linux-kernel - [PATCH v7 1/6] Revert "perf tool_pmu: More accurately set the cpus for tool events"

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Message-ID: <20260203225129.4077140-2-irogers@google.com>
Date: Tue,  3 Feb 2026 14:51:24 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	"Dr. David Alan Gilbert" <linux@...blig.org>, Yang Li <yang.lee@...ux.alibaba.com>, 
	James Clark <james.clark@...aro.org>, Thomas Falcon <thomas.falcon@...el.com>, 
	Thomas Richter <tmricht@...ux.ibm.com>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Andres Freund <andres@...razel.de>
Subject: [PATCH v7 1/6] Revert "perf tool_pmu: More accurately set the cpus
 for tool events"

This reverts commit d8d8a0b3603a9a8fa207cf9e4f292e81dc5d1008.

The setting of a user CPU map can cause an empty intersection when
combined with CPU 0 and the event removed. This later triggers a segv
in the stat-shadow logic. Let's put back a full online CPU map for now
by reverting this patch.

Reported-by: Andres Freund <andres@...razel.de>
Closes: https://lore.kernel.org/linux-perf-users/cgja46br2smmznxs7kbeabs6zgv3b4olfqgh2fdp5mxk2yom4v@w6jjgov6hdi6/
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/parse-events.c |  9 ++-------
 tools/perf/util/tool_pmu.c     | 19 -------------------
 tools/perf/util/tool_pmu.h     |  1 -
 3 files changed, 2 insertions(+), 27 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index d4647ded340f..f631bf7a919f 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -30,7 +30,6 @@
 #include "util/event.h"
 #include "util/bpf-filter.h"
 #include "util/stat.h"
-#include "util/tool_pmu.h"
 #include "util/util.h"
 #include "tracepoint.h"
 #include <api/fs/tracing_path.h>
@@ -230,12 +229,8 @@ __add_event(struct list_head *list, int *idx,
 	if (pmu) {
 		is_pmu_core = pmu->is_core;
 		pmu_cpus = perf_cpu_map__get(pmu->cpus);
-		if (perf_cpu_map__is_empty(pmu_cpus)) {
-			if (perf_pmu__is_tool(pmu))
-				pmu_cpus = tool_pmu__cpus(attr);
-			else
-				pmu_cpus = cpu_map__online();
-		}
+		if (perf_cpu_map__is_empty(pmu_cpus))
+			pmu_cpus = cpu_map__online();
 	} else {
 		is_pmu_core = (attr->type == PERF_TYPE_HARDWARE ||
 			       attr->type == PERF_TYPE_HW_CACHE);
diff --git a/tools/perf/util/tool_pmu.c b/tools/perf/util/tool_pmu.c
index 37c4eae0bef1..6a9df3dc0e07 100644
--- a/tools/perf/util/tool_pmu.c
+++ b/tools/perf/util/tool_pmu.c
@@ -2,7 +2,6 @@
 #include "cgroup.h"
 #include "counts.h"
 #include "cputopo.h"
-#include "debug.h"
 #include "evsel.h"
 #include "pmu.h"
 #include "print-events.h"
@@ -14,7 +13,6 @@
 #include <api/fs/fs.h>
 #include <api/io.h>
 #include <internal/threadmap.h>
-#include <perf/cpumap.h>
 #include <perf/threadmap.h>
 #include <fcntl.h>
 #include <strings.h>
@@ -111,23 +109,6 @@ const char *evsel__tool_pmu_event_name(const struct evsel *evsel)
 	return tool_pmu__event_to_str(evsel->core.attr.config);
 }
 
-struct perf_cpu_map *tool_pmu__cpus(struct perf_event_attr *attr)
-{
-	static struct perf_cpu_map *cpu0_map;
-	enum tool_pmu_event event = (enum tool_pmu_event)attr->config;
-
-	if (event <= TOOL_PMU__EVENT_NONE || event >= TOOL_PMU__EVENT_MAX) {
-		pr_err("Invalid tool PMU event config %llx\n", attr->config);
-		return NULL;
-	}
-	if (event == TOOL_PMU__EVENT_USER_TIME || event == TOOL_PMU__EVENT_SYSTEM_TIME)
-		return cpu_map__online();
-
-	if (!cpu0_map)
-		cpu0_map = perf_cpu_map__new_int(0);
-	return perf_cpu_map__get(cpu0_map);
-}
-
 static bool read_until_char(struct io *io, char e)
 {
 	int c;
diff --git a/tools/perf/util/tool_pmu.h b/tools/perf/util/tool_pmu.h
index ea343d1983d3..f1714001bc1d 100644
--- a/tools/perf/util/tool_pmu.h
+++ b/tools/perf/util/tool_pmu.h
@@ -46,7 +46,6 @@ bool tool_pmu__read_event(enum tool_pmu_event ev,
 u64 tool_pmu__cpu_slots_per_cycle(void);
 
 bool perf_pmu__is_tool(const struct perf_pmu *pmu);
-struct perf_cpu_map *tool_pmu__cpus(struct perf_event_attr *attr);
 
 bool evsel__is_tool(const struct evsel *evsel);
 enum tool_pmu_event evsel__tool_event(const struct evsel *evsel);
-- 
2.53.0.rc2.204.g2597b5adb4-goog