[PATCH v3] Support SHF_GNU_RETAIN ELF Section Flag
Jozef Lawrynowicz
jozef.l@mittosystems.com
Mon Oct 19 19:47:10 GMT 2020
Ping for this with a small amendment - removed the unnecessary skip
list in the LD tests.
On Fri, Oct 09, 2020 at 11:59:47AM +0100, Jozef Lawrynowicz wrote:
> The attached patch is version 3 of the SHF_GNU_RETAIN patch that was
> previously discussed here:
>
> Version 1:
> https://sourceware.org/pipermail/binutils/2020-September/113406.html
> Version 2:
> https://sourceware.org/pipermail/binutils/2020-October/113559.html
>
> The following changes have been made since version 2:
> - Removed "if it is unused" phrase from SHF_GNU_RETAIN definition.
> The definition now reads:
> "The link editor should not garbage collect the section."
> - Aligned OSABI error messages in bfd/elf.c with those in
> gas/config/obj-elf.c.
> - Added OSABI checks before SHF_GNU_RETAIN is used in bfd/elflink.c.
> - Added OSABI checks and new tests before SHF_GNU_RETAIN and
> SHF_GNU_MBIND are used in binutils/readelf.c.
> - Removed support in GAS for unique sections to be created with the same
> name, but different states for SHF_GNU_RETAIN. This exception is not
> required for SHF_GNU_RETAIN support.
> - Added warning/error message when SHF_GNU_RETAIN state is not
> consistent when changing sections. Added tests for this.
> - Added support for flags in the SHF_MASKOS range to be set with numeric
> values to the flags argument of the .section directive. Added tests
> for this.
>
> I've successfully regtested the patch for the Binutils, GAS and LD
> testsuites for the following targets:
>
> aarch64-elf arc-elf arm-eabi arm-elf avr-elf bfin-elf cr16-elf cris-elf
> crx-elf csky-elf d10v-elf d30v-elf dlx-elf epiphany-elf fr30-elf frv-elf
> ft32-elf h8300-elf hppa-elf i386-elf ip2k-elf iq2000-elf lm32-elf
> m32c-elf m32r-elf m68hc11-elf m68hc12-elf m68k-elf mcore-elf mep-elf
> metag-elf microblaze-elf mips-elf moxie-elf msp430-elf mt-elf nios2-elf
> or1k-elf pj-elf ppc-elf pru-elf riscv-elf rl78-elf rx-elf s12z-elf
> score-elf sh-elf sparc-elf spu-elf tic6x-elf tilegx-elf tilepro-elf
> v850-elf visium-elf wasm32-elf xgate-elf xstormy16-elf xtensa-elf
> z80-elf.
>
> Ok to apply?
>
> Thanks,
> Jozef
> From 9709145da0644b6657a892ad8e513ace81359c7d Mon Sep 17 00:00:00 2001
> From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
> Date: Fri, 9 Oct 2020 11:52:55 +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.
>
> =======================================================================
>
> 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:
>
> 2020-10-09 Jozef Lawrynowicz <jozef.l@mittosystems.com>
> H.J. Lu <hongjiu.lu@intel.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:
>
> 2020-10-09 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 tests.
> 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/readelf-maskos-1a.d: New test.
> * testsuite/binutils-all/readelf-maskos-1b.d: New test.
> * testsuite/binutils-all/readelf-maskos.s: New test.
> * testsuite/binutils-all/retain1.s: New test.
> * testsuite/binutils-all/retain1a.d: New test.
> * testsuite/binutils-all/retain1b.d: New test.
>
> gas/ChangeLog:
>
> 2020-10-09 Jozef Lawrynowicz <jozef.l@mittosystems.com>
> H.J. Lu <hongjiu.lu@intel.com>
>
> * NEWS: Announce SHF_GNU_RETAIN.
> * config/obj-elf.c (get_section_by_match): Update struct member name.
> (obj_elf_change_section): Warn/error for state change of SHF_GNU_RETAIN.
> (obj_elf_parse_section_letters): Handle 'R' flag.
> Handle numeric flag values within the SHF_MASKOS range.
> (obj_elf_section): Validate SHF_GNU_RETAIN usage.
> * 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.
> * testsuite/gas/elf/section24.d: New test.
> * testsuite/gas/elf/section24.l: New test.
> * testsuite/gas/elf/section24.s: New test.
>
> include/ChangeLog:
>
> 2020-10-09 Jozef Lawrynowicz <jozef.l@mittosystems.com>
>
> * elf/common.h (SHF_GNU_RETAIN): Define.
>
> ld/ChangeLog:
>
> 2020-10-09 Jozef Lawrynowicz <jozef.l@mittosystems.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.
