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, 407 insertions, 0 deletions

diff --git a/tools/perf/util/trace-event-scripting.c b/tools/perf/util/trace-event-scripting.c
new file mode 100644
index 000000000..dc584ac31
--- /dev/null
+++ b/tools/perf/util/trace-event-scripting.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * trace-event-scripting.  Scripting engine common and initialization code.
+ *
+ * Copyright (C) 2009-2010 Tom Zanussi <tzanussi@gmail.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#ifdef HAVE_LIBTRACEEVENT
+#include <event-parse.h>
+#endif
+
+#include "debug.h"
+#include "event.h"
+#include "trace-event.h"
+#include "evsel.h"
+#include <linux/perf_event.h>
+#include <linux/zalloc.h>
+#include "util/sample.h"
+
+unsigned int scripting_max_stack = PERF_MAX_STACK_DEPTH;
+
+struct scripting_context *scripting_context;
+
+struct script_spec {
+	struct list_head	node;
+	struct scripting_ops	*ops;
+	char			spec[];
+};
+
+static LIST_HEAD(script_specs);
+
+static struct script_spec *script_spec__new(const char *spec,
+					    struct scripting_ops *ops)
+{
+	struct script_spec *s = malloc(sizeof(*s) + strlen(spec) + 1);
+
+	if (s != NULL) {
+		strcpy(s->spec, spec);
+		s->ops = ops;
+	}
+
+	return s;
+}
+
+static void script_spec__add(struct script_spec *s)
+{
+	list_add_tail(&s->node, &script_specs);
+}
+
+static struct script_spec *script_spec__find(const char *spec)
+{
+	struct script_spec *s;
+
+	list_for_each_entry(s, &script_specs, node)
+		if (strcasecmp(s->spec, spec) == 0)
+			return s;
+	return NULL;
+}
+
+static int script_spec_register(const char *spec, struct scripting_ops *ops)
+{
+	struct script_spec *s;
+
+	s = script_spec__find(spec);
+	if (s)
+		return -1;
+
+	s = script_spec__new(spec, ops);
+	if (!s)
+		return -1;
+
+	script_spec__add(s);
+	return 0;
+}
+
+struct scripting_ops *script_spec__lookup(const char *spec)
+{
+	struct script_spec *s = script_spec__find(spec);
+
+	if (!s)
+		return NULL;
+
+	return s->ops;
+}
+
+int script_spec__for_each(int (*cb)(struct scripting_ops *ops, const char *spec))
+{
+	struct script_spec *s;
+	int ret = 0;
+
+	list_for_each_entry(s, &script_specs, node) {
+		ret = cb(s->ops, s->spec);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+void scripting_context__update(struct scripting_context *c,
+			       union perf_event *event,
+			       struct perf_sample *sample,
+			       struct addr_location *al,
+			       struct addr_location *addr_al)
+{
+#ifdef HAVE_LIBTRACEEVENT
+	const struct tep_event *tp_format = evsel__tp_format(sample->evsel);
+
+	c->pevent = tp_format ? tp_format->tep : NULL;
+#else
+	c->pevent = NULL;
+#endif
+	c->event_data = sample->raw_data;
+	c->event = event;
+	c->sample = sample;
+	c->al = al;
+	c->addr_al = addr_al;
+}
+
+static int flush_script_unsupported(void)
+{
+	return 0;
+}
+
+static int stop_script_unsupported(void)
+{
+	return 0;
+}
+
+static void process_event_unsupported(union perf_event *event __maybe_unused,
+				      struct perf_sample *sample __maybe_unused,
+				      struct addr_location *al __maybe_unused,
+				      struct addr_location *addr_al __maybe_unused)
+{
+}
+
+static void print_python_unsupported_msg(void)
+{
+	fprintf(stderr, "Python scripting not supported."
