From: leo.yan@linaro.org To: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>, Peter Zijlstra <peterz@infradead.org>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Coresight ML <coresight@lists.linaro.org> Subject: Re: [PATCH] perf cs-etm: Correct CPU mode for samples Date: Tue, 30 Oct 2018 23:04:49 +0800 [thread overview] Message-ID: <20181030150449.GB8344@leoy-ThinkPad-X240s> (raw) In-Reply-To: <20181030143226.GA23310@kernel.org> Hi Arnaldo, On Tue, Oct 30, 2018 at 11:32:26AM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Oct 30, 2018 at 03:18:28PM +0800, Leo Yan escreveu: > > Since commit 9042f5e3539e ("perf tools: Stop fallbacking to kallsyms > > for vdso symbols lookup"), the kernel address cannot be properly parsed > > to kernel symbol with command 'perf script -k vmlinux'. The reason is > > CoreSight samples is always to set CPU mode as PERF_RECORD_MISC_USER, > > thus it fails to find corresponding map/dso in below flows: > > > > process_sample_event() > > `-> machine__resolve() > > `-> thread__find_map(thread, sample->cpumode, sample->ip, al); > > > > In this flow it needs to pass argument 'sample->cpumode' to tell what's > > the CPU mode, before it always passed PERF_RECORD_MISC_USER but without > > any failure until the commit 9042f5e3539e ("perf tools: Stop fallbacking > > to kallsyms for vdso symbols lookup") has been merged. The reason is > > even with the wrong CPU mode the function thread__find_map() firstly > > fails to find map but it will rollback to find kernel map for vdso > > symbols lookup. In the latest code it has removed the fallback code, > > thus if CPU mode is PERF_RECORD_MISC_USER then it cannot find map > > anymore with kernel address. > > > > This patch is to correct samples CPU mode setting, it creates a new > > helper function cs_etm__cpu_mode() to tell what's the CPU mode based on > > the address with the info from machine structure; this patch has a bit > > extension to check not only kernel and user mode, but also check for > > host/guest and hypervisor mode. Finally this patch uses the function > > in instruction and branch samples and also apply in cs_etm__mem_access() > > for a minor polishing. > > Mathieu, can I have your Acked-by, please? Leo, thanks for acting so > quickly on this one! Thanks for reivewing. Yeah, let's wait for Mathieu reviewing as well, as I know he is travelling so might be delay a bit. Just remind, we might need the similiar change for util/intel-pt.c and util/intel-bts.c when generate samples, otherwise they might have the same regression for kernel symbols. I am not the best person to change these two files, but bring up this for attention. > Now processing coresight traces should be faster, less lookups :-) Thanks! [...] Thanks, Leo Yan
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From: leo.yan@linaro.org (leo.yan at linaro.org) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] perf cs-etm: Correct CPU mode for samples Date: Tue, 30 Oct 2018 23:04:49 +0800 [thread overview] Message-ID: <20181030150449.GB8344@leoy-ThinkPad-X240s> (raw) In-Reply-To: <20181030143226.GA23310@kernel.org> Hi Arnaldo, On Tue, Oct 30, 2018 at 11:32:26AM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Oct 30, 2018 at 03:18:28PM +0800, Leo Yan escreveu: > > Since commit 9042f5e3539e ("perf tools: Stop fallbacking to kallsyms > > for vdso symbols lookup"), the kernel address cannot be properly parsed > > to kernel symbol with command 'perf script -k vmlinux'. The reason is > > CoreSight samples is always to set CPU mode as PERF_RECORD_MISC_USER, > > thus it fails to find corresponding map/dso in below flows: > > > > process_sample_event() > > `-> machine__resolve() > > `-> thread__find_map(thread, sample->cpumode, sample->ip, al); > > > > In this flow it needs to pass argument 'sample->cpumode' to tell what's > > the CPU mode, before it always passed PERF_RECORD_MISC_USER but without > > any failure until the commit 9042f5e3539e ("perf tools: Stop fallbacking > > to kallsyms for vdso symbols lookup") has been merged. The reason is > > even with the wrong CPU mode the function thread__find_map() firstly > > fails to find map but it will rollback to find kernel map for vdso > > symbols lookup. In the latest code it has removed the fallback code, > > thus if CPU mode is PERF_RECORD_MISC_USER then it cannot find map > > anymore with kernel address. > > > > This patch is to correct samples CPU mode setting, it creates a new > > helper function cs_etm__cpu_mode() to tell what's the CPU mode based on > > the address with the info from machine structure; this patch has a bit > > extension to check not only kernel and user mode, but also check for > > host/guest and hypervisor mode. Finally this patch uses the function > > in instruction and branch samples and also apply in cs_etm__mem_access() > > for a minor polishing. > > Mathieu, can I have your Acked-by, please? Leo, thanks for acting so > quickly on this one! Thanks for reivewing. Yeah, let's wait for Mathieu reviewing as well, as I know he is travelling so might be delay a bit. Just remind, we might need the similiar change for util/intel-pt.c and util/intel-bts.c when generate samples, otherwise they might have the same regression for kernel symbols. I am not the best person to change these two files, but bring up this for attention. > Now processing coresight traces should be faster, less lookups :-) Thanks! [...] Thanks, Leo Yan
next prev parent reply other threads:[~2018-10-30 15:05 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-10-30 7:18 [PATCH] perf cs-etm: Correct CPU mode for samples Leo Yan 2018-10-30 7:18 ` Leo Yan 2018-10-30 14:32 ` Arnaldo Carvalho de Melo 2018-10-30 14:32 ` Arnaldo Carvalho de Melo 2018-10-30 15:04 ` leo.yan [this message] 2018-10-30 15:04 ` leo.yan at linaro.org 2018-10-30 15:11 ` Arnaldo Carvalho de Melo 2018-10-30 15:11 ` Arnaldo Carvalho de Melo 2018-10-30 15:30 ` Adrian Hunter 2018-10-30 15:30 ` Adrian Hunter 2018-10-30 15:45 ` Arnaldo Carvalho de Melo 2018-10-30 15:45 ` Arnaldo Carvalho de Melo 2018-10-31 22:04 ` [tip:perf/urgent] " tip-bot for Leo Yan
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