> ---
> bfd/elf-bfd.h | 9 +-
> bfd/elf.c | 17 ++-
> bfd/elflink.c | 4 +-
> binutils/NEWS | 4 +
> binutils/readelf.c | 51 ++++++++-
> .../binutils-all/readelf-maskos-1a.d | 10 ++
> .../binutils-all/readelf-maskos-1b.d | 12 ++
> .../testsuite/binutils-all/readelf-maskos.s | 11 ++
> binutils/testsuite/binutils-all/readelf.exp | 9 +-
> binutils/testsuite/binutils-all/retain1.s | 104 ++++++++++++++++++
> binutils/testsuite/binutils-all/retain1a.d | 18 +++
> binutils/testsuite/binutils-all/retain1b.d | 46 ++++++++
> binutils/testsuite/lib/binutils-common.exp | 5 +-
> gas/NEWS | 5 +
> gas/config/obj-elf.c | 88 +++++++++++----
> gas/config/obj-elf.h | 3 +-
> gas/doc/as.texi | 3 +
> gas/testsuite/gas/elf/elf.exp | 5 +-
> 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 +
> gas/testsuite/gas/elf/section24.d | 18 +++
> gas/testsuite/gas/elf/section24.l | 4 +
> gas/testsuite/gas/elf/section24.s | 32 ++++++
> include/elf/common.h | 1 +
> ld/NEWS | 4 +
> ld/ld.texi | 7 ++
> 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 +++
> 51 files changed, 853 insertions(+), 44 deletions(-)
> create mode 100644 binutils/testsuite/binutils-all/readelf-maskos-1a.d
> create mode 100644 binutils/testsuite/binutils-all/readelf-maskos-1b.d
> create mode 100644 binutils/testsuite/binutils-all/readelf-maskos.s
> create mode 100644 binutils/testsuite/binutils-all/retain1.s
> create mode 100644 binutils/testsuite/binutils-all/retain1a.d
> create mode 100644 binutils/testsuite/binutils-all/retain1b.d
> 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 gas/testsuite/gas/elf/section24.d
> create mode 100644 gas/testsuite/gas/elf/section24.l
> create mode 100644 gas/testsuite/gas/elf/section24.s
> 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
>
> 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 9d7cbd52e0..dc097e825a 100644
> --- a/bfd/elf.c
> +++ b/bfd/elf.c
> @@ -1066,9 +1066,12 @@ _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;
> @@ -12464,11 +12467,17 @@ _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 e23d189b98..742254055c 100644
> --- a/bfd/elflink.c
> +++ b/bfd/elflink.c
> @@ -14103,7 +14103,9 @@ bfd_elf_gc_sections (bfd *abfd, struct bfd_link_info *info)
> == SHT_FINI_ARRAY)))
> || (elf_section_data (o)->this_hdr.sh_type == SHT_NOTE
> && elf_next_in_group (o) == NULL
> - && elf_linked_to_section (o) == NULL)))
> + && elf_linked_to_section (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..ceea7731c5 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.
> +
> 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..e6ec99a2cc 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;
> @@ -6061,10 +6062,26 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
> if (flag == SHF_PPC_VLE)
> sindex = 25;
> break;
> + }
>
> + 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;
> }
>
> if (sindex != -1)
> @@ -6107,7 +6124,6 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
> case SHF_TLS: *p = 'T'; break;
> case SHF_EXCLUDE: *p = 'E'; break;
> case SHF_COMPRESSED: *p = 'C'; break;
> - case SHF_GNU_MBIND: *p = 'D'; break;
>
> default:
> if ((filedata->file_header.e_machine == EM_X86_64
> @@ -6117,14 +6133,37 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
> *p = 'l';
> else if (filedata->file_header.e_machine == EM_ARM
> && flag == SHF_ARM_PURECODE)
> - *p = 'y';
> + *p = 'y';
> else if (filedata->file_header.e_machine == EM_PPC
> && flag == SHF_PPC_VLE)
> - *p = 'v';
> + *p = 'v';
> else if (flag & SHF_MASKOS)
> {
> - *p = 'o';
> - sh_flags &= ~ SHF_MASKOS;
> + switch (filedata->file_header.e_ident[EI_OSABI])
> + {
> + case ELFOSABI_GNU:
> + case ELFOSABI_FREEBSD:
> + if (flag == SHF_GNU_RETAIN)
> + {
> + *p = 'R';
> + break;
> + }
> + /* 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. */
> + *p = 'D';
> + break;
> + }
> + /* Fall through */
> + default:
> + *p = 'o';
> + sh_flags &= ~SHF_MASKOS;
> + break;
> + }
> }
> else if (flag & SHF_MASKPROC)
> {
> diff --git a/binutils/testsuite/binutils-all/readelf-maskos-1a.d b/binutils/testsuite/binutils-all/readelf-maskos-1a.d
> new file mode 100644
> index 0000000000..7b27358599
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/readelf-maskos-1a.d
> @@ -0,0 +1,10 @@
> +#name: Unknown SHF_MASKOS value in section
> +#source: readelf-maskos.s
> +#notarget: [supports_gnu_osabi] msp430-*-elf visium-*-elf
> +#xfail: arm-*-elf
> +#readelf: -S --wide
> +# PR26722 for the arm-*-elf XFAIL
> +
> +#...
