[PATCH V2 1/6] tools/perf: Move powerpc VPA-DTL auxtrace init into a separate file

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

The powerpc auxtrace dispatch lives entirely in
arch/powerpc/util/auxtrace.c.  As new PMUs such as HTM are added, this
file would grow to contain the recording logic for all of them.

Factor out the VPA-DTL recording initializer into its own file,
arch/powerpc/util/vpa-dtl.c, and reduce auxtrace.c to a thin dispatch
layer.  auxtrace_record__init() now detects the PMU by name and calls
the appropriate per-PMU init function:

  - vpa_dtl_recording_init() for VPA-DTL events (unchanged behaviour)
  - Further PMU entries will follow in subsequent patches

This makes room in auxtrace_record__init() for the HTM recording path
added in the next patch without growing a single monolithic file.

Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
---
Changes in V2:
- Renamed the destination file from arch/powerpc/util/vpa-dtl.c (same
  name, unchanged) but the subject and commit message are reworded to
  clearly state that the goal is to make auxtrace_record__init() a thin
  per-PMU dispatcher, not merely to "allow multiple PMUs to use auxtrace".
- Handle failure from memory allocation
- Included stdlib and limits.h
- No functional change to the VPA-DTL path itself.
- Patch is now 1/6 instead of 1/9.

 tools/perf/arch/powerpc/util/Build      |  1 +
 tools/perf/arch/powerpc/util/auxtrace.c | 84 +++-------------------
 tools/perf/arch/powerpc/util/vpa-dtl.c  | 95 +++++++++++++++++++++++++
 tools/perf/util/powerpc-vpadtl.h        |  1 +
 4 files changed, 105 insertions(+), 76 deletions(-)
 create mode 100644 tools/perf/arch/powerpc/util/vpa-dtl.c

diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
index ae928050e07a..7819c8f5af2d 100644
--- a/tools/perf/arch/powerpc/util/Build
+++ b/tools/perf/arch/powerpc/util/Build
@@ -7,3 +7,4 @@ perf-util-y += evsel.o
 perf-util-$(CONFIG_LIBDW) += skip-callchain-idx.o
 
 perf-util-y += auxtrace.o
+perf-util-y += vpa-dtl.o
diff --git a/tools/perf/arch/powerpc/util/auxtrace.c b/tools/perf/arch/powerpc/util/auxtrace.c
index 4600a1661b4f..e04a0bd61755 100644
--- a/tools/perf/arch/powerpc/util/auxtrace.c
+++ b/tools/perf/arch/powerpc/util/auxtrace.c
@@ -13,63 +13,12 @@
 #include "../../util/auxtrace.h"
 #include "../../util/powerpc-vpadtl.h"
 #include "../../util/record.h"
-#include <internal/lib.h> // page_size
-
-#define KiB(x) ((x) * 1024)
-
-static int
-powerpc_vpadtl_recording_options(struct auxtrace_record *ar __maybe_unused,
-			struct evlist *evlist __maybe_unused,
-			struct record_opts *opts)
-{
-	opts->full_auxtrace = true;
-
-	/*
-	 * Set auxtrace_mmap_pages to minimum
-	 * two pages
-	 */
-	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;
-	}
-
-	return 0;
-}
-
-static size_t powerpc_vpadtl_info_priv_size(struct auxtrace_record *itr __maybe_unused,
-					struct evlist *evlist __maybe_unused)
-{
-	return VPADTL_AUXTRACE_PRIV_SIZE;
-}
-
-static int
-powerpc_vpadtl_info_fill(struct auxtrace_record *itr __maybe_unused,
-		struct perf_session *session __maybe_unused,
-		struct perf_record_auxtrace_info *auxtrace_info,
-		size_t priv_size __maybe_unused)
-{
-	auxtrace_info->type = PERF_AUXTRACE_VPA_DTL;
-
-	return 0;
-}
-
-static void powerpc_vpadtl_free(struct auxtrace_record *itr)
-{
-	free(itr);
-}
-
-static u64 powerpc_vpadtl_reference(struct auxtrace_record *itr __maybe_unused)
-{
-	return 0;
-}
 
 struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
 						int *err)
 {
-	struct auxtrace_record *aux;
 	struct evsel *pos;
-	int found = 0;
+	struct evsel *vpa_dtl_evsel = NULL;
 
 	/*
 	 * Set err value to zero here. Any fail later
@@ -78,33 +27,16 @@ struct auxtrace_record *auxtrace_record__init(struct evlist *evlist,
 	*err = 0;
 
 	evlist__for_each_entry(evlist, pos) {
-		if (strstarts(pos->name, "vpa_dtl")) {
-			found = 1;
+		if (pos->name && strstarts(pos->name, "vpa_dtl")) {
 			pos->needs_auxtrace_mmap = true;
-			break;
+			/* Remember the first matching VPA DTL event */
+			if (!vpa_dtl_evsel)
+				vpa_dtl_evsel = pos;
 		}
 	}
 
