[PATCH v2 1/3] RISC-V: Enable shared library and PIE support for riscv*-elf

[Kito Cheng]

LGTM :)

mintsuki <mintsuki@protonmail.com>於 2026年9月9日週三，09:07寫道：

> riscv*-elf is the only RISC-V target for which ld refuses -shared and
> -pie.  elf32lriscv-defs.sh has withheld GENERATE_SHLIB_SCRIPT and
> GENERATE_PIE_SCRIPT from it since be1dce26256a ("RISC-V: Disable shared
> library support for embedded elf."), whose commit message is a ChangeLog
> entry and records no reason.  Nothing in the RISC-V backend depends on
> the exclusion, and riscv*-elf does not even set EMBEDDED.
>
> Other bare-metal ELF targets do generate the scripts.  aarch64*-elf was
> given PIE support deliberately, in 3af09e8db308 ("Support -pie for
> aarch64*-elf targets."), and arm-elf and x86_64-elf have both.  The
> general question was raised in f2aaebdb9797 ("GENERATE_SHLIB_SCRIPT vs.
> EMBEDDED.") and settled the other way: that patch was reverted in
> 8a46e447a88d, the author concluding that the ELF and program headers are
> still written to the file, so an embedded ELF target producing an ET_DYN
> image is not the mistake he had taken it for.
>
> ld/
>         * emulparams/elf32lriscv-defs.sh (GENERATE_SHLIB_SCRIPT): Set
>         unconditionally rather than only for non-riscv*-elf targets.
>         (GENERATE_PIE_SCRIPT): Likewise.
>
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Mintsuki <mintsuki@protonmail.com>
> ---
>  ld/emulparams/elf32lriscv-defs.sh | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/ld/emulparams/elf32lriscv-defs.sh
> b/ld/emulparams/elf32lriscv-defs.sh
> index 01655616..5c0dac2a 100644
> --- a/ld/emulparams/elf32lriscv-defs.sh
> +++ b/ld/emulparams/elf32lriscv-defs.sh
> @@ -16,15 +16,8 @@ if test `echo "$host" | sed -e s/64//` = `echo
> "$target" | sed -e s/64//`; then
>    esac
>  fi
>
> -# Enable shared library support for everything except an embedded elf
> target.
> -case "$target" in
> -  riscv*-elf)
> -    ;;
> -  *)
> -    GENERATE_SHLIB_SCRIPT=yes
> -    GENERATE_PIE_SCRIPT=yes
> -    ;;
> -esac
> +GENERATE_SHLIB_SCRIPT=yes
> +GENERATE_PIE_SCRIPT=yes
>
>  IREL_IN_PLT=
>  TEXT_START_ADDR=0x10000
> --
> 2.55.0
>
>
> On Wednesday, September 9th, 2026 at 9:04 AM, mintsuki <
> mintsuki@protonmail.com> wrote:
>
> > ld refuses both -shared and -pie for riscv*-elf and loongarch*-elf,
> > because their emulparams files withhold GENERATE_SHLIB_SCRIPT and
> > GENERATE_PIE_SCRIPT from those two targets specifically.  This is not
> > the EMBEDDED policy at work -- neither file sets EMBEDDED -- but a pair
> > of one-off "case $target" checks: be1dce26256a for RISC-V, copied into
> > the LoongArch port from it.  Other bare-metal ELF targets generate the
> > scripts; aarch64*-elf was given PIE support on purpose in 3af09e8db308,
> > and f2aaebdb9797, which would have taken it away from EMBEDDED targets
> > generally, was reverted in 8a46e447a88d:
> >
> >
> https://inbox.sourceware.org/binutils/20191108103411.GU6708@bubble.grove.modra.org/
> >
> > What this blocks in practice is freestanding relocatable outputs.
> > Those need -pie (or, alternatively, -shared -Bsymbolic), as already
> > supported by x86_64-elf, i686-elf, aarch64-elf, etc...
> > On riscv64-elf and loongarch64-elf compilers accept -fPIE and -fPIC,
> > but the link step using ld.bfd dies with "-pie not supported" or
> > "-shared not supported", so a bare-metal toolchain, that is otherwise
> > complete, cannot build a freestanding relocatable output. A *-linux
> > (or otherwise other hosted) ld.bfd (or LLVM's lld) has to be used
> > for the link step instead.
> >
> > Patch 2 is testsuite preparation.  Three LoongArch DT_RELR tests write
> > out the symbol index of r_info in full, and that index depends on the
> > default hash style: GNU hash requires undefined symbols to precede
> > defined ones in .dynsym, so an undefined weak in those tests sorts to
> > index 2 under the linux default of "both" and to the end of the table
> > under the bare-metal default of sysv.  The relocations themselves are
> > correct either way.  Without that patch, patch 3 turns those three from
> > unsupported into FAIL.
> >
> > Based on 2986ed8ba365 ("Constify targ_desc").  Tested with gcc 16.2.0
> > riscv64-elf and loongarch64-elf toolchains and dejagnu 1.6.3.
> > make check-ld, before and after the series:
> >
> >   riscv64-elf       541 -> 763 passes, 0 unexpected failures either way
> >   loongarch64-elf   540 -> 703 passes, 0 unexpected failures either way
> >
> > No test regresses on either target, and there are no unexpected
> > successes; the increase is the shared and PIE tests that were previously
> > skipped now running.  I have not tested the 32-bit variants, riscv32-elf
> > and loongarch32-elf, which the same emulparams files cover.
> >
> > Mintsuki (3):
> >   RISC-V: Enable shared library and PIE support for riscv*-elf
> >   ld: Pin the hash style in the LoongArch DT_RELR shared tests
> >   LoongArch: Enable shared library and PIE support for loongarch*-elf
> >
> >  ld/emulparams/elf32loongarch-defs.sh                | 11 ++---------
> >  ld/emulparams/elf32lriscv-defs.sh                   | 11 ++---------
> >  ld/emulparams/elf64loongarch-defs.sh                | 11 ++---------
> >  ld/testsuite/ld-loongarch-elf/relr-data-shared.d    |  2 +-
> >  ld/testsuite/ld-loongarch-elf/relr-discard-shared.d |  2 +-
> >  ld/testsuite/ld-loongarch-elf/relr-got-shared.d     |  2 +-
> >  6 files changed, 9 insertions(+), 30 deletions(-)
> >
>
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