> + \[[ 0-9]+\] .data.retain_var.*WAo.*
> +#pass
> diff --git a/binutils/testsuite/binutils-all/readelf-maskos-1b.d b/binutils/testsuite/binutils-all/readelf-maskos-1b.d
> new file mode 100644
> index 0000000000..2cbb58a73b
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/readelf-maskos-1b.d
> @@ -0,0 +1,12 @@
> +#name: -t (section details) for unknown SHF_MASKOS value in section
> +#source: readelf-maskos.s
> +#notarget: [supports_gnu_osabi] msp430-*-elf visium-*-elf
> +#xfail: arm-*-elf
> +#readelf: -S -t --wide
> +# PR26722 for the arm-*-elf XFAIL
> +
> +#...
> + \[[ 0-9]+\] .data.retain_var
> + PROGBITS +0+ +[0-9a-f]+ +[0-9a-f]+ +[0-9a-f]+ +0 +0 +(1|2|4|8)
> + \[00200003\]: WRITE, ALLOC, OS \(00200000\)
> +#pass
> diff --git a/binutils/testsuite/binutils-all/readelf-maskos.s b/binutils/testsuite/binutils-all/readelf-maskos.s
> new file mode 100644
> index 0000000000..d671119bca
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/readelf-maskos.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/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
> index 1fb36ae5c4..9d1d496e5c 100644
> --- a/binutils/testsuite/binutils-all/readelf.exp
> +++ b/binutils/testsuite/binutils-all/readelf.exp
> @@ -364,8 +364,15 @@ 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 "retain1a"
> + run_dump_test "retain1b"
> + run_dump_test "readelf-maskos-1a"
> + run_dump_test "readelf-maskos-1b"
> +}
>
> # 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.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/binutils-all/retain1a.d b/binutils/testsuite/binutils-all/retain1a.d
> new file mode 100644
> index 0000000000..6397ac52ae
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/retain1a.d
> @@ -0,0 +1,18 @@
> +#name: readelf SHF_GNU_RETAIN
> +#source: retain1.s
> +#target: [supports_gnu_osabi]
> +#readelf: -S --wide
> +
> +#...
> + \[[ 0-9]+\] .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/retain1b.d b/binutils/testsuite/binutils-all/retain1b.d
> new file mode 100644
> index 0000000000..12bc388ba1
> --- /dev/null
> +++ b/binutils/testsuite/binutils-all/retain1b.d
> @@ -0,0 +1,46 @@
> +#name: -t (section details) for readelf SHF_GNU_RETAIN
> +#source: retain1.s
> +#target: [supports_gnu_osabi]
> +#readelf: -S -t --wide
> +
> +#...
> + \[[ 0-9]+\] .bss.retain0
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .bss.retain1
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .data.retain2
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .bss.sretain0
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .bss.sretain1
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .data.sretain2
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .text.fnretain1
> +#...
> + \[0+200006\]: ALLOC, EXEC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .bss.lsretain0
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .bss.lsretain1
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#...
> + \[[ 0-9]+\] .data.lsretain2
> +#...
> + \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
> +#pass
> 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 1107725ea6..33005b5904 100644
> --- a/gas/NEWS
> +++ b/gas/NEWS
> @@ -30,6 +30,11 @@
>
> * 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.
> +
> 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 f061ea61f3..6586478975 100644
> --- a/gas/config/obj-elf.c
> +++ b/gas/config/obj-elf.c
> @@ -529,9 +529,9 @@ get_section_by_match (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;
>
> - return (info == match->info
> + return (sh_info == match->sh_info
> && ((bfd_section_flags (sec) & SEC_ASSEMBLER_SECTION_ID)
> == (match->flags & SEC_ASSEMBLER_SECTION_ID))
> && sec->section_id == match->section_id
> @@ -740,7 +740,7 @@ 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)
> @@ -798,7 +798,10 @@ obj_elf_change_section (const char *name,
> & (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE
> | SEC_EXCLUDE | SEC_SORT_ENTRIES | SEC_MERGE | SEC_STRINGS
> | SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD
> - | SEC_THREAD_LOCAL)))
> + | SEC_THREAD_LOCAL))
> + || ((elf_tdata (stdoutput)->has_gnu_osabi & elf_gnu_osabi_retain)
> + && ((elf_section_flags (old_sec) ^ match_p->sh_flags)
> + & SHF_GNU_RETAIN)))
> {
> if (ssect != NULL)
> as_warn (_("ignoring changed section attributes for %s"), name);
> @@ -861,6 +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;
> @@ -890,8 +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 --;
> @@ -1287,18 +1317,21 @@ 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;
> @@ -1387,26 +1420,39 @@ obj_elf_section (int push)
> done:
> demand_empty_rest_of_line ();
>
> - 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);
> - if (bed->elf_osabi == ELFOSABI_NONE)
> - 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;
> +
> + if (bed->elf_osabi != ELFOSABI_GNU
> + && bed->elf_osabi != ELFOSABI_FREEBSD
> + && bed->elf_osabi != ELFOSABI_NONE)
> + {
> + as_bad (_("%s section is supported only by GNU and FreeBSD targets"),
> + mbind_p ? "GNU_MBIND" : "GNU_RETAIN");
> + }
> + else
> + {
> + if (bed->elf_osabi == ELFOSABI_NONE)
> + bed->elf_osabi = ELFOSABI_GNU;
> +
> + 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;
> +
> + attr |= gnu_attr;
> + }
> }
> - elf_section_flags (now_seg) |= gnu_attr;
> +
> + obj_elf_change_section (name, type, attr, entsize, &match, linkonce,
> + push);
>
> if (linked_to_section_index != -1UL)
> {
> diff --git a/gas/config/obj-elf.h b/gas/config/obj-elf.h
> index 4f29572eef..0a91ed462f 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 4d5294552a..e92432a8bd 100644
> --- a/gas/doc/as.texi
> +++ b/gas/doc/as.texi
> @@ -6657,6 +6657,9 @@ 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 9d75154483..49d5a47959 100644
> --- a/gas/testsuite/gas/elf/elf.exp
> +++ b/gas/testsuite/gas/elf/elf.exp
> @@ -261,8 +261,11 @@ 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 "section24"
> run_dump_test "sh-link-zero"
> -
> 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..8aa7fcfc34
> --- /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.discard0[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX.*
> +#...
