From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 160DFC001DF for ; Wed, 2 Aug 2023 12:25:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233856AbjHBMZn (ORCPT ); Wed, 2 Aug 2023 08:25:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233880AbjHBMZk (ORCPT ); Wed, 2 Aug 2023 08:25:40 -0400 Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3A4A2720 for ; Wed, 2 Aug 2023 05:25:37 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R611e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045192;MF=tianruidong@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VouyzCy_1690979132; Received: from 30.221.140.131(mailfrom:tianruidong@linux.alibaba.com fp:SMTPD_---0VouyzCy_1690979132) by smtp.aliyun-inc.com; Wed, 02 Aug 2023 20:25:33 +0800 Message-ID: Date: Wed, 2 Aug 2023 20:25:30 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [RESEND PATCH] coresight: tmc: Explicit type conversions to prevent integer overflow Content-Language: en-US To: James Clark , coresight@lists.linaro.org Cc: mike.leach@linaro.org, alexander.shishkin@linux.intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20230714084349.31567-1-tianruidong@linux.alibaba.com> <61f11ffe-473c-a36e-c51d-9e526a6fd375@arm.com> From: Ruidong Tian In-Reply-To: <61f11ffe-473c-a36e-c51d-9e526a6fd375@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi James, Sorry, some local patch caused inaccurate information. Please allow me to reintroduce the question: If you use perf with 1G AUX buffer, you can get 1G perf data. Perf workload is kernel build here:     perf record -C 0 -m ,1G -e cs_etm// taskset -c 0 make     [ perf record: Captured and wrote 1025.557 MB perf.data ] But if you use 2G AUX buffer, perf was executed unexpectedly：     perf record -C 0 -m ,2G -e cs_etm// taskset -c 0 make     [ perf record: Captured and wrote 2.615 MB perf.data ] There are just 2.615 MB perf data rather than 2G, if you probe function "tmc_alloc_etr_buf" in coresight_tmc module, you can find some clues:   perf probe -m coresight_tmc "tmc_alloc_etr_buf size:s64"   perf record -e probe:tmc_alloc_etr_buf -aR -- perf record -C 0 -m ,2G -e cs_etm// -o cs.data taskset -c 0 make   perf script             perf 118267 [064]  4640.324670: probe:tmc_alloc_etr_buf: (ffff80007a9dce60) size_s64=-2147483648             perf 118267 [064]  4640.324681: probe:tmc_alloc_etr_buf: (ffff80007a9dce60) size_s64=1048576 It's pretty obvious what's going on here. The first call of tmc_alloc_etr_buf in alloc_etr_buf was failed because of overflow, the second call of tmc_alloc_etr_buf just alloc 1M AUX buffer which is default ETR buffer size rather than 2G. That is why we can just get 2.615MB ( 1M AUX data + perf header ). It is necessary to check the conversion from int to s64 in coresight_tmc driver. The issue[1] also exists in coresight/perf, but it's different from this topic. [1]: https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ Thanks Ruidong On 2023/7/24 23:38, James Clark wrote: > > On 14/07/2023 09:43, Ruidong Tian wrote: >> Perf cs_etm session will failed when AUX buffer > 1G. >> >> perf record -C 0 -m ,2G -e cs_etm// -- taskset -c 0 ls >> failed to mmap with 12 (Cannot allocate memory) >> >> In coresight tmc driver, "nr_pages << PAGE_SHIFT" will overflow when >> nr_pages >= 0x80000(correspond to 1G AUX buffer). Explicit convert nr_pages >> to 64 bit to avoid overflow. >> > Hi Ruidong, > > I couldn't reproduce this exact issue with the error message in the > commit message. Is it not another manifestation related to this change > [1]? I don't actually get any error message, but I was able to get a > warning in dmesg even with [1] applied. > > Does the overflow not result in a successful session but with the wrong > buffer size? > > I think the change makes sense, but maybe we also need a check for > MAX_ORDER because I can trigger the same WARN_ON from [1]. Or maybe I'm > a bit confused because of the other change and not being able to > reproduce this exactly coming at the same time. > > [1]: > https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/ > > Thanks > James > >> Signed-off-by: Ruidong Tian >> --- >> drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +- >> drivers/hwtracing/coresight/coresight-tmc.h | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> index 766325de0e29..1425ecd1cf78 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> @@ -1267,7 +1267,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, >> * than the size requested via sysfs. >> */ >> if ((nr_pages << PAGE_SHIFT) > drvdata->size) { >> - etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT), >> + etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << PAGE_SHIFT), >> 0, node, NULL); >> if (!IS_ERR(etr_buf)) >> goto done; >> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h >> index b97da39652d2..0ee48c5ba764 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc.h >> +++ b/drivers/hwtracing/coresight/coresight-tmc.h >> @@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table, >> static inline unsigned long >> tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) >> { >> - return sg_table->data_pages.nr_pages << PAGE_SHIFT; >> + return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT; >> } >> >> struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);