From 88ed91848db2f631403f61987c1093b18042a8d0 Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@google.com>
Date: Wed, 23 Aug 2023 21:13:26 -0700
Subject: [PATCH] perf pmu: Scan type early to fail an invalid PMU quickly

Scan sysfs PMU's type early so that format and aliases aren't
attempted to be loaded if the PMU name is invalid.

This is the case for event_pmu tokens in parse-events.y where a wildcard
name is first assumed to be a PMU name.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-15-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/pmu.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index b6a118226541..9e3b72d84168 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -957,12 +957,21 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
 	if (!pmu)
 		return NULL;
 
-	INIT_LIST_HEAD(&pmu->format);
-	INIT_LIST_HEAD(&pmu->aliases);
-	INIT_LIST_HEAD(&pmu->caps);
 	pmu->name = strdup(name);
 	if (!pmu->name)
 		goto err;
+
+	/*
+	 * Read type early to fail fast if a lookup name isn't a PMU. Ensure
+	 * that type value is successfully assigned (return 1).
+	 */
+	if (perf_pmu__scan_file_at(pmu, dirfd, "type", "%u", &type) != 1)
+		goto err;
+
+	INIT_LIST_HEAD(&pmu->format);
+	INIT_LIST_HEAD(&pmu->aliases);
+	INIT_LIST_HEAD(&pmu->caps);
+
 	/*
 	 * The pmu data we store & need consists of the pmu
 	 * type value and format definitions. Load both right
@@ -982,10 +991,6 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
 	pmu->is_core = is_pmu_core(name);
 	pmu->cpus = pmu_cpumask(dirfd, name, pmu->is_core);
 
-	/* Read type, and ensure that type value is successfully assigned (return 1) */
-	if (perf_pmu__scan_file_at(pmu, dirfd, "type", "%u", &type) != 1)
-		goto err;
-
 	alias_name = pmu_find_alias_name(name);
 	if (alias_name) {
 		pmu->alias_name = strdup(alias_name);