From cbac6da160859cd4ffbfc85d06774d1962f5faa3 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Thu, 1 Oct 2020 11:49:04 +0100
Subject: [PATCH] Support SHF_GNU_RETAIN ELF section flag

The SHF_GNU_RETAIN section flag is an extension to the GNU ELF OSABI.
It is defined as follows:

=======================================================================
Section Attribute Flags
+-------------------------------------+
| Name           | Value              |
+-------------------------------------+
| SHF_GNU_RETAIN | 0x200000 (1 << 21) |
+-------------------------------------+

SHF_GNU_RETAIN
  The link editor should not garbage collect the section if it is
  unused.

=======================================================================

Note that there is not a direct mapping of SHF_GNU_RETAIN to the BFD
section flag SEC_KEEP. This would prevent the user being able to
explicitly remove an SHF_GNU_RETAIN section by placing it in /DISCARD/.

bfd/ChangeLog:

2020-10-02  H.J. Lu  <hongjiu.lu@intel.com>
	Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* elf-bfd.h (enum elf_gnu_osabi): Add elf_gnu_osabi_retain.
	(struct elf_obj_tdata): Increase has_gnu_osabi to 4 bits.
	* elf.c (_bfd_elf_make_section_from_shdr): Set elf_gnu_osabi_retain
	for SHF_GNU_RETAIN.
	(_bfd_elf_final_write_processing): Report if SHF_GNU_RETAIN is
	not supported by the OSABI.
	Adjust error messages.
	* elflink.c (bfd_elf_gc_sections): gc_mark the section if
	SHF_GNU_RETAIN is set.

binutils/ChangeLog:

2020-10-02  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* NEWS: Announce SHF_GNU_RETAIN.
	* readelf.c (get_elf_section_flags): Handle SHF_GNU_RETAIN.
	Recognize SHF_GNU_RETAIN and SHF_GNU_MBIND only for supported OSABIs.
	* testsuite/binutils-all/readelf.exp: Run new test.
	Don't run run_dump_test when there isn't an assembler available.
	* testsuite/lib/binutils-common.exp (supports_gnu_osabi): Adjust
	comment.
	* testsuite/binutils-all/retain1.d: New test.
	* testsuite/binutils-all/retain1.s: New test.

gas/ChangeLog:

2020-10-02  H.J. Lu  <hongjiu.lu@intel.com>
	Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* NEWS: Announce SHF_GNU_RETAIN.
	* config/obj-elf.c (SEC_ASSEMBLER_SHF_MASK): New.
	(get_section): Use SEC_ASSEMBLER_SHF_MASK.
	(obj_elf_change_section): Update struct member name.
	(obj_elf_parse_section_letters): Handle 'R' flag.
	Handle numeric flag values within the SHF_MASKOS range.
	(obj_elf_section): Set elf_gnu_osabi_retain
	for SHF_GNU_RETAIN.
	* config/obj-elf.h (struct elf_section_match): Adjust "info" member
	name to "sh_info".  Add "sh_flags" member.
	* doc/as.texi (Section): Document 'R' flag.
	* testsuite/gas/elf/elf.exp: Run new tests.
	* testsuite/gas/elf/section10.d: Don't test SHF_GNU_RETAIN bit of
	section flag.
	* testsuite/gas/elf/section10.s: Don't set SHF_GNU_RETAIN bit of
	section flag.
	* testsuite/gas/elf/section22.d: New test.
	* testsuite/gas/elf/section22.s: New test.
	* testsuite/gas/elf/section23.s: New test.
	* testsuite/gas/elf/section23a.d: New test.
	* testsuite/gas/elf/section23b.d: New test.
	* testsuite/gas/elf/section23b.err: New test.

include/ChangeLog:

2020-10-02  Jozef Lawrynowicz  <jozef.l@mittosystems.com>

	* elf/common.h (SHF_GNU_RETAIN): Define.

ld/ChangeLog:

2020-10-02  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
	H.J. Lu  <hongjiu.lu@intel.com>

	* NEWS: Announce SHF_GNU_RETAIN.
	* ld.texi (garbage collection): Document SHF_GNU_RETAIN.
	(Output Section Discarding): Likewise.
	* testsuite/ld-elf/elf.exp: Run new tests.
	* testsuite/ld-elf/retain1.s: New test.
	* testsuite/ld-elf/retain1a.d: New test.
	* testsuite/ld-elf/retain1b.d: New test.
	* testsuite/ld-elf/retain2.d: New test.
	* testsuite/ld-elf/retain2.ld: New test.
	* testsuite/ld-elf/retain2.map: New test.
	* testsuite/ld-elf/retain3.d: New test.
	* testsuite/ld-elf/retain3.s: New test.
	* testsuite/ld-elf/retain4.d: New test.
	* testsuite/ld-elf/retain4.s: New test.
	* testsuite/ld-elf/retain5.d: New test.
	* testsuite/ld-elf/retain5.map: New test.
	* testsuite/ld-elf/retain5lib.s: New test.
	* testsuite/ld-elf/retain5main.s: New test.
	* testsuite/ld-elf/retain6a.d: New test.
	* testsuite/ld-elf/retain6b.d: New test.
	* testsuite/ld-elf/retain6lib.s: New test.
	* testsuite/ld-elf/retain6main.s: New test.
	* testsuite/ld-elf/retain7.s: New test.
	* testsuite/ld-elf/retain7a.d: New test.
	* testsuite/ld-elf/retain7b.d: New test.
---
 bfd/elf-bfd.h                               |   9 +-
 bfd/elf.c                                   |  17 +++-
 bfd/elflink.c                               |   4 +-
 binutils/NEWS                               |   4 +
 binutils/readelf.c                          |  21 +++-
 binutils/testsuite/binutils-all/readelf.exp |   6 +-
 binutils/testsuite/binutils-all/retain1.d   |  18 ++++
 binutils/testsuite/binutils-all/retain1.s   | 104 ++++++++++++++++++++
 binutils/testsuite/lib/binutils-common.exp  |   5 +-
 gas/NEWS                                    |   6 ++
 gas/config/obj-elf.c                        |  65 +++++++++---
 gas/config/obj-elf.h                        |   3 +-
 gas/doc/as.texi                             |   3 +
 gas/testsuite/gas/elf/elf.exp               |   3 +
 gas/testsuite/gas/elf/section10.d           |   4 +-
 gas/testsuite/gas/elf/section10.s           |   4 +-
 gas/testsuite/gas/elf/section22.d           |  19 ++++
 gas/testsuite/gas/elf/section22.s           |  34 +++++++
 gas/testsuite/gas/elf/section23.s           |  11 +++
 gas/testsuite/gas/elf/section23a.d          |  11 +++
 gas/testsuite/gas/elf/section23b.d          |   6 ++
 gas/testsuite/gas/elf/section23b.err        |   2 +
 include/elf/common.h                        |   1 +
 ld/NEWS                                     |   4 +
 ld/ld.texi                                  |   8 ++
 ld/testsuite/ld-elf/elf.exp                 |  11 +++
 ld/testsuite/ld-elf/retain1.s               | 104 ++++++++++++++++++++
 ld/testsuite/ld-elf/retain1a.d              |  28 ++++++
 ld/testsuite/ld-elf/retain1b.d              |  11 +++
 ld/testsuite/ld-elf/retain2.d               |   6 ++
 ld/testsuite/ld-elf/retain2.ld              |   7 ++
 ld/testsuite/ld-elf/retain2.map             |  32 ++++++
 ld/testsuite/ld-elf/retain3.d               |  12 +++
 ld/testsuite/ld-elf/retain3.s               |  19 ++++
 ld/testsuite/ld-elf/retain4.d               |  10 ++
 ld/testsuite/ld-elf/retain4.s               |  13 +++
 ld/testsuite/ld-elf/retain5.d               |  12 +++
 ld/testsuite/ld-elf/retain5.map             |   5 +
 ld/testsuite/ld-elf/retain5lib.s            |   6 ++
 ld/testsuite/ld-elf/retain5main.s           |   5 +
 ld/testsuite/ld-elf/retain6a.d              |  14 +++
 ld/testsuite/ld-elf/retain6b.d              |  11 +++
 ld/testsuite/ld-elf/retain6lib.s            |  17 ++++
 ld/testsuite/ld-elf/retain6main.s           |  13 +++
 ld/testsuite/ld-elf/retain7.s               | 104 ++++++++++++++++++++
 ld/testsuite/ld-elf/retain7a.d              |  28 ++++++
 ld/testsuite/ld-elf/retain7b.d              |  11 +++
 47 files changed, 822 insertions(+), 29 deletions(-)
 create mode 100644 binutils/testsuite/binutils-all/retain1.d
 create mode 100644 binutils/testsuite/binutils-all/retain1.s
 create mode 100644 gas/testsuite/gas/elf/section22.d
 create mode 100644 gas/testsuite/gas/elf/section22.s
 create mode 100644 gas/testsuite/gas/elf/section23.s
 create mode 100644 gas/testsuite/gas/elf/section23a.d
 create mode 100644 gas/testsuite/gas/elf/section23b.d
 create mode 100644 gas/testsuite/gas/elf/section23b.err
 create mode 100644 ld/testsuite/ld-elf/retain1.s
 create mode 100644 ld/testsuite/ld-elf/retain1a.d
 create mode 100644 ld/testsuite/ld-elf/retain1b.d
 create mode 100644 ld/testsuite/ld-elf/retain2.d
 create mode 100644 ld/testsuite/ld-elf/retain2.ld
 create mode 100644 ld/testsuite/ld-elf/retain2.map
 create mode 100644 ld/testsuite/ld-elf/retain3.d
 create mode 100644 ld/testsuite/ld-elf/retain3.s
 create mode 100644 ld/testsuite/ld-elf/retain4.d
 create mode 100644 ld/testsuite/ld-elf/retain4.s
 create mode 100644 ld/testsuite/ld-elf/retain5.d
 create mode 100644 ld/testsuite/ld-elf/retain5.map
 create mode 100644 ld/testsuite/ld-elf/retain5lib.s
 create mode 100644 ld/testsuite/ld-elf/retain5main.s
 create mode 100644 ld/testsuite/ld-elf/retain6a.d
 create mode 100644 ld/testsuite/ld-elf/retain6b.d
 create mode 100644 ld/testsuite/ld-elf/retain6lib.s
 create mode 100644 ld/testsuite/ld-elf/retain6main.s
 create mode 100644 ld/testsuite/ld-elf/retain7.s
 create mode 100644 ld/testsuite/ld-elf/retain7a.d
 create mode 100644 ld/testsuite/ld-elf/retain7b.d