> + \[..\] .data.discard1[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WA.*
> +#...
> + \[..\] .bss.discard2[ ]+NOBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WA.*
> +#...
> + \[..\] .bss.retain0[ ]+NOBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
> +#...
> + \[..\] .data.retain1[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
> +#...
> + \[..\] .text.retain2[ ]+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..66ed990e57
> --- /dev/null
> +++ b/gas/testsuite/gas/elf/section22.s
> @@ -0,0 +1,34 @@
> + .section .text.discard0,"ax",%progbits
> + .global discard0
> + .type discard0, %function
> +discard0:
> + .word 0
> +
> + .section .data.discard1,"aw"
> + .global discard1
> + .type discard1, %object
> +discard1:
> + .word 1
> +
> + .section .bss.discard2,"aw"
> + .global discard2
> + .type discard2, %object
> +discard2:
> + .zero 2
> +
> + .section .bss.retain0,"awR",%nobits
> + .global retain0
> + .type retain0, %object
> +retain0:
> + .zero 2
> +
> + .section .data.retain1,"awR",%progbits
> + .type retain1, %object
> +retain1:
> + .word 1
> +
> + .section .text.retain2,"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/gas/testsuite/gas/elf/section24.d b/gas/testsuite/gas/elf/section24.d
> new file mode 100644
> index 0000000000..5ee4aee3af
> --- /dev/null
> +++ b/gas/testsuite/gas/elf/section24.d
> @@ -0,0 +1,18 @@
> +#name: Warn for SHF_GNU_RETAIN set on existing section
> +#notarget: ![supports_gnu_osabi] rx-*-*
> +#readelf: -h -S --wide
> +#warning_output: section24.l
> +# rx-*-* does not automatically create a ".text" section when starting assembly.
> +
> +#...
> + +OS/ABI: +UNIX - GNU
> +#...
> + \[..\] .text[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX .*
> +#...
> + \[..\] .text[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR .*
> +#...
> + \[..\] .text.foo[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR .*
> +#...
> + \[..\] .text.bar[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX .*
> +#pass
> +
> diff --git a/gas/testsuite/gas/elf/section24.l b/gas/testsuite/gas/elf/section24.l
> new file mode 100644
> index 0000000000..e0ea36078c
> --- /dev/null
> +++ b/gas/testsuite/gas/elf/section24.l
> @@ -0,0 +1,4 @@
> +[^:]*: Assembler messages:
> +[^:]*:4: Warning: ignoring changed section attributes for .text
> +[^:]*:20: Warning: ignoring changed section attributes for .text.foo
> +[^:]*:30: Warning: ignoring changed section attributes for .text.bar
> diff --git a/gas/testsuite/gas/elf/section24.s b/gas/testsuite/gas/elf/section24.s
> new file mode 100644
> index 0000000000..deaff0a323
> --- /dev/null
> +++ b/gas/testsuite/gas/elf/section24.s
> @@ -0,0 +1,32 @@
> +/* The default .text section automatically created by the assembler does not
> + have the SHF_GNU_RETAIN flag set, so the "R" flag cannot be used with that,
> + or any other, default section. */
> + .section .text,"axR",%progbits
> +retain_bad:
> + .word 0
> +
> +/* A unique .text section with SHF_GNU_RETAIN applied can be created. */
> + .section .text,"axR",%progbits,unique,0
> +retain_good:
> + .word 0
> +
> +/* SHF_GNU_RETAIN can be applied to a new section. */
> + .section .text.foo,"axR",%progbits
> +foo_retain:
> + .word 0
> +
> +/* If the section is used again without SHF_GNU_RETAIN, a warning should be
> + emitted. */
> + .section .text.foo,"ax",%progbits
> +foo:
> + .word 0
> +
> + .section .text.bar,"ax",%progbits
> +bar:
> + .word 0
> +
> +/* SHF_GNU_RETAIN cannot be applied to a section which was already explicitly
> + declared without SHF_GNU_RETAIN set. */
> + .section .text.bar,"axR",%progbits
> +bar_retain:
> + .word 0
> 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..c103bcebc4 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.
