ELF: Don't generate unused section symbols

For ELF targets, section symbols are required only for relocations.
With -ffunction-sections -fdata-sections, there can be many unused
section symbols.  Sizes of libstdc++.a on Linux/x86-64 in GCC 11 are

With unused section symbols   : 39411698 bytes
Without unused section symbols: 39227002 bytes

The unused section symbols in libstdc++.a occupy more than 180 KB.

Add BSF_SECTION_SYM_USED to indicate if a section symbol should be
included in the symbol table.  The BSF_SECTION_SYM_USED should be set
if the section symbol is used for relocation or the section symbol is
always included in the symbol table.

Add keep_unused_section_symbols to bfd_target to indicate if unused
section symbols should be kept.  If TARGET_KEEP_UNUSED_SECTION_SYMBOLS
is defined as FALSE, unused ection symbols will be removed.

Tested on Linux/x86.  Other ELF backends need to:

1. Define TARGET_KEEP_UNUSED_SECTION_SYMBOLS to FALSE.
2. Mark used section symbols in assembler backend.
3. Remove unused section symbols from expected assembler and linker
outputs.

bfd/

	PR 27109
	* aix386-core.c (core_aix386_vec): Initialize
	keep_unused_section_symbol to TARGET_KEEP_UNUSED_SECTION_SYMBOLS.
	* aout-target.h (MY (vec)): Likewise.
	* binary.c (binary_vec): Likewise.
	* cisco-core.c (core_cisco_be_vec): Likewise.
	(core_cisco_le_vec): Likewise.
	* coff-alpha.c (alpha_ecoff_le_vec): Likewise.
	* coff-i386.c (TARGET_SYM): Likewise.
	(TARGET_SYM_BIG): Likewise.
	* coff-ia64.c (TARGET_SYM): Likewise.
	* coff-mips.c (mips_ecoff_le_vec): Likewise.
	(mips_ecoff_be_vec): Likewise.
	(mips_ecoff_bele_vec): Likewise.
	* coff-rs6000.c (rs6000_xcoff_vec): Likewise.
	(powerpc_xcoff_vec): Likewise.
	* coff-sh.c (sh_coff_small_vec): Likewise.
	(sh_coff_small_le_vec): Likewise.
	* coff-tic30.c (tic30_coff_vec): Likewise.
	* coff-tic54x.c (tic54x_coff0_vec): Likewise.
	(tic54x_coff0_beh_vec): Likewise.
	(tic54x_coff1_vec): Likewise.
	(tic54x_coff1_beh_vec): Likewise.
	(tic54x_coff2_vec): Likewise.
	(tic54x_coff2_beh_vec): Likewise.
	* coff-x86_64.c (TARGET_SYM): Likewise.
	(TARGET_SYM_BIG): Likewise.
	* coff64-rs6000.c (rs6000_xcoff64_vec): Likewise.
	(rs6000_xcoff64_aix_vec): Likewise.
	* coffcode.h (CREATE_BIG_COFF_TARGET_VEC): Likewise.
	(CREATE_BIGHDR_COFF_TARGET_VEC): Likewise.
	(CREATE_LITTLE_COFF_TARGET_VEC): Likewise.
	* elfxx-target.h (TARGET_BIG_SYM): Likewise.
	(TARGET_LITTLE_SYM): Likewise.
	* hppabsd-core.c (core_hppabsd_vec): Likewise.
	* hpux-core.c (core_hpux_vec): Likewise.
	* i386msdos.c (i386_msdos_vec): Likewise.
	* ihex.c (ihex_vec): Likewise.
	* irix-core.c (core_irix_vec): Likewise.
	* mach-o-target.c (TARGET_NAME): Likewise.
	* mmo.c (mmix_mmo_vec): Likewise.
	* netbsd-core.c (core_netbsd_vec): Likewise.
	* osf-core.c (core_osf_vec): Likewise.
	* pdp11.c (MY (vec)): Likewise.
	* pef.c (pef_vec): Likewise.
	(pef_xlib_vec): Likewise.
	* plugin.c (plugin_vec): Likewise.
	* ppcboot.c (powerpc_boot_vec): Likewise.
	* ptrace-core.c (core_ptrace_vec): Likewise.
	* sco5-core.c (core_sco5_vec): Likewise.
	* som.c (hppa_som_vec): Likewise.
	* srec.c (srec_vec): Likewise.
	(symbolsrec_vec): Likewise.
	* tekhex.c (tekhex_vec): Likewise.
	* trad-core.c (core_trad_vec): Likewise.
	* verilog.c (verilog_vec): Likewise.
	* vms-alpha.c (alpha_vms_vec): Likewise.
	* vms-lib.c (alpha_vms_lib_txt_vec): Likewise.
	* wasm-module.c (wasm_vec): Likewise.
	* xsym.c (sym_vec): Likewise.
	* elf.c (ignore_section_sym): Return TRUE if BSF_SECTION_SYM_USED
	isn't set.
	(elf_map_symbols): Don't include ignored section symbols.
	* elfcode.h (elf_slurp_symbol_table): Also set
	BSF_SECTION_SYM_USED on STT_SECTION symbols.
	* elflink.c (bfd_elf_final_link): Generated section symbols only
	when emitting relocations or reqired.
	* elfxx-x86.h (TARGET_KEEP_UNUSED_SECTION_SYMBOLS): New.
	* syms.c (BSF_SECTION_SYM_USED): New.
	* targets.c (TARGET_KEEP_UNUSED_SECTION_SYMBOLS): New.
	(bfd_target): Add keep_unused_section_symbols.
	(bfd_keep_unused_section_symbols): New.
	* bfd-in2.h: Regenerated.

