[PATCH V5 2/6] tools/perf: Add AUXTRACE recording support for powerpc HTM

[Athira Rajeev <atrajeev@linux.ibm.com>]

Add powerpc perf tool support for the HTM PMU AUXTRACE recording path.

Introduce htm_recording_init() and the associated auxtrace callbacks so
perf record can create PERF_RECORD_AUXTRACE records for HTM data.

htm_info_fill() stores the PMU type, number of HTM evsels, and a
(cpu, attr.config) pair for each evsel into PERF_RECORD_AUXTRACE_INFO
priv[].  The decode side reads these back to map each AUX buffer
(identified by event->auxtrace.cpu) to the correct (node, chip, core)
target when writing htm.bin.* output files.

Update auxtrace_record__init() to detect HTM events and dispatch to the
HTM-specific recording initializer.

Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
---
Changes in V5:
- htm_recording_options(): clamp aux_watermark with min_t(size_t, wm,
  UINT_MAX) before assigning to pos->core.attr.aux_watermark (u32).
  On a system with large auxtrace_mmap_pages the unclamped product can
  exceed UINT_MAX and silently truncate on 32-bit platforms.
- htm_info_fill(): iterate all CPUs in each evsel's CPU map and write
  one (cpu, config) entry per CPU instead of only the first CPU.  An
  evsel opened with -C 0,1,2 now contributes three priv[] entries, one
  per CPU, each carrying the same attr.config.  The decode side
  (powerpc_htm_process_auxtrace_event) uses event->auxtrace.cpu to look
  up the matching entry, so every CPU's AUX buffer is correctly mapped
  to its (node, chip, core, type) target and written to the right output
  file.  An evsel with no CPU map records cpu=-1 as before.

Changes in V4:
- Add explicit mutual-exclusion check in auxtrace_record__init(): if
  both vpa_dtl_evsel and htm_evsel are set after scanning the evlist,
  print an error, set *err = -EINVAL, and return NULL.  V3 silently
  fell through to prefer VPA-DTL when both PMU types were present,
  leaving HTM AUX buffers collected without a
  PERF_RECORD_AUXTRACE_INFO record and the trace undecodable.
- Drop the superfluous pos->name && null-guard from the HTM detection
  condition in auxtrace_record__init(): the condition becomes
  !strcmp(evsel__pmu_name(pos), "htm") without the leading check.
  evsel__pmu_name() handles a NULL name internally so the guard is
  redundant.
- Apply the same simplification in htm_recording_options() and
  htm_nr_events() in htm.c: remove the !pos->name || prefix from
  the evsel__pmu_name() comparisons, consistent with the dispatcher
  change above.
- Set pos->core.attr.sample_period = 1 for each HTM evsel inside
  htm_recording_options().  V3 set freq=0 and aux_watermark but did
  not set sample_period, leaving the kernel to use whatever default
  value was in the attr, which could cause the HTM event to fire at
  an unintended rate.

Changes in V3:
- Switch HTM event detection in auxtrace_record__init() from
strstarts(pos->name, "htm") to !strcmp(evsel__pmu_name(pos), "htm"),
matching the kernel-assigned PMU name and preventing false
matches on user-named events.
- Switch htm_recording_options(), htm_nr_events(), and the
loop in htm_info_fill() from strstarts(pos->name, "htm")
to evsel__pmu_name(), consistent with the above and with
patches 4 and 6.
- Add #include <linux/zalloc.h> to htm.c for zalloc().
- Set auxtrace_info->type = PERF_AUXTRACE_POWERPC_HTM directly
in htm_info_fill(), removing the placeholder comment. (V2
deferred this to patch 5; it is cleaner to set it in the same
patch that defines the enum.)
- Set aux_watermark to half the AUX ring-buffer size
(auxtrace_mmap_pages * page_size / 2) so there is always
headroom for hardware to write while userspace drains. V2 set
it to the full buffer size, risking data loss under back-pressure.
- Add PERF_AUXTRACE_POWERPC_HTM to the enum auxtrace_type in
util/auxtrace.h and add #include "powerpc-htm.h" plus a stub
case PERF_AUXTRACE_POWERPC_HTM: (falls through to
PERF_AUXTRACE_UNKNOWN) in util/auxtrace.c in this patch, so
the enum is defined before it is used in htm_info_fill().
(V2 did this in patch 5.)

