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, 289 insertions, 0 deletions

diff --git a/tools/perf/util/values.c b/tools/perf/util/values.c
new file mode 100644
index 000000000..6eaddfcf8
--- /dev/null
+++ b/tools/perf/util/values.c
@@ -0,0 +1,289 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <linux/zalloc.h>
+
+#include "values.h"
+#include "debug.h"
+#include "evsel.h"
+
+int perf_read_values_init(struct perf_read_values *values)
+{
+	values->threads_max = 16;
+	values->pid = calloc(values->threads_max, sizeof(*values->pid));
+	values->tid = calloc(values->threads_max, sizeof(*values->tid));
+	values->value = calloc(values->threads_max, sizeof(*values->value));
+	if (!values->pid || !values->tid || !values->value) {
+		pr_debug("failed to allocate read_values threads arrays");
+		goto out_free_pid;
+	}
+	values->threads = 0;
+
+	values->counters_max = 16;
+	values->counters = malloc(values->counters_max * sizeof(*values->counters));
+	if (!values->counters) {
+		pr_debug("failed to allocate read_values counters array");
+		goto out_free_counter;
+	}
+	values->num_counters = 0;
+
+	return 0;
+
+out_free_counter:
+	zfree(&values->counters);
+out_free_pid:
+	zfree(&values->pid);
+	zfree(&values->tid);
+	zfree(&values->value);
+	return -ENOMEM;
+}
+
+void perf_read_values_destroy(struct perf_read_values *values)
+{
+	int i;
+
+	if (!values->threads_max || !values->counters_max)
+		return;
+
+	for (i = 0; i < values->threads; i++)
+		zfree(&values->value[i]);
+	zfree(&values->value);
+	zfree(&values->pid);
+	zfree(&values->tid);
+	zfree(&values->counters);
+}
+
+static int perf_read_values__enlarge_threads(struct perf_read_values *values)
+{
+	int nthreads_max = values->threads_max * 2;
+	void *npid = realloc(values->pid, nthreads_max * sizeof(*values->pid)),
+	     *ntid = realloc(values->tid, nthreads_max * sizeof(*values->tid)),
+	     *nvalue = realloc(values->value, nthreads_max * sizeof(*values->value));
+
+	if (!npid || !ntid || !nvalue)
+		goto out_err;
+
+	values->threads_max = nthreads_max;
+	values->pid = npid;
+	values->tid = ntid;
+	values->value = nvalue;
+	return 0;
+out_err:
+	free(npid);
+	free(ntid);
+	free(nvalue);
+	pr_debug("failed to enlarge read_values threads arrays");
+	return -ENOMEM;
+}
+
+static int perf_read_values__findnew_thread(struct perf_read_values *values,
+					    u32 pid, u32 tid)
+{
+	int i;
+
+	for (i = 0; i < values->threads; i++)
+		if (values->pid[i] == pid && values->tid[i] == tid)
+			return i;
+
+	if (values->threads == values->threads_max) {
+		i = perf_read_values__enlarge_threads(values);
+		if (i < 0)
+			return i;
+	}
+
+	i = values->threads;
+
+	values->value[i] = calloc(values->counters_max, sizeof(**values->value));
+	if (!values->value[i]) {
+		pr_debug("failed to allocate read_values counters array");
+		return -ENOMEM;
+	}
+	values->pid[i] = pid;
+	values->tid[i] = tid;
+	values->threads = i + 1;
+
+	return i;
+}
+
+static int perf_read_values__enlarge_counters(struct perf_read_values *values)
+{
+	int counters_max = values->counters_max * 2;
+	struct evsel **new_counters = realloc(values->counters,
+					     counters_max * sizeof(*values->counters));
+
+	if (!new_counters) {
+		pr_debug("failed to enlarge read_values counters array");
+		goto out_enomem;
+	}
+
+	for (int i = 0; i < values->threads; i++) {
+		u64 *value = realloc(values->value[i], counters_max * sizeof(**values->value));
+
+		if (!value) {
+			pr_debug("failed to enlarge read_values ->values array");
+			goto out_free_counters;
+		}
+
+		for (int j = values->counters_max; j < counters_max; j++)
+			value[j] = 0;
+
+		values->value[i] = value;
+	}
+
+	values->counters_max = counters_max;
+	values->counters = new_counters;
+
+	return 0;
+out_free_counters:
+	free(new_counters);
+out_enomem:
+	return -ENOMEM;
+}
+
+static int perf_read_values__findnew_counter(struct perf_read_values *values,
+					     struct evsel *evsel)
