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References: <20230521160426.1881124-1-masahiroy@kernel.org> <20230521160426.1881124-9-masahiroy@kernel.org>
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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Thu, 25 May 2023 10:20:36 -0700
Message-ID: <CAKwvOdmDRNXQd0oDCjV1XdCk4coEd4_=V_idpObc9ibuVwOWgw@mail.gmail.com>
Subject: Re: [PATCH v6 08/20] modpost: remove is_shndx_special() check from section_rel(a)
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        Nathan Chancellor <nathan@kernel.org>,
        Nicolas Schier <nicolas@fjasle.eu>
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On Sun, May 21, 2023 at 9:05=E2=80=AFAM Masahiro Yamada <masahiroy@kernel.o=
rg> wrote:
>
> This check is unneeded. Without it, sec_name() will returns the null
> string "", then section_mismatch() will return immediately.
>
> Anyway, special section indices rarely appear in these loops.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>
> Changes in v6:
>   - Remove is_shndx_special() definition
>
>  scripts/mod/modpost.c | 16 ++++------------
>  scripts/mod/modpost.h |  5 -----
>  2 files changed, 4 insertions(+), 17 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index f364738a236e..40fac4f64fcd 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -1361,7 +1361,6 @@ static int addend_mips_rel(struct elf_info *elf, El=
f_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;
> @@ -1404,11 +1403,8 @@ static void section_rela(const char *modname, stru=
ct elf_info *elf,
>                                 continue;
>                         break;
>                 }
> -               sym =3D 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);
>         }
>  }
> @@ -1416,7 +1412,6 @@ static void section_rela(const char *modname, struc=
t 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;
> @@ -1463,11 +1458,8 @@ static void section_rel(const char *modname, struc=
t elf_info *elf,
>                 default:
>                         fatal("Please add code to calculate addend for th=
is architecture\n");
>                 }
> -               sym =3D 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);
>         }
>  }
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 1178f40a73f3..b1e2d95f8047 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -151,11 +151,6 @@ struct elf_info {
>         Elf32_Word   *symtab_shndx_stop;
>  };
>
> -static inline int is_shndx_special(unsigned int i)
> -{
> -       return i !=3D SHN_XINDEX && i >=3D SHN_LORESERVE && i <=3D SHN_HI=
RESERVE;
> -}
> -
>  /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
>  static inline unsigned int get_secindex(const struct elf_info *info,
>                                         const Elf_Sym *sym)
> --
> 2.39.2
>


--=20
Thanks,
~Nick Desaulniers