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 140a98594d..ffb75f7919 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1897,14 +1897,15 @@ struct output_elf_obj_tdata
   bfd_boolean flags_init;
 };
 
-/* Indicate if the bfd contains SHF_GNU_MBIND sections or symbols that
-   have the STT_GNU_IFUNC symbol type or STB_GNU_UNIQUE binding.  Used
-   to set the osabi field in the ELF header structure.  */
+/* Indicate if the bfd contains SHF_GNU_MBIND/SHF_GNU_RETAIN sections or
+   symbols that have the STT_GNU_IFUNC symbol type or STB_GNU_UNIQUE
+   binding.  Used to set the osabi field in the ELF header structure.  */
 enum elf_gnu_osabi
 {
   elf_gnu_osabi_mbind = 1 << 0,
   elf_gnu_osabi_ifunc = 1 << 1,
   elf_gnu_osabi_unique = 1 << 2,
+  elf_gnu_osabi_retain = 1 << 3,
 };
 
 typedef struct elf_section_list
@@ -2034,7 +2035,7 @@ struct elf_obj_tdata
   ENUM_BITFIELD (dynamic_lib_link_class) dyn_lib_class : 4;
 
   /* Whether the bfd uses OS specific bits that require ELFOSABI_GNU.  */
-  ENUM_BITFIELD (elf_gnu_osabi) has_gnu_osabi : 3;
+  ENUM_BITFIELD (elf_gnu_osabi) has_gnu_osabi : 4;
 
   /* Whether if the bfd contains the GNU_PROPERTY_NO_COPY_ON_PROTECTED
      property.  */
diff --git a/bfd/elf.c b/bfd/elf.c
index 00594020c9..5daf8ec0f5 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1068,9 +1068,12 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
       /* FIXME: We should not recognize SHF_GNU_MBIND for ELFOSABI_NONE,
 	 but binutils as of 2019-07-23 did not set the EI_OSABI header
 	 byte.  */
-    case ELFOSABI_NONE:
     case ELFOSABI_GNU:
     case ELFOSABI_FREEBSD:
+      if ((hdr->sh_flags & SHF_GNU_RETAIN) != 0)
+	elf_tdata (abfd)->has_gnu_osabi |= elf_gnu_osabi_retain;
+      /* Fall through */
+    case ELFOSABI_NONE:
       if ((hdr->sh_flags & SHF_GNU_MBIND) != 0)
 	elf_tdata (abfd)->has_gnu_osabi |= elf_gnu_osabi_mbind;
       break;
@@ -12476,11 +12479,17 @@ _bfd_elf_final_write_processing (bfd *abfd)
 	       && i_ehdrp->e_ident[EI_OSABI] != ELFOSABI_FREEBSD)
 	{
 	  if (elf_tdata (abfd)->has_gnu_osabi & elf_gnu_osabi_mbind)
-	    _bfd_error_handler (_("GNU_MBIND section is unsupported"));
+	    _bfd_error_handler (_("GNU_MBIND section is supported only by GNU "
+				  "and FreeBSD targets"));
 	  if (elf_tdata (abfd)->has_gnu_osabi & elf_gnu_osabi_ifunc)
-	    _bfd_error_handler (_("symbol type STT_GNU_IFUNC is unsupported"));
+	    _bfd_error_handler (_("symbol type STT_GNU_IFUNC is supported "
+				  "only by GNU and FreeBSD targets"));
 	  if (elf_tdata (abfd)->has_gnu_osabi & elf_gnu_osabi_unique)
-	    _bfd_error_handler (_("symbol binding STB_GNU_UNIQUE is unsupported"));
+	    _bfd_error_handler (_("symbol binding STB_GNU_UNIQUE is supported "
+				  "only by GNU and FreeBSD targets"));
+	  if (elf_tdata (abfd)->has_gnu_osabi & elf_gnu_osabi_retain)
+	    _bfd_error_handler (_("GNU_RETAIN section is supported "
+				  "only by GNU and FreeBSD targets"));
 	  bfd_set_error (bfd_error_sorry);
 	  return FALSE;
 	}
diff --git a/bfd/elflink.c b/bfd/elflink.c
index b6937293e8..6efd181a32 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -14102,7 +14102,9 @@ bfd_elf_gc_sections (bfd *abfd, struct bfd_link_info *info)
 			|| (elf_section_data (o)->this_hdr.sh_type
 			    == SHT_FINI_ARRAY)))
 		|| (elf_section_data (o)->this_hdr.sh_type == SHT_NOTE
-		    && elf_next_in_group (o) == NULL )))
+		    && elf_next_in_group (o) == NULL)
+		|| (elf_tdata (sub)->has_gnu_osabi & elf_gnu_osabi_retain
+		    && elf_section_flags (o) & SHF_GNU_RETAIN)))
 	  {
 	    if (!_bfd_elf_gc_mark (info, o, gc_mark_hook))
 	      return FALSE;
diff --git a/binutils/NEWS b/binutils/NEWS
index c0dc73d7d8..6c7d3f3953 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -4,6 +4,10 @@
   symbol names.  In addition the --demangle=<style>, --no-demangle,
   --recurse-limit and --no-recurse-limit options are also now availale.
 