+{
+	int i;
+
+	for (i = 0; i < values->num_counters; i++)
+		if (values->counters[i] == evsel)
+			return i;
+
+	if (values->num_counters == values->counters_max) {
+		int err = perf_read_values__enlarge_counters(values);
+
+		if (err)
+			return err;
+	}
+
+	i = values->num_counters++;
+	values->counters[i] = evsel;
+
+	return i;
+}
+
+int perf_read_values_add_value(struct perf_read_values *values,
+				u32 pid, u32 tid,
+				struct evsel *evsel, u64 value)
+{
+	int tindex, cindex;
+
+	tindex = perf_read_values__findnew_thread(values, pid, tid);
+	if (tindex < 0)
+		return tindex;
+	cindex = perf_read_values__findnew_counter(values, evsel);
+	if (cindex < 0)
+		return cindex;
+
+	values->value[tindex][cindex] += value;
+	return 0;
+}
+
+static void perf_read_values__display_pretty(FILE *fp,
+					     struct perf_read_values *values)
+{
+	int i, j;
+	int pidwidth, tidwidth;
+	int *counterwidth;
+
+	counterwidth = malloc(values->num_counters * sizeof(*counterwidth));
+	if (!counterwidth) {
+		fprintf(fp, "INTERNAL ERROR: Failed to allocate counterwidth array\n");
+		return;
+	}
+	tidwidth = 3;
+	pidwidth = 3;
+	for (j = 0; j < values->num_counters; j++)
+		counterwidth[j] = strlen(evsel__name(values->counters[j]));
+	for (i = 0; i < values->threads; i++) {
+		int width;
+
+		width = snprintf(NULL, 0, "%d", values->pid[i]);
+		if (width > pidwidth)
+			pidwidth = width;
+		width = snprintf(NULL, 0, "%d", values->tid[i]);
+		if (width > tidwidth)
+			tidwidth = width;
+		for (j = 0; j < values->num_counters; j++) {
+			width = snprintf(NULL, 0, "%" PRIu64, values->value[i][j]);
+			if (width > counterwidth[j])
+				counterwidth[j] = width;
+		}
+	}
+
+	fprintf(fp, "# %*s  %*s", pidwidth, "PID", tidwidth, "TID");
+	for (j = 0; j < values->num_counters; j++)
+		fprintf(fp, "  %*s", counterwidth[j], evsel__name(values->counters[j]));
+	fprintf(fp, "\n");
+
+	for (i = 0; i < values->threads; i++) {
+		fprintf(fp, "  %*d  %*d", pidwidth, values->pid[i],
+			tidwidth, values->tid[i]);
+		for (j = 0; j < values->num_counters; j++)
+			fprintf(fp, "  %*" PRIu64,
+				counterwidth[j], values->value[i][j]);
+		fprintf(fp, "\n");
+	}
+	free(counterwidth);
+}
+
+static void perf_read_values__display_raw(FILE *fp,
+					  struct perf_read_values *values)
+{
+	int width, pidwidth, tidwidth, namewidth, rawwidth, countwidth;
+	int i, j;
+
+	tidwidth = 3; /* TID */
+	pidwidth = 3; /* PID */
+	namewidth = 4; /* "Name" */
+	rawwidth = 3; /* "Raw" */
+	countwidth = 5; /* "Count" */
+
+	for (i = 0; i < values->threads; i++) {
+		width = snprintf(NULL, 0, "%d", values->pid[i]);
+		if (width > pidwidth)
+			pidwidth = width;
+		width = snprintf(NULL, 0, "%d", values->tid[i]);
+		if (width > tidwidth)
+			tidwidth = width;
+	}
+	for (j = 0; j < values->num_counters; j++) {
+		width = strlen(evsel__name(values->counters[j]));
+		if (width > namewidth)
+			namewidth = width;
+		width = snprintf(NULL, 0, "%x", values->counters[j]->core.idx);
+		if (width > rawwidth)
+			rawwidth = width;
+	}
+	for (i = 0; i < values->threads; i++) {
+		for (j = 0; j < values->num_counters; j++) {
+			width = snprintf(NULL, 0, "%" PRIu64, values->value[i][j]);
+			if (width > countwidth)
+				countwidth = width;
+		}
+	}
+
+	fprintf(fp, "# %*s  %*s  %*s  %*s  %*s\n",
+		pidwidth, "PID", tidwidth, "TID",
+		namewidth, "Name", rawwidth, "Raw",
+		countwidth, "Count");
+	for (i = 0; i < values->threads; i++)
+		for (j = 0; j < values->num_counters; j++)
+			fprintf(fp, "  %*d  %*d  %*s  %*x  %*" PRIu64,
+				pidwidth, values->pid[i],
+				tidwidth, values->tid[i],
+				namewidth, evsel__name(values->counters[j]),
+				rawwidth, values->counters[j]->core.idx,
+				countwidth, values->value[i][j]);
+}
+
+void perf_read_values_display(FILE *fp, struct perf_read_values *values, int raw)
+{
+	if (raw)
+		perf_read_values__display_raw(fp, values);
+	else
+		perf_read_values__display_pretty(fp, values);
+}