binutils/

	PR 27109
	* objcopy.c (copy_object): Handle section symbols for
	non-relocatable inputs.
	* testsuite/binutils-all/readelf.exp (readelf_test): Check
	is_elf_unused_section_symbols.
	* testsuite/binutils-all/readelf.s-64: Updated.
	* testsuite/binutils-all/readelf.ss: Likewise.
	* testsuite/binutils-all/readelf.ss-64: Likewise.
	* testsuite/binutils-all/readelf.s-64-unused: New file.
	* testsuite/binutils-all/readelf.ss-64-unused: Likewise.
	* testsuite/binutils-all/readelf.ss-unused: Likewise.
	* testsuite/lib/binutils-common.exp
	(is_elf_unused_section_symbols): New proc.

gas/ChangeLog:

	PR 27109
	* read.c (s_reloc): Call symbol_mark_used_in_reloc on the
	section symbol.
	* subsegs.c (subseg_set_rest): Set BSF_SECTION_SYM_USED if needed.
	* write.c (adjust_reloc_syms): Call symbol_mark_used_in_reloc
	on the section symbol.
	(set_symtab): Don't generate unused section symbols.
	(maybe_generate_build_notes): Call symbol_mark_used_in_reloc
	on the section symbol.
	* config/obj-elf.c (elf_adjust_symtab): Call
	symbol_mark_used_in_reloc on the group signature symbol.
	* testsuite/gas/cfi/cfi-label.d: Remove unused section symbols
	from expected output.
	* testsuite/gas/elf/elf.exp (run_elf_list_test): Check
	is_elf_unused_section_symbols.
	* testsuite/gas/elf/section2.e: Updated.
	* testsuite/gas/elf/section2.e-unused: New file.
	* testsuite/gas/elf/symver.d: Remove unused section symbols.
	* testsuite/gas/i386/ilp32/elf/symver.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-size-1.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-size-3.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-size-5.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-unwind.d: Likewise.
	* testsuite/gas/i386/size-1.d: Likewise.
	* testsuite/gas/i386/size-3.d: Likewise.
	* testsuite/gas/i386/svr4.d: Likewise.
	* testsuite/gas/i386/x86-64-size-1.d: Likewise.
	* testsuite/gas/i386/x86-64-size-3.d: Likewise.
	* testsuite/gas/i386/x86-64-size-5.d: Likewise.
	* testsuite/gas/i386/x86-64-unwind.d: Likewise.