+* Add support for the SHF_GNU_RETAIN ELF section flag.
+  This flag specifies that the section should not be garbage collected by the
+  linker if it is unused.
+
 Changes in 2.35:
 
 * Changed readelf's display of symbol names when wide mode is not enabled.
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 9ba4e29a65..5b3e508aef 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -5977,6 +5977,8 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
       /* 24 */ { STRING_COMMA_LEN ("GNU_MBIND") },
       /* VLE specific.  */
       /* 25 */ { STRING_COMMA_LEN ("VLE") },
+      /* GNU specific.  */
+      /* 26 */ { STRING_COMMA_LEN ("GNU_RETAIN") },
     };
 
   if (do_section_details)
@@ -6009,7 +6011,6 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
 	    case SHF_TLS:		sindex = 9; break;
 	    case SHF_EXCLUDE:		sindex = 18; break;
 	    case SHF_COMPRESSED:	sindex = 20; break;
-	    case SHF_GNU_MBIND:		sindex = 24; break;
 
 	    default:
 	      sindex = -1;
@@ -6063,6 +6064,23 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
 		  break;
 
 		default:
+		  switch (filedata->file_header.e_ident[EI_OSABI])
+		    {
+		    case ELFOSABI_GNU:
+		    case ELFOSABI_FREEBSD:
+		      if (flag == SHF_GNU_RETAIN)
+			sindex = 26;
+		      /* Fall through */
+		    case ELFOSABI_NONE:
+		      if (flag == SHF_GNU_MBIND)
+			/* We should not recognize SHF_GNU_MBIND for
+			   ELFOSABI_NONE, but binutils as of 2019-07-23 did
+			   not set the EI_OSABI header byte.  */
+			sindex = 24;
+		      break;
+		    default:
+		      break;
+		    }
 		  break;
 		}
 	    }
@@ -6108,6 +6126,7 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
 	    case SHF_EXCLUDE:		*p = 'E'; break;
 	    case SHF_COMPRESSED:	*p = 'C'; break;
 	    case SHF_GNU_MBIND:		*p = 'D'; break;
+	    case SHF_GNU_RETAIN:	*p = 'R'; break;
 
 	    default:
 	      if ((filedata->file_header.e_machine == EM_X86_64
diff --git a/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
index 1fb36ae5c4..6dea09e305 100644
--- a/binutils/testsuite/binutils-all/readelf.exp
+++ b/binutils/testsuite/binutils-all/readelf.exp
@@ -364,8 +364,12 @@ readelf_wi_test
 readelf_compressed_wa_test
 
 readelf_dump_test
-run_dump_test "pr25543"
 
+# These dump tests require an assembler.
+if {[which $AS] != 0} then {
+    run_dump_test "pr25543"
+    run_dump_test "retain1"
+}
 
 # PR 13482 - Check for off-by-one errors when dumping .note sections.
 if {![binutils_assemble $srcdir/$subdir/version.s tmpdir/version.o]} then {
diff --git a/binutils/testsuite/binutils-all/retain1.d b/binutils/testsuite/binutils-all/retain1.d
new file mode 100644
index 0000000000..01cd32a475
--- /dev/null
+++ b/binutils/testsuite/binutils-all/retain1.d
@@ -0,0 +1,18 @@
+#source: retain1.s
+#readelf: -S --wide
+#name: readelf SHF_GNU_RETAIN
+#notarget: ![supports_gnu_osabi]
+
+#...
+  \[[ 0-9]+\] .bss.retain0.*WAR.*
+  \[[ 0-9]+\] .bss.retain1.*WAR.*
+  \[[ 0-9]+\] .data.retain2.*WAR.*
+  \[[ 0-9]+\] .bss.sretain0.*WAR.*
+  \[[ 0-9]+\] .bss.sretain1.*WAR.*
+  \[[ 0-9]+\] .data.sretain2.*WAR.*
+  \[[ 0-9]+\] .text.fnretain1.*AXR.*
+#...
+  \[[ 0-9]+\] .bss.lsretain0.*WAR.*
+  \[[ 0-9]+\] .bss.lsretain1.*WAR.*
+  \[[ 0-9]+\] .data.lsretain2.*WAR.*
+#pass
diff --git a/binutils/testsuite/binutils-all/retain1.s b/binutils/testsuite/binutils-all/retain1.s
new file mode 100644
index 0000000000..f7716faabe
--- /dev/null
+++ b/binutils/testsuite/binutils-all/retain1.s
@@ -0,0 +1,104 @@
+	.global	discard0
+	.section	.bss.discard0,"aw"
+	.type	discard0, %object
+discard0:
+	.zero	2
+
+	.global	discard1
+	.section	.bss.discard1,"aw"
+	.type	discard1, %object
+discard1:
+	.zero	2
+
+	.global	discard2
+	.section	.data.discard2,"aw"
+	.type	discard2, %object
+discard2:
+	.word	1
+
+	.section	.bss.sdiscard0,"aw"
+	.type	sdiscard0, %object
+sdiscard0:
+	.zero	2
+
+	.section	.bss.sdiscard1,"aw"
+	.type	sdiscard1, %object
+sdiscard1:
+	.zero	2
+
+	.section	.data.sdiscard2,"aw"
+	.type	sdiscard2, %object
+sdiscard2:
+	.word	1
+
+	.section	.text.fndiscard0,"ax"
+	.global	fndiscard0
+	.type	fndiscard0, %function
+fndiscard0:
+	.word 0
+
+	.global	retain0
+	.section	.bss.retain0,"awR"
+	.type	retain0, %object
+retain0:
+	.zero	2
+
+	.global	retain1
+	.section	.bss.retain1,"awR"
+	.type	retain1, %object
+retain1:
+	.zero	2
+
+	.global	retain2
+	.section	.data.retain2,"awR"
+	.type	retain2, %object
+retain2:
+	.word	1
+
+	.section	.bss.sretain0,"awR"
+	.type	sretain0, %object
+sretain0:
+	.zero	2
+
+	.section	.bss.sretain1,"awR"
+	.type	sretain1, %object
+sretain1:
+	.zero	2
+
+	.section	.data.sretain2,"aRw"
+	.type	sretain2, %object
+sretain2:
+	.word	1
+
+	.section	.text.fnretain1,"Rax"
+	.global	fnretain1
+	.type	fnretain1, %function
+fnretain1:
+	.word	0
+
+	.section	.text.fndiscard2,"ax"
+	.global	fndiscard2
+	.type	fndiscard2, %function
+fndiscard2:
+	.word	0
+
+	.section	.bss.lsretain0,"awR"
+	.type	lsretain0.2, %object
+lsretain0.2:
+	.zero	2
+
+	.section	.bss.lsretain1,"aRw"
+	.type	lsretain1.1, %object
+lsretain1.1:
+	.zero	2
+
+	.section	.data.lsretain2,"aRw"
+	.type	lsretain2.0, %object
+lsretain2.0:
+	.word	1
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/binutils/testsuite/lib/binutils-common.exp b/binutils/testsuite/lib/binutils-common.exp
index b9a1e6e4bc..a43639bafb 100644
--- a/binutils/testsuite/lib/binutils-common.exp
+++ b/binutils/testsuite/lib/binutils-common.exp
@@ -195,13 +195,15 @@ proc match_target { target } {
 
