[PATCH V6 21/26] coresight: etm-perf: new PMU driver for ETM tracers

Mathieu Poirier
2015-12-03T21:08:14Z

Perf is a well known and used tool for performance monitoring
and much more. A such it is an ideal candidate for integration
with coresight based HW tracing.

This patch introduces a PMU that represent a coresight tracer to
the Perf core.

Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/Makefile | 3 +-
drivers/hwtracing/coresight/coresight-etm-perf.c | 447 +++++++++++++++++++++++
drivers/hwtracing/coresight/coresight-etm-perf.h | 32 ++
drivers/hwtracing/coresight/coresight-etm3x.c | 7 +
include/linux/coresight-pmu.h | 27 ++
5 files changed, 515 insertions(+), 1 deletion(-)
create mode 100644 drivers/hwtracing/coresight/coresight-etm-perf.c
create mode 100644 drivers/hwtracing/coresight/coresight-etm-perf.h
create mode 100644 include/linux/coresight-pmu.h

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 233d66cf22d3..cf8c6d689747 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
coresight-replicator.o
obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o \
- coresight-etm3x-sysfs.o
+ coresight-etm3x-sysfs.o \
+ coresight-etm-perf.o
obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o
obj-$(CONFIG_CORESIGHT_QCOM_REPLICATOR) += coresight-replicator-qcom.o
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
new file mode 100644
index 000000000000..510780490ea9
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -0,0 +1,447 @@
+/*
+ * Copyright(C) 2015 Linaro Limited. All rights reserved.
+ * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/coresight.h>
+#include <linux/coresight-pmu.h>
+#include <linux/cpumask.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/perf_event.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "coresight-priv.h"
+
+static struct pmu etm_pmu;
+static bool etm_perf_up;
+
+/**
+ * struct etm_cpu_data - Coresight specifics accociated to a single CPU
+ * @src_config: The tracer configuration.
+ * @snk_config: The sink configuration.
+ * @patch: The path from source to sink.
+ */
+struct etm_cpu_data {
+ void *src_config;
+ void *snk_config;
+ struct list_head *path;
+};
+
+/**
+ * struct etm_event_data - Coresight specifics associated to an event
+ * @mask: Hold the CPU(s) this event was set for.
+ * @cpu_data: An array of cpu data, each slot for one CPU.
+ */
+struct etm_event_data {
+ cpumask_t mask;
+ struct etm_cpu_data **cpu_data;
+};
+
+static DEFINE_PER_CPU(struct perf_output_handle, ctx_handle);
+static DEFINE_PER_CPU(struct coresight_device *, csdev_src);
+
+/* ETMv3.5/PTM's ETMCR is 'config' */
+PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC));
+PMU_FORMAT_ATTR(timestamp, "config:" __stringify(ETM_OPT_TS));
+
+static struct attribute *etm_config_formats_attr[] = {
+ &format_attr_cycacc.attr,
+ &format_attr_timestamp.attr,
+ NULL,
+};
+
+static struct attribute_group etm_pmu_format_group = {
+ .name = "format",
+ .attrs = etm_config_formats_attr,
+};
+
+static const struct attribute_group *etm_pmu_attr_groups[] = {
+ &etm_pmu_format_group,
+ NULL,
+};
+
+static void etm_event_read(struct perf_event *event) {}
+
+static int etm_event_init(struct perf_event *event)
+{
+ if (event->attr.type != etm_pmu.type)
+ return -ENOENT;
+
+ if (event->cpu >= nr_cpu_ids)
+ return -EINVAL;
+
+ return 0;
+}
+
+static void free_cpu_data(int cpu, struct etm_cpu_data *cpu_data)
+{
