From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from conuserg-12.nifty.com (conuserg-12.nifty.com [210.131.2.79]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 935851FBB for ; Sun, 1 May 2022 08:42:30 +0000 (UTC) Received: from grover.sesame (133-32-177-133.west.xps.vectant.ne.jp [133.32.177.133]) (authenticated) by conuserg-12.nifty.com with ESMTP id 2418f2S2008518; Sun, 1 May 2022 17:41:12 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-12.nifty.com 2418f2S2008518 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1651394472; bh=GPcoq5UmVXCtNYinWnkOBgyynm/22Xa0IYnJlhllxx8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e59m/v0iJt1xlzsi/cefKqY8/FDkHpd9nO83IG7HXKSBzM1mjRoJYuyISzsGr134w VvjNH7mQ+ffcwJLy1KEPKJYJjHHp8F/QiJwHcY4T4Ejibpbv6701vvAXUewLJ3zJud fF+5fWI3t0Oanxi0a74Q4QMfZB5hFfGM4cks4yRetUFL8xwH0bfs0ADFaXbmGdIxsj NJ7rlJS/W5kx6pvzqdLyFGaoZAC2XUIFRuCNIxnraOf7nryWLnWujicvocvA3x5d9d sRvSLzp0YZ41N00nmtyfXX0xSqy4esyXh3lGDgn8OeufnrBLYUe3n0k/W++Potu7Y0 fAjpQpqIpYj0Q== X-Nifty-SrcIP: [133.32.177.133] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Nicolas Schier , Michal Marek , Nathan Chancellor , Nick Desaulniers , llvm@lists.linux.dev Subject: [PATCH v2 15/26] kbuild: record symbol versions in *.cmd files Date: Sun, 1 May 2022 17:40:21 +0900 Message-Id: <20220501084032.1025918-16-masahiroy@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220501084032.1025918-1-masahiroy@kernel.org> References: <20220501084032.1025918-1-masahiroy@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When CONFIG_MODVERSIONS=y, the output from genksyms is saved in separate *.symversions files, and will be used much later when CONFIG_LTO_CLANG=y because it is impossible to update LLVM bit code here. This approach is not robust because: - *.symversions may or may not exist. If *.symversions does not exist, we never know if it is missing for legitimate reason (i.e. no EXPORT_SYMBOL) or something bad has happened (for example, the user accidentally deleted it). Once it occurs, it is not self-healing because *.symversions is generated as a side effect. - stale (i.e. invalid) *.symversions might be picked up if an object is generated in a non-ordinary way, and corresponding *.symversions (, which was generated by old builds) just happen to exist. A more robust approach is to save symbol versions in *.cmd files because: - *.cmd always exists (if the object is generated by if_changed rule or friends). Even if the user accidentally deletes it, it will be regenerated in the next build. - *.cmd is always re-generated when the object is updated. This avoid stale version information being picked up. I will remove *.symversions later. Signed-off-by: Masahiro Yamada Tested-by: Nicolas Schier Reviewed-by: Nicolas Schier --- Changes in v2: - Fix CONFIG_MODULE_REL_CRCS=y case scripts/Makefile.build | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f6a506318795..a1023868775f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -171,10 +171,17 @@ ifdef CONFIG_MODVERSIONS # Generate .o.symversions files for each .o with exported symbols, and link these # to the kernel and/or modules at the end. + +genksyms_format_rel_crc := [^_]*__crc_\([^ ]*\) = \.; LONG(\([^)]*\)).* +genksyms_format_normal := __crc_\(.*\) = \(.*\); +genksyms_format := $(if $(CONFIG_MODULE_REL_CRCS),$(genksyms_format_rel_crc),$(genksyms_format_normal)) + gen_symversions = \ if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then \ $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \ > $@.symversions; \ + sed -n 's/$(genksyms_format)/$(pound)SYMVER \1 \2/p' $@.symversions \ + >> $(dot-target).cmd; \ else \ rm -f $@.symversions; \ fi -- 2.32.0