 # True if the ELF target supports setting the ELF header OSABI field
 # to ELFOSABI_GNU or ELFOSABI_FREEBSD, a requirement for STT_GNU_IFUNC
-# symbol and SHF_GNU_MBIND section support.
+# symbol and SHF_GNU_MBIND or SHF_GNU_RETAIN section support.
 #
 # This generally depends on the target OS only, however there are a
 # number of exceptions for bare metal targets as follows.  The MSP430
 # and Visium targets set OSABI to ELFOSABI_STANDALONE.  Likewise
 # non-EABI ARM targets set OSABI to ELFOSABI_ARM
 #
+# Non-Linux HPPA defaults to ELFOSABI_HPUX.
+#
 # Note that some TI C6X targets use ELFOSABI_C6000_* but one doesn't,
 # so we don't try to sort out tic6x here.  (The effect is that linker
 # testcases will generally need to exclude tic6x or use a -m option.)
@@ -227,6 +229,7 @@ proc supports_gnu_osabi {} {
     }
     if { [istarget "arm*-*-*"]
 	 || [istarget "msp430-*-*"]
+	 || [istarget "hppa-unknown-elf"]
 	 || [istarget "visium-*-*"] } {
 	return 0
     }
diff --git a/gas/NEWS b/gas/NEWS
index 7ae58506ec..2056967a35 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -16,6 +16,12 @@
 
 * Configure with --enable-x86-used-note by default for Linux/x86.
 
+* Add support for the "R" flag in the .section directive.
+  This flag requires ELFOSABI_GNU or ELFOSABI_FREEBSD, and applies the
+  ELF SHF_GNU_RETAIN flag to the specified section.  This flag specifies
+  the section should not be garbage collected by the linker if it is
+  unused.
+
 Changes in 2.35:
 
 * X86 NaCl target support is removed.
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index b1c99020a3..4d6c8ef921 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -517,6 +517,10 @@ struct section_stack
 
 static struct section_stack *section_stack;
 
+/* Create unique input sections for sections with the same name, but different
+   values for the flags in this mask.  */
+#define SEC_ASSEMBLER_SHF_MASK SHF_GNU_RETAIN
+
 static bfd_boolean
 get_section (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, void *inf)
 {
@@ -525,9 +529,12 @@ get_section (bfd *abfd ATTRIBUTE_UNUSED, asection *sec, void *inf)
   const char *group_name = elf_group_name (sec);
   const char *linked_to_symbol_name
     = sec->map_head.linked_to_symbol_name;
-  unsigned int info = elf_section_data (sec)->this_hdr.sh_info;
+  unsigned int sh_info = elf_section_data (sec)->this_hdr.sh_info;
+  bfd_vma sh_flags = (elf_section_data (sec)->this_hdr.sh_flags
+		      & SEC_ASSEMBLER_SHF_MASK);
 
-  return (info == match->info
+  return (sh_info == match->sh_info
+	  && sh_flags == match->sh_flags
 	  && ((bfd_section_flags (sec) & SEC_ASSEMBLER_SECTION_ID)
 	       == (match->flags & SEC_ASSEMBLER_SECTION_ID))
 	  && sec->section_id == match->section_id
@@ -736,7 +743,7 @@ obj_elf_change_section (const char *name,
 	type = bfd_elf_get_default_section_type (flags);
       elf_section_type (sec) = type;
       elf_section_flags (sec) = attr;
-      elf_section_data (sec)->this_hdr.sh_info = match_p->info;
+      elf_section_data (sec)->this_hdr.sh_info = match_p->sh_info;
 
       /* Prevent SEC_HAS_CONTENTS from being inadvertently set.  */
       if (type == SHT_NOBITS)
@@ -857,6 +864,9 @@ obj_elf_parse_section_letters (char *str, size_t len,
 	case 'd':
 	  *gnu_attr |= SHF_GNU_MBIND;
 	  break;
+	case 'R':
+	  *gnu_attr |= SHF_GNU_RETAIN;
+	  break;
 	case '?':
 	  *is_clone = TRUE;
 	  break;
@@ -886,8 +896,32 @@ obj_elf_parse_section_letters (char *str, size_t len,
 	      if (ISDIGIT (*str))
 		{
 		  char * end;
+		  struct elf_backend_data *bed;
+		  bfd_vma numeric_flags = strtoul (str, &end, 0);
+
+		  attr |= numeric_flags;
+
+		  bed = (struct elf_backend_data *)
+		    get_elf_backend_data (stdoutput);
+
+		  if (bed->elf_osabi == ELFOSABI_NONE
+		      || bed->elf_osabi == ELFOSABI_STANDALONE
+		      || bed->elf_osabi == ELFOSABI_GNU
+		      || bed->elf_osabi == ELFOSABI_FREEBSD)
+		    {
+		      /* Add flags in the SHF_MASKOS range to gnu_attr for
+			 OSABIs that support those flags.
+			 Also adding the flags for ELFOSABI_{NONE,STANDALONE}
+			 allows them to be validated later in obj_elf_section.
+			 We can't just always set these bits in gnu_attr for
+			 all OSABIs, since Binutils does not recognize all
+			 SHF_MASKOS bits for non-GNU OSABIs.  It's therefore
+			 possible that numeric flags are being used to set bits
+			 in the SHF_MASKOS range for those targets, and we
+			 don't want assembly to fail in those situations.  */
+		      *gnu_attr |= (numeric_flags & SHF_MASKOS);
+		    }
 
-		  attr |= strtoul (str, & end, 0);
 		  /* Update str and len, allowing for the fact that
 		     we will execute str++ and len-- below.  */
 		  end --;
@@ -1250,18 +1284,21 @@ obj_elf_section (int push)
 	      if (ISDIGIT (* input_line_pointer))
 		{
 		  char *t = input_line_pointer;
-		  match.info = strtoul (input_line_pointer,
+		  match.sh_info = strtoul (input_line_pointer,
 					&input_line_pointer, 0);
-		  if (match.info == (unsigned int) -1)
+		  if (match.sh_info == (unsigned int) -1)
 		    {
 		      as_warn (_("unsupported mbind section info: %s"), t);
-		      match.info = 0;
+		      match.sh_info = 0;
 		    }
 		}
 	      else
 		input_line_pointer = save;
 	    }
 
