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

Nick Desaulniers
2023-05-17T21:24:49Z

On Wed, May 17, 2023 at 2:23 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> 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?

Either way,
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

>
> > ---
> >
> > 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

--
Thanks,
~Nick Desaulniers