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, 465 insertions, 0 deletions

diff --git a/tools/perf/util/bpf-trace-summary.c b/tools/perf/util/bpf-trace-summary.c
new file mode 100644
index 000000000..9a31dbf06
--- /dev/null
+++ b/tools/perf/util/bpf-trace-summary.c
@@ -0,0 +1,465 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <errno.h>
+#include <inttypes.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "dwarf-regs.h" /* for EM_HOST */
+#include "trace/beauty/syscalltbl.h"
+#include "util/cgroup.h"
+#include "util/hashmap.h"
+#include "util/trace.h"
+#include "util/util.h"
+#include <bpf/bpf.h>
+#include <linux/rbtree.h>
+#include <linux/time64.h>
+#include <tools/libc_compat.h> /* reallocarray */
+
+#include "bpf_skel/syscall_summary.h"
+#include "bpf_skel/syscall_summary.skel.h"
+
+
+static struct syscall_summary_bpf *skel;
+static struct rb_root cgroups = RB_ROOT;
+
+int trace_prepare_bpf_summary(enum trace_summary_mode mode)
+{
+	skel = syscall_summary_bpf__open();
+	if (skel == NULL) {
+		fprintf(stderr, "failed to open syscall summary bpf skeleton\n");
+		return -1;
+	}
+
+	if (mode == SUMMARY__BY_THREAD)
+		skel->rodata->aggr_mode = SYSCALL_AGGR_THREAD;
+	else if (mode == SUMMARY__BY_CGROUP)
+		skel->rodata->aggr_mode = SYSCALL_AGGR_CGROUP;
+	else
+		skel->rodata->aggr_mode = SYSCALL_AGGR_CPU;
+
+	if (cgroup_is_v2("perf_event") > 0)
+		skel->rodata->use_cgroup_v2 = 1;
+
+	if (syscall_summary_bpf__load(skel) < 0) {
+		fprintf(stderr, "failed to load syscall summary bpf skeleton\n");
+		return -1;
+	}
+
+	if (syscall_summary_bpf__attach(skel) < 0) {
+		fprintf(stderr, "failed to attach syscall summary bpf skeleton\n");
+		return -1;
+	}
+
+	if (mode == SUMMARY__BY_CGROUP)
+		read_all_cgroups(&cgroups);
+
+	return 0;
+}
+
+void trace_start_bpf_summary(void)
+{
+	skel->bss->enabled = 1;
+}
+
+void trace_end_bpf_summary(void)
+{
+	skel->bss->enabled = 0;
+}
+
+struct syscall_node {
+	int syscall_nr;
+	struct syscall_stats stats;
+};
+
+static double rel_stddev(struct syscall_stats *stat)
+{
+	double variance, average;
+
+	if (stat->count < 2)
+		return 0;
+
+	average = (double)stat->total_time / stat->count;
+
+	variance = stat->squared_sum;
+	variance -= (stat->total_time * stat->total_time) / stat->count;
+	variance /= stat->count - 1;
+
+	return 100 * sqrt(variance / stat->count) / average;
+}
+
+/*
+ * The syscall_data is to maintain syscall stats ordered by total time.
+ * It supports different summary modes like per-thread or global.
+ *
+ * For per-thread stats, it uses two-level data strurcture -
+ * syscall_data is keyed by TID and has an array of nodes which
+ * represents each syscall for the thread.
+ *
+ * For global stats, it's still two-level technically but we don't need
+ * per-cpu analysis so it's keyed by the syscall number to combine stats
+ * from different CPUs.  And syscall_data always has a syscall_node so
+ * it can effectively work as flat hierarchy.
+ *
+ * For per-cgroup stats, it uses two-level data structure like thread
+ * syscall_data is keyed by CGROUP and has an array of node which
+ * represents each syscall for the cgroup.