+	  if ((gnu_attr & SHF_GNU_RETAIN) != 0)
+	    match.sh_flags |= SHF_GNU_RETAIN;
+
 	  if (*input_line_pointer == ',')
 	    {
 	      char *save = input_line_pointer;
@@ -1352,11 +1389,12 @@ obj_elf_section (int push)
   obj_elf_change_section (name, type, attr, entsize, &match, linkonce,
 			  push);
 
-  if ((gnu_attr & SHF_GNU_MBIND) != 0)
+  if ((gnu_attr & (SHF_GNU_MBIND | SHF_GNU_RETAIN)) != 0)
     {
       struct elf_backend_data *bed;
+      bfd_boolean mbind_p = (gnu_attr & SHF_GNU_MBIND) != 0;
 
-      if ((attr & SHF_ALLOC) == 0)
+      if (mbind_p && (attr & SHF_ALLOC) == 0)
 	as_bad (_("SHF_ALLOC isn't set for GNU_MBIND section: %s"), name);
 
       bed = (struct elf_backend_data *) get_elf_backend_data (stdoutput);
@@ -1364,9 +1402,12 @@ obj_elf_section (int push)
 	bed->elf_osabi = ELFOSABI_GNU;
       else if (bed->elf_osabi != ELFOSABI_GNU
 	       && bed->elf_osabi != ELFOSABI_FREEBSD)
-	as_bad (_("GNU_MBIND section is supported only by GNU "
-		  "and FreeBSD targets"));
-      elf_tdata (stdoutput)->has_gnu_osabi |= elf_gnu_osabi_mbind;
+	as_bad (_("%s section is supported only by GNU and FreeBSD targets"),
+		mbind_p ? "GNU_MBIND" : "GNU_RETAIN");
+      if (mbind_p)
+	elf_tdata (stdoutput)->has_gnu_osabi |= elf_gnu_osabi_mbind;
+      if ((gnu_attr & SHF_GNU_RETAIN) != 0)
+	elf_tdata (stdoutput)->has_gnu_osabi |= elf_gnu_osabi_retain;
     }
   elf_section_flags (now_seg) |= gnu_attr;
 
diff --git a/gas/config/obj-elf.h b/gas/config/obj-elf.h
index b39a1a1ab6..6eb0a8ede4 100644
--- a/gas/config/obj-elf.h
+++ b/gas/config/obj-elf.h
@@ -106,8 +106,9 @@ struct elf_section_match
 {
   const char *group_name;
   const char *linked_to_symbol_name;
-  unsigned int info;
   unsigned int section_id;
+  unsigned int sh_info;		/* ELF section information.  */
+  bfd_vma sh_flags;		/* ELF section flags.  */
   flagword flags;
 };
 
diff --git a/gas/doc/as.texi b/gas/doc/as.texi
index b88c1f9997..a697ccb2c1 100644
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -6649,6 +6649,9 @@ section is a member of a section group
 section is used for thread-local-storage
 @item ?
 section is a member of the previously-current section's group, if any
+@item R
+retained section (apply SHF_GNU_RETAIN to prevent linker garbage
+collection, GNU ELF extension)
 @item @code{<number>}
 a numeric value indicating the bits to be set in the ELF section header's flags
 field.  Note - if one or more of the alphabetic characters described above is
diff --git a/gas/testsuite/gas/elf/elf.exp b/gas/testsuite/gas/elf/elf.exp
index 135ade24ec..7c89bea91b 100644
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -257,6 +257,9 @@ if { [is_elf_format] } then {
     run_dump_test "section19"
     run_dump_test "section20"
     run_dump_test "section21"
+    run_dump_test "section22"
+    run_dump_test "section23a"
+    run_dump_test "section23b"
     run_dump_test "dwarf2-1" $dump_opts
     run_dump_test "dwarf2-2" $dump_opts
     run_dump_test "dwarf2-3" $dump_opts
diff --git a/gas/testsuite/gas/elf/section10.d b/gas/testsuite/gas/elf/section10.d
index 554a791f1d..6aa7b088b1 100644
--- a/gas/testsuite/gas/elf/section10.d
+++ b/gas/testsuite/gas/elf/section10.d
@@ -18,7 +18,7 @@
 #...
 [ 	]*\[.*\][ 	]+sec3
 [ 	]*PROGBITS.*
-[ 	]*\[.*fefff030\]: MERGE, STRINGS,.* EXCLUDE, OS \(.*ef00000\), PROC \(.*[3467]0000000\), UNKNOWN \(0+0ff000\)
+[ 	]*\[.*fedff030\]: MERGE, STRINGS,.* EXCLUDE, OS \(.*ed00000\), PROC \(.*[3467]0000000\), UNKNOWN \(0+0ff000\)
 #...
 [ 	]*\[.*\][ 	]+sec4
 [ 	]*LOOS\+0x11[ 	].*
@@ -26,7 +26,7 @@
 #...
 [ 	]*\[.*\][ 	]+sec5
 [ 	]*LOUSER\+0x9[ 	].*
-[ 	]*\[.*feff0000\]:.* EXCLUDE, OS \(.*ef00000\), PROC \(.*[3467]0000000\), UNKNOWN \(.*f0000\)
+[ 	]*\[.*fedf0000\]:.* EXCLUDE, OS \(.*ed00000\), PROC \(.*[3467]0000000\), UNKNOWN \(.*f0000\)
 [ 	]*\[.*\][ 	]+.data.foo
 [ 	]*LOUSER\+0x7f000000[ 	].*
 [ 	]*\[0+003\]: WRITE, ALLOC
diff --git a/gas/testsuite/gas/elf/section10.s b/gas/testsuite/gas/elf/section10.s
index 29f1184523..d52b3458fb 100644
--- a/gas/testsuite/gas/elf/section10.s
+++ b/gas/testsuite/gas/elf/section10.s
@@ -7,7 +7,7 @@
 	.word 2
 
 	# Make sure that specifying further arguments to .sections is still supported
-	.section sec3, "0xfefff000MS", %progbits, 32
+	.section sec3, "0xfedff000MS", %progbits, 32
 	.word 3
 
 	# Make sure that extra flags can be set for well known sections as well.
@@ -19,7 +19,7 @@
 	.word 5
 
 	# Test both together, with a quoted type value.
-	.section sec5, "0xfeff0000", "0x80000009"
+	.section sec5, "0xfedf0000", "0x80000009"
 	.word 6
 
