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[50.116.10.16]) by smtp.gmail.com with ESMTPSA id k5sm6182091pgo.45.2019.08.12.00.02.40 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 12 Aug 2019 00:02:44 -0700 (PDT) Date: Mon, 12 Aug 2019 15:02:36 +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 , David Miller , Milian Wolff , Donald Yandt , Davidlohr Bueso , Wei Li , Mark Drayton , "Tzvetomir Stoyanov (VMware)" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, clang-built-linux@googlegroups.com, Mathieu Poirier Subject: Re: [PATCH v4 1/2] perf machine: Support arch's specific kernel start address Message-ID: <20190812070236.GA8062@leoy-ThinkPad-X240s> References: <20190810072135.27072-1-leo.yan@linaro.org> <20190810072135.27072-2-leo.yan@linaro.org> 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: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Aug 12, 2019 at 09:37:33AM +0300, Adrian Hunter wrote: > On 10/08/19 10:21 AM, Leo Yan wrote: > > machine__get_kernel_start() gives out the kernel start address; some > > architectures need to tweak the start address so that can reflect the > > kernel start address correctly. This is not only for x86_64 arch, but > > it is also required by other architectures, e.g. arm/arm64 needs to > > tweak the kernel start address so can include the kernel memory regions > > which are used before the '_stext' symbol. > > > > This patch refactors machine__get_kernel_start() by adding a weak > > arch__fix_kernel_text_start(), any architecture can implement it to > > tweak its specific start address; this also allows the arch specific > > code to be placed into 'arch' folder. > > > > Signed-off-by: Leo Yan > > --- > > tools/perf/arch/x86/util/machine.c | 10 ++++++++++ > > tools/perf/util/machine.c | 13 +++++++------ > > tools/perf/util/machine.h | 2 ++ > > 3 files changed, 19 insertions(+), 6 deletions(-) > > > > diff --git a/tools/perf/arch/x86/util/machine.c b/tools/perf/arch/x86/util/machine.c > > index 1e9ec783b9a1..9f012131534a 100644 > > --- a/tools/perf/arch/x86/util/machine.c > > +++ b/tools/perf/arch/x86/util/machine.c > > @@ -101,4 +101,14 @@ int machine__create_extra_kernel_maps(struct machine *machine, > > return ret; > > } > > > > +void arch__fix_kernel_text_start(u64 *start) > > +{ > > + /* > > + * On x86_64, PTI entry trampolines are less than the > > + * start of kernel text, but still above 2^63. So leave > > + * kernel_start = 1ULL << 63 for x86_64. > > + */ > > + *start = 1ULL << 63; > > +} > > That is needed for reporting x86 data on any arch i.e. it is not specific to > the compile-time architecture, it is specific to the perf.data file > architecture, which is what machine__is() compares. So, this looks wrong. Thanks for reviewing, Adrian. If so, I think we should extend the function machine__get_kernel_start() as below; for building successfully, will always define the macro ARM_PRE_START_SIZE in Makefile.config. @Arnaldo, @Adrian, Please let me know if this works for you? diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index f6ee7fbad3e4..30a0ff627263 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2687,13 +2687,26 @@ int machine__get_kernel_start(struct machine *machine) machine->kernel_start = 1ULL << 63; if (map) { err = map__load(map); + if (err) + return err; + /* * On x86_64, PTI entry trampolines are less than the * start of kernel text, but still above 2^63. So leave * kernel_start = 1ULL << 63 for x86_64. */ - if (!err && !machine__is(machine, "x86_64")) + if (!machine__is(machine, "x86_64")) machine->kernel_start = map->start; + + /* + * On arm/arm64, some memory regions are prior to '_stext' + * symbol; to reflect the complete kernel address space, + * compensate these pre-defined regions for kernel start + * address. + */ + if (machine__is(machine, "arm64") || + machine__is(machine, "arm")) + machine->kernel_start -= ARM_PRE_START_SIZE; } return err; } Thanks, Leo Yan > > + > > #endif > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > > index f6ee7fbad3e4..603518835692 100644 > > --- a/tools/perf/util/machine.c > > +++ b/tools/perf/util/machine.c > > @@ -2671,6 +2671,10 @@ int machine__nr_cpus_avail(struct machine *machine) > > return machine ? perf_env__nr_cpus_avail(machine->env) : 0; > > } > > > > +void __weak arch__fix_kernel_text_start(u64 *start __maybe_unused) > > +{ > > +} > > + > > int machine__get_kernel_start(struct machine *machine) > > { > > struct map *map = machine__kernel_map(machine); > > @@ -2687,14 +2691,11 @@ int machine__get_kernel_start(struct machine *machine) > > machine->kernel_start = 1ULL << 63; > > if (map) { > > err = map__load(map); > > - /* > > - * On x86_64, PTI entry trampolines are less than the > > - * start of kernel text, but still above 2^63. So leave > > - * kernel_start = 1ULL << 63 for x86_64. > > - */ > > - if (!err && !machine__is(machine, "x86_64")) > > + if (!err) > > machine->kernel_start = map->start; > > } > > + > > + arch__fix_kernel_text_start(&machine->kernel_start); > > return err; > > } > > > > diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h > > index ef803f08ae12..9cb459f4bfbc 100644 > > --- a/tools/perf/util/machine.h > > +++ b/tools/perf/util/machine.h > > @@ -278,6 +278,8 @@ void machine__get_kallsyms_filename(struct machine *machine, char *buf, > > int machine__create_extra_kernel_maps(struct machine *machine, > > struct dso *kernel); > > > > +void arch__fix_kernel_text_start(u64 *start); > > + > > /* Kernel-space maps for symbols that are outside the main kernel map and module maps */ > > struct extra_kernel_map { > > u64 start; > > >