linux-kernel - Re: [PATCH] kbuild: use objtool-args-y to clean up objtool arguments

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Message-ID: <CAK7LNASAJPb06oE7yAhAtAWSB5_So_1PP8L8jgnkpgEb035JoA@mail.gmail.com>
Date:   Sat, 3 Sep 2022 10:11:04 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: use objtool-args-y to clean up objtool arguments

On Fri, Sep 2, 2022 at 10:11 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Based on Linus' patch.
>
> Link: https://lore.kernel.org/lkml/CAHk-=wgjTMQgiKzBZTmb=uWGDEQxDdyF1+qxBkODYciuNsmwnw@mail.gmail.com/
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
>  scripts/Makefile.lib       | 31 ++++++++++++++++---------------
>  scripts/Makefile.vmlinux_o | 17 ++++++++---------
>  2 files changed, 24 insertions(+), 24 deletions(-)
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index b594705d571a..731f735240f8 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -229,25 +229,26 @@ ifdef CONFIG_OBJTOOL
>
>  objtool := $(objtree)/tools/objtool/objtool
>
> -objtool_args =                                                         \
> -       $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label)        \
> -       $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr)              \
> -       $(if $(CONFIG_X86_KERNEL_IBT), --ibt)                           \
> -       $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)             \
> -       $(if $(CONFIG_UNWINDER_ORC), --orc)                             \
> -       $(if $(CONFIG_RETPOLINE), --retpoline)                          \
> -       $(if $(CONFIG_RETHUNK), --rethunk)                              \
> -       $(if $(CONFIG_SLS), --sls)                                      \
> -       $(if $(CONFIG_STACK_VALIDATION), --stackval)                    \
> -       $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call)          \
> -       $(if $(CONFIG_HAVE_UACCESS_VALIDATION), --uaccess)              \
> +objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK)            += --hacks=jump_label
> +objtool-args-$(CONFIG_HAVE_NOINSTR_HACK)               += --hacks=noinstr
> +objtool-args-$(CONFIG_X86_KERNEL_IBT)                  += --ibt
> +objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL)       += --mcount
> +objtool-args-$(CONFIG_UNWINDER_ORC)                    += --orc
> +objtool-args-$(CONFIG_RETPOLINE)                       += --retpoline
> +objtool-args-$(CONFIG_RETHUNK)                         += --rethunk
> +objtool-args-$(CONFIG_SLS)                             += --sls
> +objtool-args-$(CONFIG_STACK_VALIDATION)                        += --stackval
> +objtool-args-$(CONFIG_HAVE_STATIC_CALL_INLINE)         += --static-call
> +objtool-args-$(CONFIG_HAVE_UACCESS_VALIDATION)         += --uaccess
> +objtool-args-$(CONFIG_GCOV_KERNEL)                     += --no-unreachable
> +
> +objtool-args = $(objtool-args-y)                                       \
>         $(if $(delay-objtool), --link)                                  \
> -       $(if $(part-of-module), --module)                               \
> -       $(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
> +       $(if $(part-of-module), --module)
>
>  delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT))
>
> -cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@)
> +cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
>  cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd)
>
>  endif # CONFIG_OBJTOOL
> diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
> index 81a4e0484457..df928a6717a1 100644
> --- a/scripts/Makefile.vmlinux_o
> +++ b/scripts/Makefile.vmlinux_o
> @@ -35,18 +35,17 @@ endif
>
>  objtool-enabled := $(or $(delay-objtool),$(CONFIG_NOINSTR_VALIDATION))
>
> -# Reuse objtool_args defined in scripts/Makefile.lib if LTO or IBT is enabled.
> +# Reuse objtool-args-y defined in scripts/Makefile.lib if LTO or IBT is enabled.
> +# (Expand objtool-args-y to a simple variable to avoid circular reference)
>  #
>  # Add some more flags as needed.
> -# --no-unreachable and --link might be added twice, but it is fine.
> -#
> -# Expand objtool_args to a simple variable to avoid circular reference.
> +# --no-unreachable might be added twice, but it is fine.
> +
> +objtool-args-$(delay-objtool)                  := $(objtool-args-y)

This line is wrong. I will change like follows:

objtool-args-y    := $(if $(delay-objtool), $(objtool-args-y))



> +objtool-args-$(CONFIG_GCOV_KERNEL)             += --no-unreachable
> +objtool-args-$(CONFIG_NOINSTR_VALIDATION)      += --noinstr $(if $(CONFIG_CPU_UNRET_ENTRY), --unret))
>
> -objtool_args := \
> -       $(if $(delay-objtool),$(objtool_args)) \
> -       $(if $(CONFIG_NOINSTR_VALIDATION), --noinstr $(if $(CONFIG_CPU_UNRET_ENTRY), --unret)) \
> -       $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
> -       --link
> +objtool-args = $(objtool-args-y) --link
>
>  # Link of vmlinux.o used for section mismatch analysis
>  # ---------------------------------------------------------------------------
> --
> 2.34.1
>


-- 
Best Regards
Masahiro Yamada