ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 236 insertions, 0 deletions

diff --git a/tools/perf/tests/topology.c b/tools/perf/tests/topology.c
new file mode 100644
index 000000000..77cb8318c
--- /dev/null
+++ b/tools/perf/tests/topology.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <perf/cpumap.h>
+#include "cpumap.h"
+#include "tests.h"
+#include "session.h"
+#include "evlist.h"
+#include "debug.h"
+#include "pmus.h"
+#include "target.h"
+#include <linux/err.h>
+#include "dwarf-regs.h"
+
+#define TEMPL "/tmp/perf-test-XXXXXX"
+#define DATA_SIZE	10
+
+static int get_temp(char *path)
+{
+	int fd;
+
+	strcpy(path, TEMPL);
+
+	fd = mkstemp(path);
+	if (fd < 0) {
+		perror("mkstemp failed");
+		return -1;
+	}
+
+	close(fd);
+	return 0;
+}
+
+static int session_write_header(char *path)
+{
+	struct perf_session *session;
+	struct perf_data data = {
+		.path = path,
+		.mode = PERF_DATA_MODE_WRITE,
+	};
+	struct target target = {};
+
+	session = perf_session__new(&data, NULL);
+	TEST_ASSERT_VAL("can't get session", !IS_ERR(session));
+
+	session->evlist = evlist__new_default(&target, /*sample_callchains=*/false);
+	TEST_ASSERT_VAL("can't get evlist", session->evlist);
+	evlist__set_session(session->evlist, session);
+
+	perf_header__set_feat(&session->header, HEADER_CPU_TOPOLOGY);
+	perf_header__set_feat(&session->header, HEADER_NRCPUS);
+	perf_header__set_feat(&session->header, HEADER_ARCH);
+
+	session->header.data_size += DATA_SIZE;
+
+	TEST_ASSERT_VAL("failed to write header",
+			!perf_session__write_header(session, session->evlist,
+						    perf_data__fd(&data), true));
+
+	evlist__put(session->evlist);
+	perf_session__delete(session);
+
+	return 0;
+}
+
+static int check_cpu_topology(char *path, struct perf_cpu_map *map)
+{
+	struct perf_session *session;
+	struct perf_data data = {
+		.path = path,
+		.mode = PERF_DATA_MODE_READ,
+	};
+	unsigned int i;
+	struct aggr_cpu_id id;
+	struct perf_cpu cpu;
+	struct perf_env *env;
+	uint16_t e_machine;
+
+	session = perf_session__new(&data, NULL);
+	TEST_ASSERT_VAL("can't get session", !IS_ERR(session));
+	env = perf_session__env(session);
+	cpu__setup_cpunode_map();
+
+	/* On platforms with large numbers of CPUs process_cpu_topology()
+	 * might issue an error while reading the perf.data file section
+	 * HEADER_CPU_TOPOLOGY and the cpu_topology_map pointed to by member
+	 * cpu is a NULL pointer.
+	 * Example: On s390
+	 *   CPU 0 is on core_id 0 and physical_package_id 6
+	 *   CPU 1 is on core_id 1 and physical_package_id 3
+	 *
+	 *   Core_id and physical_package_id are platform and architecture
+	 *   dependent and might have higher numbers than the CPU id.
+	 *   This actually depends on the configuration.
+	 *
+	 *  In this case process_cpu_topology() prints error message:
+	 *  "socket_id number is too big. You may need to upgrade the
+	 *  perf tool."
+	 *
+	 *  This is the reason why this test might be skipped. aarch64 and
+	 *  s390 always write this part of the header, even when the above
+	 *  condition is true (see do_core_id_test in header.c). So always
+	 *  run this test on those platforms.
+	 */
+	e_machine = perf_env__e_machine(env, NULL);
+
+	if (!env->cpu && e_machine != EM_S390 && e_machine != EM_AARCH64)
+		return TEST_SKIP;
+
+	/*
+	 * In powerpc pSeries platform, not all the topology information
+	 * are exposed via sysfs. Due to restriction, detail like
+	 * physical_package_id will be set to -1. Hence skip this
+	 * test if physical_package_id returns -1 for cpu from perf_cpu_map.