> +
> Changes in 2.35:
>
> * X86 NaCl target support is removed.
> diff --git a/ld/ld.texi b/ld/ld.texi
> index ee592df6c2..849006f0fb 100644
> --- a/ld/ld.texi
> +++ b/ld/ld.texi
> @@ -1787,6 +1787,9 @@ 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.
> +
> @kindex --print-gc-sections
> @kindex --no-print-gc-sections
> @cindex garbage collection
> @@ -5232,6 +5235,10 @@ 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.
> +
> 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
> --
> 2.28.0
>
-------------- next part --------------
>From 3a89108b2a9e466be7fe82a0f19cd6978d96e3ec Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Mon, 19 Oct 2020 20:43:17 +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.
=======================================================================
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:
2020-10-19 Jozef Lawrynowicz <jozef.l@mittosystems.com>
H.J. Lu <hongjiu.lu@intel.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:
2020-10-19 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 tests.
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/readelf-maskos-1a.d: New test.
* testsuite/binutils-all/readelf-maskos-1b.d: New test.
* testsuite/binutils-all/readelf-maskos.s: New test.
* testsuite/binutils-all/retain1.s: New test.
* testsuite/binutils-all/retain1a.d: New test.
* testsuite/binutils-all/retain1b.d: New test.
gas/ChangeLog:
2020-10-19 Jozef Lawrynowicz <jozef.l@mittosystems.com>
H.J. Lu <hongjiu.lu@intel.com>
* NEWS: Announce SHF_GNU_RETAIN.
* config/obj-elf.c (get_section_by_match): Update struct member name.
(obj_elf_change_section): Warn/error for state change of SHF_GNU_RETAIN.
(obj_elf_parse_section_letters): Handle 'R' flag.
Handle numeric flag values within the SHF_MASKOS range.
(obj_elf_section): Validate SHF_GNU_RETAIN usage.
* 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.
* testsuite/gas/elf/section24.d: New test.
* testsuite/gas/elf/section24.l: New test.
* testsuite/gas/elf/section24.s: New test.
include/ChangeLog:
2020-10-19 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* elf/common.h (SHF_GNU_RETAIN): Define.
ld/ChangeLog:
2020-10-19 Jozef Lawrynowicz <jozef.l@mittosystems.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.
---
bfd/elf-bfd.h | 9 +-
bfd/elf.c | 17 ++-
bfd/elflink.c | 4 +-
binutils/NEWS | 4 +
binutils/readelf.c | 51 ++++++++-
.../binutils-all/readelf-maskos-1a.d | 10 ++
.../binutils-all/readelf-maskos-1b.d | 12 ++
.../testsuite/binutils-all/readelf-maskos.s | 11 ++
binutils/testsuite/binutils-all/readelf.exp | 9 +-
binutils/testsuite/binutils-all/retain1.s | 104 ++++++++++++++++++
binutils/testsuite/binutils-all/retain1a.d | 18 +++
binutils/testsuite/binutils-all/retain1b.d | 46 ++++++++
binutils/testsuite/lib/binutils-common.exp | 5 +-
gas/NEWS | 5 +
gas/config/obj-elf.c | 88 +++++++++++----
gas/config/obj-elf.h | 3 +-
gas/doc/as.texi | 3 +
gas/testsuite/gas/elf/elf.exp | 5 +-
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 +
gas/testsuite/gas/elf/section24.d | 18 +++
gas/testsuite/gas/elf/section24.l | 4 +
gas/testsuite/gas/elf/section24.s | 32 ++++++
include/elf/common.h | 1 +
ld/NEWS | 4 +
ld/ld.texi | 7 ++
ld/testsuite/ld-elf/elf.exp | 11 ++
ld/testsuite/ld-elf/retain1.s | 104 ++++++++++++++++++
ld/testsuite/ld-elf/retain1a.d | 27 +++++
ld/testsuite/ld-elf/retain1b.d | 10 ++
ld/testsuite/ld-elf/retain2.d | 5 +
ld/testsuite/ld-elf/retain2.ld | 7 ++
ld/testsuite/ld-elf/retain2.map | 32 ++++++
ld/testsuite/ld-elf/retain3.d | 11 ++
ld/testsuite/ld-elf/retain3.s | 19 ++++
ld/testsuite/ld-elf/retain4.d | 9 ++
ld/testsuite/ld-elf/retain4.s | 13 +++
ld/testsuite/ld-elf/retain5.d | 11 ++
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 | 13 +++
ld/testsuite/ld-elf/retain6b.d | 10 ++
ld/testsuite/ld-elf/retain6lib.s | 17 +++
ld/testsuite/ld-elf/retain6main.s | 13 +++
51 files changed, 845 insertions(+), 44 deletions(-)
create mode 100644 binutils/testsuite/binutils-all/readelf-maskos-1a.d
create mode 100644 binutils/testsuite/binutils-all/readelf-maskos-1b.d
create mode 100644 binutils/testsuite/binutils-all/readelf-maskos.s
create mode 100644 binutils/testsuite/binutils-all/retain1.s
create mode 100644 binutils/testsuite/binutils-all/retain1a.d
create mode 100644 binutils/testsuite/binutils-all/retain1b.d
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 gas/testsuite/gas/elf/section24.d
create mode 100644 gas/testsuite/gas/elf/section24.l
create mode 100644 gas/testsuite/gas/elf/section24.s
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
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 9d7cbd52e0..dc097e825a 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1066,9 +1066,12 @@ _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;
@@ -12464,11 +12467,17 @@ _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 e23d189b98..742254055c 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -14103,7 +14103,9 @@ bfd_elf_gc_sections (bfd *abfd, struct bfd_link_info *info)
== SHT_FINI_ARRAY)))
|| (elf_section_data (o)->this_hdr.sh_type == SHT_NOTE
&& elf_next_in_group (o) == NULL
- && elf_linked_to_section (o) == NULL)))
+ && elf_linked_to_section (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..ceea7731c5 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.
