Re: [PATCH v5 14/21] modpost: remove is_shndx_special() check from section_rel(a)

Nick Desaulniers
2023-05-17T21:23:59Z

On Sun, May 14, 2023 at 8:28 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> This check is unneeded. Without it, sec_name() will returns the null
> string "", then section_mismatch() will return immediately.
>
> Anyway, special section indices do not appear quite often in these
> loops.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Could almost eliminate is_shndx_special after this. I think there's
only one callsite after this? (I should check with the series applied;
this patch fails to apply on mainline if that's relevant for potential
merge conflicts).

Does doing that additional work speed things up though?

> ---
>
> scripts/mod/modpost.c | 16 ++++------------
> 1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 0ef9d6964b6a..28db215ecc71 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1370,7 +1370,6 @@ static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
> static void section_rela(const char *modname, struct elf_info *elf,
> Elf_Shdr *sechdr)
> {
> - Elf_Sym *sym;
> Elf_Rela *rela;
> Elf_Rela r;
> unsigned int r_sym;
> @@ -1413,11 +1412,8 @@ static void section_rela(const char *modname, struct elf_info *elf,
> continue;
> break;
> }
> - sym = elf->symtab_start + r_sym;
> - /* Skip special sections */
> - if (is_shndx_special(sym->st_shndx))
> - continue;
> - check_section_mismatch(modname, elf, sym,
> +
> + check_section_mismatch(modname, elf, elf->symtab_start + r_sym,
> fsecndx, fromsec, r.r_offset, r.r_addend);
> }
> }
> @@ -1425,7 +1421,6 @@ static void section_rela(const char *modname, struct elf_info *elf,
> static void section_rel(const char *modname, struct elf_info *elf,
> Elf_Shdr *sechdr)
> {
> - Elf_Sym *sym;
> Elf_Rel *rel;
> Elf_Rela r;
> unsigned int r_sym;
> @@ -1472,11 +1467,8 @@ static void section_rel(const char *modname, struct elf_info *elf,
> default:
> fatal("Please add code to calculate addend for this architecture\n");
> }
> - sym = elf->symtab_start + r_sym;
> - /* Skip special sections */
> - if (is_shndx_special(sym->st_shndx))
> - continue;
> - check_section_mismatch(modname, elf, sym,
> +
> + check_section_mismatch(modname, elf, elf->symtab_start + r_sym,
> fsecndx, fromsec, r.r_offset, r.r_addend);
> }
> }
> --
> 2.39.2
>

--
Thanks,
~Nick Desaulniers