[PATCH v2 0/4] Introduce support for CFI landing pad PLT generation in RISC-V

[Nelson Chu]

Thanks Kito :-)  These cfi series in binutils look good to me.  But the
binutils part looks like just one piece of the puzzle.  It changes the plt
format, so glibc and linux probably need to update something; and also
seems to need gcc codegen support to add GNU property hints in
assembly code.  From the test cases, it seems the cfi support in binutils
are triggered only if the assembly code or objects have GNU properties for
cfi, so it shouldn't affect current plt stuff and linux works.  Therefore,
I am Okay to commit them if other projects, like gcc, glibc or linux, need
binutils to commit cfi stuff first, but it would also be good if we can
know whether the cfi stuff really works and are ready in other projects
before we commit binutils part.

cc other binutils maintainers, Jeff, and people that I think they
probably need to know the progress of cfi stuff.

Thanks
Nelson

On Wed, Jun 11, 2025 at 4:34 PM Kito Cheng <kito.cheng@sifive.com> wrote:

> This patch set introduces support for CFI landing pad PLT generation in
> RISC-V.
>
> Change since V1:
>
> - Move setup_plt_values to the first patch.
> - Drop unnessary changeon riscv_elfNN_set_options.
> - Fix up coding style.
>
> Kito Cheng (4):
>   RISC-V: Refactor PLT generation
>   RISC-V: Add GNU_PROPERTY_RISCV_FEATURE_1_CFI_SS and
>     GNU_PROPERTY_RISCV_FEATURE_1_CFI_LP_UNLABELED
>   RISC-V: Implment the merge logic for GNU_PROPERTY_RISCV_FEATURE_1_AND
>   RISC-V: Support for unlabeled landing pad PLT generation
>
>  bfd/elfnn-riscv.c                             | 306 ++++++++++++++++--
>  bfd/elfxx-riscv.c                             | 170 ++++++++++
>  bfd/elfxx-riscv.h                             |  19 ++
>  binutils/readelf.c                            |  39 +++
>  .../riscv/property-cfi-lp-unlabeled.d         |   8 +
>  .../binutils-all/riscv/property-cfi-ss.d      |   8 +
>  .../testsuite/binutils-all/riscv/property.s   |  41 +++
>  include/elf/common.h                          |   5 +
>  include/opcode/riscv.h                        |   1 +
>  ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp    |   8 +
>  .../ld-riscv-elf/property-combine-and-1.d     |   6 +
>  .../ld-riscv-elf/property-combine-and-2.d     |  11 +
>  .../ld-riscv-elf/property-combine-and-3.d     |  11 +
>  .../ld-riscv-elf/property-zicfilp-unlabeled.d |  10 +
>  .../ld-riscv-elf/property-zicfilp-unlabeled.s |  21 ++
>  ld/testsuite/ld-riscv-elf/property-zicfiss.d  |  10 +
>  ld/testsuite/ld-riscv-elf/property-zicfiss.s  |  21 ++
>  ld/testsuite/ld-riscv-elf/property1.s         |  21 ++
>  ld/testsuite/ld-riscv-elf/property2.s         |   5 +
>  ld/testsuite/ld-riscv-elf/property3.s         |  21 ++
>  ld/testsuite/ld-riscv-elf/property4.s         |  21 ++
>  .../ld-riscv-elf/zicfilp-unlabeled-plt.d      |  35 ++
>  .../ld-riscv-elf/zicfilp-unlabeled-plt.s      |  21 ++
>  23 files changed, 784 insertions(+), 35 deletions(-)
>  create mode 100644
> binutils/testsuite/binutils-all/riscv/property-cfi-lp-unlabeled.d
>  create mode 100644 binutils/testsuite/binutils-all/riscv/property-cfi-ss.d
>  create mode 100644 binutils/testsuite/binutils-all/riscv/property.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-combine-and-1.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-combine-and-2.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-combine-and-3.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-zicfilp-unlabeled.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-zicfilp-unlabeled.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-zicfiss.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/property-zicfiss.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property1.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property2.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property3.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/property4.s
>  create mode 100644 ld/testsuite/ld-riscv-elf/zicfilp-unlabeled-plt.d
>  create mode 100644 ld/testsuite/ld-riscv-elf/zicfilp-unlabeled-plt.s
>
> --
> 2.34.1
>
>
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