PING [PATCH] gold: Support SHF_GNU_RETAIN
H.J. Lu
hjl.tools@gmail.com
Mon Dec 14 14:59:28 GMT 2020
On Wed, Dec 9, 2020 at 8:07 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Keep input SHF_GNU_RETAIN sections and strip output SHF_GNU_RETAIN for
> GNU/FreBSD ELFOSABIs.
>
> elfcpp/
>
> PR gold/27039
> * elfcpp.h (SHF): Add SHF_GNU_RETAIN.
>
> gold/
>
> PR gold/27039
> * layout.cc (Layout::layout): Strip SHF_GNU_RETAIN.
> * object.cc (Sized_relobj_file::Sized_relobj_file): Initialize
> osabi_.
> (Sized_relobj_file::do_layout): Keep SHF_GNU_RETAIN sections for
> GNU/FreBSD ELFOSABIs.
> * object.h (Sized_relobj_file): Add osabi() and osabi_.
> * testsuite/Makefile.am (check_SCRIPTS): Add retain.sh.
> (check_DATA): Add retain_1.out retain_2.out.
> (MOSTLYCLEANFILES): Add retain_1 retain_2.
> (retain_1.out): New target.
> (retain_1): Likewise.
> (retain_1.o): Likewise.
> (retain_2.out): Likewise.
> (retain_2): Likewise.
> (retain_2.o): Likewise.
> * testsuite/Makefile.in: Regenerated.
> * testsuite/retain.sh: New file.
> * testsuite/retain_1.s: Likewise.
> * testsuite/retain_2.s: Likewise.
> ---
> elfcpp/elfcpp.h | 1 +
> gold/layout.cc | 20 +++++--
> gold/object.cc | 7 ++-
> gold/object.h | 7 +++
> gold/testsuite/Makefile.am | 16 ++++++
> gold/testsuite/Makefile.in | 26 ++++++++--
> gold/testsuite/retain.sh | 60 +++++++++++++++++++++
> gold/testsuite/retain_1.s | 104 +++++++++++++++++++++++++++++++++++++
> gold/testsuite/retain_2.s | 22 ++++++++
> 9 files changed, 254 insertions(+), 9 deletions(-)
> create mode 100755 gold/testsuite/retain.sh
> create mode 100644 gold/testsuite/retain_1.s
> create mode 100644 gold/testsuite/retain_2.s
>
> diff --git a/elfcpp/elfcpp.h b/elfcpp/elfcpp.h
> index 4b6ff94a65..2d333e992f 100644
> --- a/elfcpp/elfcpp.h
> +++ b/elfcpp/elfcpp.h
> @@ -438,6 +438,7 @@ enum SHF
> SHF_TLS = 0x400,
> SHF_COMPRESSED = 0x800,
> SHF_MASKOS = 0x0ff00000,
> + SHF_GNU_RETAIN = 0x200000,
> SHF_MASKPROC = 0xf0000000,
>
> // Indicates this section requires ordering in relation to
> diff --git a/gold/layout.cc b/gold/layout.cc
> index 8563f11099..9c245a8e76 100644
> --- a/gold/layout.cc
> +++ b/gold/layout.cc
> @@ -1186,10 +1186,18 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
> = (parameters->options().text_unlikely_segment()
> && is_prefix_of(".text.unlikely",
> object->section_name(shndx).c_str()));
> + elfcpp::Elf_Xword ignored_flags;
> + elfcpp::ELFOSABI osabi = object->osabi();
> + if (osabi == elfcpp::ELFOSABI_GNU
> + || osabi == elfcpp::ELFOSABI_FREEBSD)
> + ignored_flags = elfcpp::SHF_GNU_RETAIN;
> + else
> + ignored_flags = 0;
> if (text_unlikely_segment)
> {
> elfcpp::Elf_Xword flags
> - = this->get_output_section_flags(shdr.get_sh_flags());
> + = this->get_output_section_flags(shdr.get_sh_flags()
> + & ~ignored_flags);
>
> Stringpool::Key name_key;
> const char* os_name = this->namepool_.add(".text.unlikely", true,
> @@ -1212,16 +1220,18 @@ Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx,
> if (it == this->section_segment_map_.end())
> {
> os = this->choose_output_section(object, name, sh_type,
> - shdr.get_sh_flags(), true,
> - ORDER_INVALID, false, false,
> - true);
> + (shdr.get_sh_flags()
> + & ~ignored_flags),
> + true, ORDER_INVALID,
> + false, false, true);
> }
> else
> {
> // We know the name of the output section, directly call
> // get_output_section here by-passing choose_output_section.
