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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat, 28 May 2022 02:41:06 +0900
Message-ID: <CAK7LNAQkUJO=8GprusO6-o7=_yg2zVDPHecoNN_075a_Y4U-7w@mail.gmail.com>
Subject: Re: [PATCH v7 8/8] kbuild: rebuild multi-object modules when objtool
 is updated
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        clang-built-linux <llvm@lists.linux.dev>,
        Helge Deller <deller@gmx.de>,
        Parisc List <linux-parisc@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nicolas Schier <n.schier@avm.de>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>
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On Sat, May 28, 2022 at 12:50 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>
> On Fri, May 27, 2022 at 07:01:55PM +0900, Masahiro Yamada wrote:
> > When CONFIG_LTO_CLANG or CONFIG_X86_KERNEL_IBT is enabled, objtool for
> > multi-object modules is postponed until the objects are linked together.
> >
> > Make sure to re-run objtool and re-link multi-object modules when
> > objtool is updated.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > Reviewed-by: Kees Cook <keescook@chromium.org>
> > Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > Tested-by: Nathan Chancellor <nathan@kernel.org>
> > Reviewed-by: Nicolas Schier <n.schier@avm.de>
> > Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
>
> Hi Masahiro,
>
> Is it also possible to rebuild vmlinux.o when objtool changes, for
> CONFIG_LTO_CLANG, CONFIG_X86_KERNEL_IBT, or CONFIG_NOINSTR_VALIDATION?
> That doesn't seem to be happening.
>
> --
> Josh

Yes.
Actually, it is already on my TODO list,
but it requires more effort.

I will aim for v5.20.


-- 
Best Regards
Masahiro Yamada