 	# Test that declaring an extended version of a known special section works.
diff --git a/gas/testsuite/gas/elf/section22.d b/gas/testsuite/gas/elf/section22.d
new file mode 100644
index 0000000000..27d9127745
--- /dev/null
+++ b/gas/testsuite/gas/elf/section22.d
@@ -0,0 +1,19 @@
+#readelf: -h -S --wide
+#name: SHF_GNU_RETAIN sections 22
+#notarget: ![supports_gnu_osabi]
+
+#...
+ +OS/ABI: +UNIX - GNU
+#...
+  \[..\] .text[ 	]+PROGBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00  AX.*
+#...
+  \[..\] .data[ 	]+PROGBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00  WA.*
+#...
+  \[..\] .bss[ 	]+NOBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00  WA.*
+#...
+  \[..\] .bss[ 	]+NOBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
+#...
+  \[..\] .data[ 	]+PROGBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
+#...
+  \[..\] .text[ 	]+PROGBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR.*
+#pass
diff --git a/gas/testsuite/gas/elf/section22.s b/gas/testsuite/gas/elf/section22.s
new file mode 100644
index 0000000000..6e2b95c1e8
--- /dev/null
+++ b/gas/testsuite/gas/elf/section22.s
@@ -0,0 +1,34 @@
+	.section	.text,"ax",%progbits
+	.global	discard0
+	.type	discard0, %function
+discard0:
+	.word	0
+
+	.section	.data,"aw"
+	.global	discard1
+	.type	discard1, %object
+discard1:
+	.word	1
+
+	.section	.bss,"aw"
+	.global	discard2
+	.type	discard2, %object
+discard2:
+	.zero	2
+
+	.section	.bss,"awR",%nobits
+	.global	retain0
+	.type	retain0, %object
+retain0:
+	.zero	2
+
+	.section	.data,"awR",%progbits
+	.type	retain1, %object
+retain1:
+	.word	1
+
+	.section	.text,"axR",%progbits
+	.global	retain2
+	.type	retain2, %function
+retain2:
+	.word	0
diff --git a/gas/testsuite/gas/elf/section23.s b/gas/testsuite/gas/elf/section23.s
new file mode 100644
index 0000000000..d671119bca
--- /dev/null
+++ b/gas/testsuite/gas/elf/section23.s
@@ -0,0 +1,11 @@
+  .section	.data.retain_var,"0x200003"
+	.global	retain_var
+	.type	retain_var, %object
+retain_var:
+	.long	2
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/gas/testsuite/gas/elf/section23a.d b/gas/testsuite/gas/elf/section23a.d
new file mode 100644
index 0000000000..1d850d9e8e
--- /dev/null
+++ b/gas/testsuite/gas/elf/section23a.d
@@ -0,0 +1,11 @@
+#name: SHF_GNU_RETAIN set with numeric flag value in .section
+#source: section23.s
+#target: [supports_gnu_osabi]
+#readelf: -h -S --wide
+
+#...
+ +OS/ABI: +UNIX - GNU
+#...
+  \[..\] .data.retain_var[ 	]+PROGBITS[ 	]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
+#pass
+
diff --git a/gas/testsuite/gas/elf/section23b.d b/gas/testsuite/gas/elf/section23b.d
new file mode 100644
index 0000000000..c85200e5ff
--- /dev/null
+++ b/gas/testsuite/gas/elf/section23b.d
@@ -0,0 +1,6 @@
+#name: SHF_GNU_RETAIN set with numeric flag value in .section for non-GNU OSABI target
+#source: section23.s
+#error_output: section23b.err
+#target: msp430-*-elf visium-*-elf
+
+# This test only runs for targets which set ELFOSABI_STANDALONE.
diff --git a/gas/testsuite/gas/elf/section23b.err b/gas/testsuite/gas/elf/section23b.err
new file mode 100644
index 0000000000..83de60c397
--- /dev/null
+++ b/gas/testsuite/gas/elf/section23b.err
@@ -0,0 +1,2 @@
+.*: Assembler messages:
+.*:1: Error: GNU_RETAIN section is supported only by GNU and FreeBSD targets
diff --git a/include/elf/common.h b/include/elf/common.h
index 571e21af29..c01e562c78 100644
--- a/include/elf/common.h
+++ b/include/elf/common.h
@@ -554,6 +554,7 @@
 /* #define SHF_MASKOS	0x0F000000    *//* OS-specific semantics */
 #define SHF_MASKOS	0x0FF00000	/* New value, Oct 4, 1999 Draft */
 #define SHF_GNU_BUILD_NOTE    (1 << 20)	/* Section contains GNU BUILD ATTRIBUTE notes.  */
+#define SHF_GNU_RETAIN	      (1 << 21)	/* Section should not be garbage collected by the linker.  */
 #define SHF_MASKPROC	0xF0000000	/* Processor-specific semantics */
 
 /* This used to be implemented as a processor specific section flag.
diff --git a/ld/NEWS b/ld/NEWS
index e4ae43b257..72cdf0edd3 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -15,6 +15,10 @@
   unless you are working on a project that has its own analogue
   of symbol tables that are not reflected in the ELF symtabs.
 
+* Add support for the SHF_GNU_RETAIN ELF section flag.
+  This flag specifies that the section should not be garbage collected by the
+  linker if it is unused.
+
 Changes in 2.35:
 
 * X86 NaCl target support is removed.
diff --git a/ld/ld.texi b/ld/ld.texi
index ee592df6c2..526b642d78 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -1787,6 +1787,10 @@ specified either by one of the options @samp{--entry},
 @samp{--undefined}, or @samp{--gc-keep-exported} or by a @code{ENTRY}
 command in the linker script.
 
+As a GNU extension, ELF input sections marked with the
+@code{SHF_GNU_RETAIN} flag will not be garbage collected if they are
+unused.
+
 @kindex --print-gc-sections
 @kindex --no-print-gc-sections
 @cindex garbage collection
@@ -5232,6 +5236,10 @@ The special output section name @samp{/DISCARD/} may be used to discard
 input sections.  Any input sections which are assigned to an output
 section named @samp{/DISCARD/} are not included in the output file.
 
+This can be used to discard input sections marked with the ELF flag
+@code{SHF_GNU_RETAIN}, which would otherwise have been saved from linker
+garbage collection when they are unused.
+
 Note, sections that match the @samp{/DISCARD/} output section will be
 discarded even if they are in an ELF section group which has other
 members which are not being discarded.  This is deliberate.
diff --git a/ld/testsuite/ld-elf/elf.exp b/ld/testsuite/ld-elf/elf.exp
index f2ff0397c7..bd06ab0d39 100644
--- a/ld/testsuite/ld-elf/elf.exp
+++ b/ld/testsuite/ld-elf/elf.exp
@@ -119,6 +119,17 @@ if { [istarget "i?86-*-*"] || [istarget "x86_64-*-*"] } {
     set ASFLAGS "$ASFLAGS -mx86-used-note=no"
 }
 