> elfcpp::Elf_Xword flags
> - = this->get_output_section_flags(shdr.get_sh_flags());
> + = this->get_output_section_flags(shdr.get_sh_flags()
> + & ~ignored_flags);
>
> const char* os_name = it->second->name;
> Stringpool::Key name_key;
> diff --git a/gold/object.cc b/gold/object.cc
> index 61aed805c2..0e2bcc131a 100644
> --- a/gold/object.cc
> +++ b/gold/object.cc
> @@ -498,6 +498,7 @@ Sized_relobj_file<size, big_endian>::Sized_relobj_file(
> deferred_layout_relocs_(),
> output_views_(NULL)
> {
> + this->osabi_ = static_cast<elfcpp::ELFOSABI>(ehdr.get_e_ident()[elfcpp::EI_OSABI]);
> this->e_type_ = ehdr.get_e_type();
> }
>
> @@ -1716,10 +1717,14 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
>
> if (is_pass_one && parameters->options().gc_sections())
> {
> + elfcpp::ELFOSABI osabi = this->osabi();
> if (this->is_section_name_included(name)
> || layout->keep_input_section (this, name)
> || sh_type == elfcpp::SHT_INIT_ARRAY
> - || sh_type == elfcpp::SHT_FINI_ARRAY)
> + || sh_type == elfcpp::SHT_FINI_ARRAY
> + || ((osabi == elfcpp::ELFOSABI_GNU
> + || osabi == elfcpp::ELFOSABI_FREEBSD)
> + && shdr.get_sh_flags() & elfcpp::SHF_GNU_RETAIN) != 0)
> {
> symtab->gc()->worklist().push_back(Section_id(this, i));
> }
> diff --git a/gold/object.h b/gold/object.h
> index 656443f062..e73328663d 100644
> --- a/gold/object.h
> +++ b/gold/object.h
> @@ -2209,6 +2209,11 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
> e_type() const
> { return this->e_type_; }
>
> + // Return the EI_OSABI.
> + elfcpp::ELFOSABI
> + osabi() const
> + { return this->osabi_; }
> +
> // Return the number of symbols. This is only valid after
> // Object::add_symbols has been called.
> unsigned int
> @@ -2849,6 +2854,8 @@ class Sized_relobj_file : public Sized_relobj<size, big_endian>
>
> // General access to the ELF file.
> elfcpp::Elf_file<size, big_endian, Object> elf_file_;
> + // The EI_OSABI.
> + elfcpp::ELFOSABI osabi_;
> // Type of ELF file (ET_REL or ET_EXEC). ET_EXEC files are allowed
> // as input files only for the --just-symbols option.