ld/

	PR 27109
	* testsuite/ld-elf/export-class.sd: Adjust the expected output.
	* testsuite/ld-elf/loadaddr3b.d: Likewise.
	* testsuite/ld-i386/ibt-plt-1.d: Likewise.
	* testsuite/ld-i386/ibt-plt-2a.d: Likewise.
	* testsuite/ld-i386/ibt-plt-2c.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3a.d: Likewise.
	* testsuite/ld-i386/ibt-plt-3c.d: Likewise.
	* testsuite/ld-i386/pr19636-1d.d: Likewise.
	* testsuite/ld-i386/pr19636-1l.d: Likewise.
	* testsuite/ld-i386/pr19636-2c.d: Likewise.
	* testsuite/ld-ifunc/ifunc-2-i386-now.d: Likewise.
	* testsuite/ld-ifunc/ifunc-2-local-i386-now.d: Likewise.
	* testsuite/ld-ifunc/ifunc-2-local-x86-64-now.d: Likewise.
	* testsuite/ld-ifunc/ifunc-2-x86-64-now.d: Likewise.
	* testsuite/ld-ifunc/ifunc-21-x86-64.d: Likewise.
	* testsuite/ld-ifunc/ifunc-22-x86-64.d: Likewise.
	* testsuite/ld-ifunc/pr17154-i386-now.d: Likewise.
	* testsuite/ld-ifunc/pr17154-i386.d: Likewise.
	* testsuite/ld-ifunc/pr17154-x86-64-now.d: Likewise.
	* testsuite/ld-ifunc/pr17154-x86-64.d: Likewise.
	* testsuite/ld-x86-64/bnd-branch-1-now.d: Likewise.
	* testsuite/ld-x86-64/bnd-ifunc-1-now.d: Likewise.
	* testsuite/ld-x86-64/bnd-ifunc-2-now.d: Likewise.
	* testsuite/ld-x86-64/bnd-ifunc-2.d: Likewise.
	* testsuite/ld-x86-64/bnd-plt-1-now.d: Likewise.
	* testsuite/ld-x86-64/bnd-plt-1.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-1-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-1.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2a-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2a.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2c-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-2c.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3a-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3a.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3c-x32.d: Likewise.
	* testsuite/ld-x86-64/ibt-plt-3c.d: Likewise.
	* testsuite/ld-x86-64/pr19609-4e.d: Likewise.
	* testsuite/ld-x86-64/pr19609-6a.d: Likewise.
	* testsuite/ld-x86-64/pr19609-6b.d: Likewise.
	* testsuite/ld-x86-64/pr19609-7b.d: Likewise.
	* testsuite/ld-x86-64/pr19609-7d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2l.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1d.d: Likewise.
	* testsuite/ld-x86-64/pr20253-1h.d: Likewise.
	* testsuite/ld-x86-64/pr21038b-now.d: Likewise.
	* testsuite/ld-x86-64/pr21038b.d: Likewise.
	* testsuite/ld-x86-64/pr21038c-now.d: Likewise.
	* testsuite/ld-x86-64/pr21038c.d: Likewise.
	* testsuite/ld-x86-64/pr23854.d: Likewise.
	* testsuite/ld-x86-64/pr25416-3.d: Likewise.
	* testsuite/ld-x86-64/pr25416-4.d: Likewise.
	* testsuite/ld-i386/plt-pic.pd: Likewise.
	* testsuite/ld-i386/plt-pic2.dd: Likewise.
	* testsuite/ld-i386/plt.pd: Likewise.
	* testsuite/ld-i386/plt2.dd: Likewise.
	* testsuite/ld-i386/tlsbin.rd: Likewise.
	* testsuite/ld-i386/tlsbin2.rd: Likewise.
	* testsuite/ld-i386/tlsbindesc.rd: Likewise.
	* testsuite/ld-i386/tlsdesc.rd: Likewise.
	* testsuite/ld-i386/tlsgdesc.rd: Likewise.
	* testsuite/ld-i386/tlsnopic.rd: Likewise.
	* testsuite/ld-i386/tlspic.rd: Likewise.
	* testsuite/ld-i386/tlspic2.rd: Likewise.
	* testsuite/ld-x86-64/mpx3.dd: Likewise.
	* testsuite/ld-x86-64/mpx3n.dd: Likewise.
	* testsuite/ld-x86-64/mpx4.dd: Likewise.
	* testsuite/ld-x86-64/mpx4n.dd: Likewise.
	* testsuite/ld-x86-64/pe-x86-64-1.od: Likewise.
	* testsuite/ld-x86-64/pe-x86-64-2.od: Likewise.
	* testsuite/ld-x86-64/pe-x86-64-3.od: Likewise.
	* testsuite/ld-x86-64/pe-x86-64-4.od: Likewise.
	* testsuite/ld-x86-64/plt.pd: Likewise.
	* testsuite/ld-x86-64/plt2.dd: Likewise.
	* testsuite/ld-x86-64/tlsbin.rd: Likewise.
	* testsuite/ld-x86-64/tlsbin2.rd: Likewise.
	* testsuite/ld-x86-64/tlsbindesc.rd: Likewise.
	* testsuite/ld-x86-64/tlsdesc.rd: Likewise.
	* testsuite/ld-x86-64/tlsgdesc.rd: Likewise.
	* testsuite/ld-x86-64/tlspic.rd: Likewise.
	* testsuite/ld-x86-64/tlspic2.rd: Likewise.
	* testsuite/ld-elf/sec64k.exp: Check
	is_elf_unused_section_symbols.

