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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,
	Peter Zijlstra <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v2 03/13] kbuild: store the objtool command in *.cmd files
Date: Tue, 31 Aug 2021 10:23:10 -0700	[thread overview]
Message-ID: <CAKwvOd=dVBWFm_kvUc3K_9XNQKvVfNL8aUm70yU6HyG6cE-TvQ@mail.gmail.com> (raw)
In-Reply-To: <20210831074004.3195284-4-masahiroy@kernel.org>

On Tue, Aug 31, 2021 at 12:40 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> objtool_dep includes include/config/{ORC_UNWINDER,STACK_VALIDATION}
> so that all the objects are rebuilt when any of CONFIG_ORC_UNWINDER
> and CONFIG_STACK_VALIDATION is toggled.
>
> As you can see in 'objtool_args', there are more CONFIG options
> that affect the objtool command line.
>
> Adding more and more include/config/* is ugly and unmaintainable.
>
> Another issue is that non-standard objects are needlessly rebuilt.
> Objects specified as OBJECT_FILES_NON_STANDARD is not processed by
> objtool, but they are rebuilt anyway when CONFIG_ORC_UNWINDER or
> CONFIG_STACK_VALIDATION is toggled. This is not a big deal, but
> better to fix.
>
> A cleaner and more precise fix is to include the objtool command in
> *.cmd files so any command change is naturally detected by if_change.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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

> ---
>
>  scripts/Makefile.build | 14 +++++---------
>  1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index e78096cd396b..021ae0146913 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -155,7 +155,7 @@ $(obj)/%.ll: $(src)/%.c FORCE
>  # (See cmd_cc_o_c + relevant part of rule_cc_o_c)
>
>  quiet_cmd_cc_o_c = CC $(quiet_modtag)  $@
> -      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
> +      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool)
>
>  ifdef CONFIG_MODVERSIONS
>  # When module versioning is enabled the following steps are executed:
> @@ -243,7 +243,7 @@ ifndef CONFIG_LTO_CLANG
>  # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file
>  cmd_objtool = $(if $(patsubst y%,, \
>         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
> -       $(objtool) $(objtool_args) $@)
> +       ; $(objtool) $(objtool_args) $@)
>  objtool_obj = $(if $(patsubst y%,, \
>         $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \
>         $(objtool))
> @@ -251,10 +251,8 @@ objtool_obj = $(if $(patsubst y%,, \
>  endif # CONFIG_LTO_CLANG
>  endif # CONFIG_STACK_VALIDATION
>
> -# Rebuild all objects when objtool changes, or is enabled/disabled.
> -objtool_dep = $(objtool_obj)                                   \
> -             $(wildcard include/config/ORC_UNWINDER            \
> -                        include/config/STACK_VALIDATION)
> +# Rebuild all objects when objtool changes
> +objtool_dep = $(objtool_obj)
>
>  ifdef CONFIG_TRIM_UNUSED_KSYMS
>  cmd_gen_ksymdeps = \
> @@ -269,7 +267,6 @@ define rule_cc_o_c
>         $(call cmd,gen_ksymdeps)
>         $(call cmd,checksrc)
>         $(call cmd,checkdoc)
> -       $(call cmd,objtool)
>         $(call cmd,modversions_c)
>         $(call cmd,record_mcount)
>  endef
> @@ -277,7 +274,6 @@ endef
>  define rule_as_o_S
>         $(call cmd_and_fixdep,as_o_S)
>         $(call cmd,gen_ksymdeps)
> -       $(call cmd,objtool)
>         $(call cmd,modversions_S)
>  endef
>
> @@ -365,7 +361,7 @@ $(obj)/%.s: $(src)/%.S FORCE
>         $(call if_changed_dep,cpp_s_S)
>
>  quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
> -      cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
> +      cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $< $(cmd_objtool)
>
>  ifdef CONFIG_ASM_MODVERSIONS
>
> --
> 2.30.2
>


-- 
Thanks,
~Nick Desaulniers

  reply	other threads:[~2021-08-31 17:23 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 [this message]
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
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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