+ */
+struct syscall_data {
+	u64 key; /* tid if AGGR_THREAD, syscall-nr if AGGR_CPU, cgroup if AGGR_CGROUP */
+	int nr_events;
+	int nr_nodes;
+	u64 total_time;
+	struct syscall_node *nodes;
+};
+
+static int datacmp(const void *a, const void *b)
+{
+	const struct syscall_data * const *sa = a;
+	const struct syscall_data * const *sb = b;
+
+	return (*sa)->total_time > (*sb)->total_time ? -1 : 1;
+}
+
+static int nodecmp(const void *a, const void *b)
+{
+	const struct syscall_node *na = a;
+	const struct syscall_node *nb = b;
+
+	return na->stats.total_time > nb->stats.total_time ? -1 : 1;
+}
+
+static size_t sc_node_hash(long key, void *ctx __maybe_unused)
+{
+	return key;
+}
+
+static bool sc_node_equal(long key1, long key2, void *ctx __maybe_unused)
+{
+	return key1 == key2;
+}
+
+static int print_common_stats(struct syscall_data *data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+
+	if (max_summary == 0 || max_summary > data->nr_nodes)
+		max_summary = data->nr_nodes;
+
+	for (int i = 0; i < max_summary; i++) {
+		struct syscall_node *node = &data->nodes[i];
+		struct syscall_stats *stat = &node->stats;
+		double total = (double)(stat->total_time) / NSEC_PER_MSEC;
+		double min = (double)(stat->min_time) / NSEC_PER_MSEC;
+		double max = (double)(stat->max_time) / NSEC_PER_MSEC;
+		double avg = total / stat->count;
+		const char *name;
+
+		/* TODO: support other ABIs */
+		name = syscalltbl__name(EM_HOST, node->syscall_nr);
+		if (name)
+			printed += fprintf(fp, "   %-15s", name);
+		else
+			printed += fprintf(fp, "   syscall:%-7d", node->syscall_nr);
+
+		printed += fprintf(fp, " %8u %6u %9.3f %9.3f %9.3f %9.3f %9.2f%%\n",
+				   stat->count, stat->error, total, min, avg, max,
+				   rel_stddev(stat));
+	}
+	return printed;
+}
+
+static int update_thread_stats(struct hashmap *hash, struct syscall_key *map_key,
+			       struct syscall_stats *map_data)
+{
+	struct syscall_data *data;
+	struct syscall_node *nodes;
+
+	if (!hashmap__find(hash, map_key->cpu_or_tid, &data)) {
+		data = zalloc(sizeof(*data));
+		if (data == NULL)
+			return -ENOMEM;
+
+		data->key = map_key->cpu_or_tid;
+		if (hashmap__add(hash, data->key, data) < 0) {
+			free(data);
+			return -ENOMEM;
+		}
+	}
+
+	/* update thread total stats */
+	data->nr_events += map_data->count;
+	data->total_time += map_data->total_time;
+
+	nodes = reallocarray(data->nodes, data->nr_nodes + 1, sizeof(*nodes));
+	if (nodes == NULL)
+		return -ENOMEM;
+
+	data->nodes = nodes;
+	nodes = &data->nodes[data->nr_nodes++];
+	nodes->syscall_nr = map_key->nr;
+
+	/* each thread has an entry for each syscall, just use the stat */
+	memcpy(&nodes->stats, map_data, sizeof(*map_data));
+	return 0;
+}
+
+static int print_thread_stat(struct syscall_data *data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+
+	qsort(data->nodes, data->nr_nodes, sizeof(*data->nodes), nodecmp);
+
+	printed += fprintf(fp, " thread (%d), ", (int)data->key);
+	printed += fprintf(fp, "%d events\n\n", data->nr_events);
+
+	printed += fprintf(fp, "   syscall            calls  errors  total       min       avg       max       stddev\n");
+	printed += fprintf(fp, "                                     (msec)    (msec)    (msec)    (msec)        (%%)\n");
+	printed += fprintf(fp, "   --------------- --------  ------ -------- --------- --------- ---------     ------\n");