Changes in V2:
- htm_info_fill() now stores a (cpu, attr.config) pair for every HTM
  evsel into PERF_RECORD_AUXTRACE_INFO priv[].  V1 stored only the PMU
  type and a single config value; there was no per-CPU mapping.
- The priv[] layout is formalised in util/powerpc-htm.h with enum
  constants POWERPC_HTM_PMU_TYPE, POWERPC_HTM_NUM_EVENTS, and
  POWERPC_HTM_EVENT_DATA and the helper macros HTM_AUXTRACE_PRIV_FIXED
  and HTM_AUXTRACE_PRIV_SIZE(n).  V1 used bare numeric offsets.
- PERF_SAMPLE_RAW is enabled in the recording options so that memory
  configuration records emitted by the kernel driver are captured
  alongside the AUX stream.  V1 added this in a later patch.
- PERF_AUXTRACE_POWERPC_HTM type constant is set in htm_info_fill()
  (wired up in patch 5 once the enum is defined).
- Patch is now 2/6 instead of 2/9.

 tools/perf/arch/powerpc/util/Build      |   1 +
 tools/perf/arch/powerpc/util/auxtrace.c |  22 +++
 tools/perf/arch/powerpc/util/htm.c      | 185 ++++++++++++++++++++++++
 tools/perf/util/auxtrace.c              |   2 +
 tools/perf/util/auxtrace.h              |   1 +
 tools/perf/util/powerpc-htm.h           |  43 ++++++
 6 files changed, 254 insertions(+)
 create mode 100644 tools/perf/arch/powerpc/util/htm.c
 create mode 100644 tools/perf/util/powerpc-htm.h

diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
index 7819c8f5af2d..297152591046 100644
--- a/tools/perf/arch/powerpc/util/Build
+++ b/tools/perf/arch/powerpc/util/Build
@@ -8,3 +8,4 @@ perf-util-$(CONFIG_LIBDW) += skip-callchain-idx.o
 
 perf-util-y += auxtrace.o
 perf-util-y += vpa-dtl.o
+perf-util-y += htm.o
diff --git a/tools/perf/arch/powerpc/util/auxtrace.c b/tools/perf/arch/powerpc/util/auxtrace.c
index e04a0bd61755..9936d1910256 100644
--- a/tools/perf/arch/powerpc/util/auxtrace.c
+++ b/tools/perf/arch/powerpc/util/auxtrace.c
@@ -12,13 +12,16 @@
 #include "../../util/debug.h"
 #include "../../util/auxtrace.h"
 #include "../../util/powerpc-vpadtl.h"
+#include "../../util/powerpc-htm.h"
 #include "../../util/record.h"
+#include <string.h>
 
 struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
 						int *err)
 {
 	struct evsel *pos;
 	struct evsel *vpa_dtl_evsel = NULL;
+	struct evsel *htm_evsel = NULL;
 
 	/*
 	 * Set err value to zero here. Any fail later
@@ -32,11 +35,30 @@ struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
 			/* Remember the first matching VPA DTL event */
 			if (!vpa_dtl_evsel)
 				vpa_dtl_evsel = pos;
+		} else if (!strcmp(evsel__pmu_name(pos), "htm")) {
+			pos->needs_auxtrace_mmap = true;
+			/* Remember the first matching HTM event */
+			if (!htm_evsel)
+				htm_evsel = pos;
 		}
 	}
 
+	/*
+	 * Only one auxtrace PMU can be initialised per session.  Reject
+	 * concurrent VPA DTL and HTM events: HTM AUX buffers would be
+	 * collected without a PERF_RECORD_AUXTRACE_INFO record, making
+	 * the trace undecodable.
+	 */
+	if (vpa_dtl_evsel && htm_evsel) {
+		pr_err("Cannot record VPA DTL and HTM auxtrace events simultaneously\n");
+		*err = -EINVAL;
+		return NULL;
+	}
+
 	if (vpa_dtl_evsel)
 		return vpa_dtl_recording_init(vpa_dtl_evsel, err);
+	else if (htm_evsel)
+		return htm_recording_init(htm_evsel, err);
 