10 files changed, 144 insertions, 10 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index c3b21c6a7a7..c308759c989 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,19 @@
+2021-01-07  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR 27109
+	* objcopy.c (copy_object): Handle section symbols for
+	non-relocatable inputs.
+	* testsuite/binutils-all/readelf.exp (readelf_test): Check
+	is_elf_unused_section_symbols.
+	* testsuite/binutils-all/readelf.s-64: Updated.
+	* testsuite/binutils-all/readelf.ss: Likewise.
+	* testsuite/binutils-all/readelf.ss-64: Likewise.
+	* testsuite/binutils-all/readelf.s-64-unused: New file.
+	* testsuite/binutils-all/readelf.ss-64-unused: Likewise.
+	* testsuite/binutils-all/readelf.ss-unused: Likewise.
+	* testsuite/lib/binutils-common.exp
+	(is_elf_unused_section_symbols): New proc.
+
 2021-01-06  Reuben Thomas  <rrt@sc3d.org>
 
 	* binutils/readelf.c: Correct grammar in comment.
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 560e7c648d1..62ee22202ff 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -3204,6 +3204,30 @@ copy_object (bfd *ibfd, bfd *obfd, const bfd_arch_info_type *input_arch)
   if (convert_debugging)
     dhandle = read_debugging_info (ibfd, isympp, symcount, FALSE);
 
+   if ((obfd->flags & (EXEC_P | DYNAMIC)) != 0
+       && (obfd->flags & HAS_RELOC) == 0)
+    {
+      if (bfd_keep_unused_section_symbols (obfd))
+	{
+	  /* Non-relocatable inputs may not have the unused section
+	     symbols.  Mark all section symbols as used to generate
+	     section symbols.  */
+	  asection *asect;
+	  for (asect = obfd->sections; asect != NULL; asect = asect->next)
+	    if (asect->symbol)
+	      asect->symbol->flags |= BSF_SECTION_SYM_USED;
+	}
+      else
+	{
+	  /* Non-relocatable inputs may have the unused section symbols.
+	     Mark all section symbols as unused to excluded them.  */
+	  long s;
+	  for (s = 0; s < symcount; s++)
+	    if ((isympp[s]->flags & BSF_SECTION_SYM_USED))
+	      isympp[s]->flags &= ~BSF_SECTION_SYM_USED;
+	}
+    }
+
   if (strip_symbols == STRIP_DEBUG
       || strip_symbols == STRIP_ALL
       || strip_symbols == STRIP_UNNEEDED
diff --git a/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
index 4834233ad31..51d26b762b3 100644
--- a/binutils/testsuite/binutils-all/readelf.exp
+++ b/binutils/testsuite/binutils-all/readelf.exp
@@ -100,7 +100,11 @@ proc readelf_test { options binary_file regexp_file xfails } {
 	return
     }
 
