[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 2 Mar 2020 22:55:04 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Kees Cook <keescook@...omium.org>
Cc: Masahiro Yamada <masahiroy@...nel.org>,
Michal Marek <michal.lkml@...kovi.net>,
Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: Remove debug info from kallsyms linking
On Mon, Feb 24, 2020 at 9:17 PM Kees Cook <keescook@...omium.org> wrote:
>
> When CONFIG_DEBUG_INFO is enabled, the two kallsyms linking steps spend
> time collecting and writing the dwarf sections to the temporary output
> files. kallsyms does not need this information, and leaving it off
> halves their linking time. This is especially noticeable without
> CONFIG_DEBUG_INFO_REDUCED. The BTF linking stage, however, does still
> need those details.
>
> Refactor the BTF and kallsyms generation stages slightly for more
> regularized temporary names. Skip debug during kallsyms links.
>
> For a full debug info build with BTF, my link time goes from 1m06s to
> 0m54s, saving about 12 seconds, or 18%.
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
I've tested locally, seems to be generating BTF properly (I haven't
timed anything, though). See nit below, but otherwise:
Acked-by: Andrii Nakryiko <andriin@...com>
> scripts/link-vmlinux.sh | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
[...]
> @@ -106,6 +114,8 @@ gen_btf()
> {
> local pahole_ver
> local bin_arch
> + local bin_format
> + local bin_file
>
> if ! [ -x "$(command -v ${PAHOLE})" ]; then
> echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
> @@ -118,8 +128,9 @@ gen_btf()
> return 1
> fi
>
> - info "BTF" ${2}
> vmlinux_link ${1}
> +
> + info "BTF" ${2}
Any reason to exclude linking from "BTF" step? It's still a part of
BTF generation, so seems fair to have BTF encompass both vmlinux
linking and BTF generation/deduplication?
> LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
>
> # dump .BTF section into raw binary file to link with final vmlinux
[...]
Powered by blists - more mailing lists