linux-kernel - Re: [PATCH] modpost: Fix modpost's license checking

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Message-ID: <CACqU3MW=VUn64nsSA2V_eXEfEjv6xmB9yBWL8rYynH1wkHcOgw@mail.gmail.com>
Date:	Sun, 10 Jul 2011 02:08:49 -0400
From:	Arnaud Lacombe <lacombar@...il.com>
To:	Alessio Igor Bogani <abogani@...nel.org>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Jan Beulich <JBeulich@...ell.com>,
	Kbuild <linux-kbuild@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Tim Bird <tim.bird@...sony.com>,
	Anders Kaseorg <andersk@...lice.com>
Subject: Re: [PATCH] modpost: Fix modpost's license checking

Hi,

On Sat, Jul 9, 2011 at 7:13 PM, Alessio Igor Bogani <abogani@...nel.org> wrote:
> The commit f02e8a6 sorts symbols placing each of them in its own elf section.
> The sorting and merging into the canonical sections are done by the linker.
> Unfortunately modpost to generate Module.symvers file parses vmlinux
> (already linked) and all modules object files (which aren't linked yet).
> These aren't sanitized by the linker yet. That breaks modpost that can't
> detect license properly for modules.
>
> This patch makes modpost aware of  the new exported symbols structure.
>
> This work was supported by a hardware donation from the CE Linux Forum.
>
> Signed-off-by: Alessio Igor Bogani <abogani@...nel.org>
> ---
>  scripts/mod/modpost.c |   27 ++++++++++++++++++++++++++-
>  1 files changed, 26 insertions(+), 1 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 413c536..f41283c 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -254,6 +254,26 @@ static enum export export_no(const char *s)
>        return export_unknown;
>  }
>
> +static const char *sec_name(struct elf_info *elf, int secindex);
> +
> +static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
> +{
> +       const char *secname = sec_name(elf, sec);
> +
> +       if (strncmp(secname, "___ksymtab+", 11) == 0)
I'd suppose 11 here is `sizeof "___ksymtab+" - 1' ? Why not making
that explicit though a macro, ala:

#define SEC_NAME_MATCH(name, str) (strncmp(name, str, strlen(str) - 1) == 0)

This would avoid bug in the future if the string is updated but not
the size, and/or copy paste error where only the string is changed.

 - Arnaud

> +               return export_plain;
> +       else if (strncmp(secname, "___ksymtab_unused+", 18) == 0)
> +               return export_unused;
> +       else if (strncmp(secname, "___ksymtab_gpl+", 15) == 0)
> +               return export_gpl;
> +       else if (strncmp(secname, "___ksymtab_unused_gpl+", 22) == 0)
> +               return export_unused_gpl;
> +       else if (strncmp(secname, "___ksymtab_gpl_future+", 22) == 0)
> +               return export_gpl_future;
> +       else
> +               return export_unknown;
> +}
> +
>  static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
>  {
>        if (sec == elf->export_sec)
> @@ -563,7 +583,12 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
>                               Elf_Sym *sym, const char *symname)
>  {
>        unsigned int crc;
> -       enum export export = export_from_sec(info, get_secindex(info, sym));
> +       enum export export;
> +
> +       if (!is_vmlinux(mod->name) && strncmp(symname, "__ksymtab", 9) == 0)
> +               export = export_from_secname(info, get_secindex(info, sym));
> +       else
> +               export = export_from_sec(info, get_secindex(info, sym));
>
>        switch (sym->st_shndx) {
>        case SHN_COMMON:
> --
> 1.7.4.1
>
> --
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