+
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..e6ec99a2cc 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;
@@ -6061,10 +6062,26 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
if (flag == SHF_PPC_VLE)
sindex = 25;
break;
+ }
+ 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;
}
if (sindex != -1)
@@ -6107,7 +6124,6 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
case SHF_TLS: *p = 'T'; break;
case SHF_EXCLUDE: *p = 'E'; break;
case SHF_COMPRESSED: *p = 'C'; break;
- case SHF_GNU_MBIND: *p = 'D'; break;
default:
if ((filedata->file_header.e_machine == EM_X86_64
@@ -6117,14 +6133,37 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
*p = 'l';
else if (filedata->file_header.e_machine == EM_ARM
&& flag == SHF_ARM_PURECODE)
- *p = 'y';
+ *p = 'y';
else if (filedata->file_header.e_machine == EM_PPC
&& flag == SHF_PPC_VLE)
- *p = 'v';
+ *p = 'v';
else if (flag & SHF_MASKOS)
{
- *p = 'o';
- sh_flags &= ~ SHF_MASKOS;
+ switch (filedata->file_header.e_ident[EI_OSABI])
+ {
+ case ELFOSABI_GNU:
+ case ELFOSABI_FREEBSD:
+ if (flag == SHF_GNU_RETAIN)
+ {
+ *p = 'R';
+ break;
+ }
+ /* 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. */
+ *p = 'D';
+ break;
+ }
+ /* Fall through */
+ default:
+ *p = 'o';
+ sh_flags &= ~SHF_MASKOS;
+ break;
+ }
}
else if (flag & SHF_MASKPROC)
{
diff --git a/binutils/testsuite/binutils-all/readelf-maskos-1a.d b/binutils/testsuite/binutils-all/readelf-maskos-1a.d
new file mode 100644
index 0000000000..7b27358599
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf-maskos-1a.d
@@ -0,0 +1,10 @@
+#name: Unknown SHF_MASKOS value in section
+#source: readelf-maskos.s
+#notarget: [supports_gnu_osabi] msp430-*-elf visium-*-elf
+#xfail: arm-*-elf
+#readelf: -S --wide
+# PR26722 for the arm-*-elf XFAIL
+
+#...
+ \[[ 0-9]+\] .data.retain_var.*WAo.*
+#pass
diff --git a/binutils/testsuite/binutils-all/readelf-maskos-1b.d b/binutils/testsuite/binutils-all/readelf-maskos-1b.d
new file mode 100644
index 0000000000..2cbb58a73b
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf-maskos-1b.d
@@ -0,0 +1,12 @@
+#name: -t (section details) for unknown SHF_MASKOS value in section
+#source: readelf-maskos.s
+#notarget: [supports_gnu_osabi] msp430-*-elf visium-*-elf
+#xfail: arm-*-elf
+#readelf: -S -t --wide
+# PR26722 for the arm-*-elf XFAIL
+
+#...
+ \[[ 0-9]+\] .data.retain_var
+ PROGBITS +0+ +[0-9a-f]+ +[0-9a-f]+ +[0-9a-f]+ +0 +0 +(1|2|4|8)
+ \[00200003\]: WRITE, ALLOC, OS \(00200000\)
+#pass
diff --git a/binutils/testsuite/binutils-all/readelf-maskos.s b/binutils/testsuite/binutils-all/readelf-maskos.s
new file mode 100644
index 0000000000..d671119bca
--- /dev/null
+++ b/binutils/testsuite/binutils-all/readelf-maskos.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/binutils/testsuite/binutils-all/readelf.exp b/binutils/testsuite/binutils-all/readelf.exp
index 1fb36ae5c4..9d1d496e5c 100644
--- a/binutils/testsuite/binutils-all/readelf.exp
+++ b/binutils/testsuite/binutils-all/readelf.exp
@@ -364,8 +364,15 @@ 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 "retain1a"
+ run_dump_test "retain1b"
+ run_dump_test "readelf-maskos-1a"
+ run_dump_test "readelf-maskos-1b"
+}
# 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.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/binutils-all/retain1a.d b/binutils/testsuite/binutils-all/retain1a.d
new file mode 100644
index 0000000000..6397ac52ae
--- /dev/null
+++ b/binutils/testsuite/binutils-all/retain1a.d
@@ -0,0 +1,18 @@
+#name: readelf SHF_GNU_RETAIN
+#source: retain1.s
+#target: [supports_gnu_osabi]
+#readelf: -S --wide
+
+#...
