From patchwork Tue Mar 9 15:17:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 12125793 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD079C4332E for ; Tue, 9 Mar 2021 15:19:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F09265285 for ; Tue, 9 Mar 2021 15:19:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231844AbhCIPSy (ORCPT ); Tue, 9 Mar 2021 10:18:54 -0500 Received: from conuserg-09.nifty.com ([210.131.2.76]:31186 "EHLO conuserg-09.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231975AbhCIPS1 (ORCPT ); Tue, 9 Mar 2021 10:18:27 -0500 Received: from localhost.localdomain (133-32-232-101.west.xps.vectant.ne.jp [133.32.232.101]) (authenticated) by conuserg-09.nifty.com with ESMTP id 129FHiTd030658; Wed, 10 Mar 2021 00:17:45 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-09.nifty.com 129FHiTd030658 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1615303066; bh=aiZL314cCgH6pTtZI6W6PU8ZHJmV18CncdIR5eQC6Fg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sra+heZ7kORAq5P/K68lyyqZQjtoJfrhauSin9UyhFdvCwa+Uv+t+axs0pFsLm5b8 bGh6VqJWglTUDo8HgAm9AMN35eaiJPZmszccabI85+EkaolmClebLvyp6iyzk0H04b JZmGNVBXzibKH7jPIXFuupNDA8tnAu44RbGZVw+83cRKNwR5cEn7m6vH6vBTvyuAWQ h7pv8AQXjKYKzRQu6JP0O40PQTnmvGc2Xba8MUdrR0PiQD3bs4L5R5ktP9XLTS5CL0 BTHP0VaZP+2/MBfOmaoIgPJovzKqwumhLP7V00BoUPQgDMiMeEd+p7IuDsXVxfafHL DKU9LJGq/aHTA== X-Nifty-SrcIP: [133.32.232.101] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: Christoph Hellwig , Linus Torvalds , Jessica Yu , Nicolas Pitre , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Masahiro Yamada Subject: [PATCH v2 1/4] export.h: make __ksymtab_strings per-symbol section Date: Wed, 10 Mar 2021 00:17:34 +0900 Message-Id: <20210309151737.345722-2-masahiroy@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210309151737.345722-1-masahiroy@kernel.org> References: <20210309151737.345722-1-masahiroy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org The export symbol tables are placed on own sections (__ksymtab*+) and sorted by SORT (an alias of SORT_BY_NAME) because the module subsystem uses the binary search for symbol resolution. We did not have a good reason to do so for __ksymtab_strings, but now I have. To make CONFIG_TRIM_UNUSED_KSYMS work in one-pass, the linker needs to trim unused strings of symbols and namespaces. To allow per-symbol keep/drop choice, __ksymtab_strings must be placed on own sections. This keeps the string unification introduced by commit ce2b617ce8cb ("export.h: reduce __ksymtab_strings string duplication by using "MS" section flags"). For example, the empty namespaces share the same address. $ nm -n vmlinux [ snip ] ffffffff8233b6aa r __kstrtabns_IO_APIC_get_PCI_irq_vector ffffffff8233b6aa r __kstrtabns_I_BDEV ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast_continue ffffffff8233b6aa r __kstrtabns_LZ4_decompress_fast_usingDict ... I confirmed no size change in vmlinux. Signed-off-by: Masahiro Yamada --- (no changes since v1) include/asm-generic/export.h | 2 +- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/export.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h index 07a36a874dca..e847f1fde367 100644 --- a/include/asm-generic/export.h +++ b/include/asm-generic/export.h @@ -39,7 +39,7 @@ __ksymtab_\name: __put \val, __kstrtab_\name .previous - .section __ksymtab_strings,"aMS",%progbits,1 + .section __ksymtab_strings+\name,"aMS",%progbits,1 __kstrtab_\name: .asciz "\name" .previous diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 0331d5d49551..6ce6dcabdccf 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -513,7 +513,7 @@ \ /* Kernel symbol table: strings */ \ __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \ - *(__ksymtab_strings) \ + *(__ksymtab_strings+*) \ } \ \ /* __*init sections */ \ diff --git a/include/linux/export.h b/include/linux/export.h index 6271a5d9c988..01e6ab19b226 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -99,7 +99,7 @@ struct kernel_symbol { extern const char __kstrtab_##sym[]; \ extern const char __kstrtabns_##sym[]; \ __CRC_SYMBOL(sym, sec); \ - asm(" .section \"__ksymtab_strings\",\"aMS\",%progbits,1 \n" \ + asm(" .section \"__ksymtab_strings+" #sym "\",\"aMS\",%progbits,1\n" \ "__kstrtab_" #sym ": \n" \ " .asciz \"" #sym "\" \n" \ "__kstrtabns_" #sym ": \n" \