[PATCH] RISC-V: Segment fault for kernel purgatory when linking.

[Nelson Chu]

Committed, thanks.

Nelson

On Tue, Apr 30, 2024 at 1:43 PM Nelson Chu <nelson@rivosinc.com> wrote:

> Reported by Ard Biesheuvel, the followings are reproduce steps,
> https://lore.kernel.org/all/202404260640.9GQVTmrw-lkp@intel.com/T/#u
>
> The segment fault happens in the riscv_elf_finish_dynamic_sections when the
> output got section is an ABS.  Refer to MIPS code, they added an extra
> bfd_is_abs_section check to avoid ABS got, so this seems the right and
> easier
> way to go in the short-term.
>
> bfd/
>         * elfnn-riscv.c (riscv_elf_finish_dynamic_sections): Set sh_entsize
>         and fill the got entries only when the got isn't an ABS section,
> and
>         the size of got is larger than zero.  The similar goes for gotplt,
>         except we already reported error when the gotplt is an ABS.
> ---
>  bfd/elfnn-riscv.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> index 95abf2d10e2..1ecfed82972 100644
> --- a/bfd/elfnn-riscv.c
> +++ b/bfd/elfnn-riscv.c
> @@ -3569,7 +3569,7 @@ riscv_elf_finish_dynamic_sections (bfd *output_bfd,
>         }
>      }
>
> -  if (htab->elf.sgotplt)
> +  if (htab->elf.sgotplt && htab->elf.sgotplt->size > 0)
>      {
>        asection *output_section = htab->elf.sgotplt->output_section;
>
> @@ -3580,31 +3580,28 @@ riscv_elf_finish_dynamic_sections (bfd *output_bfd,
>           return false;
>         }
>
> -      if (htab->elf.sgotplt->size > 0)
> -       {
> -         /* Write the first two entries in .got.plt, needed for the
> dynamic
> -            linker.  */
> -         bfd_put_NN (output_bfd, (bfd_vma) -1,
> htab->elf.sgotplt->contents);
> -         bfd_put_NN (output_bfd, (bfd_vma) 0,
> -                     htab->elf.sgotplt->contents + GOT_ENTRY_SIZE);
> -       }
> +      /* Write the first two entries in .got.plt, needed for the dynamic
> +        linker.  */
> +      bfd_put_NN (output_bfd, (bfd_vma) -1, htab->elf.sgotplt->contents);
> +      bfd_put_NN (output_bfd, (bfd_vma) 0,
> +                 htab->elf.sgotplt->contents + GOT_ENTRY_SIZE);
>
>        elf_section_data (output_section)->this_hdr.sh_entsize =
> GOT_ENTRY_SIZE;
>      }
>
> -  if (htab->elf.sgot)
> +  if (htab->elf.sgot && htab->elf.sgot->size > 0)
>      {
>        asection *output_section = htab->elf.sgot->output_section;
>
> -      if (htab->elf.sgot->size > 0)
> +      if (!bfd_is_abs_section (output_section))
>         {
>           /* Set the first entry in the global offset table to the address
> of
>              the dynamic section.  */
>           bfd_vma val = sdyn ? sec_addr (sdyn) : 0;
>           bfd_put_NN (output_bfd, val, htab->elf.sgot->contents);
> -       }
>
> -      elf_section_data (output_section)->this_hdr.sh_entsize =
> GOT_ENTRY_SIZE;
> +         elf_section_data (output_section)->this_hdr.sh_entsize =
> GOT_ENTRY_SIZE;
> +       }
>      }
>
>    /* Fill PLT and GOT entries for local STT_GNU_IFUNC symbols.  */
> --
> 2.39.3 (Apple Git-146)
>
>
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