[PATCH v5] Support SHF_GNU_RETAIN ELF section flag
Jozef Lawrynowicz
jozef.l@mittosystems.com
Wed Nov 11 11:41:46 GMT 2020
The attached patch is the latest version of the Binutils implementation
to support the SHF_GNU_RETAIN ELF GNU OSABI section flag, used to save
sections from linker garbage collection.
Links to previous discussions are available here:
https://sourceware.org/pipermail/gnu-gabi/2020q3/000429.html
https://sourceware.org/pipermail/binutils/2020-September/113406.html
https://sourceware.org/pipermail/binutils/2020-October/113559.html
https://sourceware.org/pipermail/binutils/2020-October/113769.html
https://sourceware.org/pipermail/binutils/2020-November/113993.html
GAS supports the "R" flag to the .section directive, to mark a section
with the SHF_GNU_RETAIN flag.
LD will not garbage collect sections marked with SHF_GNU_RETAIN.
Symbol declarations in the source code marked with the "used" attribute
will not be garbage collected by the linker, as GCC will emit .section
directives with the "R" flag set.
The state of the "R" flag is merged between successive section declarations,
allowing the requirement to retain a section to be indicated to the linker,
without changing the section that the "used" symbol is placed in.
Successfully regtested the Binutils, GAS and LD testsuites for:
aarch64-elf arc-elf arm-eabi 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 x86_64-pc-linux-gnu xgate-elf
xstormy16-elf xtensa-elf z80-elf
Ok to apply?
Thanks,
Jozef
-------------- next part --------------
>From 3f3eb5d76f8e5e54b8d18bf0435ab93f2ce5f3d1 Mon Sep 17 00:00:00 2001
From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
Date: Wed, 11 Nov 2020 11:31:05 +0000
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.
=========================================================
The .section directive accepts the "R" flag, which indicates
SHF_GNU_RETAIN should be applied to the section.
There is not a direct mapping of SHF_GNU_RETAIN to the BFD
section flag SEC_KEEP. Keeping these flags separate allows
SHF_GNU_RETAIN sections to be explicitly removed by placing them in
/DISCARD/.
bfd/ChangeLog:
2020-11-11 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 (elf_link_input_bfd): Copy enabled has_gnu_osabi bits from
input BFD to output BFD.
(bfd_elf_gc_sections): gc_mark the section if SHF_GNU_RETAIN is set.
binutils/ChangeLog:
2020-11-11 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* NEWS: Announce SHF_GNU_RETAIN support.
* 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:
2020-11-11 Jozef Lawrynowicz <jozef.l@mittosystems.com>
H.J. Lu <hongjiu.lu@intel.com>
* NEWS: Announce SHF_GNU_RETAIN support.
* config/obj-elf.c (obj_elf_change_section): Merge SHF_GNU_RETAIN bit
between section declarations.
(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.
* doc/as.texi: Document 'R' flag to .section directive.
* testsuite/gas/elf/elf.exp: Run new tests.
* testsuite/gas/elf/section10.d: Unset SHF_GNU_RETAIN bit.
* testsuite/gas/elf/section10.s: Likewise.
* 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.l: New test.
* testsuite/gas/elf/section24.s: New test.
* testsuite/gas/elf/section24a.d: New test.
* testsuite/gas/elf/section24b.d: New test.
include/ChangeLog:
2020-11-11 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* elf/common.h (SHF_GNU_RETAIN): Define.
ld/ChangeLog:
2020-11-11 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* NEWS: Announce support for 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 | 21 +++-
bfd/elflink.c | 12 +-
binutils/NEWS | 4 +
binutils/readelf.c | 53 ++++++++-
.../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 | 80 +++++++++++---
gas/doc/as.texi | 3 +
gas/testsuite/gas/elf/elf.exp | 6 +-
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 | 10 ++
gas/testsuite/gas/elf/section23b.d | 6 +
gas/testsuite/gas/elf/section23b.err | 2 +
gas/testsuite/gas/elf/section24.l | 4 +
gas/testsuite/gas/elf/section24.s | 38 +++++++
gas/testsuite/gas/elf/section24a.d | 17 +++
gas/testsuite/gas/elf/section24b.d | 10 ++
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, 866 insertions(+), 41 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.l
create mode 100644 gas/testsuite/gas/elf/section24.s
create mode 100644 gas/testsuite/gas/elf/section24a.d
create mode 100644 gas/testsuite/gas/elf/section24b.d
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..8ec21d7705 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;
@@ -12454,8 +12457,8 @@ _bfd_elf_final_write_processing (bfd *abfd)
i_ehdrp->e_ident[EI_OSABI] = get_elf_backend_data (abfd)->elf_osabi;
/* Set the osabi field to ELFOSABI_GNU if the binary contains
- SHF_GNU_MBIND sections or symbols of STT_GNU_IFUNC type or
- STB_GNU_UNIQUE binding. */
+ SHF_GNU_MBIND or SHF_GNU_RETAIN sections or symbols of STT_GNU_IFUNC type
+ or STB_GNU_UNIQUE binding. */
if (elf_tdata (abfd)->has_gnu_osabi != 0)
{
if (i_ehdrp->e_ident[EI_OSABI] == ELFOSABI_NONE)
@@ -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..346424cb55 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -10733,6 +10733,14 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
extsymoff = symtab_hdr->sh_info;
}
+ /* Enable GNU OSABI features in the output BFD that are used in the input
+ BFD. */
+ if (bed->elf_osabi == ELFOSABI_NONE
+ || bed->elf_osabi == ELFOSABI_GNU
+ || bed->elf_osabi == ELFOSABI_FREEBSD)
+ elf_tdata (output_bfd)->has_gnu_osabi
+ |= elf_tdata (input_bfd)->has_gnu_osabi;
+
/* Read the local symbols. */
isymbuf = (Elf_Internal_Sym *) symtab_hdr->contents;
if (isymbuf == NULL && locsymcount != 0)
@@ -14103,7 +14111,9 @@ 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 35e4e303e1..32c264d74e 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -7,6 +7,10 @@
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 03cfc97464..372bb0e578 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -5996,6 +5996,8 @@ 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)
@@ -6028,7 +6030,6 @@ 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;
@@ -6080,10 +6081,28 @@ get_elf_section_flags (Filedata * filedata, bfd_vma sh_flags)
if (flag == SHF_PPC_VLE)
sindex = 25;
break;
+ default:
+ 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)
@@ -6126,7 +6145,6 @@ 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
@@ -6136,14 +6154,37 @@ 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 41cc668e61..41b1d9dde3 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -44,6 +44,11 @@
* Configure with --enable-x86-used-note by default for Linux/x86.
