From patchwork Sun Jul 14 15:28:17 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Denis Efremov (Oracle)" X-Patchwork-Id: 11043235 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 392E213BD for ; Sun, 14 Jul 2019 15:28:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1BB67203B9 for ; Sun, 14 Jul 2019 15:28:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0C1B021327; Sun, 14 Jul 2019 15:28:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 90BBE203B9 for ; Sun, 14 Jul 2019 15:28:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726799AbfGNP2a (ORCPT ); Sun, 14 Jul 2019 11:28:30 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:45006 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726783AbfGNP23 (ORCPT ); Sun, 14 Jul 2019 11:28:29 -0400 Received: by mail-wr1-f67.google.com with SMTP id p17so14478781wrf.11; Sun, 14 Jul 2019 08:28:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+L3gCIHx5QSGA5TZkqN231Uus0yuqleYr/9QpWKEyyk=; b=q5OrpkcmMay2C2UrsqJPY+961rrwrKfB5q/Zrc7UFiTCacamt1WhaseT9l8E+gRchz bqsM6aVsKuJ12KniNAE2+QJnpuebgAmwAw5lumcl+tiJQYjMTZTeyWB49QVmWDTYKWBR bhD4D1VkF2SIUXOlAwaJoda3AUDHPSEswMiKoXe1i1VfWJSNnr8lnjl90guT/W+zk8eD oMqJt9Gc+HWj0axwpcdiFlxLIhAQSSMjmLzwOqIUJ/yVcXKx2gq4E92/KI1hAx/kSOGb 3tSZEiGa+vDGjkybSqhFTSXI173EOuu64gCKljuIPEmtcQDBVUBnpJn6Rn9qMsQ7CHty 2lYQ== X-Gm-Message-State: APjAAAW5AdsWiIpo+zvkcHORT17M/VR2xrPCq8kd+K05NuJcdwbLhZy5 1ap0VtxohOj3lVdWZ9SDwZU= X-Google-Smtp-Source: APXvYqyWrYvavk3k2izd2KnljkEDCmQPkIDVsBUNkmmQx3UMsHoNBVmdsvVzNp/sLIOVy0qtoKCDog== X-Received: by 2002:adf:dcc2:: with SMTP id x2mr11403035wrm.55.1563118106361; Sun, 14 Jul 2019 08:28:26 -0700 (PDT) Received: from localhost.localdomain (broadband-188-32-48-208.ip.moscow.rt.ru. [188.32.48.208]) by smtp.googlemail.com with ESMTPSA id i18sm16399265wrp.91.2019.07.14.08.28.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 14 Jul 2019 08:28:25 -0700 (PDT) From: Denis Efremov To: Masahiro Yamada Cc: Denis Efremov , Michal Marek , Emil Velikov , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH] modpost: check for static EXPORT_SYMBOL* functions Date: Sun, 14 Jul 2019 18:28:17 +0300 Message-Id: <20190714152817.24693-1-efremov@linux.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch adds a check to warn about static EXPORT_SYMBOL* functions during the modpost. In most of the cases, a static symbol marked for exporting is an odd combination that should be fixed either by deleting the exporting mark or by removing the static attribute and adding the appropriate declaration to headers. If this check will be considered useful, I will resend the patch with review fixes. Currently, this check emits the warnings on the following symbols, most of which are accepted to be fixed: 1. "sas_wait_eh" [drivers/scsi/libsas/libsas] Patch: https://lkml.org/lkml/2019/7/8/970 (accepted) 2. "torture_onoff_cleanup" [kernel/torture] "torture_shuffle_cleanup" [kernel/torture] Patch: https://lkml.org/lkml/2019/7/4/411 (accepted) 3. "LZ4HC_setExternalDict" [lib/lz4/lz4hc_compress] Patch: https://lkml.org/lkml/2019/7/8/842 4. "drm_client_close" [drivers/gpu/drm/drm] Patch: https://lkml.org/lkml/2019/7/3/758 (accepted) 5. "gve_probe" [drivers/net/ethernet/google/gve/gve] Patch: https://lkml.org/lkml/2019/7/14/65 6. "i2c_new_client_device" [vmlinux] "i2c_new_dummy_device" [vmlinux] Patch: https://lkml.org/lkml/2019/7/7/226 (fixed in a different patch) 7. "ahci_em_messages" [drivers/ata/libahci] Patch: https://lkml.org/lkml/2019/7/10/550 (reviwed) 8. "ftrace_set_clr_event" [vmlinux] Patch: https://lkml.org/lkml/2019/7/4/609 (reviwed) 9. "rmi_2d_sensor_set_input_params" [drivers/input/rmi4/rmi_core] Patch: https://lkml.org/lkml/2019/7/8/999 10. "empty_zero_page" [vmlinux] 11. "phys_base" [vmlinux] 12. "hypercall_page" [vmlinux] Similar commits: 1. 