+
+	printed += print_common_stats(data, max_summary, fp);
+	printed += fprintf(fp, "\n\n");
+
+	return printed;
+}
+
+static int print_thread_stats(struct syscall_data **data, int nr_data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+
+	for (int i = 0; i < nr_data; i++)
+		printed += print_thread_stat(data[i], max_summary, fp);
+
+	return printed;
+}
+
+static int update_total_stats(struct hashmap *hash, struct syscall_key *map_key,
+			      struct syscall_stats *map_data)
+{
+	struct syscall_data *data;
+	struct syscall_stats *stat;
+
+	if (!hashmap__find(hash, map_key->nr, &data)) {
+		data = zalloc(sizeof(*data));
+		if (data == NULL)
+			return -ENOMEM;
+
+		data->nodes = zalloc(sizeof(*data->nodes));
+		if (data->nodes == NULL) {
+			free(data);
+			return -ENOMEM;
+		}
+
+		data->nr_nodes = 1;
+		data->key = map_key->nr;
+		data->nodes->syscall_nr = data->key;
+
+		if (hashmap__add(hash, data->key, data) < 0) {
+			free(data->nodes);
+			free(data);
+			return -ENOMEM;
+		}
+	}
+
+	/* update total stats for this syscall */
+	data->nr_events += map_data->count;
+	data->total_time += map_data->total_time;
+
+	/* This is sum of the same syscall from different CPUs */
+	stat = &data->nodes->stats;
+
+	stat->total_time += map_data->total_time;
+	stat->squared_sum += map_data->squared_sum;
+	stat->count += map_data->count;
+	stat->error += map_data->error;
+
+	if (stat->max_time < map_data->max_time)
+		stat->max_time = map_data->max_time;
+	if (stat->min_time > map_data->min_time || stat->min_time == 0)
+		stat->min_time = map_data->min_time;
+
+	return 0;
+}
+
+static int print_total_stats(struct syscall_data **data, int nr_data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+	int nr_events = 0;
+
+	for (int i = 0; i < nr_data; i++)
+		nr_events += data[i]->nr_events;
+
+	printed += fprintf(fp, " total, %d events\n\n", nr_events);
+
+	printed += fprintf(fp, "   syscall            calls  errors  total       min       avg       max       stddev\n");
+	printed += fprintf(fp, "                                     (msec)    (msec)    (msec)    (msec)        (%%)\n");
+	printed += fprintf(fp, "   --------------- --------  ------ -------- --------- --------- ---------     ------\n");
+
+	if (max_summary == 0 || max_summary > nr_data)
+		max_summary = nr_data;
+
+	for (int i = 0; i < max_summary; i++)
+		printed += print_common_stats(data[i], max_summary, fp);
+
+	printed += fprintf(fp, "\n\n");
+	return printed;
+}
+
+static int update_cgroup_stats(struct hashmap *hash, struct syscall_key *map_key,
+			       struct syscall_stats *map_data)
+{
+	struct syscall_data *data;
+	struct syscall_node *nodes;
+
+	if (!hashmap__find(hash, map_key->cgroup, &data)) {
+		data = zalloc(sizeof(*data));
+		if (data == NULL)
+			return -ENOMEM;
+
+		data->key = map_key->cgroup;
+		if (hashmap__add(hash, data->key, data) < 0) {
+			free(data);
+			return -ENOMEM;
+		}
+	}
+
+	/* update thread total stats */
+	data->nr_events += map_data->count;
+	data->total_time += map_data->total_time;
+
+	nodes = reallocarray(data->nodes, data->nr_nodes + 1, sizeof(*nodes));
+	if (nodes == NULL)
+		return -ENOMEM;
+
+	data->nodes = nodes;
+	nodes = &data->nodes[data->nr_nodes++];
+	nodes->syscall_nr = map_key->nr;
+
+	/* each thread has an entry for each syscall, just use the stat */
