linux-kernel - [PATCH 26/35] perf tools: Handle injected guest kernel mmap event

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Message-Id: <20220711093218.10967-27-adrian.hunter@intel.com>
Date:   Mon, 11 Jul 2022 12:32:09 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: [PATCH 26/35] perf tools: Handle injected guest kernel mmap event

If a kernel mmap event was recorded inside a guest and injected into a host
perf.data file, then it will match a host mmap_name not a guest mmap_name,
see machine__set_mmap_name(). So try matching a host mmap_name in that
case.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/machine.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 27d1a38f44c3..8f657225fb02 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1742,6 +1742,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 	struct map *map;
 	enum dso_space_type dso_space;
 	bool is_kernel_mmap;
+	const char *mmap_name = machine->mmap_name;
 
 	/* If we have maps from kcore then we do not need or want any others */
 	if (machine__uses_kcore(machine))
@@ -1752,8 +1753,16 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 	else
 		dso_space = DSO_SPACE__KERNEL_GUEST;
 
-	is_kernel_mmap = memcmp(xm->name, machine->mmap_name,
-				strlen(machine->mmap_name) - 1) == 0;
+	is_kernel_mmap = memcmp(xm->name, mmap_name, strlen(mmap_name) - 1) == 0;
+	if (!is_kernel_mmap && !machine__is_host(machine)) {
+		/*
+		 * If the event was recorded inside the guest and injected into
+		 * the host perf.data file, then it will match a host mmap_name,
+		 * so try that - see machine__set_mmap_name().
+		 */
+		mmap_name = "[kernel.kallsyms]";
+		is_kernel_mmap = memcmp(xm->name, mmap_name, strlen(mmap_name) - 1) == 0;
+	}
 	if (xm->name[0] == '/' ||
 	    (!is_kernel_mmap && xm->name[0] == '[')) {
 		map = machine__addnew_module_map(machine, xm->start,
@@ -1767,7 +1776,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 			dso__set_build_id(map->dso, bid);
 
 	} else if (is_kernel_mmap) {
-		const char *symbol_name = (xm->name + strlen(machine->mmap_name));
+		const char *symbol_name = xm->name + strlen(mmap_name);
 		/*
 		 * Should be there already, from the build-id table in
 		 * the header.
-- 
2.25.1