	/* new_vers_pattern */
-  NULL	/* extra_map_file_text */
+  NULL,	/* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/elf-generic.em b/ld/emultempl/elf-generic.em
index 29af264440c..9ff544a3b74 100644
--- a/ld/emultempl/elf-generic.em
+++ b/ld/emultempl/elf-generic.em
@@ -25,3 +25,7 @@ 
 fragment <<EOF
 
 EOF
+# Put these extra routines in ld${EMULATION_NAME}_emulation
+#
+LDEMUL_EMIT_CTF_EARLY=ldelf_emit_ctf_early
+LDEMUL_EXAMINE_STRTAB_FOR_CTF=ldelf_examine_strtab_for_ctf
diff --git a/ld/emultempl/elf.em b/ld/emultempl/elf.em
index 5fec4d4a244..ea341eaf134 100644
--- a/ld/emultempl/elf.em
+++ b/ld/emultempl/elf.em
@@ -899,6 +899,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   ${LDEMUL_RECOGNIZED_FILE-ldelf_load_symbols},
   ${LDEMUL_FIND_POTENTIAL_LIBRARIES-NULL},
   ${LDEMUL_NEW_VERS_PATTERN-NULL},
-  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL}
+  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL},
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/generic.em b/ld/emultempl/generic.em
index 5cfe5a78a57..e9ebba3be7b 100644
--- a/ld/emultempl/generic.em
+++ b/ld/emultempl/generic.em
@@ -157,6 +157,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   ${LDEMUL_RECOGNIZED_FILE-NULL},
   ${LDEMUL_FIND_POTENTIAL_LIBRARIES-NULL},
   ${LDEMUL_NEW_VERS_PATTERN-NULL},
-  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL}
+  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL},
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/linux.em b/ld/emultempl/linux.em
index 5a01155984e..fdd7bbd42be 100644
--- a/ld/emultempl/linux.em
+++ b/ld/emultempl/linux.em
@@ -209,6 +209,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   NULL,	/* recognized file */
   NULL,	/* find_potential_libraries */
   NULL,	/* new_vers_pattern */
-  NULL	/* extra_map_file_text */
+  NULL,	/* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/msp430.em b/ld/emultempl/msp430.em
index 8f254895289..71f5d66f7ea 100644
--- a/ld/emultempl/msp430.em
+++ b/ld/emultempl/msp430.em
@@ -844,7 +844,9 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   ${LDEMUL_RECOGNIZED_FILE-NULL},
   ${LDEMUL_FIND_POTENTIAL_LIBRARIES-NULL},
   ${LDEMUL_NEW_VERS_PATTERN-NULL},
-  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL}
+  ${LDEMUL_EXTRA_MAP_FILE_TEXT-NULL},
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
 # 
diff --git a/ld/emultempl/pe.em b/ld/emultempl/pe.em
index c1932d79ade..79dd1f82df4 100644
--- a/ld/emultempl/pe.em
+++ b/ld/emultempl/pe.em
@@ -2366,6 +2366,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   gld_${EMULATION_NAME}_recognized_file,
   gld_${EMULATION_NAME}_find_potential_libraries,
   NULL,	/* new_vers_pattern.  */
-  NULL	/* extra_map_file_text.  */
+  NULL,	/* extra_map_file_text.  */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/pep.em b/ld/emultempl/pep.em
index ab2a989bc59..7ad4bd51b51 100644
--- a/ld/emultempl/pep.em
+++ b/ld/emultempl/pep.em
@@ -2165,6 +2165,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   gld_${EMULATION_NAME}_recognized_file,
   gld_${EMULATION_NAME}_find_potential_libraries,
   NULL,	/* new_vers_pattern.  */
-  NULL	/* extra_map_file_text */
+  NULL,	/* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/ticoff.em b/ld/emultempl/ticoff.em
index 65b03b668f3..3e9056f5fbd 100644
--- a/ld/emultempl/ticoff.em
+++ b/ld/emultempl/ticoff.em
@@ -182,6 +182,8 @@  struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
   NULL, /* recognized file */
   NULL,	/* find_potential_libraries */
   NULL,	/* new_vers_pattern */
-  NULL  /* extra_map_file_text */
+  NULL,  /* extra_map_file_text */
+  ${LDEMUL_EMIT_CTF_EARLY-NULL},
+  ${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
 };
 EOF
diff --git a/ld/emultempl/vanilla.em b/ld/emultempl/vanilla.em
index c57950ab6b3..f3654fda2d1 100644
--- a/ld/emultempl/vanilla.em
+++ b/ld/emultempl/vanilla.em
@@ -83,6 +83,8 @@  struct ld_emulation_xfer_struct ld_vanilla_emulation =
   NULL,	/* recognized file */