 	return NULL;
 }
diff --git a/tools/perf/arch/powerpc/util/htm.c b/tools/perf/arch/powerpc/util/htm.c
new file mode 100644
index 000000000000..d2fdef488032
--- /dev/null
+++ b/tools/perf/arch/powerpc/util/htm.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HTM AUX tracing support
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/zalloc.h>
+#include <stdlib.h>
+#include <limits.h>
+#include "../../util/evsel.h"
+#include "../../util/evlist.h"
+#include "../../util/session.h"
+#include "../../util/debug.h"
+#include "../../util/auxtrace.h"
+#include "../../util/powerpc-htm.h"
+#include "../../util/record.h"
+#include <internal/lib.h> /* page_size */
+#include <errno.h>
+
+#define KiB(x) ((x) * 1024)
+
+struct htm_recording {
+	struct auxtrace_record	itr;
+	struct evsel		*evsel;
+};
+
+static int
+htm_recording_options(struct auxtrace_record *itr __maybe_unused,
+		      struct evlist *evlist,
+		      struct record_opts *opts)
+{
+	struct evsel *pos;
+
+	opts->full_auxtrace = true;
+
+	if (!opts->auxtrace_mmap_pages) {
+		opts->auxtrace_mmap_pages = KiB(128) / page_size;
+		if (opts->mmap_pages == UINT_MAX)
+			opts->mmap_pages = KiB(256) / page_size;
+	}
+
+	evlist__for_each_entry(evlist, pos) {
+		size_t wm;
+
+		if (strcmp(evsel__pmu_name(pos), "htm"))
+			continue;
+		wm = opts->auxtrace_mmap_pages * (size_t)page_size / 2;
+		pos->core.attr.aux_watermark = min_t(size_t, wm, UINT_MAX);
+		pos->core.attr.sample_type |= PERF_SAMPLE_RAW;
+		pos->core.attr.freq = 0;
+		pos->core.attr.sample_period = 1;
+		pos->needs_auxtrace_mmap = true;
+	}
+
+	return 0;
+}
+
+/* Count htm evsels in the evlist */
+static int htm_nr_events(struct evlist *evlist)
+{
+	struct evsel *pos;
+	int n = 0;
+
+	evlist__for_each_entry(evlist, pos) {
+		if (!strcmp(evsel__pmu_name(pos), "htm"))
+			n++;
+	}
+	return n;
+}
+
+static size_t htm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
+				 struct evlist *evlist)
+{
+	return HTM_AUXTRACE_PRIV_SIZE(htm_nr_events(evlist));
+}
+
+/*
+ * Fill the PERF_RECORD_AUXTRACE_INFO private data with:
+ *   priv[POWERPC_HTM_PMU_TYPE]   = pmu->type of the first htm evsel
+ *   priv[POWERPC_HTM_NUM_EVENTS] = total number of HTM CPU entries
+ *   priv[POWERPC_HTM_EVENT_DATA + n*2]     = CPU number for nth entry
+ *   priv[POWERPC_HTM_EVENT_DATA + n*2 + 1] = attr.config for nth entry
+ *
+ * One entry is written per CPU in each evsel's cpu map.  An evsel opened
+ * with -C 0,1,2 contributes three entries (one per CPU), each carrying
+ * the same attr.config.  The decode side uses event->auxtrace.cpu to look
+ * up the matching config and derive (node, chip, core) for the output
+ * file name.
+ */
+static int
+htm_info_fill(struct auxtrace_record *itr,
+	      struct perf_session *session,
+	      struct perf_record_auxtrace_info *auxtrace_info,
+	      size_t priv_size)
+{
+	struct htm_recording *htm_r = container_of(itr, struct htm_recording, itr);
+	struct evlist *evlist = session->evlist;
+	struct evsel *pos;
+	int n = 0;
+	int expected_n = htm_nr_events(evlist);
+
+	if (priv_size != HTM_AUXTRACE_PRIV_SIZE(expected_n))
+		return -EINVAL;
+
+	auxtrace_info->type = PERF_AUXTRACE_POWERPC_HTM;
+	auxtrace_info->priv[POWERPC_HTM_PMU_TYPE] = htm_r->evsel->core.attr.type;
+	auxtrace_info->priv[POWERPC_HTM_NUM_EVENTS] = expected_n;
+
+	evlist__for_each_entry(evlist, pos) {
+		struct perf_cpu_map *cpus;
+		int i, nr;
+
+		if (strcmp(evsel__pmu_name(pos), "htm"))
+			continue;
+
+		/*
+		 * Emit one (cpu, config) entry for every CPU in this evsel's
+		 * map.  perf record -C 0,1,2 creates one evsel with a
+		 * three-entry cpu map; each CPU gets its own AUX buffer and
+		 * must be individually mapped so the decoder can match
+		 * event->auxtrace.cpu to the correct (node, chip, core).
+		 */
+		cpus = evsel__cpus(pos);
+		nr = cpus ? perf_cpu_map__nr(cpus) : 0;
+
+		if (nr > 0) {
+			for (i = 0; i < nr; i++) {
+				int cpu = perf_cpu_map__cpu(cpus, i).cpu;
+
+				auxtrace_info->priv[POWERPC_HTM_EVENT_DATA + n * 2]     = cpu;
+				auxtrace_info->priv[POWERPC_HTM_EVENT_DATA + n * 2 + 1] =
+								pos->core.attr.config;
+				n++;
+			}
+		} else {
+			/* cpu-agnostic evsel: record cpu = -1 */
+			auxtrace_info->priv[POWERPC_HTM_EVENT_DATA + n * 2]     = (u64)-1;
+			auxtrace_info->priv[POWERPC_HTM_EVENT_DATA + n * 2 + 1] =
+							pos->core.attr.config;
+			n++;
+		}
+	}
+
+	return 0;
+}
+
+static u64 htm_reference(struct auxtrace_record *itr __maybe_unused)
+{
+	return 0;
+}
+
+static void htm_free(struct auxtrace_record *itr)
+{
+	struct htm_recording *htm_r = container_of(itr, struct htm_recording, itr);
+
+	free(htm_r);
+}
+
+struct auxtrace_record *htm_recording_init(struct evsel *pos, int *err)
+{
+	struct htm_recording *htm_r;
+
+	/*
+	 * To obtain the auxtrace buffer file descriptor, the auxtrace event
+	 * must come first.
+	 */
+	evlist__to_front(pos->evlist, pos);
+
+	htm_r = zalloc(sizeof(*htm_r));
+	if (!htm_r) {
+		pr_debug("htm_recording allocation failed (-ENOMEM)\n");
+		*err = -ENOMEM;
+		return NULL;
+	}
+
+	htm_r->evsel = pos;
+	htm_r->itr.recording_options = htm_recording_options;
+	htm_r->itr.info_priv_size    = htm_info_priv_size;
+	htm_r->itr.info_fill         = htm_info_fill;
+	htm_r->itr.free              = htm_free;
+	htm_r->itr.reference         = htm_reference;
+	return &htm_r->itr;
+}
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index aa749e1c3036..bf08f41d623f 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -56,6 +56,7 @@
 #include "s390-cpumsf.h"
 #include "util/mmap.h"
 #include "powerpc-vpadtl.h"
+#include "powerpc-htm.h"
 