> int e_type_;
> diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
> index 739ea98dbe..abaaba6661 100644
> --- a/gold/testsuite/Makefile.am
> +++ b/gold/testsuite/Makefile.am
> @@ -4466,4 +4466,20 @@ pr26936c.o: pr26936c.s
> pr26936d.o: pr26936d.s
> $(TEST_AS) --gen-debug -mx86-used-note=yes -o $@ $<
>
> +check_SCRIPTS += retain.sh
> +check_DATA += retain_1.out retain_2.out
> +MOSTLYCLEANFILES += retain_1 retain_2
> +retain_1.out: retain_1
> + $(TEST_NM) $< >$@
> +retain_1: retain_1.o ../ld-new
> + ../ld-new -e _start --gc-sections -o $@ retain_1.o
> +retain_1.o: retain_1.s
> + $(TEST_AS) -o $@ $<
> +retain_2.out: retain_2
> + $(TEST_READELF) -d $< >$@
> +retain_2: retain_2.o ../ld-new
> + ../ld-new -pie -e _start --gc-sections -o $@ retain_2.o
> +retain_2.o: retain_2.s
> + $(TEST_AS) -o $@ $<
> +
> endif DEFAULT_TARGET_X86_64
> diff --git a/gold/testsuite/Makefile.in b/gold/testsuite/Makefile.in
> index 2c03a992cf..79aed4a763 100644
> --- a/gold/testsuite/Makefile.in
> +++ b/gold/testsuite/Makefile.in
> @@ -1143,12 +1143,13 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
> @DEFAULT_TARGET_S390_TRUE@@NATIVE_OR_CROSS_LINKER_TRUE@ split_s390x_z4_ns split_s390x_n1_ns split_s390x_n2_ns split_s390x_r
>
> @DEFAULT_TARGET_X86_64_TRUE@am__append_116 = *.dwo *.dwp pr26936a \
> -@DEFAULT_TARGET_X86_64_TRUE@ pr26936b
> +@DEFAULT_TARGET_X86_64_TRUE@ pr26936b retain_1 retain_2
> @DEFAULT_TARGET_X86_64_TRUE@am__append_117 = dwp_test_1.sh \
> -@DEFAULT_TARGET_X86_64_TRUE@ dwp_test_2.sh pr26936.sh
> +@DEFAULT_TARGET_X86_64_TRUE@ dwp_test_2.sh pr26936.sh retain.sh
> @DEFAULT_TARGET_X86_64_TRUE@am__append_118 = dwp_test_1.stdout \
> @DEFAULT_TARGET_X86_64_TRUE@ dwp_test_2.stdout pr26936a.stdout \
> -@DEFAULT_TARGET_X86_64_TRUE@ pr26936b.stdout
> +@DEFAULT_TARGET_X86_64_TRUE@ pr26936b.stdout retain_1.out \
> +@DEFAULT_TARGET_X86_64_TRUE@ retain_2.out
> subdir = testsuite
> ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
> am__aclocal_m4_deps = $(top_srcdir)/../config/ax_pthread.m4 \
> @@ -6492,6 +6493,13 @@ pr26936.sh.log: pr26936.sh
> --log-file $$b.log --trs-file $$b.trs \
> $(am__common_driver_flags) $(AM_LOG_DRIVER_FLAGS) $(LOG_DRIVER_FLAGS) -- $(LOG_COMPILE) \
> "$$tst" $(AM_TESTS_FD_REDIRECT)
> +retain.sh.log: retain.sh
> + @p='retain.sh'; \
> + b='retain.sh'; \
> + $(am__check_pre) $(LOG_DRIVER) --test-name "$$f" \
> + --log-file $$b.log --trs-file $$b.trs \
> + $(am__common_driver_flags) $(AM_LOG_DRIVER_FLAGS) $(LOG_DRIVER_FLAGS) -- $(LOG_COMPILE) \
> + "$$tst" $(AM_TESTS_FD_REDIRECT)
> object_unittest.log: object_unittest$(EXEEXT)
> @p='object_unittest$(EXEEXT)'; \
> b='object_unittest'; \
> @@ -10463,6 +10471,18 @@ uninstall-am:
> @DEFAULT_TARGET_X86_64_TRUE@ $(TEST_AS) --gen-debug -mx86-used-note=yes -o $@ $<
> @DEFAULT_TARGET_X86_64_TRUE@pr26936d.o: pr26936d.s
> @DEFAULT_TARGET_X86_64_TRUE@ $(TEST_AS) --gen-debug -mx86-used-note=yes -o $@ $<
> +@DEFAULT_TARGET_X86_64_TRUE@retain_1.out: retain_1
> +@DEFAULT_TARGET_X86_64_TRUE@ $(TEST_NM) $< >$@
> +@DEFAULT_TARGET_X86_64_TRUE@retain_1: retain_1.o ../ld-new
> +@DEFAULT_TARGET_X86_64_TRUE@ ../ld-new -e _start --gc-sections -o $@ retain_1.o
> +@DEFAULT_TARGET_X86_64_TRUE@retain_1.o: retain_1.s
> +@DEFAULT_TARGET_X86_64_TRUE@ $(TEST_AS) -o $@ $<
> +@DEFAULT_TARGET_X86_64_TRUE@retain_2.out: retain_2
> +@DEFAULT_TARGET_X86_64_TRUE@ $(TEST_READELF) -d $< >$@
> +@DEFAULT_TARGET_X86_64_TRUE@retain_2: retain_2.o ../ld-new
> +@DEFAULT_TARGET_X86_64_TRUE@ ../ld-new -pie -e _start --gc-sections -o $@ retain_2.o
> +@DEFAULT_TARGET_X86_64_TRUE@retain_2.o: retain_2.s
> +@DEFAULT_TARGET_X86_64_TRUE@ $(TEST_AS) -o $@ $<
>
> # Tell versions [3.59,3.63) of GNU make to not export all variables.