+ \[[ 0-9]+\] .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/retain1b.d b/binutils/testsuite/binutils-all/retain1b.d
new file mode 100644
index 0000000000..12bc388ba1
--- /dev/null
+++ b/binutils/testsuite/binutils-all/retain1b.d
@@ -0,0 +1,46 @@
+#name: -t (section details) for readelf SHF_GNU_RETAIN
+#source: retain1.s
+#target: [supports_gnu_osabi]
+#readelf: -S -t --wide
+
+#...
+ \[[ 0-9]+\] .bss.retain0
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .bss.retain1
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .data.retain2
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .bss.sretain0
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .bss.sretain1
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .data.sretain2
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .text.fnretain1
+#...
+ \[0+200006\]: ALLOC, EXEC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .bss.lsretain0
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .bss.lsretain1
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#...
+ \[[ 0-9]+\] .data.lsretain2
+#...
+ \[0+200003\]: WRITE, ALLOC, GNU_RETAIN
+#pass
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 1107725ea6..33005b5904 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -30,6 +30,11 @@
* 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.
+
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 f061ea61f3..6586478975 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -529,9 +529,9 @@ get_section_by_match (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;
- return (info == match->info
+ return (sh_info == match->sh_info
&& ((bfd_section_flags (sec) & SEC_ASSEMBLER_SECTION_ID)
== (match->flags & SEC_ASSEMBLER_SECTION_ID))
&& sec->section_id == match->section_id
@@ -740,7 +740,7 @@ 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)
@@ -798,7 +798,10 @@ obj_elf_change_section (const char *name,
& (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE
| SEC_EXCLUDE | SEC_SORT_ENTRIES | SEC_MERGE | SEC_STRINGS
| SEC_LINK_ONCE | SEC_LINK_DUPLICATES_DISCARD
- | SEC_THREAD_LOCAL)))
+ | SEC_THREAD_LOCAL))
+ || ((elf_tdata (stdoutput)->has_gnu_osabi & elf_gnu_osabi_retain)
+ && ((elf_section_flags (old_sec) ^ match_p->sh_flags)
+ & SHF_GNU_RETAIN)))
{
if (ssect != NULL)
as_warn (_("ignoring changed section attributes for %s"), name);
@@ -861,6 +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;
@@ -890,8 +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 --;
@@ -1287,18 +1317,21 @@ 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;
@@ -1387,26 +1420,39 @@ obj_elf_section (int push)
done:
demand_empty_rest_of_line ();
- 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);
- if (bed->elf_osabi == ELFOSABI_NONE)
- 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;
+
+ if (bed->elf_osabi != ELFOSABI_GNU
+ && bed->elf_osabi != ELFOSABI_FREEBSD
+ && bed->elf_osabi != ELFOSABI_NONE)
+ {
+ as_bad (_("%s section is supported only by GNU and FreeBSD targets"),
+ mbind_p ? "GNU_MBIND" : "GNU_RETAIN");
+ }
+ else
+ {
+ if (bed->elf_osabi == ELFOSABI_NONE)
+ bed->elf_osabi = ELFOSABI_GNU;
+
+ 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;
+
+ attr |= gnu_attr;
+ }
}
- elf_section_flags (now_seg) |= gnu_attr;
+
+ obj_elf_change_section (name, type, attr, entsize, &match, linkonce,
+ push);
if (linked_to_section_index != -1UL)
{
diff --git a/gas/config/obj-elf.h b/gas/config/obj-elf.h
index 4f29572eef..0a91ed462f 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 4d5294552a..e92432a8bd 100644
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -6657,6 +6657,9 @@ 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 9d75154483..49d5a47959 100644
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -261,8 +261,11 @@ 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 "section24"
run_dump_test "sh-link-zero"
-
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..8aa7fcfc34
--- /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.discard0[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX.*
+#...
+ \[..\] .data.discard1[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WA.*
+#...
+ \[..\] .bss.discard2[ ]+NOBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WA.*
+#...
+ \[..\] .bss.retain0[ ]+NOBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
+#...
+ \[..\] .data.retain1[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR.*
+#...
