Re: [PATCH v5 07/21] modpost: squash extable_mismatch_handler() into default_mismatch_handler()

Nick Desaulniers
2023-05-17T20:56:01Z

On Sun, May 14, 2023 at 8:28 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Merging these two reduces several lines of code. The extable section
> mismatch is already distinguished by EXTABLE_TO_NON_TEXT.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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

> ---
>
> scripts/mod/modpost.c | 84 ++++++++++++++-----------------------------
> 1 file changed, 26 insertions(+), 58 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 0bda2f22c985..49357a716519 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -881,27 +881,14 @@ enum mismatch {
> * targeting sections in this array (white-list). Can be empty.
> *
> * @mismatch: Type of mismatch.
> - *
> - * @handler: Specific handler to call when a match is found. If NULL,
> - * default_mismatch_handler() will be called.
> - *
> */
> struct sectioncheck {
> const char *fromsec[20];
> const char *bad_tosec[20];
> const char *good_tosec[20];
> enum mismatch mismatch;
> - void (*handler)(const char *modname, struct elf_info *elf,
> - const struct sectioncheck* const mismatch,
> - Elf_Rela *r, Elf_Sym *sym, const char *fromsec);
> -
> };
>
> -static void extable_mismatch_handler(const char *modname, struct elf_info *elf,
> - const struct sectioncheck* const mismatch,
> - Elf_Rela *r, Elf_Sym *sym,
> - const char *fromsec);
> -
> static const struct sectioncheck sectioncheck[] = {
> /* Do not reference init/exit code/data from
> * normal code and data
> @@ -974,7 +961,6 @@ static const struct sectioncheck sectioncheck[] = {
> .bad_tosec = { ".altinstr_replacement", NULL },
> .good_tosec = {ALL_TEXT_SECTIONS , NULL},
> .mismatch = EXTABLE_TO_NON_TEXT,
> - .handler = extable_mismatch_handler,
> }
> };
>
> @@ -1255,60 +1241,42 @@ static void default_mismatch_handler(const char *modname, struct elf_info *elf,
> modname, tosym, tosec);
> break;
> case EXTABLE_TO_NON_TEXT:
> - fatal("There's a special handler for this mismatch type, we should never get here.\n");
> + warn("%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n",
> + modname, fromsec, (long)r->r_offset, tosec, tosym);
> +
> + if (match(tosec, mismatch->bad_tosec))
> + fatal("The relocation at %s+0x%lx references\n"
> + "section \"%s\" which is black-listed.\n"
> + "Something is seriously wrong and should be fixed.\n"
> + "You might get more information about where this is\n"
> + "coming from by using scripts/check_extable.sh %s\n",
> + fromsec, (long)r->r_offset, tosec, modname);
> + else if (is_executable_section(elf, get_secindex(elf, sym)))
> + warn("The relocation at %s+0x%lx references\n"
> + "section \"%s\" which is not in the list of\n"
> + "authorized sections. If you're adding a new section\n"
> + "and/or if this reference is valid, add \"%s\" to the\n"
> + "list of authorized sections to jump to on fault.\n"
> + "This can be achieved by adding \"%s\" to\n"
> + "OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n",
> + fromsec, (long)r->r_offset, tosec, tosec, tosec);
> + else
> + error("%s+0x%lx references non-executable section '%s'\n",
> + fromsec, (long)r->r_offset, tosec);
> break;
> }
> }
>
> -static void extable_mismatch_handler(const char* modname, struct elf_info *elf,
> - const struct sectioncheck* const mismatch,
> - Elf_Rela* r, Elf_Sym* sym,
> - const char *fromsec)
> -{
> - const char* tosec = sec_name(elf, get_secindex(elf, sym));
> - Elf_Sym *tosym = find_elf_symbol(elf, r->r_addend, sym);
> - const char *tosym_name = sym_name(elf, tosym);
> -
> - sec_mismatch_count++;
> -
> - warn("%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n",
> - modname, fromsec, (long)r->r_offset, tosec, tosym_name);
> -
> - if (match(tosec, mismatch->bad_tosec))
> - fatal("The relocation at %s+0x%lx references\n"
> - "section \"%s\" which is black-listed.\n"
> - "Something is seriously wrong and should be fixed.\n"
> - "You might get more information about where this is\n"
> - "coming from by using scripts/check_extable.sh %s\n",
> - fromsec, (long)r->r_offset, tosec, modname);
> - else if (is_executable_section(elf, get_secindex(elf, sym)))
> - warn("The relocation at %s+0x%lx references\n"
> - "section \"%s\" which is not in the list of\n"
> - "authorized sections. If you're adding a new section\n"
> - "and/or if this reference is valid, add \"%s\" to the\n"
> - "list of authorized sections to jump to on fault.\n"
> - "This can be achieved by adding \"%s\" to\n"
> - "OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n",
> - fromsec, (long)r->r_offset, tosec, tosec, tosec);
> - else
> - error("%s+0x%lx references non-executable section '%s'\n",
> - fromsec, (long)r->r_offset, tosec);
> -}
> -
> static void check_section_mismatch(const char *modname, struct elf_info *elf,
> Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
> {
> const char *tosec = sec_name(elf, get_secindex(elf, sym));
> const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec);
>
> - if (mismatch) {
> - if (mismatch->handler)
> - mismatch->handler(modname, elf, mismatch,
> - r, sym, fromsec);
> - else
> - default_mismatch_handler(modname, elf, mismatch,
> - r, sym, fromsec);
> - }
> + if (!mismatch)
> + return;
> +
> + default_mismatch_handler(modname, elf, mismatch, r, sym, fromsec);
> }
>
> static unsigned int *reloc_location(struct elf_info *elf,
> --
> 2.39.2
>

--
Thanks,
~Nick Desaulniers