+ struct coresight_device *sink, *csdev;
+
+ csdev = per_cpu(csdev_src, cpu);
+ if (!csdev)
+ return;
+
+ if (source_ops(csdev)->put_config)
+ source_ops(csdev)->put_config(cpu_data->src_config);
+
+ /* No need to continue if there isn't a path to work with */
+ if (!cpu_data->path)
+ return;
+
+ sink = coresight_get_sink(cpu_data->path);
+ if (sink_ops(sink)->put_config)
+ sink_ops(sink)->put_config(cpu_data->snk_config);
+
+ coresight_release_path(cpu_data->path);
+}
+
+static void free_event_data(struct etm_event_data *event_data)
+{
+ int cpu;
+ cpumask_t *mask = &event_data->mask;
+
+ for_each_cpu(cpu, mask) {
+ if (event_data->cpu_data[cpu])
+ free_cpu_data(cpu, event_data->cpu_data[cpu]);
+ kfree(event_data->cpu_data[cpu]);
+ }
+
+ kfree(event_data->cpu_data);
+ kfree(event_data);
+}
+
+static void *alloc_event_data(int cpu)
+{
+ int lcpu, size;
+ cpumask_t *mask;
+ struct etm_cpu_data *cpu_data;
+ struct etm_event_data *event_data;
+
+ /* First get memory for the session's data */
+ event_data = kzalloc(sizeof(struct etm_event_data), GFP_KERNEL);
+ if (!event_data)
+ return NULL;
+
+ /* Make sure nothing disappears under us */
+ get_online_cpus();
+ size = num_online_cpus();
+
+ mask = &event_data->mask;
+ if (cpu != -1)
+ cpumask_set_cpu(cpu, mask);
+ else
+ cpumask_copy(mask, cpu_online_mask);
+ put_online_cpus();
+
+ /*
+ * Allocate an array of cpu_data to work with. That array is mainly
+ * serving as a quick way of retrieving trace configuration data
+ * associated to each CPU by using the number of those CPUs as
+ * indexes. The expense of unused memory when dealing with single
+ * CPU trace scenarios is small compared to the search cost of
+ * using an optimized array size.
+ */
+ event_data->cpu_data = kcalloc(size,
+ sizeof(struct etm_cpu_data *),
+ GFP_KERNEL);
+ if (!event_data->cpu_data)
+ goto free_event_data;
+
+ /* Allocate a cpu_data for each CPU this event is dealing with */
+ for_each_cpu(lcpu, mask) {
+ cpu_data = kzalloc(sizeof(struct etm_cpu_data), GFP_KERNEL);
+ if (!cpu_data)
+ goto free_event_data;
+
+ event_data->cpu_data[lcpu] = cpu_data;
+ }
+
+out:
+ return event_data;
+
+free_event_data:
+ free_event_data(event_data);
+ event_data = NULL;
+
+ goto out;
+}
+
+static void *etm_setup_aux(struct perf_event *event, void **pages,
+ int nr_pages, bool overwrite)
+{
+ int cpu;
+ cpumask_t *mask;
+ struct etm_event_data *event_data = NULL;
+ struct coresight_device *csdev;
+
+ event_data = alloc_event_data(event->cpu);
+ if (!event_data)
+ return NULL;
+
+ mask = &event_data->mask;
+
+ for_each_cpu(cpu, mask) {
+ struct etm_cpu_data *cpu_data;
+ struct coresight_device *sink;
+
+ csdev = per_cpu(csdev_src, cpu);
+ if (!csdev)
+ goto err;
+
+ cpu_data = event_data->cpu_data[cpu];
+
+ /* Get the tracer's config from perf */
+ if (!source_ops(csdev)->get_config)
+ goto err;
+
+ /*
+ * Since CPUs can be associated with different tracers on the
+ * same SoC and that tracers have different ways of
+ * configuring trace options, parse and collect each CPU's
+ * configuration before the trace run starts. That way the
+ * parsing/processing of options happens only once and not
+ * on the fast path.
+ */
+ cpu_data->src_config =
+ source_ops(csdev)->get_config(csdev, event);
+ if (!cpu_data->src_config)
+ goto err;
+
+ /*
+ * Building a path doesn't enable it, it simply builds a
+ * list of devices from source to sink that can be
+ * referenced later when the path is actually needed.