   NULL,	/* find_potential_libraries */
   NULL,	/* new_vers_pattern */
-  NULL	/* extra_map_file_text */
+  NULL,	/* extra_map_file_text */
+  NULL, /* emit_ctf_early */
+  NULL  /* examine_strtab_for_ctf */
 };
 EOF
diff --git a/ld/ldelfgen.c b/ld/ldelfgen.c
index 142a669db9c..887bfbcef28 100644
--- a/ld/ldelfgen.c
+++ b/ld/ldelfgen.c
@@ -73,3 +73,113 @@  ldelf_map_segments (bfd_boolean need_layout)
   if (tries == 0)
     einfo (_("%F%P: looping in map_segments"));
 }
+
+/* We want to emit CTF early if and only if we are not targetting ELF with this
+   invocation.  */
+
+int
+ldelf_emit_ctf_early (void)
+{
+  if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour)
+    return 0;
+  return 1;
+}
+
+/* Callbacks used to map from bfd types to libctf types, under libctf's
+   control.  */
+
+struct ctf_strsym_iter_cb_arg
+{
+  struct elf_sym_strtab *syms;
+  bfd_size_type symcount;
+  struct elf_strtab_hash *symstrtab;
+  size_t next_i;
+  size_t next_idx;
+};
+
+/* Return strings from the strtab to libctf, one by one.  Returns NULL when
+   iteration is complete.  */
+
+static const char *
+ldelf_ctf_strtab_iter_cb (uint32_t *offset, void *arg_)
+{
+  bfd_size_type off;
+  const char *ret;
+
+  struct ctf_strsym_iter_cb_arg *arg =
+    (struct ctf_strsym_iter_cb_arg *) arg_;
+
+  /* There is no zeroth string.  */
+  if (arg->next_i == 0)
+    arg->next_i = 1;
+
+  if (arg->next_i >= _bfd_elf_strtab_len (arg->symstrtab))
+    {
+      arg->next_i = 0;
+      return NULL;
+    }
+
+  ret = _bfd_elf_strtab_str (arg->symstrtab, arg->next_i++, &off);
+  *offset = off;
+
+  /* If we've overflowed, we cannot share any further strings: the CTF
+     format cannot encode strings with such high offsets.  */
+  if (*offset != off)
+    return NULL;
+
+  return ret;
+}
+
+/* Return symbols from the symbol table to libctf, one by one.  We assume (and
+   assert) that the symbols in the elf_link_hash_table are in strictly ascending
+   order, and that none will be added in between existing ones.  Returns NULL
+   when iteration is complete.  */
+
+static struct ctf_link_sym *
+ldelf_ctf_symbols_iter_cb (struct ctf_link_sym *dest,
+                                           void *arg_)
+{
+  struct ctf_strsym_iter_cb_arg *arg =
+    (struct ctf_strsym_iter_cb_arg *) arg_;
+
+  if (arg->next_i > arg->symcount)
+    {
+      arg->next_i = 0;
+      arg->next_idx = 0;
+      return NULL;
+    }
+
+  ASSERT (arg->syms[arg->next_i].dest_index == arg->next_idx);
+  dest->st_name = _bfd_elf_strtab_str (arg->symstrtab, arg->next_i, NULL);
+  dest->st_shndx = arg->syms[arg->next_i].sym.st_shndx;
+  dest->st_type = ELF_ST_TYPE (arg->syms[arg->next_i].sym.st_info);
+  dest->st_value = arg->syms[arg->next_i].sym.st_value;
+  arg->next_i++;
+  return dest;
+}
+
+void
+ldelf_examine_strtab_for_ctf
+  (ctf_file_t *ctf_output, struct elf_sym_strtab *syms,
+   bfd_size_type symcount, struct elf_strtab_hash *symstrtab)
+{
+  struct ctf_strsym_iter_cb_arg args = { syms, symcount, symstrtab,
+                                          0, 0 };
+   if (!ctf_output)
+     return;
+
+   if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour
+       && !bfd_link_relocatable (&link_info))
+    {
+      if (ctf_link_add_strtab (ctf_output, ldelf_ctf_strtab_iter_cb,
+                               &args) < 0)
+        einfo (_("%F%P: warning: CTF strtab association failed; strings will "
+                 "not be shared: %s\n"),
+               ctf_errmsg (ctf_errno (ctf_output)));
+
+      if (ctf_link_shuffle_syms (ctf_output, ldelf_ctf_symbols_iter_cb,
+                                 &args) < 0)
+        einfo (_("%F%P: warning: CTF symbol shuffling failed; slight space "
+                 "cost: %s\n"), ctf_errmsg (ctf_errno (ctf_output)));
+    }
+}
diff --git a/ld/ldelfgen.h b/ld/ldelfgen.h
index 328446006c3..62b85dc8121 100644
--- a/ld/ldelfgen.h
+++ b/ld/ldelfgen.h
@@ -18,4 +18,15 @@ 
    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
    MA 02110-1301, USA.  */
 
