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From: Masahiro Yamada <masahiroy@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 06/13] kbuild: reuse $(cmd_objtool) for cmd_cc_lto_link_modules
Date: Fri, 3 Sep 2021 09:39:14 +0900	[thread overview]
Message-ID: <CAK7LNATkducKiw8==u4477JGfyb5vnvbp2gM2s9ndZ_8owXfeg@mail.gmail.com> (raw)
In-Reply-To: <202108311034.D4B1410@keescook>

On Wed, Sep 1, 2021 at 2:35 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Tue, Aug 31, 2021 at 04:39:57PM +0900, Masahiro Yamada wrote:
> > For CONFIG_LTO_CLANG=y, the objtool processing is not possible at the
> > compilation, hence postponed by the link time.
> >
> > Reuse $(cmd_objtool) for CONFIG_LTO_CLANG=y by defining objtool-enabled
> > properly.
> >
> > For CONFIG_LTO_CLANG=y:
> >
> >   objtool-enabled is off for %.o compilation
> >   objtool-enabled is on  for %.lto link
> >
> > For CONFIG_LTO_CLANG=n:
> >
> >   objtool-enabled is on for %.o compilation
> >       (but, it depends on OBJECT_FILE_NON_STANDARD)
> >
> > Set part-of-module := y for %.lto.o to avoid repeating --module.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> >
> >  scripts/Makefile.build | 28 +++++++++++++++++-----------
> >  1 file changed, 17 insertions(+), 11 deletions(-)
> >
> > diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> > index 21b55f37a23f..afc906cd7256 100644
> > --- a/scripts/Makefile.build
> > +++ b/scripts/Makefile.build
> > @@ -236,20 +236,26 @@ objtool_args =                                                          \
> >       $(if $(CONFIG_X86_SMAP), --uaccess)                             \
> >       $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)
> >
> > -ifndef CONFIG_LTO_CLANG
> > +cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
> > +cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
> > +
> > +endif # CONFIG_STACK_VALIDATION
> > +
> > +ifdef CONFIG_LTO_CLANG
> > +
> > +# Skip objtool for LLVM bitcode
> > +$(obj)/%o: objtool-enabled :=
>
> Is this intentionally "%o" instead of "%.o"?

Good catch.

No, it is not intentional.

I will fix "%o" to "%.o"


> (And it later overridden by the "%.lto.o" rule?

No, opposite.

While building %.lto.o, we want to set objtool-enabled.
But, we want to cancel it for %.o




-- 
Best Regards
Masahiro Yamada

  reply	other threads:[~2021-09-03  0:40 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31  7:39 [PATCH v2 00/13] kbuild: second round of Clang LTO refactoring Masahiro Yamada
2021-08-31  7:39 ` [PATCH v2 01/13] kbuild: move objtool_args back to scripts/Makefile.build Masahiro Yamada
2021-09-04 18:18   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 02/13] kbuild: rename __objtool_obj to objtool Masahiro Yamada
2021-08-31 17:16   ` Nick Desaulniers
2021-08-31 17:29   ` Kees Cook
2021-09-04 18:19   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 03/13] kbuild: store the objtool command in *.cmd files Masahiro Yamada
2021-08-31 17:23   ` Nick Desaulniers
2021-08-31 17:30   ` Kees Cook
2021-09-04 18:04   ` Josh Poimboeuf
2021-09-04 18:45     ` Josh Poimboeuf
2021-09-08 16:12       ` Masahiro Yamada
2021-08-31  7:39 ` [PATCH v2 04/13] kbuild: factor out OBJECT_FILES_NON_STANDARD check into a macro Masahiro Yamada
2021-08-31 17:25   ` Nick Desaulniers
2021-08-31 17:31   ` Kees Cook
2021-09-04 18:59   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION Masahiro Yamada
2021-08-31 17:32   ` Kees Cook
2021-09-03  0:43     ` Masahiro Yamada
2021-08-31 17:33   ` Nick Desaulniers
2021-09-02 23:42     ` Masahiro Yamada
2021-09-04 19:04   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 06/13] kbuild: reuse $(cmd_objtool) for cmd_cc_lto_link_modules Masahiro Yamada
2021-08-31 17:35   ` Kees Cook
2021-09-03  0:39     ` Masahiro Yamada [this message]
2021-09-03  1:49       ` Kees Cook
2021-09-04 19:11   ` Josh Poimboeuf
2021-08-31  7:39 ` [PATCH v2 07/13] kbuild: do not create built-in.a.symversions or lib.a.symversions Masahiro Yamada
2021-08-31 17:36   ` Kees Cook
2021-08-31  7:39 ` [PATCH v2 08/13] kbuild: build modules in the same way with/without Clang LTO Masahiro Yamada
2021-08-31 17:39   ` Kees Cook
2021-08-31 17:46   ` Nick Desaulniers
2021-08-31  7:40 ` [PATCH v2 09/13] kbuild: add cmd_and_savecmd macro Masahiro Yamada
2021-08-31 17:39   ` Kees Cook
2021-08-31  7:40 ` [PATCH v2 10/13] kbuild: rebuild modules when objtool is updated for CONFIG_LTO_CLANG Masahiro Yamada
2021-08-31 17:40   ` Kees Cook
2021-09-04 19:13   ` Josh Poimboeuf
2021-08-31  7:40 ` [PATCH v2 11/13] kbuild: always postpone CRC links for module versioning Masahiro Yamada
2021-08-31  7:40 ` [PATCH v2 12/13] kbuild: merge cmd_modversions_c and cmd_modversions_S Masahiro Yamada
2021-08-31  7:40 ` [PATCH v2 13/13] kbuild: merge cmd_ar_builtin and cmd_ar_module Masahiro Yamada

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