+# Build libraries required for SHF_GNU_RETAIN tests.
+if { [check_gc_sections_available] && [supports_gnu_osabi] } {
+    run_ld_link_tests [list \
+	[list "Build libretain5.a" "" "" "" \
+	    {retain5lib.s} {} "libretain5.a"] \
+	[list "Build libretain6.a" "" "" "" \
+	    {retain6lib.s} {} "libretain6.a"] \
+	]
+}
+
+
 set test_list [lsort [glob -nocomplain $srcdir/$subdir/*.d]]
 foreach t $test_list {
     # We need to strip the ".d", but can leave the dirname.
diff --git a/ld/testsuite/ld-elf/retain1.s b/ld/testsuite/ld-elf/retain1.s
new file mode 100644
index 0000000000..f7716faabe
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain1.s
@@ -0,0 +1,104 @@
+	.global	discard0
+	.section	.bss.discard0,"aw"
+	.type	discard0, %object
+discard0:
+	.zero	2
+
+	.global	discard1
+	.section	.bss.discard1,"aw"
+	.type	discard1, %object
+discard1:
+	.zero	2
+
+	.global	discard2
+	.section	.data.discard2,"aw"
+	.type	discard2, %object
+discard2:
+	.word	1
+
+	.section	.bss.sdiscard0,"aw"
+	.type	sdiscard0, %object
+sdiscard0:
+	.zero	2
+
+	.section	.bss.sdiscard1,"aw"
+	.type	sdiscard1, %object
+sdiscard1:
+	.zero	2
+
+	.section	.data.sdiscard2,"aw"
+	.type	sdiscard2, %object
+sdiscard2:
+	.word	1
+
+	.section	.text.fndiscard0,"ax"
+	.global	fndiscard0
+	.type	fndiscard0, %function
+fndiscard0:
+	.word 0
+
+	.global	retain0
+	.section	.bss.retain0,"awR"
+	.type	retain0, %object
+retain0:
+	.zero	2
+
+	.global	retain1
+	.section	.bss.retain1,"awR"
+	.type	retain1, %object
+retain1:
+	.zero	2
+
+	.global	retain2
+	.section	.data.retain2,"awR"
+	.type	retain2, %object
+retain2:
+	.word	1
+
+	.section	.bss.sretain0,"awR"
+	.type	sretain0, %object
+sretain0:
+	.zero	2
+
+	.section	.bss.sretain1,"awR"
+	.type	sretain1, %object
+sretain1:
+	.zero	2
+
+	.section	.data.sretain2,"aRw"
+	.type	sretain2, %object
+sretain2:
+	.word	1
+
+	.section	.text.fnretain1,"Rax"
+	.global	fnretain1
+	.type	fnretain1, %function
+fnretain1:
+	.word	0
+
+	.section	.text.fndiscard2,"ax"
+	.global	fndiscard2
+	.type	fndiscard2, %function
+fndiscard2:
+	.word	0
+
+	.section	.bss.lsretain0,"awR"
+	.type	lsretain0.2, %object
+lsretain0.2:
+	.zero	2
+
+	.section	.bss.lsretain1,"aRw"
+	.type	lsretain1.1, %object
+lsretain1.1:
+	.zero	2
+
+	.section	.data.lsretain2,"aRw"
+	.type	lsretain2.0, %object
+lsretain2.0:
+	.word	1
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain1a.d b/ld/testsuite/ld-elf/retain1a.d
new file mode 100644
index 0000000000..75abb9856c
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain1a.d
@@ -0,0 +1,28 @@
+#name: SHF_GNU_RETAIN 1a
+#source: retain1.s
+#ld: -e _start --gc-sections
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#...
+[0-9a-f]+ . fnretain1
+#...
+[0-9a-f]+ . lsretain0.2
+#...
+[0-9a-f]+ . lsretain1.1
+#...
+[0-9a-f]+ . lsretain2.0
+#...
+[0-9a-f]+ . retain0
+#...
+[0-9a-f]+ . retain1
+#...
+[0-9a-f]+ . retain2
+#...
+[0-9a-f]+ . sretain0
+#...
+[0-9a-f]+ . sretain1
+#...
+[0-9a-f]+ . sretain2
+#pass
diff --git a/ld/testsuite/ld-elf/retain1b.d b/ld/testsuite/ld-elf/retain1b.d
new file mode 100644
index 0000000000..815c0150f5
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain1b.d
@@ -0,0 +1,11 @@
+#name: SHF_GNU_RETAIN 1b
+#source: retain1.s
+#ld: -e _start --gc-sections
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#nm: -n
+
+#failif
+#...
+[0-9a-f]+ . .*discard.*
+#...
diff --git a/ld/testsuite/ld-elf/retain2.d b/ld/testsuite/ld-elf/retain2.d
new file mode 100644
index 0000000000..11efd6ddb8
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain2.d
@@ -0,0 +1,6 @@
+#name: SHF_GNU_RETAIN 2 (remove SHF_GNU_RETAIN sections by placing in /DISCARD/)
+#source: retain1.s
+#ld: -e _start -Map=retain2.map --gc-sections --script=retain2.ld
+#map: retain2.map
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
diff --git a/ld/testsuite/ld-elf/retain2.ld b/ld/testsuite/ld-elf/retain2.ld
new file mode 100644
index 0000000000..8ef982753c
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain2.ld
@@ -0,0 +1,7 @@
+SECTIONS
+{
+  /DISCARD/ :
+  {
+    *(.text.fnretain1)
+  }
+}
diff --git a/ld/testsuite/ld-elf/retain2.map b/ld/testsuite/ld-elf/retain2.map
new file mode 100644
index 0000000000..4028aa1f58
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain2.map
@@ -0,0 +1,32 @@
+# Test that .text.fnretain1, which has the SHF_GNU_RETAIN flag, can still be
+# explicitly discarded from the output file.
+
+#...
+Discarded input sections
+
+ .text.*
+#...
+ .data.*
+#...
+ .bss.*
+#...
+ .bss.discard0.*
+#...
+ .bss.discard1.*
+#...
+ .data.discard2.*
+#...
+ .bss.sdiscard0.*
+#...
+ .bss.sdiscard1.*
+#...
+ .data.sdiscard2.*
+#...
+ .text.fndiscard0.*
+#...
+ .text.fnretain1.*
+#...
+ .text.fndiscard2.*
+#...
+Memory Configuration
+#pass
diff --git a/ld/testsuite/ld-elf/retain3.d b/ld/testsuite/ld-elf/retain3.d
new file mode 100644
index 0000000000..911f5b7594
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain3.d
@@ -0,0 +1,12 @@
+#name: SHF_GNU_RETAIN 3 (keep sections referenced by retained sections)
+#source: retain3.s
+#ld: -e _start --gc-sections
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#...
+[0-9a-f]+ . bar
+#...
+[0-9a-f]+ . foo
+#pass
diff --git a/ld/testsuite/ld-elf/retain3.s b/ld/testsuite/ld-elf/retain3.s
new file mode 100644
index 0000000000..ce315cbaa6
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain3.s
@@ -0,0 +1,19 @@
+/* The retention of bar should also prevent foo from being gc'ed, since bar
+   references foo.  */
+	.section	.text.foo,"ax"
+	.global	foo
+	.type	foo, %function
+foo:
+	.word 0
+
+	.section	.text.bar,"axR"
+	.global	bar
+	.type	bar, %function
+bar:
+	.long foo
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain4.d b/ld/testsuite/ld-elf/retain4.d
new file mode 100644
index 0000000000..e94898d681
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain4.d
@@ -0,0 +1,10 @@
+#name: SHF_GNU_RETAIN 4 (keep orphaned sections when not discarding)
+#source: retain4.s
+#ld: -e _start --gc-sections --orphan-handling=place
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#...
+[0-9a-f]+ . orphaned_fn
+#pass
diff --git a/ld/testsuite/ld-elf/retain4.s b/ld/testsuite/ld-elf/retain4.s
new file mode 100644
index 0000000000..9f350cd3b2
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain4.s
@@ -0,0 +1,13 @@
+/* A section which doesn't match any linker script input section rules but
+   has SHF_GNU_RETAIN applied should not be garbage collected.  */
+	.section	.orphaned_section,"axR"
+	.global	orphaned_fn
