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[45.79.221.244]) by smtp.gmail.com with ESMTPSA id c1sm665566qkm.70.2019.09.04.01.59.16 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 04 Sep 2019 01:59:22 -0700 (PDT) Date: Wed, 4 Sep 2019 16:59:12 +0800 From: Leo Yan To: Adrian Hunter Cc: Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, clang-built-linux@googlegroups.com, Mathieu Poirier , Peter Zijlstra , Suzuki Poulouse , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5] perf machine: arm/arm64: Improve completeness for kernel address space Message-ID: <20190904085912.GA27922@leoy-ThinkPad-X240s> References: <20190815082521.16885-1-leo.yan@linaro.org> <20190815113242.GA28881@leoy-ThinkPad-X240s> <20190816014541.GA17960@leoy-ThinkPad-X240s> <363577f1-097e-eddd-a6ca-b23f644dd8ce@intel.com> <20190826125105.GA3288@leoy-ThinkPad-X240s> <20190902141511.GF4931@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Adrian, On Wed, Sep 04, 2019 at 10:26:13AM +0300, Adrian Hunter wrote: [...] > > Could you take chance to review my below replying? I'd like to get > > your confirmation before I send out offical patch. > > It is not necessary to do kallsyms__parse for x86_64, so it would be better > to check the arch before calling that. Thanks for suggestion, will do it in the formal patch. > However in general, having to copy and use kallsyms with perf.data if on a > different arch does not seem very user friendly. Agree. Seems it's more reasonable to save related info in perf.data; TBH, I have no idea for how to do that. > But really that is up to Arnaldo. @Arnaldo, if possible could you take a look for below change? If you don't think below code is the right thing and it's not a common issue, then maybe it's more feasible to resolve this issue only for Arm CoreSight specific. Please let me know how about you think for this? Thanks, Leo Yan > >> For your question for taking a perf.data file to a machine with a > >> different architecture, we can firstly use command 'perf buildid-list' > >> to print out the buildid for kallsyms, based on the dumped buildid we > >> can find out the location for the saved kallsyms file; then we can use > >> option '--kallsyms' to specify the offline kallsyms file and use the > >> offline kallsyms to fixup kernel start address. The detailed commands > >> are listed as below: > >> > >> root@debian:~# perf buildid-list > >> 7b36dfca8317ef74974ebd7ee5ec0a8b35c97640 [kernel.kallsyms] > >> 56b84aa88a1bcfe222a97a53698b92723a3977ca /usr/lib/systemd/systemd > >> 0956b952e9cd673d48ff2cfeb1a9dbd0c853e686 /usr/lib/aarch64-linux-gnu/libm-2.28.so > >> [...] > >> > >> root@debian:~# perf script --kallsyms ~/.debug/\[kernel.kallsyms\]/7b36dfca8317ef74974ebd7ee5ec0a8b35c97640/kallsyms > >> > >> The amended patch is as below, please review and always welcome > >> any suggestions or comments! > >> > >> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > >> index 5734460fc89e..593f05cc453f 100644 > >> --- a/tools/perf/util/machine.c > >> +++ b/tools/perf/util/machine.c > >> @@ -2672,9 +2672,26 @@ int machine__nr_cpus_avail(struct machine *machine) > >> return machine ? perf_env__nr_cpus_avail(machine->env) : 0; > >> } > >> > >> +static int machine__fixup_kernel_start(void *arg, > >> + const char *name __maybe_unused, > >> + char type, > >> + u64 start) > >> +{ > >> + struct machine *machine = arg; > >> + > >> + type = toupper(type); > >> + > >> + /* Fixup for text, weak, data and bss sections. */ > >> + if (type == 'T' || type == 'W' || type == 'D' || type == 'B') > >> + machine->kernel_start = min(machine->kernel_start, start); > >> + > >> + return 0; > >> +} > >> + > >> int machine__get_kernel_start(struct machine *machine) > >> { > >> struct map *map = machine__kernel_map(machine); > >> + char filename[PATH_MAX]; > >> int err = 0; > >> > >> /* > >> @@ -2696,6 +2713,22 @@ int machine__get_kernel_start(struct machine *machine) > >> if (!err && !machine__is(machine, "x86_64")) > >> machine->kernel_start = map->start; > >> } > >> + > >> + if (symbol_conf.kallsyms_name != NULL) { > >> + strncpy(filename, symbol_conf.kallsyms_name, PATH_MAX); > >> + } else { > >> + machine__get_kallsyms_filename(machine, filename, PATH_MAX); > >> + > >> + if (symbol__restricted_filename(filename, "/proc/kallsyms")) > >> + goto out; > >> + } > >> + > >> + if (kallsyms__parse(filename, machine, machine__fixup_kernel_start)) > >> + pr_warning("Fail to fixup kernel start address. skipping...\n"); > >> + > >> +out: > >> return err; > >> } > >> > >> > >> Thanks, > >> Leo Yan > > >