+	memcpy(&nodes->stats, map_data, sizeof(*map_data));
+	return 0;
+}
+
+static int print_cgroup_stat(struct syscall_data *data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+	struct cgroup *cgrp = __cgroup__find(&cgroups, data->key);
+
+	qsort(data->nodes, data->nr_nodes, sizeof(*data->nodes), nodecmp);
+
+	if (cgrp)
+		printed += fprintf(fp, " cgroup %s,", cgrp->name);
+	else
+		printed += fprintf(fp, " cgroup id:%lu,", (unsigned long)data->key);
+
+	printed += fprintf(fp, " %d events\n\n", data->nr_events);
+
+	printed += fprintf(fp, "   syscall            calls  errors  total       min       avg       max       stddev\n");
+	printed += fprintf(fp, "                                     (msec)    (msec)    (msec)    (msec)        (%%)\n");
+	printed += fprintf(fp, "   --------------- --------  ------ -------- --------- --------- ---------     ------\n");
+
+	printed += print_common_stats(data, max_summary, fp);
+	printed += fprintf(fp, "\n\n");
+
+	return printed;
+}
+
+static int print_cgroup_stats(struct syscall_data **data, int nr_data, int max_summary, FILE *fp)
+{
+	int printed = 0;
+
+	for (int i = 0; i < nr_data; i++)
+		printed += print_cgroup_stat(data[i], max_summary, fp);
+
+	return printed;
+}
+
+int trace_print_bpf_summary(FILE *fp, int max_summary)
+{
+	struct bpf_map *map = skel->maps.syscall_stats_map;
+	struct syscall_key *prev_key, key;
+	struct syscall_data **data = NULL;
+	struct hashmap schash;
+	struct hashmap_entry *entry;
+	int nr_data = 0;
+	int printed = 0;
+	int i;
+	size_t bkt;
+
+	hashmap__init(&schash, sc_node_hash, sc_node_equal, /*ctx=*/NULL);
+
+	printed = fprintf(fp, "\n Summary of events:\n\n");
+
+	/* get stats from the bpf map */
+	prev_key = NULL;
+	while (!bpf_map__get_next_key(map, prev_key, &key, sizeof(key))) {
+		struct syscall_stats stat;
+
+		if (!bpf_map__lookup_elem(map, &key, sizeof(key), &stat, sizeof(stat), 0)) {
+			switch (skel->rodata->aggr_mode) {
+			case SYSCALL_AGGR_THREAD:
+				update_thread_stats(&schash, &key, &stat);
+				break;
+			case SYSCALL_AGGR_CPU:
+				update_total_stats(&schash, &key, &stat);
+				break;
+			case SYSCALL_AGGR_CGROUP:
+				update_cgroup_stats(&schash, &key, &stat);
+				break;
+			default:
+				break;
+			}
+		}
+
+		prev_key = &key;
+	}
+
+	nr_data = hashmap__size(&schash);
+	data = calloc(nr_data, sizeof(*data));
+	if (data == NULL)
+		goto out;
+
+	i = 0;
+	hashmap__for_each_entry(&schash, entry, bkt)
+		data[i++] = entry->pvalue;
+
+	qsort(data, nr_data, sizeof(*data), datacmp);
+
+	switch (skel->rodata->aggr_mode) {
+	case SYSCALL_AGGR_THREAD:
+		printed += print_thread_stats(data, nr_data, max_summary, fp);
+		break;
+	case SYSCALL_AGGR_CPU:
+		printed += print_total_stats(data, nr_data, max_summary, fp);
+		break;
+	case SYSCALL_AGGR_CGROUP:
+		printed += print_cgroup_stats(data, nr_data, max_summary, fp);
+		break;
+	default:
+		break;
+	}
+
+	for (i = 0; i < nr_data && data; i++) {
+		free(data[i]->nodes);
+		free(data[i]);
+	}
+	free(data);
+
+out:
+	hashmap__clear(&schash);
+	return printed;
+}
+
+void trace_cleanup_bpf_summary(void)
+{
+	if (!RB_EMPTY_ROOT(&cgroups)) {
+		struct cgroup *cgrp, *tmp;
+
+		rbtree_postorder_for_each_entry_safe(cgrp, tmp, &cgroups, node)
+			cgroup__put(cgrp);
+
+		cgroups = RB_ROOT;
+	}
+
+	syscall_summary_bpf__destroy(skel);
+}