-	if (!found)
-		return NULL;
-
-	/*
-	 * To obtain the auxtrace buffer file descriptor, the auxtrace event
-	 * must come first.
-	 */
-	evlist__to_front(pos->evlist, pos);
-
-	aux = zalloc(sizeof(*aux));
-	if (aux == NULL) {
-		pr_debug("aux record is NULL\n");
-		*err = -ENOMEM;
-		return NULL;
-	}
+	if (vpa_dtl_evsel)
+		return vpa_dtl_recording_init(vpa_dtl_evsel, err);
 
-	aux->recording_options = powerpc_vpadtl_recording_options;
-	aux->info_priv_size = powerpc_vpadtl_info_priv_size;
-	aux->info_fill = powerpc_vpadtl_info_fill;
-	aux->free = powerpc_vpadtl_free;
-	aux->reference = powerpc_vpadtl_reference;
-	return aux;
+	return NULL;
 }
diff --git a/tools/perf/arch/powerpc/util/vpa-dtl.c b/tools/perf/arch/powerpc/util/vpa-dtl.c
new file mode 100644
index 000000000000..fde388d87477
--- /dev/null
+++ b/tools/perf/arch/powerpc/util/vpa-dtl.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VPA DTL AUX tracing support
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <limits.h>
+#include "../../util/cpumap.h"
+#include "../../util/evsel.h"
+#include "../../util/evlist.h"
+#include "../../util/session.h"
+#include "../../util/util.h"
+#include "../../util/debug.h"
+#include "../../util/auxtrace.h"
+#include "../../util/powerpc-vpadtl.h"
+#include "../../util/record.h"
+#include <internal/lib.h> // page_size
+
+#define KiB(x) ((x) * 1024)
+
+static int
+powerpc_vpadtl_recording_options(struct auxtrace_record *ar __maybe_unused,
+			struct evlist *evlist __maybe_unused,
+			struct record_opts *opts)
+{
+	opts->full_auxtrace = true;
+
+	/*
+	 * Set auxtrace_mmap_pages to minimum
+	 * two pages
+	 */
+	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;
+	}
+
+	return 0;
+}
+
+static size_t powerpc_vpadtl_info_priv_size(struct auxtrace_record *itr __maybe_unused,
+					struct evlist *evlist __maybe_unused)
+{
+	return VPADTL_AUXTRACE_PRIV_SIZE;
+}
+
+static int
+powerpc_vpadtl_info_fill(struct auxtrace_record *itr __maybe_unused,
+		struct perf_session *session __maybe_unused,
+		struct perf_record_auxtrace_info *auxtrace_info,
+		size_t priv_size __maybe_unused)
+{
+	auxtrace_info->type = PERF_AUXTRACE_VPA_DTL;
+
+	return 0;
+}
+
+static void powerpc_vpadtl_free(struct auxtrace_record *itr)
+{
+	free(itr);
+}
+
+static u64 powerpc_vpadtl_reference(struct auxtrace_record *itr __maybe_unused)
+{
+	return 0;
+}
+
+struct auxtrace_record *vpa_dtl_recording_init(struct evsel *pos, int *err)
+{
+	struct auxtrace_record *aux;
+
+	/*
+	 * To obtain the auxtrace buffer file descriptor, the auxtrace event
+	 * must come first.
+	 */
+	evlist__to_front(pos->evlist, pos);
+
+	aux = zalloc(sizeof(*aux));
+	if (aux == NULL) {
+		pr_debug("aux record allocation failed (-ENOMEM)\n");
+		*err = -ENOMEM;
+		return NULL;
+	}
+
+	aux->recording_options = powerpc_vpadtl_recording_options;
+	aux->info_priv_size = powerpc_vpadtl_info_priv_size;
+	aux->info_fill = powerpc_vpadtl_info_fill;
+	aux->free = powerpc_vpadtl_free;
+	aux->reference = powerpc_vpadtl_reference;
+	return aux;
+}
diff --git a/tools/perf/util/powerpc-vpadtl.h b/tools/perf/util/powerpc-vpadtl.h
index ca809660b9bb..41e09b17a353 100644
--- a/tools/perf/util/powerpc-vpadtl.h
+++ b/tools/perf/util/powerpc-vpadtl.h
@@ -20,4 +20,5 @@ struct perf_pmu;
 int powerpc_vpadtl_process_auxtrace_info(union perf_event *event,
 				  struct perf_session *session);
 
+struct auxtrace_record *vpa_dtl_recording_init(struct evsel *pos, int *err);
 #endif
-- 
2.43.0