+	.type	orphaned_fn, %function
+orphaned_fn:
+	.word 0
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain5.d b/ld/testsuite/ld-elf/retain5.d
new file mode 100644
index 0000000000..378799599e
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain5.d
@@ -0,0 +1,12 @@
+#name: SHF_GNU_RETAIN 5 (don't pull SHF_GNU_RETAIN section out of lib)
+#source: retain5main.s
+#ld: --gc-sections -e _start --print-gc-sections -Ltmpdir -lretain5 -Map=retain5.map
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#map: retain5.map
+#DUMPPROG: nm
+
+#failif
+#...
+[0-9a-f]+ . foo
+#...
diff --git a/ld/testsuite/ld-elf/retain5.map b/ld/testsuite/ld-elf/retain5.map
new file mode 100644
index 0000000000..6b97c2a220
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain5.map
@@ -0,0 +1,5 @@
+# Check that the library was actually loaded to catch any false PASS.
+
+#...
+LOAD tmpdir/libretain5.a
+#pass
diff --git a/ld/testsuite/ld-elf/retain5lib.s b/ld/testsuite/ld-elf/retain5lib.s
new file mode 100644
index 0000000000..4e83731719
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain5lib.s
@@ -0,0 +1,6 @@
+/* The link will fail if foo is included because undefined_sym is not defined.  */
+	.section	.text.foo,"axR"
+	.global	foo
+	.type	foo, %function
+foo:
+	.long undefined_sym
diff --git a/ld/testsuite/ld-elf/retain5main.s b/ld/testsuite/ld-elf/retain5main.s
new file mode 100644
index 0000000000..89a7784d13
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain5main.s
@@ -0,0 +1,5 @@
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain6a.d b/ld/testsuite/ld-elf/retain6a.d
new file mode 100644
index 0000000000..92872deffc
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6a.d
@@ -0,0 +1,14 @@
+#name: SHF_GNU_RETAIN 6a (pull section out of lib required by SHF_GNU_RETAIN section)
+#source: retain6main.s
+#ld: --gc-sections -e _start -u bar -Ltmpdir -lretain6
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#...
+[0-9a-f]+ . bar
+#...
+[0-9a-f]+ . retain_from_lib
+#...
+[0-9a-f]+ . retained_fn
+#pass
diff --git a/ld/testsuite/ld-elf/retain6b.d b/ld/testsuite/ld-elf/retain6b.d
new file mode 100644
index 0000000000..a797bf7837
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6b.d
@@ -0,0 +1,11 @@
+#name: SHF_GNU_RETAIN 6b (pull section out of lib required by SHF_GNU_RETAIN section)
+#source: retain6main.s
+#ld: --gc-sections -e _start -u bar -Ltmpdir -lretain6
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#failif
+#...
+[0-9a-f]+ . .*discard.*
+#...
diff --git a/ld/testsuite/ld-elf/retain6lib.s b/ld/testsuite/ld-elf/retain6lib.s
new file mode 100644
index 0000000000..a393dbac61
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6lib.s
@@ -0,0 +1,17 @@
+	.section	.text.bar,"ax"
+	.global	bar
+	.type	bar, %function
+bar:
+	.word 0
+
+	.section	.text.retain_from_lib,"axR"
+	.global	retain_from_lib
+	.type	retain_from_lib, %function
+retain_from_lib:
+	.word 0
+
+	.section	.text.discard_from_lib,"ax"
+	.global	discard_from_lib
+	.type	discard_from_lib, %function
+discard_from_lib:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain6main.s b/ld/testsuite/ld-elf/retain6main.s
new file mode 100644
index 0000000000..a66c5b3247
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6main.s
@@ -0,0 +1,13 @@
+/* Undefined symbol reference in retained section .text.retained_fn requires
+   symbol definition to be pulled out of library.  */
+	.section	.text.retained_fn,"axR"
+	.global	retained_fn
+	.type	retained_fn, %function
+retained_fn:
+	.long bar
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain7.s b/ld/testsuite/ld-elf/retain7.s
new file mode 100644
index 0000000000..2d80947fbd
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain7.s
@@ -0,0 +1,104 @@
+	.section	.bss,"aw"
+	.global	discard0
+	.type	discard0, %object
+discard0:
+	.zero	2
+
+	.section	.bss,"aw"
+	.global	discard1
+	.type	discard1, %object
+discard1:
+	.zero	2
+
+	.section	.data,"aw"
+	.global	discard2
+	.type	discard2, %object
+discard2:
+	.word	1
+
+	.section	.bss,"aw"
+	.type	sdiscard0, %object
+sdiscard0:
+	.zero	2
+
+	.section	.bss,"aw"
+	.type	sdiscard1, %object
+sdiscard1:
+	.zero	2
+
+	.section	.data,"aw"
+	.type	sdiscard2, %object
+sdiscard2:
+	.word	1
+
+	.text
+	.global	fndiscard0
+	.type	fndiscard0, %function
+fndiscard0:
+	.word 0
+
+	.section	.bss,"awR"
+	.global	retain0
+	.type	retain0, %object
+retain0:
+	.zero	2
+
+	.section	.bss,"awR"
+	.global	retain1
+	.type	retain1, %object
+retain1:
+	.zero	2
+
+	.section	.data,"awR"
+	.global	retain2
+	.type	retain2, %object
+retain2:
+	.word	1
+
+	.section	.bss,"awR"
+	.type	sretain0, %object
+sretain0:
+	.zero	2
+
+	.section	.bss,"awR"
+	.type	sretain1, %object
+sretain1:
+	.zero	2
+
+	.section	.data,"aRw"
+	.type	sretain2, %object
+sretain2:
+	.word	1
+
+	.section	.text,"Rax"
+	.global	fnretain1
+	.type	fnretain1, %function
+fnretain1:
+	.word	0
+
+	.section	.text,"ax"
+	.global	fndiscard2
+	.type	fndiscard2, %function
+fndiscard2:
+	.word	0
+
+	.section	.bss,"awR"
+	.type	lsretain0.2, %object
+lsretain0.2:
+	.zero	2
+
+	.section	.bss,"aRw"
+	.type	lsretain1.1, %object
+lsretain1.1:
+	.zero	2
+
+	.section	.data,"aRw"
+	.type	lsretain2.0, %object
+lsretain2.0:
+	.word	1
+
+	.section	.text._start,"ax"
+	.global	_start
+	.type	_start, %function
+_start:
+	.word 0
diff --git a/ld/testsuite/ld-elf/retain7a.d b/ld/testsuite/ld-elf/retain7a.d
new file mode 100644
index 0000000000..055bb74da9
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain7a.d
@@ -0,0 +1,28 @@
+#name: SHF_GNU_RETAIN 7a (flag applied to default section names)
+#source: retain7.s
+#ld: -e _start --gc-sections
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#DUMPPROG: nm
+
+#...
+[0-9a-f]+ . fnretain1
+#...
+[0-9a-f]+ . lsretain0.2
+#...
+[0-9a-f]+ . lsretain1.1
+#...
+[0-9a-f]+ . lsretain2.0
+#...
+[0-9a-f]+ . retain0
+#...
+[0-9a-f]+ . retain1
+#...
+[0-9a-f]+ . retain2
+#...
+[0-9a-f]+ . sretain0
+#...
+[0-9a-f]+ . sretain1
+#...
+[0-9a-f]+ . sretain2
+#pass
diff --git a/ld/testsuite/ld-elf/retain7b.d b/ld/testsuite/ld-elf/retain7b.d
new file mode 100644
index 0000000000..f268047c35
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain7b.d
@@ -0,0 +1,11 @@
+#name: SHF_GNU_RETAIN 7b (flag applied to default section names)
+#source: retain7.s
+#ld: -e _start --gc-sections
+#skip: mep-*-* dlx-*-* d30v-*-* pj-*-* pru-*-* xgate-*-* s12z-*-*
+#notarget: ![supports_gnu_osabi] ![check_gc_sections_available]
+#nm: -n
+
+#failif
+#...
+[0-9a-f]+ . .*discard.*
+#...
-- 
2.28.0