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
next prev parent 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 Clang LTO 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
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