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From: Nick Desaulniers <ndesaulniers@google.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org,
	Michal Marek <michal.lkml@markovi.net>,
	linux-kernel@vger.kernel.org,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION
Date: Tue, 31 Aug 2021 10:33:14 -0700	[thread overview]
Message-ID: <CAKwvOdmsnuv6qa5USKqqhg419FGD55U2zGw_KngmBcz_UDOOcg@mail.gmail.com> (raw)
In-Reply-To: <20210831074004.3195284-6-masahiroy@kernel.org>

On Tue, Aug 31, 2021 at 12:40 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Redo commit 8852c5524029 ("kbuild: Fix objtool dependency for
> 'OBJECT_FILES_NON_STANDARD_<obj> := n'") to add the objtool
> dependency in a cleaner way.
>
> Using .SECONDEXPANSION ends up with unreadable code due to escaped
> dollars. Also, it is not efficient because the second half of
> Makefile.build is parsed twice every time.
>
> Append the objtool dependency to the *.cmd files at the build time.
>
> This is what fixdep and gen_ksymdeps.sh already do. So, following the
> same pattern seems a natural solution.
>
> This allows us to drop $$(objtool_deps) entirely.

s/objtool_deps/objtool_dep/

>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

You and Josh should be cc'ing each other explicitly on these kind of changes.

> ---
>
>  scripts/Makefile.build | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 720a86642f48..21b55f37a23f 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -246,14 +246,11 @@ objtool-enabled = $(if $(filter-out y%, \
>         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y)
>
>  cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
> -objtool_obj = $(if $(objtool-enabled), $(objtool))
> +cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
>
>  endif # CONFIG_LTO_CLANG
>  endif # CONFIG_STACK_VALIDATION
>
> -# Rebuild all objects when objtool changes
> -objtool_dep = $(objtool_obj)
> -
>  ifdef CONFIG_TRIM_UNUSED_KSYMS
>  cmd_gen_ksymdeps = \
>         $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd
> @@ -267,6 +264,7 @@ define rule_cc_o_c
>         $(call cmd,gen_ksymdeps)
>         $(call cmd,checksrc)
>         $(call cmd,checkdoc)
> +       $(call cmd,gen_objtooldep)
>         $(call cmd,modversions_c)
>         $(call cmd,record_mcount)
>  endef
> @@ -274,12 +272,12 @@ endef
>  define rule_as_o_S
>         $(call cmd_and_fixdep,as_o_S)
>         $(call cmd,gen_ksymdeps)
> +       $(call cmd,gen_objtooldep)
>         $(call cmd,modversions_S)
>  endef
>
>  # Built-in and composite module parts
> -.SECONDEXPANSION:
> -$(obj)/%.o: $(src)/%.c $(recordmcount_source) $$(objtool_dep) FORCE
> +$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
>         $(call if_changed_rule,cc_o_c)
>         $(call cmd,force_checksrc)
>
> @@ -380,7 +378,7 @@ cmd_modversions_S =                                                         \
>         fi
>  endif
>
> -$(obj)/%.o: $(src)/%.S $$(objtool_dep) FORCE
> +$(obj)/%.o: $(src)/%.S FORCE
>         $(call if_changed_rule,as_o_S)
>
>  targets += $(filter-out $(subdir-builtin), $(real-obj-y))
> --
> 2.30.2
>


-- 
Thanks,
~Nick Desaulniers

  parent reply	other threads:[~2021-08-31 17:33 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 [this message]
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
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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