+#include "sysdep.h"
+#include "bfd.h"
+#include "ctf-api.h"
+
+struct elf_sym_strtab;
+struct elf_strtab_hash;
+
 extern void ldelf_map_segments (bfd_boolean);
+extern int ldelf_emit_ctf_early (void);
+extern void ldelf_examine_strtab_for_ctf
+  (ctf_file_t *ctf_output, struct elf_sym_strtab *syms,
+   bfd_size_type symcount, struct elf_strtab_hash *symstrtab);
diff --git a/ld/ldemul.c b/ld/ldemul.c
index 16ddb6dcf54..b9dd007a858 100644
--- a/ld/ldemul.c
+++ b/ld/ldemul.c
@@ -371,3 +371,25 @@  ldemul_extra_map_file_text (bfd *abfd, struct bfd_link_info *info, FILE *mapf)
   if (ld_emulation->extra_map_file_text)
     ld_emulation->extra_map_file_text (abfd, info, mapf);
 }
+
+int
+ldemul_emit_ctf_early (void)
+{
+  if (ld_emulation->emit_ctf_early)
+    return ld_emulation->emit_ctf_early ();
+  /* If the emulation doesn't know if it wants to emit CTF early, it is going
+     to do so.  */
+  return 1;
+}
+
+void
+ldemul_examine_strtab_for_ctf (ctf_file_t *ctf_output,
+                               struct elf_sym_strtab *syms,
+                               bfd_size_type symcount,
+                               struct elf_strtab_hash *symstrtab)
+
+{
+  if (ld_emulation->examine_strtab_for_ctf)
+    ld_emulation->examine_strtab_for_ctf (ctf_output, syms,
+                                          symcount, symstrtab);
+}
diff --git a/ld/ldemul.h b/ld/ldemul.h
index 5b6549f837b..1de29d05843 100644
--- a/ld/ldemul.h
+++ b/ld/ldemul.h
@@ -100,6 +100,14 @@  extern struct bfd_elf_version_expr *ldemul_new_vers_pattern
   (struct bfd_elf_version_expr *);
 extern void ldemul_extra_map_file_text
   (bfd *, struct bfd_link_info *, FILE *);
+/* Return 1 if we are emitting CTF early, and 0 if ldemul_examine_strtab_for_ctf
+   will be called by the target.  */
+extern int ldemul_emit_ctf_early
+  (void);
+/* Called from per-target code to examine the strtab and symtab.  */
+extern void ldemul_examine_strtab_for_ctf
+  (ctf_file_t *, struct elf_sym_strtab *, bfd_size_type,
+   struct elf_strtab_hash *);
 
 typedef struct ld_emulation_xfer_struct {
   /* Run before parsing the command line and script file.
@@ -208,6 +216,19 @@  typedef struct ld_emulation_xfer_struct {
   void (*extra_map_file_text)
     (bfd *, struct bfd_link_info *, FILE *);
 