> # Otherwise a system limit (for SysV at least) may be exceeded.
> diff --git a/gold/testsuite/retain.sh b/gold/testsuite/retain.sh
> new file mode 100755
> index 0000000000..0f5c6951c5
> --- /dev/null
> +++ b/gold/testsuite/retain.sh
> @@ -0,0 +1,60 @@
> +#!/bin/sh
> +
> +# retain.sh -- Tests for SHF_GNU_RETAIN.
> +
> +# Copyright (C) 2020 Free Software Foundation, Inc.
> +
> +# This file is part of gold.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write to the Free Software
> +# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
> +# MA 02110-1301, USA.
> +
> +set -e
> +
> +check()
> +{
> + number_of_occurrence=`egrep "$2" ./$1 -o | wc -l`
> + if [ $number_of_occurrence != $3 ]
> + then
> + echo "$1: \"$2\" $3: Failed"
> + status=1
> + fi
> +}
> +
> +status=0
> +check retain_1.out " T fnretain1" 1
> +check retain_1.out " b lsretain0.2" 1
> +check retain_1.out " b lsretain1.1" 1
> +check retain_1.out " d lsretain2.0" 1
> +check retain_1.out " B retain0" 1
> +check retain_1.out " B retain1" 1
> +check retain_1.out " D retain2" 1
> +check retain_1.out " b sretain0" 1
> +check retain_1.out " b sretain1" 1
> +check retain_1.out " d sretain2" 1
> +if grep discard retain_1.out
> +then
> + echo "retain_1.out: Garbage collection failed"
> + status=1
> +fi
> +
> +check retain_2.out " \(PREINIT_ARRAY\)" 1
> +check retain_2.out " \(PREINIT_ARRAYSZ\)" 1
> +check retain_2.out " \(INIT_ARRAY\)" 1
> +check retain_2.out " \(INIT_ARRAYSZ\)" 1
> +check retain_2.out " \(FINI_ARRAY\)" 1
> +check retain_2.out " \(FINI_ARRAYSZ\)" 1
> +
> +exit $status
> diff --git a/gold/testsuite/retain_1.s b/gold/testsuite/retain_1.s
> new file mode 100644
> index 0000000000..f7716faabe
> --- /dev/null
> +++ b/gold/testsuite/retain_1.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/gold/testsuite/retain_2.s b/gold/testsuite/retain_2.s
> new file mode 100644
> index 0000000000..67d86d10cb
> --- /dev/null
> +++ b/gold/testsuite/retain_2.s
> @@ -0,0 +1,22 @@
> + .section .preinit_array.01000,"aw",%preinit_array
> + .dc.a 0
> +
> + .section .init_array.01000,"aw",%init_array
> + .dc.a 0
> +
> + .section .fini_array.01000,"aw",%fini_array
> + .dc.a 0
> +
> + .section .preinit_array.01000,"awR",%preinit_array
> + .dc.a 0
> +
> + .section .init_array.01000,"awR",%init_array
> + .dc.a 0
> +
> + .section .fini_array.01000,"awR",%fini_array
> + .dc.a 0
> +
> + .text
> + .globl _start
> +_start:
> + .dc.a 0
> --
> 2.29.2
>
Hi Cary,
Gold is broken with SHF_GNU_RETAIN is used. I'd like to fix it before
2.36 is released. Do you have any comments for this patch?
Thanks.
--
H.J.
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