ELF dynsyms

Many ELF targets arrange to emit a number of section symbols in
.dynsym for use by dynamic relocations.  This happens before the
dynamic relocations are output, and the need for those symbols
determined.  In most cases they are not needed.  A proper analysis of
the need for dynamic section symbols is target specific and tedious,
so this patch just excludes them in the obvious case when no
dynamic relocations are present.

The patch also runs the new pr23161 and pr23162 tests on more targets.

bfd/
	* elf-bfd.h (struct elf_link_hash_table): Add "dynamic_relocs".
	* elflink.c (_bfd_elf_init_2_index_sections): Comment fix.
	(_bfd_elf_add_dynamic_entry): Set "dynamic_relocs".
	(_bfd_elf_link_renumber_dynsyms): Exclude all section symbols when
	"dynamic_relocs" is not set.
	* elfxx-mips.c (count_section_dynsyms): Likewise.
ld/
	* testsuite/ld-elf/readelf.exp: Delete DUMP and selection of
	variant ver_def.vd.
	* testsuite/ld-elf/ver_def-tic6x.vd: Delete.
	* testsuite/ld-elf/shared.exp: Run most pr23161 and pr23162 tests for
	linux, nacl and gnu targets.
	* testsuite/ld-mips-elf/mips-elf.exp: Set base_syms to 1.
	* testsuite/ld-elf/pr23161a.rd: Don't check reloc type.  Allow any
	order of __bss_start, _edata and _end.
	* testsuite/ld-elf/pr23161b.rd: Don't check plt and dyn relocs.
	Allow and order of __bss_start, _edata and _end.
	* testsuite/ld-elf/pr23162.rd: Fail if __bss_start, _edata or _end
	relocs are present rather than testing for no relocations.
	* testsuite/ld-aarch64/gc-plt-relocs.d,
	* testsuite/ld-aarch64/ifunc-1-local.d,
	* testsuite/ld-aarch64/ifunc-1.d,
	* testsuite/ld-aarch64/ifunc-2-local.d,
	* testsuite/ld-aarch64/ifunc-2.d,
	* testsuite/ld-aarch64/ifunc-21.d,
	* testsuite/ld-aarch64/ifunc-3a.d,
	* testsuite/ld-arm/farcall-mixed-lib-v4t.d,
	* testsuite/ld-arm/farcall-mixed-lib.d,
	* testsuite/ld-arm/gc-hidden-1.d,
	* testsuite/ld-arm/tls-gdesc-got.d,
	* testsuite/ld-arm/tls-lib-loc.d,
	* testsuite/ld-arm/tls-longplt-lib.d,
	* testsuite/ld-arm/tls-thumb1.d,
	* testsuite/ld-cris/libdso-10.d,
	* testsuite/ld-cris/libdso-11.d,
	* testsuite/ld-cris/libdso-13b.d,
	* testsuite/ld-cris/libdso-14.d,
	* testsuite/ld-cris/libdso-15.d,
	* testsuite/ld-cris/pic-gc-72.d,
	* testsuite/ld-cris/pic-gc-73.d,
	* testsuite/ld-cris/tls-gc-71.d,
	* testsuite/ld-mips-elf/mips16-pic-4a.nd,
	* testsuite/ld-mips-elf/pic-and-nonpic-3a.dd,
	* testsuite/ld-mips-elf/pie-n32.d,
	* testsuite/ld-mips-elf/pie-n64.d,
	* testsuite/ld-mips-elf/pie-o32.d: Update for removed dynamic
	section symbols.

4 files changed, 18 insertions, 1 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index d9465d5..2aa411d 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,14 @@
 2018-06-14  Alan Modra  <amodra@gmail.com>
 
+	* elf-bfd.h (struct elf_link_hash_table): Add "dynamic_relocs".
+	* elflink.c (_bfd_elf_init_2_index_sections): Comment fix.
+	(_bfd_elf_add_dynamic_entry): Set "dynamic_relocs".
+	(_bfd_elf_link_renumber_dynsyms): Exclude all section symbols when
+	"dynamic_relocs" is not set.
+	* elfxx-mips.c (count_section_dynsyms): Likewise.
+
+2018-06-14  Alan Modra  <amodra@gmail.com>
+
 	PR 23282
 	* bfdio.c (bfd_seek): Optimize away seeks to current position.
 
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 032e11f..788fdf8 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -543,6 +543,9 @@ struct elf_link_hash_table
      when linking against or generating a shared object.  */
   bfd_boolean dynamic_sections_created;
 
+  /* Whether dynamic relocations are present.  */
+  bfd_boolean dynamic_relocs;
+
   /* True if this target has relocatable executables, so needs dynamic
      section symbols.  */
   bfd_boolean is_relocatable_executable;
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 9dfd3e9..36e0c37 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -953,6 +953,7 @@ _bfd_elf_link_renumber_dynsyms (bfd *output_bfd,
       for (p = output_bfd->sections; p ; p = p->next)
 	if ((p->flags & SEC_EXCLUDE) == 0
 	    && (p->flags & SEC_ALLOC) != 0
+	    && elf_hash_table (info)->dynamic_relocs
 	    && !(*bed->elf_backend_omit_section_dynsym) (output_bfd, info, p))
 	  {
 	    ++dynsymcount;
@@ -3456,6 +3457,9 @@ _bfd_elf_add_dynamic_entry (struct bfd_link_info *info,
   if (! is_elf_hash_table (hash_table))
     return FALSE;
 
+  if (tag == DT_RELA || tag == DT_REL)
+    hash_table->dynamic_relocs = TRUE;
+
   bed = get_elf_backend_data (hash_table->dynobj);
   s = bfd_get_linker_section (hash_table->dynobj, ".dynamic");
   BFD_ASSERT (s != NULL);
@@ -7015,7 +7019,7 @@ _bfd_elf_init_2_index_sections (bfd *output_bfd, struct bfd_link_info *info)
   asection *s;
 
   /* Data first, since setting text_index_section changes
-     _bfd_elf_link_omit_section_dynsym.  */
+     _bfd_elf_omit_section_dynsym_default.  */
   for (s = output_bfd->sections; s != NULL; s = s->next)
     if (((s->flags & (SEC_EXCLUDE | SEC_ALLOC | SEC_READONLY)) == SEC_ALLOC)
 	&& !_bfd_elf_omit_section_dynsym_default (output_bfd, info, s))
diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index 205faa6..6e2f6fe 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -3813,6 +3813,7 @@ count_section_dynsyms (bfd *output_bfd, struct bfd_link_info *info)
       for (p = output_bfd->sections; p ; p = p->next)
 	if ((p->flags & SEC_EXCLUDE) == 0
 	    && (p->flags & SEC_ALLOC) != 0
+	    && elf_hash_table (info)->dynamic_relocs
 	    && !(*bed->elf_backend_omit_section_dynsym) (output_bfd, info, p))
 	  ++count;
     }