+ */
+ cpu_data->path = coresight_build_path(csdev);
+ if (!cpu_data->path)
+ goto err;
+
+ /* Grab the sink at the end of the path */
+ sink = coresight_get_sink(cpu_data->path);
+ if (!sink)
+ goto err;
+
+ if (!sink_ops(sink)->get_config)
+ goto err;
+
+ /* Finally get the AUX specific data from the sink buffer */
+ cpu_data->snk_config =
+ sink_ops(sink)->get_config(sink, cpu, pages,
+ nr_pages, overwrite);
+ if (!cpu_data->snk_config)
+ goto err;
+
+ }
+
+out:
+ return event_data;
+
+err:
+ free_event_data(event_data);
+ event_data = NULL;
+ goto out;
+
+ return NULL;
+}
+
+static void etm_free_aux(void *data)
+{
+ free_event_data(data);
+}
+
+static void etm_event_stop(struct perf_event *event, int mode)
+{
+ bool lost;
+ int cpu = smp_processor_id();
+ unsigned long size;
+ struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
+ struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
+ struct etm_event_data *event_data = perf_get_aux(handle);
+ struct etm_cpu_data *cpu_data = event_data->cpu_data[cpu];
+
+ if (event->hw.state == PERF_HES_STOPPED)
+ return;
+
+ if (!csdev || !cpu_data)
+ return;
+
+ sink = coresight_get_sink(cpu_data->path);
+ if (!sink)
+ return;
+
+ /* stop tracer */
+ source_ops(csdev)->disable(csdev);
+
+ /* tell the core */
+ event->hw.state = PERF_HES_STOPPED;
+
+ if (mode & PERF_EF_UPDATE) {
+ if (WARN_ON_ONCE(handle->event != event))
+ return;
+
+ /* update trace information */
+ if (!sink_ops(sink)->update_buffer)
+ return;
+
+ sink_ops(sink)->update_buffer(sink, handle,
+ cpu_data->snk_config);
+
+ if (!sink_ops(sink)->reset_buffer)
+ return;
+
+ size = sink_ops(sink)->reset_buffer(sink, handle,
+ cpu_data->snk_config,
+ &lost);
+
+ perf_aux_output_end(handle, size, lost);
+ }
+
+ /* Disabling the path make its elements available to other sessions */
+ coresight_disable_path(cpu_data->path);
+}
+
+static void etm_event_start(struct perf_event *event, int flags)
+{
+ int cpu = smp_processor_id();
+ struct etm_cpu_data *cpu_data;
+ struct etm_event_data *event_data;
+ struct perf_output_handle *handle = this_cpu_ptr(&ctx_handle);
+ struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
+
+ if (!csdev)
+ goto fail;
+
+ /*
+ * Deal with the ring buffer API and get a handle on the
+ * session's information.
+ */
+ event_data = perf_aux_output_begin(handle, event);
+ if (WARN_ON_ONCE(!event_data))
+ goto fail;
+
+ /* Get the session information for this CPU */
+ cpu_data = event_data->cpu_data[cpu];
+
+ /* We need a sink, no need to continue without one */
+ sink = coresight_get_sink(cpu_data->path);
+ if (!sink || !sink_ops(sink)->set_buffer)
+ goto fail_end_stop;
+
+ /* Configure the sink */
+ if (sink_ops(sink)->set_buffer(sink, handle,
+ cpu_data->snk_config))
+ goto fail_end_stop;
+
+ if (!source_ops(csdev)->set_config)
+ goto fail_end_stop;
+
+ /* Configure the tracer */
+ source_ops(csdev)->set_config(csdev, cpu_data->src_config);
+
+ /* Nothing will happen without a path */
+ if (coresight_enable_path(cpu_data->path, CS_MODE_PERF))
+ goto fail_end_stop;
+
+ /* Tell the perf core the event is alive */
+ event->hw.state = 0;
+
+ /* Finally enable the tracer */
+ if (source_ops(csdev)->enable(csdev, CS_MODE_PERF))
+ goto fail_end_stop;
+
+out:
+ return;
+
+fail_end_stop:
+ perf_aux_output_end(handle, 0, true);
+fail:
+ event->hw.state = PERF_HES_STOPPED;
+ goto out;
+}
+