+ \[..\] .text.retain2[ ]+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..66ed990e57
--- /dev/null
+++ b/gas/testsuite/gas/elf/section22.s
@@ -0,0 +1,34 @@
+ .section .text.discard0,"ax",%progbits
+ .global discard0
+ .type discard0, %function
+discard0:
+ .word 0
+
+ .section .data.discard1,"aw"
+ .global discard1
+ .type discard1, %object
+discard1:
+ .word 1
+
+ .section .bss.discard2,"aw"
+ .global discard2
+ .type discard2, %object
+discard2:
+ .zero 2
+
+ .section .bss.retain0,"awR",%nobits
+ .global retain0
+ .type retain0, %object
+retain0:
+ .zero 2
+
+ .section .data.retain1,"awR",%progbits
+ .type retain1, %object
+retain1:
+ .word 1
+
+ .section .text.retain2,"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/gas/testsuite/gas/elf/section24.d b/gas/testsuite/gas/elf/section24.d
new file mode 100644
index 0000000000..5ee4aee3af
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24.d
@@ -0,0 +1,18 @@
+#name: Warn for SHF_GNU_RETAIN set on existing section
+#notarget: ![supports_gnu_osabi] rx-*-*
+#readelf: -h -S --wide
+#warning_output: section24.l
+# rx-*-* does not automatically create a ".text" section when starting assembly.
+
+#...
+ +OS/ABI: +UNIX - GNU
+#...
+ \[..\] .text[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX .*
+#...
+ \[..\] .text[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR .*
+#...
+ \[..\] .text.foo[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR .*
+#...
+ \[..\] .text.bar[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AX .*
+#pass
+
diff --git a/gas/testsuite/gas/elf/section24.l b/gas/testsuite/gas/elf/section24.l
new file mode 100644
index 0000000000..e0ea36078c
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24.l
@@ -0,0 +1,4 @@
+[^:]*: Assembler messages:
+[^:]*:4: Warning: ignoring changed section attributes for .text
+[^:]*:20: Warning: ignoring changed section attributes for .text.foo
+[^:]*:30: Warning: ignoring changed section attributes for .text.bar
diff --git a/gas/testsuite/gas/elf/section24.s b/gas/testsuite/gas/elf/section24.s
new file mode 100644
index 0000000000..deaff0a323
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24.s
@@ -0,0 +1,32 @@
+/* The default .text section automatically created by the assembler does not
+ have the SHF_GNU_RETAIN flag set, so the "R" flag cannot be used with that,
+ or any other, default section. */
+ .section .text,"axR",%progbits
+retain_bad:
+ .word 0
+
+/* A unique .text section with SHF_GNU_RETAIN applied can be created. */
+ .section .text,"axR",%progbits,unique,0
+retain_good:
+ .word 0
+
+/* SHF_GNU_RETAIN can be applied to a new section. */
+ .section .text.foo,"axR",%progbits
+foo_retain:
+ .word 0
+
+/* If the section is used again without SHF_GNU_RETAIN, a warning should be
+ emitted. */
+ .section .text.foo,"ax",%progbits
+foo:
+ .word 0
+
+ .section .text.bar,"ax",%progbits
+bar:
+ .word 0
+
+/* SHF_GNU_RETAIN cannot be applied to a section which was already explicitly
+ declared without SHF_GNU_RETAIN set. */
+ .section .text.bar,"axR",%progbits
+bar_retain:
+ .word 0
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..c103bcebc4 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.
+
Changes in 2.35:
* X86 NaCl target support is removed.
diff --git a/ld/ld.texi b/ld/ld.texi
index ee592df6c2..849006f0fb 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -1787,6 +1787,9 @@ 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.
+
@kindex --print-gc-sections
@kindex --no-print-gc-sections
@cindex garbage collection
@@ -5232,6 +5235,10 @@ 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.
+
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..29adb5d2c9
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain1a.d
@@ -0,0 +1,27 @@
+#name: SHF_GNU_RETAIN 1a
+#source: retain1.s
+#ld: -e _start --gc-sections
+#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..b1cafc9d1c
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain1b.d
@@ -0,0 +1,10 @@
+#name: SHF_GNU_RETAIN 1b
+#source: retain1.s
+#ld: -e _start --gc-sections
+#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..1a63f51aab
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain2.d
@@ -0,0 +1,5 @@
+#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
+#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..3c81a88e51
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain3.d
@@ -0,0 +1,11 @@
+#name: SHF_GNU_RETAIN 3 (keep sections referenced by retained sections)
+#source: retain3.s
+#ld: -e _start --gc-sections
+#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..b423fb9584
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain4.d
@@ -0,0 +1,9 @@
+#name: SHF_GNU_RETAIN 4 (keep orphaned sections when not discarding)
+#source: retain4.s
+#ld: -e _start --gc-sections --orphan-handling=place
+#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..86e85f8da5
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain5.d
@@ -0,0 +1,11 @@
+#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
+#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..aa93117ae7
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6a.d
@@ -0,0 +1,13 @@
+#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
+#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..f29ba71dd9
--- /dev/null
+++ b/ld/testsuite/ld-elf/retain6b.d
@@ -0,0 +1,10 @@
+#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
+#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
--
2.28.0
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