+  /* If this returns true, we emit CTF as early as possible: if false, we emit
+     CTF once the strtab and symtab are laid out.  */
+  int (*emit_ctf_early)
+    (void);
+
+  /* Called to examine the string and symbol table late enough in linking that
+     they are finally laid out.  If emit_ctf_early returns true, this is not
+     called and ldemul_maybe_emit_ctf() emits CTF in 'early' mode: otherwise, it
+     waits until 'late'. (Late mode needs explicit support at per-target link
+     time to get called at all).  If set, called by ld when the examine_strtab
+     bfd_link_callback is invoked by per-target code.  */
+  void (*examine_strtab_for_ctf) (ctf_file_t *, struct elf_sym_strtab *,
+                                  bfd_size_type, struct elf_strtab_hash *);
 } ld_emulation_xfer_type;
 
 typedef enum {
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 1a49f69d908..376fc8dfbc1 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -127,6 +127,7 @@  bfd_boolean delete_output_file_on_failure = FALSE;
 struct lang_phdr *lang_phdr_list;
 struct lang_nocrossrefs *nocrossref_list;
 struct asneeded_minfo **asneeded_list_tail;
+static ctf_file_t *ctf_output;
 
  /* Functions that traverse the linker script and might evaluate
     DEFINED() need to increment this at the start of the traversal.  */
@@ -150,6 +151,12 @@  int lang_statement_iteration = 0;
 
 #define SECTION_NAME_MAP_LENGTH (16)
 
+/* CTF sections smaller than this are not compressed: compression of
+   dictionaries this small doesn't gain much, and this lets consumers mmap the
+   sections directly out of the ELF file and use them with no decompression
+   overhead if they want to.  */
+#define CTF_COMPRESSION_THRESHOLD 4096
+
 void *
 stat_alloc (size_t size)
 {
@@ -3585,6 +3592,186 @@  open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
     einfo ("%F");
 }
 
