From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2 3/7] coresight: Use event attributes for sink selection References: <20190122181144.26645-1-mathieu.poirier@linaro.org> <20190122181144.26645-4-mathieu.poirier@linaro.org> From: Suzuki K Poulose Message-ID: <5ce969d1-847f-cc89-a074-1697e21ce6e5@arm.com> Date: Wed, 30 Jan 2019 17:49:12 +0000 MIME-Version: 1.0 In-Reply-To: <20190122181144.26645-4-mathieu.poirier@linaro.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org List-Archive: To: mathieu.poirier@linaro.org, acme@kernel.org, peterz@infradead.org Cc: mark.rutland@arm.com, linux-s390@vger.kernel.org, alexander.shishkin@linux.intel.com, gregkh@linuxfoundation.org, heiko.carstens@de.ibm.com, adrian.hunter@intel.com, will.deacon@arm.com, ast@kernel.org, mingo@redhat.com, linux-arm-kernel@lists.infradead.org, hpa@zytor.com, schwidefsky@de.ibm.com, namhyung@kernel.org, tglx@linutronix.de, jolsa@redhat.com, linux-kernel@vger.kernel.org List-ID: On 01/22/2019 06:11 PM, Mathieu Poirier wrote: > This patch uses the information conveyed by perf_event::attr::config2 > to select a sink to use for the session. That way a sink can easily be > selected to be used by more than one source, something that isn't currently > possible with the sysfs implementation. > > Signed-off-by: Mathieu Poirier > --- > .../hwtracing/coresight/coresight-etm-perf.c | 24 ++++++------ > drivers/hwtracing/coresight/coresight-priv.h | 1 + > drivers/hwtracing/coresight/coresight.c | 39 +++++++++++++++++++ > 3 files changed, 52 insertions(+), 12 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c > index c68a0036532c..ea031eb673b3 100644 > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c > @@ -31,11 +31,14 @@ static DEFINE_PER_CPU(struct coresight_device *, csdev_src); > PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC)); > PMU_FORMAT_ATTR(timestamp, "config:" __stringify(ETM_OPT_TS)); > PMU_FORMAT_ATTR(retstack, "config:" __stringify(ETM_OPT_RETSTK)); > +/* Sink ID - same for all ETMs */ > +PMU_FORMAT_ATTR(sinkid, "config2:0-31"); > > static struct attribute *etm_config_formats_attr[] = { > &format_attr_cycacc.attr, > &format_attr_timestamp.attr, > &format_attr_retstack.attr, > + &format_attr_sinkid.attr, > NULL, > }; > > @@ -191,6 +194,7 @@ static void etm_free_aux(void *data) > static void *etm_setup_aux(struct perf_event *event, void **pages, > int nr_pages, bool overwrite) > { > + u32 id; > int cpu = event->cpu; > cpumask_t *mask; > struct coresight_device *sink; > @@ -201,18 +205,14 @@ static void *etm_setup_aux(struct perf_event *event, void **pages, > return NULL; > INIT_WORK(&event_data->work, free_event_data); > > - /* > - * In theory nothing prevent tracers in a trace session from being > - * associated with different sinks, nor having a sink per tracer. But > - * until we have HW with this kind of topology we need to assume tracers > - * in a trace session are using the same sink. Therefore go through > - * the coresight bus and pick the first enabled sink. > - * > - * When operated from sysFS users are responsible to enable the sink > - * while from perf, the perf tools will do it based on the choice made > - * on the cmd line. As such the "enable_sink" flag in sysFS is reset. > - */ > - sink = coresight_get_enabled_sink(true); > + /* First get the selected sink from user space. */ > + if (event->attr.config2) { > + id = (u32)event->attr.config2; > + sink = coresight_get_sink_by_id(id); > + } else { > + sink = coresight_get_enabled_sink(true); > + } > + > if (!sink || !sink_ops(sink)->alloc_buffer) > goto err; > > diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h > index 579f34943bf1..b936c6d7e13f 100644 > --- a/drivers/hwtracing/coresight/coresight-priv.h > +++ b/drivers/hwtracing/coresight/coresight-priv.h > @@ -147,6 +147,7 @@ void coresight_disable_path(struct list_head *path); > int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data); > struct coresight_device *coresight_get_sink(struct list_head *path); > struct coresight_device *coresight_get_enabled_sink(bool reset); > +struct coresight_device *coresight_get_sink_by_id(u32 id); > struct list_head *coresight_build_path(struct coresight_device *csdev, > struct coresight_device *sink); > void coresight_release_path(struct list_head *path); > diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c > index d7fa90be6f42..c5f2df186a19 100644 > --- a/drivers/hwtracing/coresight/coresight.c > +++ b/drivers/hwtracing/coresight/coresight.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -541,6 +542,44 @@ struct coresight_device *coresight_get_enabled_sink(bool deactivate) > return dev ? to_coresight_device(dev) : NULL; > } > > +static int coresight_sink_by_id(struct device *dev, void *data) > +{ > + struct coresight_device *csdev = to_coresight_device(dev); > + u32 hash; > + > + if (csdev->type == CORESIGHT_DEV_TYPE_SINK || > + csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) { > + /* > + * See function etm_perf_sink_name_show() to know where this > + * comes from. > + */ > + hash = hashlen_hash(hashlen_string(NULL, dev_name(dev))); > + > + if (hash == (*(u32 *)data)) > + return 1; > + } > + > + return 0; > +} > + > +/** > + * coresight_get_sink_by_id - returns the sink that matches the id > + * @id: Id of the sink to match > + * > + * The name of a sink is unique, whether it is found on the AMBA bus or > + * otherwise. As such the hash of that name can easily be used to identify > + * a sink. > + */ > +struct coresight_device *coresight_get_sink_by_id(u32 id) > +{ > + struct device *dev = NULL; > + > + dev = bus_find_device(&coresight_bustype, NULL, &id, > + coresight_sink_by_id); > + > + return dev ? to_coresight_device(dev) : NULL; > +} > + The patch looks good to me. As mentioned in the previous patch, we may be able to optimize the look up a bit using dev_ext_attribute. Either way, Reviewed-by: Suzuki K Poulose _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel