diff mbox

[RESEND,2/2] perf tools: adding coresight etm PMU record capabilities

Message ID 1466182922-14426-3-git-send-email-mathieu.poirier@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Mathieu Poirier June 17, 2016, 5:02 p.m. UTC
Coresight ETMs are IP blocks used to perform HW assisted tracing
on a CPU core.  This patch introduce the required auxiliary API
functions allowing the perf core to interact with a tracer.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 MAINTAINERS                         |   3 +
 tools/perf/arch/arm/util/Build      |   2 +-
 tools/perf/arch/arm/util/auxtrace.c |  54 ++++
 tools/perf/arch/arm/util/cs-etm.c   | 559 ++++++++++++++++++++++++++++++++++++
 tools/perf/arch/arm/util/cs-etm.h   |  23 ++
 tools/perf/arch/arm64/util/Build    |   4 +
 tools/perf/util/auxtrace.c          |   1 +
 tools/perf/util/auxtrace.h          |   1 +
 tools/perf/util/cs-etm.h            |  74 +++++
 9 files changed, 720 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/arch/arm/util/auxtrace.c
 create mode 100644 tools/perf/arch/arm/util/cs-etm.c
 create mode 100644 tools/perf/arch/arm/util/cs-etm.h
 create mode 100644 tools/perf/util/cs-etm.h

Comments

Adrian Hunter July 13, 2016, 11:40 a.m. UTC | #1
On 17/06/16 20:02, Mathieu Poirier wrote:
> Coresight ETMs are IP blocks used to perform HW assisted tracing
> on a CPU core.  This patch introduce the required auxiliary API
> functions allowing the perf core to interact with a tracer.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
>  MAINTAINERS                         |   3 +
>  tools/perf/arch/arm/util/Build      |   2 +-
>  tools/perf/arch/arm/util/auxtrace.c |  54 ++++
>  tools/perf/arch/arm/util/cs-etm.c   | 559 ++++++++++++++++++++++++++++++++++++
>  tools/perf/arch/arm/util/cs-etm.h   |  23 ++
>  tools/perf/arch/arm64/util/Build    |   4 +
>  tools/perf/util/auxtrace.c          |   1 +
>  tools/perf/util/auxtrace.h          |   1 +
>  tools/perf/util/cs-etm.h            |  74 +++++
>  9 files changed, 720 insertions(+), 1 deletion(-)
>  create mode 100644 tools/perf/arch/arm/util/auxtrace.c
>  create mode 100644 tools/perf/arch/arm/util/cs-etm.c
>  create mode 100644 tools/perf/arch/arm/util/cs-etm.h
>  create mode 100644 tools/perf/util/cs-etm.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index d3451007718b..4fa03b03bfc5 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1086,6 +1086,9 @@ F:	Documentation/trace/coresight.txt
>  F:	Documentation/devicetree/bindings/arm/coresight.txt
>  F:	Documentation/ABI/testing/sysfs-bus-coresight-devices-*
>  F:	tools/perf/arch/arm/util/pmu.c
> +F:	tools/perf/arch/arm/util/auxtrace.c
> +F:	tools/perf/arch/arm/util/cs_etm.c
> +F:	tools/perf/arch/arm/util/cs_etm.h

File names have changed from having '_' to '-'
Also FWIW there is now tools/perf/util/cs-etm.h

As last time, there is no decoder, which still begs the question: is there
anything you can actually do with the perf.data file?

Otherwise:

Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Mathieu Poirier July 13, 2016, 3:11 p.m. UTC | #2
On 13 July 2016 at 05:40, Adrian Hunter <adrian.hunter@intel.com> wrote:
> On 17/06/16 20:02, Mathieu Poirier wrote:
>> Coresight ETMs are IP blocks used to perform HW assisted tracing
>> on a CPU core.  This patch introduce the required auxiliary API
>> functions allowing the perf core to interact with a tracer.
>>
>> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>> ---
>>  MAINTAINERS                         |   3 +
>>  tools/perf/arch/arm/util/Build      |   2 +-
>>  tools/perf/arch/arm/util/auxtrace.c |  54 ++++
>>  tools/perf/arch/arm/util/cs-etm.c   | 559 ++++++++++++++++++++++++++++++++++++
>>  tools/perf/arch/arm/util/cs-etm.h   |  23 ++
>>  tools/perf/arch/arm64/util/Build    |   4 +
>>  tools/perf/util/auxtrace.c          |   1 +
>>  tools/perf/util/auxtrace.h          |   1 +
>>  tools/perf/util/cs-etm.h            |  74 +++++
>>  9 files changed, 720 insertions(+), 1 deletion(-)
>>  create mode 100644 tools/perf/arch/arm/util/auxtrace.c
>>  create mode 100644 tools/perf/arch/arm/util/cs-etm.c
>>  create mode 100644 tools/perf/arch/arm/util/cs-etm.h
>>  create mode 100644 tools/perf/util/cs-etm.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index d3451007718b..4fa03b03bfc5 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -1086,6 +1086,9 @@ F:      Documentation/trace/coresight.txt
>>  F:   Documentation/devicetree/bindings/arm/coresight.txt
>>  F:   Documentation/ABI/testing/sysfs-bus-coresight-devices-*
>>  F:   tools/perf/arch/arm/util/pmu.c
>> +F:   tools/perf/arch/arm/util/auxtrace.c
>> +F:   tools/perf/arch/arm/util/cs_etm.c
>> +F:   tools/perf/arch/arm/util/cs_etm.h
>
> File names have changed from having '_' to '-'

Yes, I will change that.

> Also FWIW there is now tools/perf/util/cs-etm.h

Ok

>
> As last time, there is no decoder, which still begs the question: is there
> anything you can actually do with the perf.data file?

We are proceeding incrementally - this is only the first set in a
suite of upcoming submission.  The whole solution can be found here
[1] and the decoding library, called OpenCSD, here [2].  File
"HOWTO.md" in the latter details how to compile the components in
order to build a working environment.

>
> Otherwise:
>
> Acked-by: Adrian Hunter <adrian.hunter@intel.com>
>

Thanks for your time,
Mathieu

[1]. https://github.com/Linaro/OpenCSD/commits/perf-opencsd-4.7-rc4
[2]. https://github.com/Linaro/OpenCSD/tree/opencsd-0v003
Arnaldo Carvalho de Melo July 13, 2016, 3:15 p.m. UTC | #3
Em Wed, Jul 13, 2016 at 09:11:46AM -0600, Mathieu Poirier escreveu:
> [1]. https://github.com/Linaro/OpenCSD/commits/perf-opencsd-4.7-rc4
> [2]. https://github.com/Linaro/OpenCSD/tree/opencsd-0v003

https://github.com/Linaro/OpenCSD/tree/opencsd-0v003 points to:

How the Library is used in Linux perf

The library and additional infrastructure for programming CoreSight
components has been integrated with the standard linux perfomance
analysis tool perf.

See HOWTO.md for details.

------------------------

But the HOWTO.md link gives me a 404 :-\

https://github.com/Linaro/OpenCSD/blob/opencsd-0v003/@ref%20howto_perf

- Arnaldo
Mathieu Poirier July 13, 2016, 5:23 p.m. UTC | #4
On 13 July 2016 at 09:15, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> Em Wed, Jul 13, 2016 at 09:11:46AM -0600, Mathieu Poirier escreveu:
>> [1]. https://github.com/Linaro/OpenCSD/commits/perf-opencsd-4.7-rc4
>> [2]. https://github.com/Linaro/OpenCSD/tree/opencsd-0v003
>
> https://github.com/Linaro/OpenCSD/tree/opencsd-0v003 points to:
>
> How the Library is used in Linux perf
>
> The library and additional infrastructure for programming CoreSight
> components has been integrated with the standard linux perfomance
> analysis tool perf.
>
> See HOWTO.md for details.
>
> ------------------------
>
> But the HOWTO.md link gives me a 404 :-\
>
> https://github.com/Linaro/OpenCSD/blob/opencsd-0v003/@ref%20howto_perf

Apologies for that.  This here will work:

https://github.com/Linaro/OpenCSD/blob/opencsd-0v003/HOWTO.md

I will do a respin of the patchset with Adrian' comments taken into account.

>
> - Arnaldo
diff mbox

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index d3451007718b..4fa03b03bfc5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1086,6 +1086,9 @@  F:	Documentation/trace/coresight.txt
 F:	Documentation/devicetree/bindings/arm/coresight.txt
 F:	Documentation/ABI/testing/sysfs-bus-coresight-devices-*
 F:	tools/perf/arch/arm/util/pmu.c
+F:	tools/perf/arch/arm/util/auxtrace.c
+F:	tools/perf/arch/arm/util/cs_etm.c
+F:	tools/perf/arch/arm/util/cs_etm.h
 
 ARM/CORGI MACHINE SUPPORT
 M:	Richard Purdie <rpurdie@rpsys.net>
diff --git a/tools/perf/arch/arm/util/Build b/tools/perf/arch/arm/util/Build
index 66ab0b05549c..71de3fc40502 100644
--- a/tools/perf/arch/arm/util/Build
+++ b/tools/perf/arch/arm/util/Build
@@ -3,4 +3,4 @@  libperf-$(CONFIG_DWARF) += dwarf-regs.o
 libperf-$(CONFIG_LIBUNWIND)          += unwind-libunwind.o
 libperf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
 
-libperf-$(CONFIG_AUXTRACE) += pmu.o
+libperf-$(CONFIG_AUXTRACE) += pmu.o auxtrace.o cs-etm.o
diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c
new file mode 100644
index 000000000000..95c38b683159
--- /dev/null
+++ b/tools/perf/arch/arm/util/auxtrace.c
@@ -0,0 +1,54 @@ 
+/*
+ * 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 <stdbool.h>
+#include <linux/coresight-pmu.h>
+
+#include "../../util/auxtrace.h"
+#include "../../util/evlist.h"
+#include "../../util/pmu.h"
+#include "cs-etm.h"
+
+struct auxtrace_record
+*auxtrace_record__init(struct perf_evlist *evlist, int *err)
+{
+	struct perf_pmu	*cs_etm_pmu;
+	struct perf_evsel *evsel;
+	bool found_etm = false;
+
+	cs_etm_pmu = perf_pmu__find(CORESIGHT_ETM_PMU_NAME);
+
+	if (evlist) {
+		evlist__for_each(evlist, evsel) {
+			if (cs_etm_pmu &&
+			    evsel->attr.type == cs_etm_pmu->type)
+				found_etm = true;
+		}
+	}
+
+	if (found_etm)
+		return cs_etm_record_init(err);
+
+	/*
+	 * Clear 'err' even if we haven't found a cs_etm event - that way perf
+	 * record can still be used even if tracers aren't present.  The NULL
+	 * return value will take care of telling the infrastructure HW tracing
+	 * isn't available.
+	 */
+	*err = 0;
+	return NULL;
+}
diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
new file mode 100644
index 000000000000..57f488f59438
--- /dev/null
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -0,0 +1,559 @@ 
+/*
+ * 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 <api/fs/fs.h>
+#include <linux/bitops.h>
+#include <linux/coresight-pmu.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/types.h>
+
+#include "cs-etm.h"
+#include "../../perf.h"
+#include "../../util/auxtrace.h"
+#include "../../util/cpumap.h"
+#include "../../util/evlist.h"
+#include "../../util/pmu.h"
+#include "../../util/thread_map.h"
+#include "../../util/cs-etm.h"
+
+#include <stdlib.h>
+
+struct cs_etm_recording {
+	struct auxtrace_record	itr;
+	struct perf_pmu		*cs_etm_pmu;
+	struct perf_evlist	*evlist;
+	bool			snapshot_mode;
+	size_t			snapshot_size;
+};
+
+static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu);
+
+static int cs_etm_parse_snapshot_options(struct auxtrace_record *itr,
+					 struct record_opts *opts,
+					 const char *str)
+{
+	struct cs_etm_recording *ptr =
+				container_of(itr, struct cs_etm_recording, itr);
+	unsigned long long snapshot_size = 0;
+	char *endptr;
+
+	if (str) {
+		snapshot_size = strtoull(str, &endptr, 0);
+		if (*endptr || snapshot_size > SIZE_MAX)
+			return -1;
+	}
+
+	opts->auxtrace_snapshot_mode = true;
+	opts->auxtrace_snapshot_size = snapshot_size;
+	ptr->snapshot_size = snapshot_size;
+
+	return 0;
+}
+
+static int cs_etm_recording_options(struct auxtrace_record *itr,
+				    struct perf_evlist *evlist,
+				    struct record_opts *opts)
+{
+	struct cs_etm_recording *ptr =
+				container_of(itr, struct cs_etm_recording, itr);
+	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
+	struct perf_evsel *evsel, *cs_etm_evsel = NULL;
+	const struct cpu_map *cpus = evlist->cpus;
+	bool privileged = (geteuid() == 0 || perf_event_paranoid() < 0);
+
+	ptr->evlist = evlist;
+	ptr->snapshot_mode = opts->auxtrace_snapshot_mode;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->attr.type == cs_etm_pmu->type) {
+			if (cs_etm_evsel) {
+				pr_err("There may be only one %s event\n",
+				       CORESIGHT_ETM_PMU_NAME);
+				return -EINVAL;
+			}
+			evsel->attr.freq = 0;
+			evsel->attr.sample_period = 1;
+			cs_etm_evsel = evsel;
+			opts->full_auxtrace = true;
+		}
+	}
+
+	/* no need to continue if at least one event of interest was found */
+	if (!cs_etm_evsel)
+		return 0;
+
+	if (opts->use_clockid) {
+		pr_err("Cannot use clockid (-k option) with %s\n",
+		       CORESIGHT_ETM_PMU_NAME);
+		return -EINVAL;
+	}
+
+	/* we are in snapshot mode */
+	if (opts->auxtrace_snapshot_mode) {
+		/*
+		 * No size were given to '-S' or '-m,', so go with
+		 * the default
+		 */
+		if (!opts->auxtrace_snapshot_size &&
+		    !opts->auxtrace_mmap_pages) {
+			if (privileged) {
+				opts->auxtrace_mmap_pages = MiB(4) / page_size;
+			} else {
+				opts->auxtrace_mmap_pages =
+							KiB(128) / page_size;
+				if (opts->mmap_pages == UINT_MAX)
+					opts->mmap_pages = KiB(256) / page_size;
+			}
+		} else if (!opts->auxtrace_mmap_pages && !privileged &&
+						opts->mmap_pages == UINT_MAX) {
+			opts->mmap_pages = KiB(256) / page_size;
+		}
+
+		/*
+		 * '-m,xyz' was specified but no snapshot size, so make the
+		 * snapshot size as big as the auxtrace mmap area.
+		 */
+		if (!opts->auxtrace_snapshot_size) {
+			opts->auxtrace_snapshot_size =
+				opts->auxtrace_mmap_pages * (size_t)page_size;
+		}
+
+		/*
+		 * -Sxyz was specified but no auxtrace mmap area, so make the
+		 * auxtrace mmap area big enough to fit the requested snapshot
+		 * size.
+		 */
+		if (!opts->auxtrace_mmap_pages) {
+			size_t sz = opts->auxtrace_snapshot_size;
+
+			sz = round_up(sz, page_size) / page_size;
+			opts->auxtrace_mmap_pages = roundup_pow_of_two(sz);
+		}
+
+		/* Snapshost size can't be bigger than the auxtrace area */
+		if (opts->auxtrace_snapshot_size >
+				opts->auxtrace_mmap_pages * (size_t)page_size) {
+			pr_err("Snapshot size %zu must not be greater than AUX area tracing mmap size %zu\n",
+			       opts->auxtrace_snapshot_size,
+			       opts->auxtrace_mmap_pages * (size_t)page_size);
+			return -EINVAL;
+		}
+
+		/* Something went wrong somewhere - this shouldn't happen */
+		if (!opts->auxtrace_snapshot_size ||
+		    !opts->auxtrace_mmap_pages) {
+			pr_err("Failed to calculate default snapshot size and/or AUX area tracing mmap pages\n");
+			return -EINVAL;
+		}
+	}
+
+	/* We are in full trace mode but '-m,xyz' wasn't specified */
+	if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) {
+		if (privileged) {
+			opts->auxtrace_mmap_pages = MiB(4) / page_size;
+		} else {
+			opts->auxtrace_mmap_pages = KiB(128) / page_size;
+			if (opts->mmap_pages == UINT_MAX)
+				opts->mmap_pages = KiB(256) / page_size;
+		}
+
+	}
+
+	/* Validate auxtrace_mmap_pages provided by user */
+	if (opts->auxtrace_mmap_pages) {
+		unsigned int max_page = (KiB(128) / page_size);
+		size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
+
+		if (!privileged &&
+		    opts->auxtrace_mmap_pages > max_page) {
+			opts->auxtrace_mmap_pages = max_page;
+			pr_err("auxtrace too big, truncating to %d\n",
+			       max_page);
+		}
+
+		if (!is_power_of_2(sz)) {
+			pr_err("Invalid mmap size for %s: must be a power of 2\n",
+			       CORESIGHT_ETM_PMU_NAME);
+			return -EINVAL;
+		}
+	}
+
+	if (opts->auxtrace_snapshot_mode)
+		pr_debug2("%s snapshot size: %zu\n", CORESIGHT_ETM_PMU_NAME,
+			  opts->auxtrace_snapshot_size);
+
+	if (cs_etm_evsel) {
+		/*
+		 * To obtain the auxtrace buffer file descriptor, the auxtrace
+		 * event must come first.
+		 */
+		perf_evlist__to_front(evlist, cs_etm_evsel);
+		/*
+		 * In the case of per-cpu mmaps, we need the CPU on the
+		 * AUX event.
+		 */
+		if (!cpu_map__empty(cpus))
+			perf_evsel__set_sample_bit(cs_etm_evsel, CPU);
+	}
+
+	/* Add dummy event to keep tracking */
+	if (opts->full_auxtrace) {
+		struct perf_evsel *tracking_evsel;
+		int err;
+
+		err = parse_events(evlist, "dummy:u", NULL);
+		if (err)
+			return err;
+
+		tracking_evsel = perf_evlist__last(evlist);
+		perf_evlist__set_tracking_event(evlist, tracking_evsel);
+
+		tracking_evsel->attr.freq = 0;
+		tracking_evsel->attr.sample_period = 1;
+
+		/* In per-cpu case, always need the time of mmap events etc */
+		if (!cpu_map__empty(cpus))
+			perf_evsel__set_sample_bit(tracking_evsel, TIME);
+	}
+
+	return 0;
+}
+
+static u64 cs_etm_get_config(struct auxtrace_record *itr)
+{
+	u64 config = 0;
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
+	struct perf_evlist *evlist = ptr->evlist;
+	struct perf_evsel *evsel;
+
+	evlist__for_each(evlist, evsel) {
+		if (evsel->attr.type == cs_etm_pmu->type) {
+			/*
+			 * Variable perf_event_attr::config is assigned to
+			 * ETMv3/PTM.  The bit fields have been made to match
+			 * the ETMv3.5 ETRMCR register specification.  See the
+			 * PMU_FORMAT_ATTR() declarations in
+			 * drivers/hwtracing/coresight/coresight-perf.c for
+			 * details.
+			 */
+			config = evsel->attr.config;
+			break;
+		}
+	}
+
+	return config;
+}
+
+static size_t
+cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
+		      struct perf_evlist *evlist __maybe_unused)
+{
+	int i;
+	int etmv3 = 0, etmv4 = 0;
+	const struct cpu_map *cpus = evlist->cpus;
+
+	/* cpu map is not empty, we have specific CPUs to work with */
+	if (!cpu_map__empty(cpus)) {
+		for (i = 0; i < cpu_map__nr(cpus); i++) {
+			if (cs_etm_is_etmv4(itr, cpus->map[i]))
+				etmv4++;
+			else
+				etmv3++;
+		}
+	} else {
+		/* get configuration for all CPUs in the system */
+		for (i = 0; i < cpu__max_cpu(); i++) {
+			if (cs_etm_is_etmv4(itr, i))
+				etmv4++;
+			else
+				etmv3++;
+		}
+	}
+
+	return (CS_ETM_HEADER_SIZE +
+	       (etmv4 * CS_ETMV4_PRIV_SIZE) +
+	       (etmv3 * CS_ETMV3_PRIV_SIZE));
+}
+
+static const char *metadata_etmv3_ro[CS_ETM_PRIV_MAX] = {
+	[CS_ETM_ETMCCER]	= "mgmt/etmccer",
+	[CS_ETM_ETMIDR]		= "mgmt/etmidr",
+};
+
+static const char *metadata_etmv4_ro[CS_ETMV4_PRIV_MAX] = {
+	[CS_ETMV4_TRCIDR0]		= "trcidr/trcidr0",
+	[CS_ETMV4_TRCIDR1]		= "trcidr/trcidr1",
+	[CS_ETMV4_TRCIDR2]		= "trcidr/trcidr2",
+	[CS_ETMV4_TRCIDR8]		= "trcidr/trcidr8",
+	[CS_ETMV4_TRCAUTHSTATUS]	= "mgmt/trcauthstatus",
+};
+
+static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
+{
+	bool ret = false;
+	char path[PATH_MAX];
+	int scan;
+	unsigned int val;
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
+
+	/* Take any of the RO files for ETMv4 and see if it present */
+	snprintf(path, PATH_MAX, "cpu%d/%s",
+		 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
+	scan = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);
+
+	/* The file was read successfully, we have a winner */
+	if (scan == 1)
+		ret = true;
+
+	return ret;
+}
+
+static int cs_etm_get_ro(struct perf_pmu *pmu, int cpu, const char *path)
+{
+	char pmu_path[PATH_MAX];
+	int scan;
+	unsigned int val = 0;
+
+	/* Get RO metadata from sysfs */
+	snprintf(pmu_path, PATH_MAX, "cpu%d/%s", cpu, path);
+
+	scan = perf_pmu__scan_file(pmu, pmu_path, "%x", &val);
+	if (scan != 1)
+		pr_err("%s: error reading: %s\n", __func__, pmu_path);
+
+	return val;
+}
+
+static void cs_etm_get_metadata(int cpu, u32 *offset,
+				struct auxtrace_record *itr,
+				struct auxtrace_info_event *info)
+{
+	u32 increment;
+	u64 magic;
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
+
+	/* first see what kind of tracer this cpu is affined to */
+	if (cs_etm_is_etmv4(itr, cpu)) {
+		magic = __perf_cs_etmv4_magic;
+		/* Get trace configuration register */
+		info->priv[*offset + CS_ETMV4_TRCCONFIGR] =
+						cs_etm_get_config(itr);
+		/* Get traceID from the framework */
+		info->priv[*offset + CS_ETMV4_TRCTRACEIDR] =
+						coresight_get_trace_id(cpu);
+		/* Get read-only information from sysFS */
+		info->priv[*offset + CS_ETMV4_TRCIDR0] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
+		info->priv[*offset + CS_ETMV4_TRCIDR1] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv4_ro[CS_ETMV4_TRCIDR1]);
+		info->priv[*offset + CS_ETMV4_TRCIDR2] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv4_ro[CS_ETMV4_TRCIDR2]);
+		info->priv[*offset + CS_ETMV4_TRCIDR8] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv4_ro[CS_ETMV4_TRCIDR8]);
+		info->priv[*offset + CS_ETMV4_TRCAUTHSTATUS] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv4_ro
+				      [CS_ETMV4_TRCAUTHSTATUS]);
+
+		/* How much space was used */
+		increment = CS_ETMV4_PRIV_MAX;
+	} else {
+		magic = __perf_cs_etmv3_magic;
+		/* Get configuration register */
+		info->priv[*offset + CS_ETM_ETMCR] = cs_etm_get_config(itr);
+		/* Get traceID from the framework */
+		info->priv[*offset + CS_ETM_ETMTRACEIDR] =
+						coresight_get_trace_id(cpu);
+		/* Get read-only information from sysFS */
+		info->priv[*offset + CS_ETM_ETMCCER] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv3_ro[CS_ETM_ETMCCER]);
+		info->priv[*offset + CS_ETM_ETMIDR] =
+			cs_etm_get_ro(cs_etm_pmu, cpu,
+				      metadata_etmv3_ro[CS_ETM_ETMIDR]);
+
+		/* How much space was used */
+		increment = CS_ETM_PRIV_MAX;
+	}
+
+	/* Build generic header portion */
+	info->priv[*offset + CS_ETM_MAGIC] = magic;
+	info->priv[*offset + CS_ETM_CPU] = cpu;
+	/* Where the next CPU entry should start from */
+	*offset += increment;
+}
+
+static int cs_etm_info_fill(struct auxtrace_record *itr,
+			    struct perf_session *session,
+			    struct auxtrace_info_event *info,
+			    size_t priv_size)
+{
+	int i;
+	u32 offset;
+	u64 nr_cpu, type;
+	const struct cpu_map *cpus = session->evlist->cpus;
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
+
+	if (priv_size != cs_etm_info_priv_size(itr, session->evlist))
+		return -EINVAL;
+
+	if (!session->evlist->nr_mmaps)
+		return -EINVAL;
+
+	/* If the cpu_map is empty all CPUs are involved */
+	nr_cpu = cpu_map__empty(cpus) ? cpu__max_cpu() : cpu_map__nr(cpus);
+	/* Get PMU type as dynamically assigned by the core */
+	type = cs_etm_pmu->type;
+
+	/* First fill out the session header */
+	info->type = PERF_AUXTRACE_CS_ETM;
+	info->priv[CS_HEADER_VERSION_0] = 0;
+	info->priv[CS_PMU_TYPE_CPUS] = type << 32;
+	info->priv[CS_PMU_TYPE_CPUS] |= nr_cpu;
+	info->priv[CS_ETM_SNAPSHOT] = ptr->snapshot_mode;
+
+	offset = CS_ETM_SNAPSHOT + 1;
+
+	/* cpu map is not empty, we have specific CPUs to work with */
+	if (!cpu_map__empty(cpus)) {
+		for (i = 0; i < cpu_map__nr(cpus) && offset < priv_size; i++)
+			cs_etm_get_metadata(cpus->map[i], &offset, itr, info);
+	} else {
+		/* get configuration for all CPUs in the system */
+		for (i = 0; i < cpu__max_cpu(); i++)
+			cs_etm_get_metadata(i, &offset, itr, info);
+	}
+
+	return 0;
+}
+
+static int cs_etm_find_snapshot(struct auxtrace_record *itr __maybe_unused,
+				int idx, struct auxtrace_mmap *mm,
+				unsigned char *data __maybe_unused,
+				u64 *head, u64 *old)
+{
+	pr_debug3("%s: mmap index %d old head %zu new head %zu size %zu\n",
+		  __func__, idx, (size_t)*old, (size_t)*head, mm->len);
+
+	*old = *head;
+	*head += mm->len;
+
+	return 0;
+}
+
+static int cs_etm_snapshot_start(struct auxtrace_record *itr)
+{
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->cs_etm_pmu->type)
+			return perf_evsel__disable(evsel);
+	}
+	return -EINVAL;
+}
+
+static int cs_etm_snapshot_finish(struct auxtrace_record *itr)
+{
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->cs_etm_pmu->type)
+			return perf_evsel__enable(evsel);
+	}
+	return -EINVAL;
+}
+
+static u64 cs_etm_reference(struct auxtrace_record *itr __maybe_unused)
+{
+	return (((u64) rand() <<  0) & 0x00000000FFFFFFFFull) |
+		(((u64) rand() << 32) & 0xFFFFFFFF00000000ull);
+}
+
+static void cs_etm_recording_free(struct auxtrace_record *itr)
+{
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	free(ptr);
+}
+
+static int cs_etm_read_finish(struct auxtrace_record *itr, int idx)
+{
+	struct cs_etm_recording *ptr =
+			container_of(itr, struct cs_etm_recording, itr);
+	struct perf_evsel *evsel;
+
+	evlist__for_each(ptr->evlist, evsel) {
+		if (evsel->attr.type == ptr->cs_etm_pmu->type)
+			return perf_evlist__enable_event_idx(ptr->evlist,
+							     evsel, idx);
+	}
+
+	return -EINVAL;
+}
+
+struct auxtrace_record *cs_etm_record_init(int *err)
+{
+	struct perf_pmu *cs_etm_pmu;
+	struct cs_etm_recording *ptr;
+
+	cs_etm_pmu = perf_pmu__find(CORESIGHT_ETM_PMU_NAME);
+
+	if (!cs_etm_pmu) {
+		*err = -EINVAL;
+		goto out;
+	}
+
+	ptr = zalloc(sizeof(struct cs_etm_recording));
+	if (!ptr) {
+		*err = -ENOMEM;
+		goto out;
+	}
+
+	ptr->cs_etm_pmu			= cs_etm_pmu;
+	ptr->itr.parse_snapshot_options	= cs_etm_parse_snapshot_options;
+	ptr->itr.recording_options	= cs_etm_recording_options;
+	ptr->itr.info_priv_size		= cs_etm_info_priv_size;
+	ptr->itr.info_fill		= cs_etm_info_fill;
+	ptr->itr.find_snapshot		= cs_etm_find_snapshot;
+	ptr->itr.snapshot_start		= cs_etm_snapshot_start;
+	ptr->itr.snapshot_finish	= cs_etm_snapshot_finish;
+	ptr->itr.reference		= cs_etm_reference;
+	ptr->itr.free			= cs_etm_recording_free;
+	ptr->itr.read_finish		= cs_etm_read_finish;
+
+	*err = 0;
+	return &ptr->itr;
+out:
+	return NULL;
+}
diff --git a/tools/perf/arch/arm/util/cs-etm.h b/tools/perf/arch/arm/util/cs-etm.h
new file mode 100644
index 000000000000..909f486d02d1
--- /dev/null
+++ b/tools/perf/arch/arm/util/cs-etm.h
@@ -0,0 +1,23 @@ 
+/*
+ * 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 INCLUDE__PERF_CS_ETM_H__
+#define INCLUDE__PERF_CS_ETM_H__
+
+struct auxtrace_record *cs_etm_record_init(int *err);
+
+#endif
diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
index e58123a8912b..f92918154fec 100644
--- a/tools/perf/arch/arm64/util/Build
+++ b/tools/perf/arch/arm64/util/Build
@@ -1,2 +1,6 @@ 
 libperf-$(CONFIG_DWARF)     += dwarf-regs.o
 libperf-$(CONFIG_LIBUNWIND) += unwind-libunwind.o
+
+libperf-$(CONFIG_AUXTRACE) += ../../arm/util/pmu.o \
+			      ../../arm/util/auxtrace.o \
+			      ../../arm/util/cs-etm.o
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index c9169011e55e..c0aba8e839aa 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -892,6 +892,7 @@  int perf_event__process_auxtrace_info(struct perf_tool *tool __maybe_unused,
 		return intel_pt_process_auxtrace_info(event, session);
 	case PERF_AUXTRACE_INTEL_BTS:
 		return intel_bts_process_auxtrace_info(event, session);
+	case PERF_AUXTRACE_CS_ETM:
 	case PERF_AUXTRACE_UNKNOWN:
 	default:
 		return -EINVAL;
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 767989e0e312..d62ec4b262b0 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -41,6 +41,7 @@  enum auxtrace_type {
 	PERF_AUXTRACE_UNKNOWN,
 	PERF_AUXTRACE_INTEL_PT,
 	PERF_AUXTRACE_INTEL_BTS,
+	PERF_AUXTRACE_CS_ETM,
 };
 
 enum itrace_period_type {
diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
new file mode 100644
index 000000000000..3cc6bc3263fe
--- /dev/null
+++ b/tools/perf/util/cs-etm.h
@@ -0,0 +1,74 @@ 
+/*
+ * 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 INCLUDE__UTIL_PERF_CS_ETM_H__
+#define INCLUDE__UTIL_PERF_CS_ETM_H__
+
+/* Versionning header in case things need tro change in the future.  That way
+ * decoding of old snapshot is still possible.
+ */
+enum {
+	/* Starting with 0x0 */
+	CS_HEADER_VERSION_0,
+	/* PMU->type (32 bit), total # of CPUs (32 bit) */
+	CS_PMU_TYPE_CPUS,
+	CS_ETM_SNAPSHOT,
+	CS_HEADER_VERSION_0_MAX,
+};
+
+/* Beginning of header common to both ETMv3 and V4 */
+enum {
+	CS_ETM_MAGIC,
+	CS_ETM_CPU,
+};
+
+/* ETMv3/PTM metadata */
+enum {
+	/* Dynamic, configurable parameters */
+	CS_ETM_ETMCR = CS_ETM_CPU + 1,
+	CS_ETM_ETMTRACEIDR,
+	/* RO, taken from sysFS */
+	CS_ETM_ETMCCER,
+	CS_ETM_ETMIDR,
+	CS_ETM_PRIV_MAX,
+};
+
+/* ETMv4 metadata */
+enum {
+	/* Dynamic, configurable parameters */
+	CS_ETMV4_TRCCONFIGR = CS_ETM_CPU + 1,
+	CS_ETMV4_TRCTRACEIDR,
+	/* RO, taken from sysFS */
+	CS_ETMV4_TRCIDR0,
+	CS_ETMV4_TRCIDR1,
+	CS_ETMV4_TRCIDR2,
+	CS_ETMV4_TRCIDR8,
+	CS_ETMV4_TRCAUTHSTATUS,
+	CS_ETMV4_PRIV_MAX,
+};
+
+#define KiB(x) ((x) * 1024)
+#define MiB(x) ((x) * 1024 * 1024)
+
+#define CS_ETM_HEADER_SIZE (CS_HEADER_VERSION_0_MAX * sizeof(u64))
+
+static const u64 __perf_cs_etmv3_magic   = 0x3030303030303030ULL;
+static const u64 __perf_cs_etmv4_magic   = 0x4040404040404040ULL;
+#define CS_ETMV3_PRIV_SIZE (CS_ETM_PRIV_MAX * sizeof(u64))
+#define CS_ETMV4_PRIV_SIZE (CS_ETMV4_PRIV_MAX * sizeof(u64))
+
+#endif