+		"  Install libpython and rebuild perf to enable it.\n"
+		"For example:\n  # apt-get install python-dev (ubuntu)"
+		"\n  # yum install python-devel (Fedora)"
+		"\n  etc.\n");
+}
+
+static int python_start_script_unsupported(const char *script __maybe_unused,
+					   int argc __maybe_unused,
+					   const char **argv __maybe_unused,
+					   struct perf_session *session __maybe_unused)
+{
+	print_python_unsupported_msg();
+
+	return -1;
+}
+
+static int python_generate_script_unsupported(struct tep_handle *pevent
+					      __maybe_unused,
+					      const char *outfile
+					      __maybe_unused)
+{
+	print_python_unsupported_msg();
+
+	return -1;
+}
+
+struct scripting_ops python_scripting_unsupported_ops = {
+	.name = "Python",
+	.dirname = "python",
+	.start_script = python_start_script_unsupported,
+	.flush_script = flush_script_unsupported,
+	.stop_script = stop_script_unsupported,
+	.process_event = process_event_unsupported,
+	.generate_script = python_generate_script_unsupported,
+};
+
+static void register_python_scripting(struct scripting_ops *scripting_ops)
+{
+	if (scripting_context == NULL)
+		scripting_context = malloc(sizeof(*scripting_context));
+
+       if (scripting_context == NULL ||
+	   script_spec_register("Python", scripting_ops) ||
+	   script_spec_register("py", scripting_ops)) {
+		pr_err("Error registering Python script extension: disabling it\n");
+		zfree(&scripting_context);
+	}
+}
+
+#ifndef HAVE_LIBPYTHON_SUPPORT
+void setup_python_scripting(void)
+{
+	register_python_scripting(&python_scripting_unsupported_ops);
+}
+#else
+extern struct scripting_ops python_scripting_ops;
+
+void setup_python_scripting(void)
+{
+	register_python_scripting(&python_scripting_ops);
+}
+#endif
+
+#ifdef HAVE_LIBTRACEEVENT
+static void print_perl_unsupported_msg(void)
+{
+	fprintf(stderr, "Perl scripting not supported."
+		"  Install libperl and rebuild perf to enable it.\n"
+		"For example:\n  # apt-get install libperl-dev (ubuntu)"
+		"\n  # yum install 'perl(ExtUtils::Embed)' (Fedora)"
+		"\n  etc.\n");
+}
+
+static int perl_start_script_unsupported(const char *script __maybe_unused,
+					 int argc __maybe_unused,
+					 const char **argv __maybe_unused,
+					 struct perf_session *session __maybe_unused)
+{
+	print_perl_unsupported_msg();
+
+	return -1;
+}
+
+static int perl_generate_script_unsupported(struct tep_handle *pevent
+					    __maybe_unused,
+					    const char *outfile __maybe_unused)
+{
+	print_perl_unsupported_msg();
+
+	return -1;
+}
+
+struct scripting_ops perl_scripting_unsupported_ops = {
+	.name = "Perl",
+	.dirname = "perl",
+	.start_script = perl_start_script_unsupported,
+	.flush_script = flush_script_unsupported,
+	.stop_script = stop_script_unsupported,
+	.process_event = process_event_unsupported,
+	.generate_script = perl_generate_script_unsupported,
+};
+
+static void register_perl_scripting(struct scripting_ops *scripting_ops)
+{
+	if (scripting_context == NULL)
+		scripting_context = malloc(sizeof(*scripting_context));
+
+       if (scripting_context == NULL ||
+	   script_spec_register("Perl", scripting_ops) ||
+	   script_spec_register("pl", scripting_ops)) {
+		pr_err("Error registering Perl script extension: disabling it\n");
+		zfree(&scripting_context);
+	}
+}
+
+#ifndef HAVE_LIBPERL_SUPPORT
+void setup_perl_scripting(void)
+{
+	register_perl_scripting(&perl_scripting_unsupported_ops);
+}
