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[2620:137:e000::1:20]) by mx.google.com with ESMTP id vs15-20020a170907138f00b008785a767444si5119824ejb.955.2023.01.27.09.04.42; Fri, 27 Jan 2023 09:05:05 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=Jt20okou; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234813AbjA0RDL (ORCPT + 99 others); Fri, 27 Jan 2023 12:03:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234759AbjA0RDC (ORCPT ); Fri, 27 Jan 2023 12:03:02 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAEF77FA35; Fri, 27 Jan 2023 09:02:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674838961; x=1706374961; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=djN+DaiLKdmHNtBi7i7A/82f34FiMzl4e3xwGKBci1s=; b=Jt20okou5d6RmZ/HOKZqyVoyd1JNopMXDSmFZfGqcSFPgpcjSaNmjb/l F7IhWjU5jaVNScsPBcfjjJ/b6YLU6/EAwJp179k7iLsIMY/wWhXXQU6Jk sKgcLYasDOhGs/Hike82mt8RCEJ3UpPoLfXemJFe10YUfar8T9qcjJKD1 9UKrnkIEW/B/lHLJZKHT1qcQLD79sph9b/FfaKyXmp5RVwHx3/+GbK9xS IAVLmzu+IcZfkgAcIyI7IWqUwv04bQuTWTBFUfFlDgUA1TotS6Z/FluiQ KdVhs5Dd6IlW4WZpt/JqES4f1XmjYOIir35Ii1uwQqTnij48IDmp5aCMf g==; X-IronPort-AV: E=McAfee;i="6500,9779,10603"; a="310754123" X-IronPort-AV: E=Sophos;i="5.97,251,1669104000"; d="scan'208";a="310754123" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2023 09:02:39 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10603"; a="726739180" X-IronPort-AV: E=Sophos;i="5.97,251,1669104000"; d="scan'208";a="726739180" Received: from ahunter6-mobl1.ger.corp.intel.com (HELO ahunter-VirtualBox.home\044ger.corp.intel.com) ([10.252.57.171]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jan 2023 09:02:37 -0800 From: Adrian Hunter To: Arnaldo Carvalho de Melo Cc: Jiri Olsa , Namhyung Kim , Ian Rogers , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH 2/9] perf symbols: Add support for x86 .plt.sec Date: Fri, 27 Jan 2023 19:02:15 +0200 Message-Id: <20230127170222.9895-3-adrian.hunter@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230127170222.9895-1-adrian.hunter@intel.com> References: <20230127170222.9895-1-adrian.hunter@intel.com> MIME-Version: 1.0 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE, SPF_NONE,URI_NOVOWEL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1756196090157945817?= X-GMAIL-MSGID: =?utf-8?q?1756196090157945817?= The section .plt.sec was originally added for MPX and was first called .plt.bnd. While MPX has been deprecated, .plt.sec is now also used for IBT. On x86_64, IBT seems to be enabled by default, but can be switched off using gcc option -fcf-protection=none. On 32-bit, option -z ibt will enable IBT. With .plt.sec, calls are made into .plt.sec instead of .plt, so it makes more sense to put the symbols there instead of .plt. A notable difference is that .plt.sec does not have a header entry. For x86, when synthesizing symbols for plt, use offset and entry size of .plt.sec instead of .plt when there is a .plt.sec section. Example on Ubuntu 22.04 gcc 11.3: Before: $ cat tstpltlib.c void fn1(void) {} void fn2(void) {} void fn3(void) {} void fn4(void) {} $ cat tstplt.c void fn1(void); void fn2(void); void fn3(void); void fn4(void); int main() { fn4(); fn1(); fn2(); fn3(); return 0; } $ gcc --version gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 Copyright (C) 2021 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ gcc -Wall -Wextra -shared -o libtstpltlib.so tstpltlib.c $ gcc -Wall -Wextra -o tstplt tstplt.c -L . -ltstpltlib -Wl,-rpath=$(pwd) $ readelf -SW tstplt | grep 'plt\|Name' [Nr] Name Type Address Off Size ES Flg Lk Inf Al [11] .rela.plt RELA 0000000000000698 000698 000060 18 AI 6 24 8 [13] .plt PROGBITS 0000000000001020 001020 000050 10 AX 0 0 16 [14] .plt.got PROGBITS 0000000000001070 001070 000010 10 AX 0 0 16 [15] .plt.sec PROGBITS 0000000000001080 001080 000040 10 AX 0 0 16 $ perf record -e intel_pt//u --filter 'filter main @ ./tstplt' ./tstplt [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.015 MB perf.data ] $ perf script --itrace=be --ns -F+flags,-event,+addr,-period,-comm,-tid,-cpu,-dso 38970.522546686: tr strt 0 [unknown] => 55fc222a81a9 main+0x0 38970.522546686: tr end call 55fc222a81b1 main+0x8 => 55fc222a80a0 [unknown] 38970.522546687: tr strt 0 [unknown] => 55fc222a81b6 main+0xd 38970.522546687: tr end call 55fc222a81b6 main+0xd => 55fc222a8080 [unknown] 38970.522546688: tr strt 0 [unknown] => 55fc222a81bb main+0x12 38970.522546688: tr end call 55fc222a81bb main+0x12 => 55fc222a80b0 [unknown] 38970.522546688: tr strt 0 [unknown] => 55fc222a81c0 main+0x17 38970.522546688: tr end call 55fc222a81c0 main+0x17 => 55fc222a8090 [unknown] 38970.522546689: tr strt 0 [unknown] => 55fc222a81c5 main+0x1c 38970.522546894: tr end return 55fc222a81cb main+0x22 => 7f3a4dc29d90 __libc_start_call_main+0x80 After: $ perf script --itrace=be --ns -F+flags,-event,+addr,-period,-comm,-tid,-cpu,-dso 38970.522546686: tr strt 0 [unknown] => 55fc222a81a9 main+0x0 38970.522546686: tr end call 55fc222a81b1 main+0x8 => 55fc222a80a0 fn4@plt+0x0 38970.522546687: tr strt 0 [unknown] => 55fc222a81b6 main+0xd 38970.522546687: tr end call 55fc222a81b6 main+0xd => 55fc222a8080 fn1@plt+0x0 38970.522546688: tr strt 0 [unknown] => 55fc222a81bb main+0x12 38970.522546688: tr end call 55fc222a81bb main+0x12 => 55fc222a80b0 fn2@plt+0x0 38970.522546688: tr strt 0 [unknown] => 55fc222a81c0 main+0x17 38970.522546688: tr end call 55fc222a81c0 main+0x17 => 55fc222a8090 fn3@plt+0x0 38970.522546689: tr strt 0 [unknown] => 55fc222a81c5 main+0x1c 38970.522546894: tr end return 55fc222a81cb main+0x22 => 7f3a4dc29d90 __libc_start_call_main+0x80 Signed-off-by: Adrian Hunter --- tools/perf/util/symbol-elf.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 9328c162d68f..bb1b5cb3ff12 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -379,6 +379,11 @@ static bool get_plt_sizes(struct dso *dso, GElf_Ehdr *ehdr, GElf_Shdr *shdr_plt, return false; } +static bool machine_is_x86(GElf_Half e_machine) +{ + return e_machine == EM_386 || e_machine == EM_X86_64; +} + /* * We need to check if we have a .dynsym, so that we can handle the * .plt, synthesizing its symbols, that aren't on the symtabs (be it @@ -391,8 +396,8 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) uint32_t nr_rel_entries, idx; GElf_Sym sym; u64 plt_offset, plt_header_size, plt_entry_size; - GElf_Shdr shdr_plt; - struct symbol *f; + GElf_Shdr shdr_plt, plt_sec_shdr; + struct symbol *f, *plt_sym; GElf_Shdr shdr_rel_plt, shdr_dynsym; Elf_Data *syms, *symstrs; Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym; @@ -422,10 +427,23 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) return 0; /* Add a symbol for .plt header */ - f = symbol__new(shdr_plt.sh_offset, plt_header_size, STB_GLOBAL, STT_FUNC, ".plt"); - if (!f) + plt_sym = symbol__new(shdr_plt.sh_offset, plt_header_size, STB_GLOBAL, STT_FUNC, ".plt"); + if (!plt_sym) goto out_elf_end; - symbols__insert(&dso->symbols, f); + symbols__insert(&dso->symbols, plt_sym); + + /* Only x86 has .plt.sec */ + if (machine_is_x86(ehdr.e_machine) && + elf_section_by_name(elf, &ehdr, &plt_sec_shdr, ".plt.sec", NULL)) { + if (!get_plt_sizes(dso, &ehdr, &plt_sec_shdr, &plt_header_size, &plt_entry_size)) + return 0; + /* Extend .plt symbol to entire .plt */ + plt_sym->end = plt_sym->start + shdr_plt.sh_size; + /* Use .plt.sec offset */ + plt_offset = plt_sec_shdr.sh_offset; + } else { + plt_offset = shdr_plt.sh_offset + plt_header_size; + } scn_dynsym = ss->dynsym; shdr_dynsym = ss->dynshdr; @@ -474,8 +492,6 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) goto out_elf_end; nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize; - plt_offset = shdr_plt.sh_offset; - plt_offset += plt_header_size; ri.is_rela = shdr_rel_plt.sh_type == SHT_RELA;