From patchwork Wed Dec 20 15:11:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joe Lawrence X-Patchwork-Id: 756680 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8A7D3E47C for ; Wed, 20 Dec 2023 15:12:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iDFE105y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703085124; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=UGXHGx7fIiQQEp0PPgJ61uCfXTD7P90Z9jAT2290LTc=; b=iDFE105yFlH9uW8tIfOdT5NKINALYWXvs5suNqOWVwuplT/T88xZdpnO5/cIOWPBrYQQ6m yjfTYsxndbXZpnDWpUEx5eo7AAc1MiKxxIYtYkXNqT7X5Lg/uZDvYb4tuhJhQPOJRtU3Rq B8l8FaiBKZNSVluM1zjsl2bu158TvnQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-171-Pnr5I9iHMSiIgdwsThPEeg-1; Wed, 20 Dec 2023 10:12:01 -0500 X-MC-Unique: Pnr5I9iHMSiIgdwsThPEeg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DBD97868903; Wed, 20 Dec 2023 15:12:00 +0000 (UTC) Received: from jlaw-desktop.redhat.com (unknown [10.22.33.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9BFAFC15968; Wed, 20 Dec 2023 15:12:00 +0000 (UTC) From: Joe Lawrence To: live-patching@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, Alexander Gordeev , Petr Mladek Subject: [PATCH] selftests/livepatch: fix and refactor new dmesg message code Date: Wed, 20 Dec 2023 10:11:51 -0500 Message-ID: <20231220151151.267985-1-joe.lawrence@redhat.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 The livepatching kselftests rely on comparing expected vs. observed dmesg output. After each test, new dmesg entries are determined by the 'comm' utility comparing a saved, pre-test copy of dmesg to post-test dmesg output. Alexander reports that the 'comm --nocheck-order -13' invocation used by the tests can be confused when dmesg entry timestamps vary in magnitude (ie, "[ 98.820331]" vs. "[ 100.031067]"), in which case, additional messages are reported as new. The unexpected entries then spoil the test results. Instead of relying on 'comm' or 'diff' to determine new testing dmesg entries, refactor the code: - pre-test : log a unique canary dmesg entry - test : run tests, log messages - post-test : filter dmesg starting from pre-test message Reported-by: Alexander Gordeev Closes: https://lore.kernel.org/live-patching/ZYAimyPYhxVA9wKg@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com/ Signed-off-by: Joe Lawrence Tested-by: Marcos Paulo de Souza Reviewed-by: Marcos Paulo de Souza Acked-by: Miroslav Benes --- .../testing/selftests/livepatch/functions.sh | 37 +++++++++---------- 1 file changed, 17 insertions(+), 20 deletions(-) diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh index c8416c54b463..b1fd7362c2fe 100644 --- a/tools/testing/selftests/livepatch/functions.sh +++ b/tools/testing/selftests/livepatch/functions.sh @@ -42,17 +42,6 @@ function die() { exit 1 } -# save existing dmesg so we can detect new content -function save_dmesg() { - SAVED_DMESG=$(mktemp --tmpdir -t klp-dmesg-XXXXXX) - dmesg > "$SAVED_DMESG" -} - -# cleanup temporary dmesg file from save_dmesg() -function cleanup_dmesg_file() { - rm -f "$SAVED_DMESG" -} - function push_config() { DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \ awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}') @@ -99,7 +88,6 @@ function set_ftrace_enabled() { function cleanup() { pop_config - cleanup_dmesg_file } # setup_config - save the current config and set a script exit trap that @@ -280,7 +268,15 @@ function set_pre_patch_ret { function start_test { local test="$1" - save_dmesg + # Dump something unique into the dmesg log, then stash the entry + # in LAST_DMESG. The check_result() function will use it to + # find new kernel messages since the test started. + local last_dmesg_msg="livepatch kselftest timestamp: $(date --rfc-3339=ns)" + log "$last_dmesg_msg" + loop_until 'dmesg | grep -q "$last_dmesg_msg"' || + die "buffer busy? can't find canary dmesg message: $last_dmesg_msg" + LAST_DMESG=$(dmesg | grep "$last_dmesg_msg") + echo -n "TEST: $test ... " log "===== TEST: $test =====" } @@ -291,23 +287,24 @@ function check_result { local expect="$*" local result - # Note: when comparing dmesg output, the kernel log timestamps - # help differentiate repeated testing runs. Remove them with a - # post-comparison sed filter. - - result=$(dmesg | comm --nocheck-order -13 "$SAVED_DMESG" - | \ + # Test results include any new dmesg entry since LAST_DMESG, then: + # - include lines matching keywords + # - exclude lines matching keywords + # - filter out dmesg timestamp prefixes + result=$(dmesg | awk -v last_dmesg="$LAST_DMESG" 'p; $0 == last_dmesg { p=1 }' | \ grep -e 'livepatch:' -e 'test_klp' | \ grep -v '\(tainting\|taints\) kernel' | \ sed 's/^\[[ 0-9.]*\] //') if [[ "$expect" == "$result" ]] ; then echo "ok" + elif [[ "$result" == "" ]] ; then + echo -e "not ok\n\nbuffer overrun? can't find canary dmesg entry: $LAST_DMESG\n" + die "livepatch kselftest(s) failed" else echo -e "not ok\n\n$(diff -upr --label expected --label result <(echo "$expect") <(echo "$result"))\n" die "livepatch kselftest(s) failed" fi - - cleanup_dmesg_file } # check_sysfs_rights(modname, rel_path, expected_rights) - check sysfs