+/* Open the CTF sections in the input files with libctf: if any were opened,
+   create a fake input file that we'll write the merged CTF data to later
+   on.  */
+
+static void
+ldlang_open_ctf (void)
+{
+  int any_ctf = 0;
+  int err;
+
+  LANG_FOR_EACH_INPUT_STATEMENT (file)
+    {
+      asection *sect;
+
+      /* Incoming files from the compiler have a single ctf_file_t in them
+         (which is presented to us by the libctf API in a ctf_archive_t
+         wrapper): files derived from a previous relocatable link have a CTF
+         archive containing possibly many CTF files.  */
+
+      if ((file->the_ctf = ctf_bfdopen (file->the_bfd, &err)) == NULL)
+        {
+          if (err != ECTF_NOCTFDATA)
+            einfo (_("%P: warning: CTF section in `%pI' not loaded: "
+                     "its types will be discarded: `%s'\n"), file,
+                     ctf_errmsg (err));
+          continue;
+        }
+
+      /* Prevent the contents of this section from being written, while
+         requiring the section itself to be duplicated in the output.  */
+      /* This section must exist if ctf_bfdopen() succeeded.  */
+      sect = bfd_get_section_by_name (file->the_bfd, ".ctf");
+      sect->size = 0;
+      sect->flags |= SEC_NEVER_LOAD | SEC_HAS_CONTENTS | SEC_LINKER_CREATED;
+
+      any_ctf = 1;
+    }
+
+  if (!any_ctf)
+    {
+      ctf_output = NULL;
+      return;
+    }
+
+  if ((ctf_output = ctf_create (&err)) != NULL)
+    return;
+
+  einfo (_("%P: warning: CTF output not created: `s'\n"),
+         ctf_errmsg (err));
+
+  LANG_FOR_EACH_INPUT_STATEMENT (errfile)
+    ctf_close (errfile->the_ctf);
+}
+
+/* Merge together CTF sections.  After this, only the symtab-dependent
+   function and data object sections need adjustment.  */
+
+static void
+lang_merge_ctf (void)
+{
+  asection *output_sect;
+
+  if (!ctf_output)
+    return;
+
+  output_sect = bfd_get_section_by_name (link_info.output_bfd, ".ctf");
+
+  /* If the section was discarded, don't waste time merging.  */
+  if (output_sect == NULL)
+    {
+      ctf_file_close (ctf_output);
+      ctf_output = NULL;
+
+      LANG_FOR_EACH_INPUT_STATEMENT (file)
+        {
+          ctf_close (file->the_ctf);
+          file->the_ctf = NULL;
+        }
+      return;
+    }
+
+  LANG_FOR_EACH_INPUT_STATEMENT (file)
+    {
+      if (!file->the_ctf)
+        continue;
+
+      /* Takes ownership of file->u.the_ctfa.  */
+      if (ctf_link_add_ctf (ctf_output, file->the_ctf, file->filename) < 0)
+        {
+          einfo (_("%F%P: cannot link with CTF in %pB: %s\n"), file->the_bfd,
+                 ctf_errmsg (ctf_errno (ctf_output)));
+          ctf_close (file->the_ctf);
+          file->the_ctf = NULL;
+          continue;
+        }
+    }
+
+  if (ctf_link (ctf_output, CTF_LINK_SHARE_UNCONFLICTED) < 0)
+    {
+      einfo (_("%F%P: CTF linking failed; output will have no CTF section: %s\n"),
+             ctf_errmsg (ctf_errno (ctf_output)));
+      if (output_sect)
+        {
+          output_sect->size = 0;
+          output_sect->flags |= SEC_EXCLUDE;
+        }
+    }
+}
+
+/* Let the emulation examine the symbol table and strtab to help it optimize the
+   CTF, if supported.  */
+
+void
+ldlang_ctf_apply_strsym (struct elf_sym_strtab *syms, bfd_size_type symcount,
+                         struct elf_strtab_hash *symstrtab)
+{
+  ldemul_examine_strtab_for_ctf (ctf_output, syms, symcount, symstrtab);
+}
+
+/* Write out the CTF section.  Called early, if the emulation isn't going to
+   need to dedup against the strtab and symtab, then possibly called from the
+   target linker code if the dedup has happened.  */
+static void
+lang_write_ctf (int late)
+{
+  size_t output_size;
+  asection *output_sect;
+
+  if (!ctf_output)
+    return;
+
+  if (late)
+    {
+      /* Emit CTF late if this emulation says it can do so.  */
+      if (ldemul_emit_ctf_early ())
+        return;
+    }
+  else
+    {
+      if (!ldemul_emit_ctf_early ())
+        return;
+    }
+
+  /* Emit CTF.  */
+
+  output_sect = bfd_get_section_by_name (link_info.output_bfd, ".ctf");
+  if (output_sect)
+    {
+      output_sect->contents = ctf_link_write (ctf_output, &output_size,
+                                              CTF_COMPRESSION_THRESHOLD);
+      output_sect->size = output_size;
+      output_sect->flags |= SEC_IN_MEMORY | SEC_KEEP;
+
+      if (!output_sect->contents)
+        {
+          einfo (_("%F%P: CTF section emission failed; output will have no "
+                   "CTF section: %s\n"), ctf_errmsg (ctf_errno (ctf_output)));
+          output_sect->size = 0;
+          output_sect->flags |= SEC_EXCLUDE;
+        }
+    }
+
+  /* This also closes every CTF input file used in the link.  */
+  ctf_file_close (ctf_output);
+  ctf_output = NULL;
+
+  LANG_FOR_EACH_INPUT_STATEMENT (file)
+    file->the_ctf = NULL;
+}
+
+/* Write out the CTF section late, if the emulation needs that.  */
+
+void
+ldlang_write_ctf_late (void)
+{
+  /* Trigger a "late call", if the emulation needs one.  */
+
+  lang_write_ctf (1);
+}
+
 /* Add the supplied name to the symbol table as an undefined reference.
    This is a two step process as the symbol table doesn't even exist at
    the time the ld command line is processed.  First we put the name
@@ -7573,6 +7760,8 @@  lang_process (void)
   if (config.map_file != NULL)
     lang_print_asneeded ();
 
+  ldlang_open_ctf ();
+
   bfd_section_already_linked_table_free ();
 
   /* Make sure that we're not mixing architectures.  We call this
@@ -7649,6 +7838,14 @@  lang_process (void)
 	}
     }
 
+  /* Merge together CTF sections.  After this, only the symtab-dependent
+     function and data object sections need adjustment.  */
+  lang_merge_ctf ();
+
+  /* Emit the CTF, iff the emulation doesn't need to do late emission after
+     examining things laid out late, like the strtab.  */
+  lang_write_ctf (0);
+
   /* Copy forward lma regions for output sections in same lma region.  */
   lang_propagate_lma_regions ();
 
diff --git a/ld/ldlang.h b/ld/ldlang.h
index 5ab62e32792..fbd656649bc 100644
--- a/ld/ldlang.h
+++ b/ld/ldlang.h
@@ -21,6 +21,8 @@ 
 #ifndef LDLANG_H
 #define LDLANG_H
 