-    set target_machine ""
+    if { [is_elf_unused_section_symbols ] } {
+	set target_machine unused
+    } else {
+	set target_machine ""
+    }
     if [istarget "mips*-*-*"] then {
 	if [is_bad_symtab] then {
 	    set target_machine mips
diff --git a/binutils/testsuite/binutils-all/readelf.s-64 b/binutils/testsuite/binutils-all/readelf.s-64
index a1e6cd1bbd8..5582d77c372 100644
--- a/binutils/testsuite/binutils-all/readelf.s-64
+++ b/binutils/testsuite/binutils-all/readelf.s-64
@@ -18,7 +18,7 @@ Section Headers:
  +\[ .\] .symtab +SYMTAB +0000000000000000 +0+.*
 # aarch64-elf targets have one more data symbol.
 # x86 targets may have .note.gnu.property.
- +0+.* +0000000000000018 +(6|7) +(6|7) +8
+ +0+.* +0000000000000018 +(6|7) +(3|4) +8
  +\[ .\] .strtab +STRTAB +0000000000000000 +0+.*
  +0+.* +0000000000000000 .* +0 +0 +1
  +\[ .\] .shstrtab +STRTAB +0000000000000000 +[0-9a-f]+
diff --git a/binutils/testsuite/binutils-all/readelf.s-64-unused b/binutils/testsuite/binutils-all/readelf.s-64-unused
new file mode 100644
index 00000000000..a1e6cd1bbd8
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf.s-64-unused
@@ -0,0 +1,27 @@
+There are .* section headers, starting at offset .*:
+
+Section Headers:
+ +\[Nr\] Name +Type +Address +Offset
+ +Size +EntSize +Flags +Link +Info +Align
+ +\[ 0\] +NULL +0000000000000000 +00000000
+ +0000000000000000 +0000000000000000 +0 +0 +0
+ +\[ 1\] .text +PROGBITS +0000000000000000 +00000040
+ +00000000000000.. +0000000000000000 +AX +0 +0 +.*
+ +\[ 2\] .rel.+text +REL. +0+ +0+.*
+ +000000000000001. +000000000000001. +I +. +1 +8
+ +\[ 3\] .data +PROGBITS +0000000000000000 +000000(48|50)
+ +000000000000000[48] +0000000000000000 +WA +0 +0 +.*
+ +\[ 4\] .bss +NOBITS +0000000000000000 +000000(4c|50|54|58)
+ +0000000000000000 +0000000000000000 +WA +0 +0 +.*
+# x86 targets may put .note.gnu.property here.
+#...
+ +\[ .\] .symtab +SYMTAB +0000000000000000 +0+.*
+# aarch64-elf targets have one more data symbol.
+# x86 targets may have .note.gnu.property.
+ +0+.* +0000000000000018 +(6|7) +(6|7) +8
+ +\[ .\] .strtab +STRTAB +0000000000000000 +0+.*
+ +0+.* +0000000000000000 .* +0 +0 +1
+ +\[ .\] .shstrtab +STRTAB +0000000000000000 +[0-9a-f]+
+ +00000000000000.. +0000000000000000 .* +0 +0 +.*
+Key to Flags:
+#...
diff --git a/binutils/testsuite/binutils-all/readelf.ss b/binutils/testsuite/binutils-all/readelf.ss
index acc6d9390c5..5fbb5d002e3 100644
--- a/binutils/testsuite/binutils-all/readelf.ss
+++ b/binutils/testsuite/binutils-all/readelf.ss
@@ -2,10 +2,7 @@
 Symbol table '.symtab' contains .* entries:
  +Num: +Value +Size +Type +Bind +Vis +Ndx +Name
  +0: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +UND 
- +1: 00000000 +0 +SECTION +LOCAL +DEFAULT +1 
- +2: 00000000 +0 +SECTION +LOCAL +DEFAULT +[34] 
- +3: 00000000 +0 +SECTION +LOCAL +DEFAULT +[45] 
- +4: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
+ +1: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # ARM targets add the $d mapping symbol here...
 # NDS32 targets add the $d2 mapping symbol here...
 #...
diff --git a/binutils/testsuite/binutils-all/readelf.ss-64 b/binutils/testsuite/binutils-all/readelf.ss-64
index bd10cabef35..99a732f71f5 100644
--- a/binutils/testsuite/binutils-all/readelf.ss-64
+++ b/binutils/testsuite/binutils-all/readelf.ss-64
@@ -2,10 +2,7 @@
 Symbol table '.symtab' contains .* entries:
  +Num: +Value +Size +Type +Bind +Vis +Ndx +Name
  +0: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +UND 
- +1: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +1 
- +2: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +3 
- +3: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +4 
- +4: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
