[PATCH v3] elf: Don't set its DT_VERSYM entry for unversioned symbol

[H.J. Lu]

On Wed, Nov 12, 2025 at 6:38 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Tue, Nov 11, 2025 at 6:46 PM Andreas Schwab <schwab@suse.de> wrote:
> >
> > On Okt 31 2025, H.J. Lu wrote:
> >
> > > 1. Referenced symbol without '@' has no version.
> > > 2. Defined symbol without the .symver directive has no version if there
> > > is no linker version script.
> > >
> > > Symbol without version shouldn't have the base version in its DT_VERSYM
> > > entry.  Instead, its DT_VERSYM entry should be all zero to indicate that
> > > the symbol doesn't have a version.
> >
> > This breaks the testsuite of mold:
> >
>
> Why should ld change impact mold tests?
>
> >  38/428 Test  #38: x86_64-arch-x86_64-reloc ..............................***Failed    0.09 sec
> > ++ dirname /home/abuild/rpmbuild/BUILD/mold-2.40.4.60.gad08999-build/mold-2.40.4.60.gad08999/test/arch-x86_64-reloc.sh
> > + . /home/abuild/rpmbuild/BUILD/mold-2.40.4.60.gad08999-build/mold-2.40.4.60.gad08999/test/common.inc
> > ++ export LC_ALL=C
> > ++ LC_ALL=C
> > ++ '[' -z x86_64 ']'
> > ++ '[' -z '' ']'
> > ++ TESTDIR=out/test/x86_64
> > ++ CC=cc
> > ++ CXX=c++
> > ++ GCC=gcc
> > ++ GXX=g++
> > ++ OBJDUMP=objdump
> > ++ OBJCOPY=objcopy
> > ++ STRIP=strip
> > ++ QEMU=
> > +++ basename /home/abuild/rpmbuild/BUILD/mold-2.40.4.60.gad08999-build/mold-2.40.4.60.gad08999/test/arch-x86_64-reloc.sh .sh
> > ++ testname=arch-x86_64-reloc
> > ++ t=out/test/x86_64/arch-x86_64-reloc
> > ++ mkdir -p out/test/x86_64/arch-x86_64-reloc
> > ++ case $MACHINE in
> > ++ tlsdesc_opt=-mtls-dialect=gnu2
> > +++ uname
> > ++ '[' Linux = FreeBSD ']'
> > ++ trap 'on_error $LINENO' ERR
> > ++ trap on_exit EXIT
> > ++ echo -n 'Testing arch-x86_64-reloc ... '
> > Testing arch-x86_64-reloc ... ++ set -o pipefail
> > ++ set -x
> > + cat
> > + cc -fPIC -c -o out/test/x86_64/arch-x86_64-reloc/a.o -x assembler -
> > + cc -fPIC -c -o out/test/x86_64/arch-x86_64-reloc/b.o -xc -
> > + cat
> > + cc -shared -o out/test/x86_64/arch-x86_64-reloc/c.so out/test/x86_64/arch-x86_64-reloc/a.o out/test/x86_64/arch-x86_64-reloc/b.o -Wl,-z,noexecstack
> > + cat
> > + cc -B. -o out/test/x86_64/arch-x86_64-reloc/exe out/test/x86_64/arch-x86_64-reloc/c.so out/test/x86_64/arch-x86_64-reloc/d.s -no-pie
> > mold: error: undefined symbol: print
> > >>> referenced by /tmp/ccfsY4zd.o:(.text)
> > >>>               /tmp/ccfsY4zd.o
> > collect2: error: ld returned 1 exit status
> > ++ on_error 43
> > ++ code=1
> > ++ echo 'command failed: 43: $CC -B. -o $t/exe $t/c.so $t/d.s -no-pie'
> > command failed: 43: $CC -B. -o $t/exe $t/c.so $t/d.s -no-pie
> > ++ trap - EXIT
> > ++ exit 1
> >
> > Is this a bug in mold?
>
> Does
>
> $ cc -o out/test/x86_64/arch-x86_64-reloc/exe
> out/test/x86_64/arch-x86_64-reloc/c.so
> out/test/x86_64/arch-x86_64-reloc/d.s -no-pie
>
> fail with ld?  "print" isn't a function in libc.
>
> 1. Where is it defined?
> 2. What does
> "readelf -DsW" with
>
> commit 2be0f2da2100cc2b5047f5d055cd039ac494d563
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Thu Nov 6 08:20:26 2025 +0800
>
>     readelf: Display the base symbol version as empty string
>
> report on the object where "print" is defined.
> 3.  Which linker is used to generate it?
>

I opened:

https://github.com/rui314/mold/issues/1534

-- 
H.J.