+	 */
+	if (e_machine == EM_PPC64) {
+		if (cpu__get_socket_id(perf_cpu_map__cpu(map, 0)) == -1)
+			return TEST_SKIP;
+	}
+
+	TEST_ASSERT_VAL("Session header CPU map not set", env->cpu);
+
+	for (i = 0; i < (unsigned int)env->nr_cpus_avail; i++) {
+		cpu.cpu = i;
+		if (!perf_cpu_map__has(map, cpu))
+			continue;
+		pr_debug("CPU %d, core %d, socket %d\n", i,
+			 env->cpu[i].core_id,
+			 env->cpu[i].socket_id);
+	}
+
+	// Test that CPU ID contains socket, die, core and CPU
+	perf_cpu_map__for_each_cpu(cpu, i, map) {
+		id = aggr_cpu_id__cpu(cpu, NULL);
+		TEST_ASSERT_VAL("Cpu map - CPU ID doesn't match",
+				cpu.cpu == id.cpu.cpu);
+
+		TEST_ASSERT_VAL("Cpu map - Core ID doesn't match",
+			env->cpu[cpu.cpu].core_id == id.core);
+		TEST_ASSERT_VAL("Cpu map - Socket ID doesn't match",
+			env->cpu[cpu.cpu].socket_id == id.socket);
+
+		TEST_ASSERT_VAL("Cpu map - Die ID doesn't match",
+			env->cpu[cpu.cpu].die_id == id.die);
+		TEST_ASSERT_VAL("Cpu map - Node ID is set", id.node == -1);
+		TEST_ASSERT_VAL("Cpu map - Thread IDX is set", id.thread_idx == -1);
+	}
+
+	// Test that core ID contains socket, die and core
+	perf_cpu_map__for_each_cpu(cpu, i, map) {
+		id = aggr_cpu_id__core(cpu, NULL);
+		TEST_ASSERT_VAL("Core map - Core ID doesn't match",
+			env->cpu[cpu.cpu].core_id == id.core);
+
+		TEST_ASSERT_VAL("Core map - Socket ID doesn't match",
+			env->cpu[cpu.cpu].socket_id == id.socket);
+
+		TEST_ASSERT_VAL("Core map - Die ID doesn't match",
+			env->cpu[cpu.cpu].die_id == id.die);
+		TEST_ASSERT_VAL("Core map - Node ID is set", id.node == -1);
+		TEST_ASSERT_VAL("Core map - Thread IDX is set", id.thread_idx == -1);
+	}
+
+	// Test that die ID contains socket and die
+	perf_cpu_map__for_each_cpu(cpu, i, map) {
+		id = aggr_cpu_id__die(cpu, NULL);
+		TEST_ASSERT_VAL("Die map - Socket ID doesn't match",
+			env->cpu[cpu.cpu].socket_id == id.socket);
+
+		TEST_ASSERT_VAL("Die map - Die ID doesn't match",
+			env->cpu[cpu.cpu].die_id == id.die);
+
+		TEST_ASSERT_VAL("Die map - Node ID is set", id.node == -1);
+		TEST_ASSERT_VAL("Die map - Core is set", id.core == -1);
+		TEST_ASSERT_VAL("Die map - CPU is set", id.cpu.cpu == -1);
+		TEST_ASSERT_VAL("Die map - Thread IDX is set", id.thread_idx == -1);
+	}
+
+	// Test that socket ID contains only socket
+	perf_cpu_map__for_each_cpu(cpu, i, map) {
+		id = aggr_cpu_id__socket(cpu, NULL);
+		TEST_ASSERT_VAL("Socket map - Socket ID doesn't match",
+			env->cpu[cpu.cpu].socket_id == id.socket);
+
+		TEST_ASSERT_VAL("Socket map - Node ID is set", id.node == -1);
+		TEST_ASSERT_VAL("Socket map - Die ID is set", id.die == -1);
+		TEST_ASSERT_VAL("Socket map - Core is set", id.core == -1);
+		TEST_ASSERT_VAL("Socket map - CPU is set", id.cpu.cpu == -1);
+		TEST_ASSERT_VAL("Socket map - Thread IDX is set", id.thread_idx == -1);
+	}
+
+	// Test that node ID contains only node
+	perf_cpu_map__for_each_cpu(cpu, i, map) {
+		id = aggr_cpu_id__node(cpu, NULL);
+		TEST_ASSERT_VAL("Node map - Node ID doesn't match",
+				cpu__get_node(cpu) == id.node);
+		TEST_ASSERT_VAL("Node map - Socket is set", id.socket == -1);
+		TEST_ASSERT_VAL("Node map - Die ID is set", id.die == -1);
+		TEST_ASSERT_VAL("Node map - Core is set", id.core == -1);
+		TEST_ASSERT_VAL("Node map - CPU is set", id.cpu.cpu == -1);
+		TEST_ASSERT_VAL("Node map - Thread IDX is set", id.thread_idx == -1);
+	}
+	perf_session__delete(session);
+
+	return 0;
+}
+
+static int test__session_topology(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	char path[PATH_MAX];
+	struct perf_cpu_map *map;
+	int ret = TEST_FAIL;
+
+	TEST_ASSERT_VAL("can't get templ file", !get_temp(path));
+
+	pr_debug("templ file: %s\n", path);
+
+	if (session_write_header(path))
+		goto free_path;
+
+	map = perf_cpu_map__new_online_cpus();
+	if (map == NULL) {
+		pr_debug("failed to get system cpumap\n");
+		goto free_path;
+	}
+
+	ret = check_cpu_topology(path, map);
+	perf_cpu_map__put(map);
+
+free_path:
+	unlink(path);
+	return ret;
+}
+
+DEFINE_SUITE("Session topology", session_topology);