+ +1: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
 # aarch64-elf targets add the $d mapping symbol here...
 #...
  +.: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +3 static_data_symbol
diff --git a/binutils/testsuite/binutils-all/readelf.ss-64-unused b/binutils/testsuite/binutils-all/readelf.ss-64-unused
new file mode 100644
index 00000000000..bd10cabef35
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf.ss-64-unused
@@ -0,0 +1,18 @@
+
+Symbol table '.symtab' contains .* entries:
+ +Num: +Value +Size +Type +Bind +Vis +Ndx +Name
+ +0: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +UND 
+ +1: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +1 
+ +2: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +3 
+ +3: 0000000000000000 +0 +SECTION +LOCAL +DEFAULT +4 
+ +4: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
+# aarch64-elf targets add the $d mapping symbol here...
+#...
+ +.: 0000000000000000 +0 +NOTYPE +LOCAL +DEFAULT +3 static_data_symbol
+# ... or here ...
+#...
+.* +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
+ +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
+ +.: 0000000000000000 +0 +NOTYPE +GLOBAL +DEFAULT +3 data_symbol
+ +[0-9]+: 0000000000000004 +4 +(COMMON|OBJECT) +GLOBAL +DEFAULT +COM common_symbol
+#pass
diff --git a/binutils/testsuite/binutils-all/readelf.ss-unused b/binutils/testsuite/binutils-all/readelf.ss-unused
new file mode 100644
index 00000000000..acc6d9390c5
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf.ss-unused
@@ -0,0 +1,20 @@
+
+Symbol table '.symtab' contains .* entries:
+ +Num: +Value +Size +Type +Bind +Vis +Ndx +Name
+ +0: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +UND 
+ +1: 00000000 +0 +SECTION +LOCAL +DEFAULT +1 
+ +2: 00000000 +0 +SECTION +LOCAL +DEFAULT +[34] 
+ +3: 00000000 +0 +SECTION +LOCAL +DEFAULT +[45] 
+ +4: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +1 static_text_symbol
+# ARM targets add the $d mapping symbol here...
+# NDS32 targets add the $d2 mapping symbol here...
+#...
+ +.: 00000000 +0 +NOTYPE +LOCAL +DEFAULT +[34] static_data_symbol
+# v850 targets include extra SECTION symbols here for the .call_table_data
+# and .call_table_text sections.
+#...
+ +[0-9]+: 00000000 +0 +NOTYPE +GLOBAL +DEFAULT +1 text_symbol
+ +[0-9]+: 00000000 +0 +NOTYPE +GLOBAL +DEFAULT +UND external_symbol
+ +[0-9]+: 00000000 +0 +NOTYPE +GLOBAL +DEFAULT +[34] data_symbol
+ +[0-9]+: 00000004 +4 +(COMMON|OBJECT) +GLOBAL +DEFAULT +(COM|ANSI_COM) common_symbol
+#...
diff --git a/binutils/testsuite/lib/binutils-common.exp b/binutils/testsuite/lib/binutils-common.exp
index 6552d302649..616a6cad3d5 100644
--- a/binutils/testsuite/lib/binutils-common.exp
+++ b/binutils/testsuite/lib/binutils-common.exp
@@ -248,6 +248,37 @@ proc is_generic { } {
     return 0
 }
 
+# True if the object format is ELF with unused section symbols.
+proc is_elf_unused_section_symbols {} {
+    global AS ASFLAGS READELF
+
+    if {![info exists elf_unused_section_symbols_saved]} {
+	set elf_unused_section_symbols_saved 1
+	if { [is_elf_format] } {
+	    set base "empty[pid]"
+	    set src "$base.s"
+	    set obj "$base.obj"
+	    set f [open $src "w"]
+	    close $f
+	    set cmd "$AS $ASFLAGS -o $obj $src"
+	    send_log "$cmd\n"
+	    set cmdret [remote_exec host $cmd]
+	    set cmdret [lindex $cmdret 0]
+	    if { $cmdret == 0 } {
+		set cmd "$READELF -sW $obj"
+		send_log "$cmd\n"
+		set got [remote_exec host $cmd]
+		if { ![string match "*SECTION*" $got] }  {
+		    set elf_unused_section_symbols_saved 0
+		}
+	    }
+	    file delete $obj
+	    file delete $src
+	}
+    }
+    return $elf_unused_section_symbols_saved
+}
+
 # True if the ELF target supports STB_GNU_UNIQUE.
 #
 # This require ELFOSABI_GNU, and `bfd_elf_final_link'.