LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Kees Cook <keescook@chromium.org>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org,
	Sami Tolvanen <samitolvanen@google.com>,
	linux-kernel@vger.kernel.org,
	Michal Marek <michal.lkml@markovi.net>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH 06/13] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO
Date: Wed, 18 Aug 2021 19:42:18 -0700	[thread overview]
Message-ID: <202108181940.896CA4311@keescook> (raw)
In-Reply-To: <20210819005744.644908-7-masahiroy@kernel.org>

On Thu, Aug 19, 2021 at 09:57:37AM +0900, Masahiro Yamada wrote:
> When Clang LTO is enabled, vmlinux_link() reuses vmlinux.o instead of
> linking ${KBUILD_VMLINUX_OBJS} and ${KBUILD_VMLINUX_LIBS} again.
> 
> That is the only difference here, so merge the similar code.

Oh excellent! I had tried to get this merged before and was not happy
with anything I constructed. This is much cleaner. Nice! (I think I
didn't realize there could be an empty --start-group/--end-group with
no side-effects.)

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  scripts/link-vmlinux.sh | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 36ef7b37fc5d..a6c4d0bce3ba 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -154,12 +154,23 @@ vmlinux_link()
>  	local objects
>  	local strip_debug
>  	local map_option
> +	local objs
> +	local libs
>  
>  	info LD ${output}
>  
>  	# skip output file argument
>  	shift
>  
> +	if [ -n "${CONFIG_LTO_CLANG}" ]; then
> +		# Use vmlinux.o instead of performing the slow LTO link again.
> +		objs=vmlinux.o
> +		libs=
> +	else
> +		objs="${KBUILD_VMLINUX_OBJS}"
> +		libs="${KBUILD_VMLINUX_LIBS}"
> +	fi
> +
>  	# The kallsyms linking does not need debug symbols included.
>  	if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
>  		strip_debug=-Wl,--strip-debug
> @@ -170,22 +181,9 @@ vmlinux_link()
>  	fi
>  
>  	if [ "${SRCARCH}" != "um" ]; then
> -		if [ -n "${CONFIG_LTO_CLANG}" ]; then
> -			# Use vmlinux.o instead of performing the slow LTO
> -			# link again.
> -			objects="--whole-archive		\
> -				vmlinux.o 			\
> -				--no-whole-archive		\
> -				${@}"
> -		else
> -			objects="--whole-archive		\
> -				${KBUILD_VMLINUX_OBJS}		\
> -				--no-whole-archive		\
> -				--start-group			\
> -				${KBUILD_VMLINUX_LIBS}		\
> -				--end-group			\
> -				${@}"
> -		fi
> +		objects="--whole-archive ${objs} --no-whole-archive	\
> +			 --start-group ${libs} --end-group		\
> +			 $@"
>  
>  		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\
>  			${strip_debug#-Wl,}			\
> -- 
> 2.30.2
> 

-- 
Kees Cook

  reply	other threads:[~2021-08-19  2:42 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-19  0:57 [PATCH 00/13] kbuild: refactoring after " Masahiro Yamada
2021-08-19  0:57 ` [PATCH 01/13] kbuild: move objtool_args back to scripts/Makefile.build Masahiro Yamada
2021-08-19  2:45   ` Kees Cook
2021-08-19  0:57 ` [PATCH 02/13] gen_compile_commands: extract compiler command from a series of commands Masahiro Yamada
2021-08-19  6:48   ` Kees Cook
2021-08-19  0:57 ` [PATCH 03/13] kbuild: detect objtool changes correctly and remove .SECONDEXPANSION Masahiro Yamada
2021-08-19  2:55   ` Kees Cook
2021-08-19  3:18     ` Masahiro Yamada
2021-08-19  0:57 ` [PATCH 04/13] kbuild: remove unused quiet_cmd_update_lto_symversions Masahiro Yamada
2021-08-19  6:19   ` Kees Cook
2021-08-19  0:57 ` [PATCH 05/13] kbuild: remove stale *.symversions Masahiro Yamada
2021-08-19  6:29   ` Kees Cook
2021-08-19  0:57 ` [PATCH 06/13] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO Masahiro Yamada
2021-08-19  2:42   ` Kees Cook [this message]
2021-08-19  0:57 ` [PATCH 07/13] kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh Masahiro Yamada
2021-08-19  6:32   ` Kees Cook
2021-08-19  0:57 ` [PATCH 08/13] kbuild: merge vmlinux_link() between ARCH=um and other architectures Masahiro Yamada
2021-08-19  2:43   ` Kees Cook
2021-08-19  0:57 ` [PATCH 09/13] kbuild: do not create built-in.a.symversions or lib.a.symversions Masahiro Yamada
2021-08-19  6:41   ` Kees Cook
2021-08-28 11:57     ` Masahiro Yamada
2021-08-19  0:57 ` [PATCH 10/13] kbuild: build modules in the same way with/without Clang LTO Masahiro Yamada
2021-08-19  6:59   ` Kees Cook
2021-08-19  8:11     ` Masahiro Yamada
2021-08-19  0:57 ` [PATCH 11/13] kbuild: always postpone CRC links for module versioning Masahiro Yamada
2021-08-19  6:43   ` Kees Cook
2021-08-19  0:57 ` [PATCH 12/13] kbuild: merge cmd_modversions_c and cmd_modversions_S Masahiro Yamada
2021-08-19  3:06   ` Kees Cook
2021-08-19  0:57 ` [PATCH 13/13] kbuild: merge cmd_ar_builtin and cmd_ar_module Masahiro Yamada
2021-08-19  3:01   ` Kees Cook
2021-08-25  4:57 ` [PATCH 00/13] kbuild: refactoring after Clang LTO Masahiro Yamada

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=202108181940.896CA4311@keescook \
    --to=keescook@chromium.org \
    --cc=clang-built-linux@googlegroups.com \
    --cc=linux-kbuild@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=masahiroy@kernel.org \
    --cc=michal.lkml@markovi.net \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=samitolvanen@google.com \
    --subject='Re: [PATCH 06/13] kbuild: merge vmlinux_link() between the ordinary link and Clang LTO' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).