+static void etm_event_del(struct perf_event *event, int mode)
+{
+ etm_event_stop(event, PERF_EF_UPDATE);
+}
+
+static int etm_event_add(struct perf_event *event, int mode)
+{
+ int ret = 0;
+ struct hw_perf_event *hwc = &event->hw;
+
+ if (mode & PERF_EF_START) {
+ etm_event_start(event, 0);
+ if (hwc->state & PERF_HES_STOPPED)
+ ret = -EINVAL;
+ } else {
+ hwc->state = PERF_HES_STOPPED;
+ }
+
+ return ret;
+}
+
+int etm_perf_symlink(struct coresight_device *csdev, bool link)
+{
+ char entry[sizeof("cpu9999999")];
+ int ret = 0, cpu = source_ops(csdev)->cpu_id(csdev);
+ struct device *pmu_dev = etm_pmu.dev;
+ struct device *cs_dev = &csdev->dev;
+
+ sprintf(entry, "cpu%d", cpu);
+
+ if (!etm_perf_up)
+ return -EPROBE_DEFER;
+
+ if (link) {
+ ret = sysfs_create_link(&pmu_dev->kobj, &cs_dev->kobj, entry);
+ if (ret)
+ return ret;
+ per_cpu(csdev_src, cpu) = csdev;
+ } else {
+ sysfs_remove_link(&pmu_dev->kobj, entry);
+ per_cpu(csdev_src, cpu) = NULL;
+ }
+
+ return 0;
+}
+
+static int __init etm_perf_init(void)
+{
+ int ret;
+
+ etm_pmu.capabilities = PERF_PMU_CAP_EXCLUSIVE;
+
+ etm_pmu.attr_groups = etm_pmu_attr_groups;
+ etm_pmu.task_ctx_nr = perf_sw_context;
+ etm_pmu.read = etm_event_read;
+ etm_pmu.event_init = etm_event_init;
+ etm_pmu.setup_aux = etm_setup_aux;
+ etm_pmu.free_aux = etm_free_aux;
+ etm_pmu.stop = etm_event_stop;
+ etm_pmu.start = etm_event_start;
+ etm_pmu.del = etm_event_del;
+ etm_pmu.add = etm_event_add;
+
+ ret = perf_pmu_register(&etm_pmu, CORESIGHT_ETM_PMU_NAME, -1);
+ if (ret == 0)
+ etm_perf_up = true;
+
+ return ret;
+}
+module_init(etm_perf_init);
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h b/drivers/hwtracing/coresight/coresight-etm-perf.h
new file mode 100644
index 000000000000..87f5a134eb6f
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright(C) 2015 Linaro Limited. All rights reserved.
+ * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _CORESIGHT_ETM_PERF_H
+#define _CORESIGHT_ETM_PERF_H
+
+struct coresight_device;
+
+#ifdef CONFIG_CORESIGHT
+int etm_perf_symlink(struct coresight_device *csdev, bool link);
+
+#else
+static inline int etm_perf_symlink(struct coresight_device *csdev, bool link)
+{ return -EINVAL; }
+
+#endif /* CONFIG_CORESIGHT */
+
+#endif
diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index fbd04979e21c..6170df1b9e59 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -35,6 +35,7 @@
#include <asm/sections.h>

#include "coresight-etm.h"
+#include "coresight-etm-perf.h"

static int boot_enable;
module_param_named(boot_enable, boot_enable, int, S_IRUGO);
@@ -879,6 +880,12 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
goto err_arch_supported;
}

+ ret = etm_perf_symlink(drvdata->csdev, true);
+ if (ret) {
+ coresight_unregister(drvdata->csdev);
+ goto err_arch_supported;
+ }
+
pm_runtime_put(&adev->dev);
dev_info(dev, "%s initialized\n", (char *)id->data);

diff --git a/include/linux/coresight-pmu.h b/include/linux/coresight-pmu.h
new file mode 100644
index 000000000000..6c5386b23b10
--- /dev/null
+++ b/include/linux/coresight-pmu.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright(C) 2015 Linaro Limited. All rights reserved.
+ * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _LINUX_CORESIGHT_PMU_H
+#define _LINUX_CORESIGHT_PMU_H
+
+#define CORESIGHT_ETM_PMU_NAME "cs_etm"
+
+/* ETMv3.5/PTM's ETMCR config bit */
+#define ETM_OPT_CYCACC 12
+#define ETM_OPT_TS 28
+
+#endif
--
2.1.4