linux-kernel - [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel image

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Date:   Mon,  9 Nov 2020 22:54:04 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Song Liu <songliubraving@...com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH 13/24] perf tools: Allow mmap2 event to synthesize kernel image

Allow mmap2 event to synthesize kernel image,
so we can synthesize kernel build id data in
following changes.

It's enabled by new symbol_conf.buildid_mmap2
bool, which will be switched in following
changes.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/util/symbol_conf.h      |  3 ++-
 tools/perf/util/synthetic-events.c | 40 ++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/tools/perf/util/symbol_conf.h b/tools/perf/util/symbol_conf.h
index b916afb95ec5..b18f9c8dbb75 100644
--- a/tools/perf/util/symbol_conf.h
+++ b/tools/perf/util/symbol_conf.h
@@ -42,7 +42,8 @@ struct symbol_conf {
 			report_block,
 			report_individual_block,
 			inline_name,
-			disable_add2line_warn;
+			disable_add2line_warn,
+			buildid_mmap2;
 	const char	*vmlinux_name,
 			*kallsyms_name,
 			*source_prefix,
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 8a23391558cf..872df6d6dbef 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -988,11 +988,12 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 						perf_event__handler_t process,
 						struct machine *machine)
 {
-	size_t size;
+	union perf_event *event;
+	size_t size = symbol_conf.buildid_mmap2 ?
+			sizeof(event->mmap2) : sizeof(event->mmap);
 	struct map *map = machine__kernel_map(machine);
 	struct kmap *kmap;
 	int err;
-	union perf_event *event;
 
 	if (map == NULL)
 		return -1;
@@ -1006,7 +1007,7 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 	 * available use this, and after it is use this as a fallback for older
 	 * kernels.
 	 */
-	event = zalloc((sizeof(event->mmap) + machine->id_hdr_size));
+	event = zalloc(size + machine->id_hdr_size);
 	if (event == NULL) {
 		pr_debug("Not enough memory synthesizing mmap event "
 			 "for kernel modules\n");
@@ -1023,16 +1024,29 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 		event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
 	}
 
-	size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
-			"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
-	size = PERF_ALIGN(size, sizeof(u64));
-	event->mmap.header.type = PERF_RECORD_MMAP;
-	event->mmap.header.size = (sizeof(event->mmap) -
-			(sizeof(event->mmap.filename) - size) + machine->id_hdr_size);
-	event->mmap.pgoff = kmap->ref_reloc_sym->addr;
-	event->mmap.start = map->start;
-	event->mmap.len   = map->end - event->mmap.start;
-	event->mmap.pid   = machine->pid;
+	if (symbol_conf.buildid_mmap2) {
+		size = snprintf(event->mmap2.filename, sizeof(event->mmap2.filename),
+				"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
+		size = PERF_ALIGN(size, sizeof(u64));
+		event->mmap2.header.type = PERF_RECORD_MMAP2;
+		event->mmap2.header.size = (sizeof(event->mmap2) -
+				(sizeof(event->mmap2.filename) - size) + machine->id_hdr_size);
+		event->mmap2.pgoff = kmap->ref_reloc_sym->addr;
+		event->mmap2.start = map->start;
+		event->mmap2.len   = map->end - event->mmap.start;
+		event->mmap2.pid   = machine->pid;
+	} else {
+		size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
+				"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name) + 1;
+		size = PERF_ALIGN(size, sizeof(u64));
+		event->mmap.header.type = PERF_RECORD_MMAP;
+		event->mmap.header.size = (sizeof(event->mmap) -
+				(sizeof(event->mmap.filename) - size) + machine->id_hdr_size);
+		event->mmap.pgoff = kmap->ref_reloc_sym->addr;
+		event->mmap.start = map->start;
+		event->mmap.len   = map->end - event->mmap.start;
+		event->mmap.pid   = machine->pid;
+	}
 
 	err = perf_tool__process_synth_event(tool, event, machine, process);
 	free(event);
-- 
2.26.2