From patchwork Sun May 21 16:04:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 13249444 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1629CC77B73 for ; Sun, 21 May 2023 16:06:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230199AbjEUQGW (ORCPT ); Sun, 21 May 2023 12:06:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230271AbjEUQGB (ORCPT ); Sun, 21 May 2023 12:06:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C31E3E5D; Sun, 21 May 2023 09:05:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D215960F36; Sun, 21 May 2023 16:05:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8005C4339C; Sun, 21 May 2023 16:05:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684685136; bh=8xXXD40CCdpBx0TDe2iS4cr/q8YTKMQjxzKZ7hNzzQ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h9mDjJ7J4lr2ROglAloh48hlNF4fA1j6VJvfm4RcIGCU41B5x429jRTDCqPCspt4B R44aIg1TLHWguzW6fWzS0gfOu8+GzfWd1Ch5JUlMuHe6Tvuj4XwkiGhUS/LcAJ6hQQ GfKwKKgdjOGm9IPqRS/3ujlh0A4TJpgfVALf9BMQzrmrzHIUfYZwapP/ecPP966Vlz Ls4J8A24RpX3f7tiGX/5fApvWiz3ykHBpIdBMtS2pRolKhNV+6czzLjCn17VB9PzUq q6jSc2ebQd9l5Y90yr4+Oxm56sulIn3HRtpecRYBE+vqD4xbYEueZ/s+xyIcSXcFs3 WeI+e5pz0axYw== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Nathan Chancellor , Nick Desaulniers , Nicolas Schier , Masahiro Yamada Subject: [PATCH v6 12/20] modpost: check static EXPORT_SYMBOL* by modpost again Date: Mon, 22 May 2023 01:04:17 +0900 Message-Id: <20230521160426.1881124-13-masahiroy@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230521160426.1881124-1-masahiroy@kernel.org> References: <20230521160426.1881124-1-masahiroy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Commit 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script instead of modpost") moved the static EXPORT_SYMBOL* check from the mostpost to a shell script because I thought it must be checked per compilation unit to avoid false negatives. I came up with an idea to do this in modpost, against combined ELF files. The relocation entries in ELF will find the correct exported symbol even if there exist symbols with the same name in different compilation units. Again, the same sample code. Makefile: obj-y += foo1.o foo2.o foo1.c: #include static void foo(void) {} EXPORT_SYMBOL(foo); foo2.c: void foo(void) {} Then, modpost can catch it correctly. MODPOST Module.symvers ERROR: modpost: vmlinux: local symbol 'foo' was exported Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- Changes in v6: - Make the symbol name in the warning more precise scripts/Makefile.build | 4 --- scripts/check-local-export | 70 -------------------------------------- scripts/mod/modpost.c | 7 ++++ 3 files changed, 7 insertions(+), 74 deletions(-) delete mode 100755 scripts/check-local-export diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 6bf026a304e4..bd4123795299 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -220,8 +220,6 @@ cmd_gen_ksymdeps = \ $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd endif -cmd_check_local_export = $(srctree)/scripts/check-local-export $@ - ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),) cmd_warn_shared_object = $(if $(word 2, $(modname-multi)),$(warning $(kbuild-file): $*.o is added to multiple modules: $(modname-multi))) endif @@ -229,7 +227,6 @@ endif define rule_cc_o_c $(call cmd_and_fixdep,cc_o_c) $(call cmd,gen_ksymdeps) - $(call cmd,check_local_export) $(call cmd,checksrc) $(call cmd,checkdoc) $(call cmd,gen_objtooldep) @@ -241,7 +238,6 @@ endef define rule_as_o_S $(call cmd_and_fixdep,as_o_S) $(call cmd,gen_ksymdeps) - $(call cmd,check_local_export) $(call cmd,gen_objtooldep) $(call cmd,gen_symversions_S) $(call cmd,warn_shared_object) diff --git a/scripts/check-local-export b/scripts/check-local-export deleted file mode 100755 index 969a313b9299..000000000000 --- a/scripts/check-local-export +++ /dev/null @@ -1,70 +0,0 @@ -#!/bin/sh -# SPDX-License-Identifier: GPL-2.0-only -# -# Copyright (C) 2022 Masahiro Yamada -# Copyright (C) 2022 Owen Rafferty -# -# Exit with error if a local exported symbol is found. -# EXPORT_SYMBOL should be used for global symbols. - -set -e -pid=$$ - -# If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) shows -# 'no symbols' diagnostic (but exits with 0). It is harmless and hidden by -# '2>/dev/null'. However, it suppresses real error messages as well. Add a -# hand-crafted error message here. -# -# TODO: -# Use --quiet instead of 2>/dev/null when we upgrade the minimum version of -# binutils to 2.37, llvm to 13.0.0. -# Then, the following line will be simpler: -# { ${NM} --quiet ${1} || kill 0; } | - -{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; kill $pid; } } | -${AWK} -v "file=${1}" ' -BEGIN { - i = 0 -} - -# Skip the line if the number of fields is less than 3. -# -# case 1) -# For undefined symbols, the first field (value) is empty. -# The outout looks like this: -# " U _printk" -# It is unneeded to record undefined symbols. -# -# case 2) -# For Clang LTO, llvm-nm outputs a line with type t but empty name: -# "---------------- t" -!length($3) { - next -} - -# save (name, type) in the associative array -{ symbol_types[$3]=$2 } - -# append the exported symbol to the array -($3 ~ /^__export_symbol_(gpl)?_.*/) { - export_symbols[i] = $3 - sub(/^__export_symbol_(gpl)?_/, "", export_symbols[i]) - i++ -} - -END { - exit_code = 0 - for (j = 0; j < i; ++j) { - name = export_symbols[j] - # nm(3) says "If lowercase, the symbol is usually local" - if (symbol_types[name] ~ /[a-z]/) { - printf "%s: error: local symbol %s was exported\n", - file, name | "cat 1>&2" - exit_code = 1 - } - } - - exit exit_code -}' - -exit $? diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 8b94090d0743..dd1d066f1214 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1235,6 +1235,13 @@ static void check_export_symbol(struct module *mod, struct elf_info *elf, return; } + if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL && + ELF_ST_BIND(sym->st_info) != STB_WEAK) { + error("%s: local symbol '%s' was exported\n", mod->name, + label_name + strlen(prefix)); + return; + } + if (strcmp(label_name + strlen(prefix), name)) { error("%s: .export_symbol section references '%s', but it does not seem to be an export symbol\n", mod->name, name);