From patchwork Mon Sep 16 11:30:56 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wieczorkiewicz, Pawel" X-Patchwork-Id: 11146877 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A05F4912 for ; Mon, 16 Sep 2019 11:35:46 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7CBD72067D for ; Mon, 16 Sep 2019 11:35:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.de header.i=@amazon.de header.b="UCCE+W2T" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CBD72067D Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1i9pH8-0004FC-C6; Mon, 16 Sep 2019 11:34:34 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1i9pH7-0004Ee-BX for xen-devel@lists.xen.org; Mon, 16 Sep 2019 11:34:33 +0000 X-Inumbo-ID: f1408f3c-d875-11e9-95e0-12813bfff9fa Received: from smtp-fw-33001.amazon.com (unknown [207.171.190.10]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id f1408f3c-d875-11e9-95e0-12813bfff9fa; Mon, 16 Sep 2019 11:34:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1568633668; x=1600169668; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version; bh=KwEZeU7N+/Kq2gSuFDFYZifBQ19CKLE05Lj3wMHopGg=; b=UCCE+W2Tgr73XSyhCPfpYFa+15jZywKSLsf42NNLrybcU7HyFxF8Xw// HYCIR+rMIkj6HfBgxVdj4Sonm6h4CGMSgLa0rQXxrbs8ei6lGmf0sC8VF 7pOLKBYFIV9YWM2TfPjRLSS7MmtxqOKFrBwApVZeo26rIWrZe58YYo235 M=; X-IronPort-AV: E=Sophos;i="5.64,512,1559520000"; d="scan'208";a="832628932" Received: from sea3-co-svc-lb6-vlan2.sea.amazon.com (HELO email-inbound-relay-1a-67b371d8.us-east-1.amazon.com) ([10.47.22.34]) by smtp-border-fw-out-33001.sea14.amazon.com with ESMTP; 16 Sep 2019 11:32:02 +0000 Received: from EX13MTAUEA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1a-67b371d8.us-east-1.amazon.com (Postfix) with ESMTPS id 3EE8FA2258; Mon, 16 Sep 2019 11:31:59 +0000 (UTC) Received: from EX13D03EUC002.ant.amazon.com (10.43.164.60) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 16 Sep 2019 11:31:39 +0000 Received: from EX13MTAUWC001.ant.amazon.com (10.43.162.135) by EX13D03EUC002.ant.amazon.com (10.43.164.60) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 16 Sep 2019 11:31:38 +0000 Received: from dev-dsk-wipawel-1a-0c4e6d58.eu-west-1.amazon.com (10.4.134.33) by mail-relay.amazon.com (10.43.162.232) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Mon, 16 Sep 2019 11:31:34 +0000 From: Pawel Wieczorkiewicz To: , Date: Mon, 16 Sep 2019 11:30:56 +0000 Message-ID: <20190916113056.16592-8-wipawel@amazon.de> X-Mailer: git-send-email 2.16.5 In-Reply-To: <20190916113056.16592-1-wipawel@amazon.de> References: <20190916113056.16592-1-wipawel@amazon.de> MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [PATCH v2 7/7] livepatch-build: Strip all metadata symbols from hotpatch modules X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: wipawel@amazon.com, Stefano Stabellini , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , mpohlack@amazon.com, Tim Deegan , Pawel Wieczorkiewicz , Julien Grall , Jan Beulich Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Strip all unneeded metadata symbols from generated hotpatch modules. The metadata symbols are the symbols from metadata-like sections (e.g. '.livepatch.funcs') or livepatch hooks symbols (defined by a set of prefixes. E.g. 'livepatch_load_data_'). By default the create-diff-object does not create symbols in metadata sections. However, such symbols may be implicitly added by speciying extra entries in the sections manually (in a given patch). The symbols are not needed for the hotpatch modules and should be stripped to avoid symbol names collisions and to save hotpatch files space. Signed-off-by: Pawel Wieczorkiewicz Reviewed-by: Ross Lagerwall --- livepatch-build | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 53 insertions(+), 2 deletions(-) diff --git a/livepatch-build b/livepatch-build index 816064c..be459c9 100755 --- a/livepatch-build +++ b/livepatch-build @@ -111,10 +111,39 @@ function build_special() unset LIVEPATCH_CAPTURE_DIR } -strip_extra_symbols () +elf_section_exists () +{ + local ELF="$1" + local SEC="$2" + + objdump -h -j "$SEC" "$ELF" &> /dev/null +} + +# Extract a set of unique symbols for a specified section. +elf_extract_section_symbols () +{ + local -r ELF="$1" + local -r SEC="$2" + + if elf_section_exists "$ELF" "$SEC" + then + # Example objdump command output to be parsed: + # + # SYMBOL TABLE: + # 0000000000000000 l d .livepatch.funcs 0000000000000000 .livepatch.funcs + objdump -w -j "$SEC" -t "$ELF" | awk '/^SYMBOL TABLE:/ {seen = 1; next} seen && $NF {print $NF}' | sort -u + fi +} + +# Strip all metadata symbols belonging to a metadata section +# or whose name starts with a livepatch hook prefix. +# The function constructs the 'strip' utility command line +# and then invokes strip with that command line. +strip_metadata_symbols () { local -r FILE="$1" local -a STRIP_CMD_OPTS=() + local -a SYM_SECTIONS=(".livepatch.funcs") local -a SYM_PREFIX=("livepatch_load_data_" "livepatch_unload_data_" "livepatch_preapply_data_" @@ -123,13 +152,35 @@ strip_extra_symbols () "livepatch_prerevert_data_" "livepatch_revert_data_" "livepatch_postrevert_data_") + local -a SYMS=() + # Enable wildcard STRIP_CMD_OPTS+=("-w") + + # Strip all livepatch hooks metadata symbols for sym in "${SYM_PREFIX[@]}"; do STRIP_CMD_OPTS+=("-N") STRIP_CMD_OPTS+=("\"${sym}*\"") done + # Find all symbols from metadata sections + # Note: There may be name conflicts between global + # and local symbols belonging to the same section. + # For the '.livepatch.funcs' section it is not a + # problem. Think about it before adding more sections. + for sec in "${SYM_SECTIONS[@]}"; do + SYMS+=($(elf_extract_section_symbols "$FILE" "$sec")) + done + + # Strip metadata sections' symbols + if [ ${#SYMS[@]} -gt 0 ] + then + for sym in "${SYMS[@]}"; do + STRIP_CMD_OPTS+=("-N") + STRIP_CMD_OPTS+=("${sym}") + done + fi + strip "${STRIP_CMD_OPTS[@]}" "$FILE" } @@ -199,7 +250,7 @@ function create_patch() "${TOOLSDIR}"/prelink $debugopt output.o "${PATCHNAME}.livepatch" "$XENSYMS" &>> "${OUTPUT}/prelink.log" || die fi - strip_extra_symbols "${PATCHNAME}.livepatch" + strip_metadata_symbols "${PATCHNAME}.livepatch" objcopy --add-section .livepatch.depends=depends.bin "${PATCHNAME}.livepatch" objcopy --set-section-flags .livepatch.depends=alloc,readonly "${PATCHNAME}.livepatch"