+* Add support for the SHF_GNU_RETAIN flag, which can be applied to
+ sections using the "R" flag in the .section directive.
+ SHF_GNU_RETAIN specifies that the section should not be garbage
+ collected by the linker. It requires the GNU or FreeBSD ELF OSABIs.
+
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..4284b424ca 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -806,9 +806,17 @@ obj_elf_change_section (const char *name,
as_bad (_("changed section attributes for %s"), name);
}
else
- /* FIXME: Maybe we should consider removing a previously set
- processor or application specific attribute as suspicious ? */
- elf_section_flags (sec) = attr;
+ {
+ /* Don't overwrite a previously set SHF_GNU_RETAIN flag for the
+ section. The entire section must be marked retained. */
+ if ((elf_tdata (stdoutput)->has_gnu_osabi & elf_gnu_osabi_retain)
+ && ((elf_section_flags (old_sec) & SHF_GNU_RETAIN)))
+ attr |= SHF_GNU_RETAIN;
+
+ /* FIXME: Maybe we should consider removing a previously set
+ processor or application specific attribute as suspicious ? */
+ elf_section_flags (sec) = attr;
+ }
if ((flags & SEC_MERGE) && old_sec->entsize != (unsigned) entsize)
as_bad (_("changed section entity size for %s"), name);
@@ -861,6 +869,9 @@ 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 +901,32 @@ 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 --;
@@ -1387,26 +1422,37 @@ 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/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..3cbbd283da 100644
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -261,8 +261,12 @@ 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 "section24a"
+ run_dump_test "section24b"
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..2e413e1cec
--- /dev/null
+++ b/gas/testsuite/gas/elf/section23a.d
@@ -0,0 +1,10 @@
+#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.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..f68302f65c
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24.s
@@ -0,0 +1,38 @@
+ .section .text,"ax",%progbits
+ .word 0
+ .section .data,"aw"
+ .word 0
+ .section .bss,"aw",%nobits
+ .word 0
+ .section .rodata,"a"
+ .word 0
+
+/* Test that we can set the "R" flag on an existing section. */
+ .section .text,"axR",%progbits
+ .word 0
+ .section .data,"awR"
+ .word 0
+ .section .bss,"awR",%nobits
+ .word 0
+ .section .rodata,"aR"
+ .word 0
+
+/* Test that the "R" flag does not get clobbered when the section is switched
+ back to. */
+ .section .text,"ax",%progbits
+ .word 0
+ .section .data,"aw"
+ .word 0
+ .section .bss,"aw",%nobits
+ .word 0
+ .section .rodata,"a"
+ .word 0
+
+ .section .text
+ .word 0
+ .section .data
+ .word 0
+ .section .bss
+ .word 0
+ .section .rodata
+ .word 0
diff --git a/gas/testsuite/gas/elf/section24a.d b/gas/testsuite/gas/elf/section24a.d
new file mode 100644
index 0000000000..8f316d3196
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24a.d
@@ -0,0 +1,17 @@
+#name: Merge SHF_GNU_RETAIN for non-unique sections
+#notarget: ![supports_gnu_osabi]
+#source: section24.s
+#readelf: -h -S --wide
+
+#...
+ +OS/ABI: +UNIX - GNU
+#...
+ \[..\] .text[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AXR .*
+#...
+ \[..\] .data[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR .*
+#...
+ \[..\] .bss[ ]+NOBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 WAR .*
+#...
+ \[..\] .rodata[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 AR .*
+#pass
+
diff --git a/gas/testsuite/gas/elf/section24b.d b/gas/testsuite/gas/elf/section24b.d
new file mode 100644
index 0000000000..451ec21635
--- /dev/null
+++ b/gas/testsuite/gas/elf/section24b.d
@@ -0,0 +1,10 @@
+#name: Merge SHF_GNU_RETAIN for non-unique sections (check no unmerged)
+#notarget: ![supports_gnu_osabi]
+#source: section24.s
+#readelf: -S --wide
+
+#failif
+#...
+ \[..\] .(text|data|bss|rodata)[ ]+PROGBITS[ ]+[0-9a-f]+ [0-9a-f]+ [0-9a-f]+ 00 [^R] .*
+#pass
+
diff --git a/include/elf/common.h b/include/elf/common.h
index b3c30e0e2f..a17cafcc70 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 81c44191d2..bb23010dad 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -23,6 +23,10 @@
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 48e78aecdb..40c209d914 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -1805,6 +1805,9 @@ 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
@@ -5265,6 +5268,10 @@ 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
--
2.29.2
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