 #include <linux/ctype.h>
 #include "symbol/kallsyms.h"
@@ -1432,6 +1433,7 @@ int perf_event__process_auxtrace_info(const struct perf_tool *tool __maybe_unuse
 	case PERF_AUXTRACE_VPA_DTL:
 		err = powerpc_vpadtl_process_auxtrace_info(event, session);
 		break;
+	case PERF_AUXTRACE_POWERPC_HTM:
 	case PERF_AUXTRACE_UNKNOWN:
 	default:
 		return -EINVAL;
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 6947f3f284c0..68b17802a419 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -46,6 +46,7 @@ enum auxtrace_type {
 	PERF_AUXTRACE_S390_CPUMSF,
 	PERF_AUXTRACE_HISI_PTT,
 	PERF_AUXTRACE_VPA_DTL,
+	PERF_AUXTRACE_POWERPC_HTM,
 };
 
 enum itrace_period_type {
diff --git a/tools/perf/util/powerpc-htm.h b/tools/perf/util/powerpc-htm.h
new file mode 100644
index 000000000000..18e39417d556
--- /dev/null
+++ b/tools/perf/util/powerpc-htm.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __POWERPC_HTM_H
+#define __POWERPC_HTM_H
+
+#include <linux/types.h>
+
+/*
+ * Layout of the private data in PERF_RECORD_AUXTRACE_INFO for HTM.
+ *
+ * priv[POWERPC_HTM_PMU_TYPE]   = htm PMU type ID (pmu->type from kernel)
+ * priv[POWERPC_HTM_NUM_EVENTS] = number of htm evsels recorded (N)
+ *
+ * Followed by N pairs (2 u64 each):
+ *   priv[POWERPC_HTM_EVENT_DATA + n*2 + 0] = CPU number for nth htm evsel
+ *   priv[POWERPC_HTM_EVENT_DATA + n*2 + 1] = attr.config for nth htm evsel
+ *
+ * Total priv entries: POWERPC_HTM_EVENT_DATA + N * 2
+ */
+enum {
+	POWERPC_HTM_PMU_TYPE  = 0,
+	POWERPC_HTM_NUM_EVENTS,
+	POWERPC_HTM_EVENT_DATA,	/* variable-length: 2 u64 per event */
+};
+
+/* Fixed header size (everything before the per-event data) */
+#define HTM_AUXTRACE_PRIV_FIXED  (POWERPC_HTM_EVENT_DATA * sizeof(u64))
+
+/* Total priv size for N htm evsels */
+#define HTM_AUXTRACE_PRIV_SIZE(n) \
+	(HTM_AUXTRACE_PRIV_FIXED + (n) * 2 * sizeof(u64))
+
+struct evsel;
+struct evlist;
+union perf_event;
+struct perf_session;
+struct auxtrace_record;
+
+struct auxtrace_record *htm_recording_init(struct evsel *pos, int *err);
+
+int powerpc_htm_process_auxtrace_info(union perf_event *event,
+				      struct perf_session *session);
+
+#endif /* __POWERPC_HTM_H */
-- 
2.53.0