+#include "ctf-api.h"
+
 #define DEFAULT_MEMORY_REGION   "*default*"
 
 typedef enum
@@ -296,6 +298,8 @@  typedef struct lang_input_statement_struct
 
   bfd *the_bfd;
 
+  ctf_archive_t *the_ctf;
+
   struct flag_info *section_flag_list;
 
   /* Next pointer for file_chain statement list.  */
@@ -677,6 +681,12 @@  extern void add_excluded_libs (const char *);
 extern bfd_boolean load_symbols
   (lang_input_statement_type *, lang_statement_list_type *);
 
+struct elf_sym_strtab;
+struct elf_strtab_hash;
+extern void ldlang_ctf_apply_strsym
+  (struct elf_sym_strtab *, bfd_size_type, struct elf_strtab_hash *);
+extern void ldlang_write_ctf_late
+  (void);
 extern bfd_boolean
 ldlang_override_segment_assignment
   (struct bfd_link_info *, bfd *, asection *, asection *, bfd_boolean);
diff --git a/ld/ldmain.c b/ld/ldmain.c
index 34c19223137..45993b70c75 100644
--- a/ld/ldmain.c
+++ b/ld/ldmain.c
@@ -148,7 +148,9 @@  static struct bfd_link_callbacks link_callbacks =
   einfo,
   info_msg,
   minfo,
-  ldlang_override_segment_assignment
+  ldlang_override_segment_assignment,
+  ldlang_ctf_apply_strsym,
+  ldlang_write_ctf_late
 };
 
 static bfd_assert_handler_type default_bfd_assert_handler;
diff --git a/ld/testsuite/ld-bootstrap/bootstrap.exp b/ld/testsuite/ld-bootstrap/bootstrap.exp
index ee9442da167..7ab4a6a5302 100644
--- a/ld/testsuite/ld-bootstrap/bootstrap.exp
+++ b/ld/testsuite/ld-bootstrap/bootstrap.exp
@@ -160,7 +160,7 @@  foreach flags $test_flags {
 	setup_xfail "mips*-*-irix5*"
     }
 
-    if ![ld_link $CC tmpdir/ld1 "$flags tmpdir/ld-partial.o $BFDLIB $LIBIBERTY $extralibs"] {
+    if ![ld_link $CC tmpdir/ld1 "$flags tmpdir/ld-partial.o $CTFLIB $BFDLIB $LIBIBERTY $extralibs"] {
 	fail $testname
 	continue
     }
@@ -177,13 +177,13 @@  foreach flags $test_flags {
     }
 
     regsub /tmpdir/ld/ $gcc_B_opt_save /tmpdir/gccld1/ gcc_B_opt
-    if ![ld_link $CC tmpdir/ld2 "$flags $OFILES $BFDLIB $LIBIBERTY $extralibs"] {
+    if ![ld_link $CC tmpdir/ld2 "$flags $OFILES $CTFLIB $BFDLIB $LIBIBERTY $extralibs"] {
 	fail $testname
 	continue
     }
 
     regsub /tmpdir/ld/ $gcc_B_opt_save /tmpdir/gccld2/ gcc_B_opt
-    if ![ld_link $CC tmpdir/ld3 "$flags $OFILES $BFDLIB $LIBIBERTY $extralibs"] {
+    if ![ld_link $CC tmpdir/ld3 "$flags $OFILES $CTFLIB $BFDLIB $LIBIBERTY $extralibs"] {
 	fail $testname
 	continue
     }
@@ -196,7 +196,7 @@  foreach flags $test_flags {
 	# generated by different linkers, tmpdir/ld1 and tmpdir/ld2.
 	# So we rebuild tmpdir/ld2 with tmpdir/ld3.
 	regsub /tmpdir/ld/ $gcc_B_opt_save /tmpdir/gccld3/ gcc_B_opt
-	if ![ld_link $CC tmpdir/ld2 "$flags $OFILES $BFDLIB $LIBIBERTY $extralibs"] {
+	if ![ld_link $CC tmpdir/ld2 "$flags $OFILES $CTFLIB $BFDLIB $LIBIBERTY $extralibs"] {
 	    fail $testname
 	    continue
 	}