54638c6eaf44 ("net: phy: make exported variables non-static") 2. 98ef2046f28b ("mm: remove the exporting of totalram_pages") 3. 73df167c819e ("s390/zcrypt: remove the exporting of ap_query_configuration") 4. a57caf8c527f ("sunrpc/cache: remove the exporting of cache_seq_next") 5. e4e4730698c9 ("crypto: skcipher - remove the exporting of skcipher_walk_next") Build time impact, allmodconfig, Dell XPS 15 9570 (measurements 3x): $ make mrproper; make allmodconfig; time make -j12; \ git checkout HEAD~1; \ make mrproper; make allmodconfig; time make -j12 1. (with patch) 17635,94s user 1895,54s system 1085% cpu 29:59,22 total (w/o patch) 17275,42s user 1803,87s system 1112% cpu 28:35,66 total 2. (with patch) 17369,51s user 1763,28s system 1111% cpu 28:41,47 total (w/o patch) 16880,50s user 1670,93s system 1113% cpu 27:46,56 total 3. (with patch) 17937,88s user 1842,53s system 1109% cpu 29:42,26 total (w/o patch) 17267,55s user 1725,09s system 1111% cpu 28:28,17 total Thus, the current implementation adds approx. 1 min for allmodconfig. However, it's possible to do the check in a more optimal way if it will be considered useful. Also, this kind of check could be implemented as a separate script instead. Here is the implementation: https://gist.github.com/evdenis/bf2322d094f0c02c0f60fe0a225848b2 Signed-off-by: Denis Efremov Acked-by: Emil Velikov --- scripts/mod/modpost.c | 35 +++++++++++++++++++++++++++++++++-- 1 file changed, 33 insertions(+), 2 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index f277e116e0eb..c51eef357721 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -169,6 +169,7 @@ struct symbol { unsigned int kernel:1; /* 1 if symbol is from kernel * (only for external modules) **/ unsigned int preloaded:1; /* 1 if symbol from Module.symvers, or crc */ + unsigned int is_static:1; /* 1 if symbol is not global */ enum export export; /* Type of export */ char name[0]; }; @@ -199,8 +200,9 @@ static struct symbol *alloc_symbol(const char *name, unsigned int weak, memset(s, 0, sizeof(*s)); strcpy(s->name, name); - s->weak = weak; - s->next = next; + s->weak = weak; + s->next = next; + s->is_static = 1; return s; } @@ -1980,6 +1982,21 @@ static void read_symbols(const char *modname) handle_modversions(mod, &info, sym, symname); handle_moddevtable(mod, &info, sym, symname); } + + // check for static EXPORT_SYMBOL_* functions && global vars + for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { + unsigned char bind = ELF_ST_BIND(sym->st_info); + unsigned char type = ELF_ST_TYPE(sym->st_info); + + if (type == STT_OBJECT || type == STT_FUNC) { + struct symbol *s = + find_symbol(remove_dot(info.strtab + sym->st_name)); + + if (s && (bind == STB_GLOBAL || bind == STB_WEAK)) + s->is_static = 0; + } + } + if (!is_vmlinux(modname) || vmlinux_section_warnings) check_sec_ref(mod, modname, &info); @@ -2425,6 +2442,7 @@ int main(int argc, char **argv) char *dump_write = NULL, *files_source = NULL; int opt; int err; + size_t n; struct ext_sym_list *extsym_iter; struct ext_sym_list *extsym_start = NULL; @@ -2520,6 +2538,19 @@ int main(int argc, char **argv) if (sec_mismatch_count && sec_mismatch_fatal) fatal("modpost: Section mismatches detected.\n" "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n"); + for (n = 0; n < SYMBOL_HASH_SIZE ; n++) { + struct symbol *s = symbolhash[n]; + + while (s) { + if (s->is_static) + warn("\"%s\" [%s] is a static %s symbol\n", + s->name, s->module->name, + export_str(s->export)); + + s = s->next; + } + } + free(buf.p); return err;