+#else
+extern struct scripting_ops perl_scripting_ops;
+
+void setup_perl_scripting(void)
+{
+	register_perl_scripting(&perl_scripting_ops);
+}
+#endif
+#endif
+
+static const struct {
+	u32 flags;
+	const char *name;
+} sample_flags[] = {
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL, "call"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_RETURN, "return"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CONDITIONAL, "jcc"},
+	{PERF_IP_FLAG_BRANCH, "jmp"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL | PERF_IP_FLAG_INTERRUPT, "int"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_RETURN | PERF_IP_FLAG_INTERRUPT, "iret"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL | PERF_IP_FLAG_SYSCALLRET, "syscall"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_RETURN | PERF_IP_FLAG_SYSCALLRET, "sysret"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_ASYNC, "async"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL | PERF_IP_FLAG_ASYNC |	PERF_IP_FLAG_INTERRUPT,
+	 "hw int"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_TX_ABORT, "tx abrt"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_TRACE_BEGIN, "tr strt"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_TRACE_END, "tr end"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL | PERF_IP_FLAG_VMENTRY, "vmentry"},
+	{PERF_IP_FLAG_BRANCH | PERF_IP_FLAG_CALL | PERF_IP_FLAG_VMEXIT, "vmexit"},
+	{0, NULL}
+};
+
+static const struct {
+	u32 flags;
+	const char *name;
+} branch_events[] = {
+	{PERF_IP_FLAG_BRANCH_MISS, "miss"},
+	{PERF_IP_FLAG_NOT_TAKEN, "not_taken"},
+	{0, NULL}
+};
+
+static int sample_flags_to_name(u32 flags, char *str, size_t size)
+{
+	int i;
+	const char *prefix;
+	int pos = 0, ret, ev_idx = 0;
+	u32 xf = flags & PERF_ADDITIONAL_STATE_MASK;
+	u32 types, events;
+	char xs[16] = { 0 };
+
+	/* Clear additional state bits */
+	flags &= ~PERF_ADDITIONAL_STATE_MASK;
+
+	if (flags & PERF_IP_FLAG_TRACE_BEGIN)
+		prefix = "tr strt ";
+	else if (flags & PERF_IP_FLAG_TRACE_END)
+		prefix = "tr end  ";
+	else
+		prefix = "";
+
+	ret = snprintf(str + pos, size - pos, "%s", prefix);
+	if (ret < 0)
+		return ret;
+	pos += ret;
+
+	flags &= ~(PERF_IP_FLAG_TRACE_BEGIN | PERF_IP_FLAG_TRACE_END);
+
+	types = flags & ~PERF_IP_FLAG_BRANCH_EVENT_MASK;
+	for (i = 0; sample_flags[i].name; i++) {
+		if (sample_flags[i].flags != types)
+			continue;
+
+		ret = snprintf(str + pos, size - pos, "%s", sample_flags[i].name);
+		if (ret < 0)
+			return ret;
+		pos += ret;
+		break;
+	}
+
+	events = flags & PERF_IP_FLAG_BRANCH_EVENT_MASK;
+	for (i = 0; branch_events[i].name; i++) {
+		if (!(branch_events[i].flags & events))
+			continue;
+
+		ret = snprintf(str + pos, size - pos, !ev_idx ? "/%s" : ",%s",
+			       branch_events[i].name);
+		if (ret < 0)
+			return ret;
+		pos += ret;
+		ev_idx++;
+	}
+
+	/* Add an end character '/' for events */
+	if (ev_idx) {
+		ret = snprintf(str + pos, size - pos, "/");
+		if (ret < 0)
+			return ret;
+		pos += ret;
+	}
+
+	if (!xf)
+		return pos;
+
+	snprintf(xs, sizeof(xs), "(%s%s%s)",
+		 flags & PERF_IP_FLAG_IN_TX ? "x" : "",
+		 flags & PERF_IP_FLAG_INTR_DISABLE ? "D" : "",
+		 flags & PERF_IP_FLAG_INTR_TOGGLE ? "t" : "");
+
+	/* Right align the string if its length is less than the limit */
+	if ((pos + strlen(xs)) < SAMPLE_FLAGS_STR_ALIGNED_SIZE)
+		ret = snprintf(str + pos, size - pos, "%*s",
+			       (int)(SAMPLE_FLAGS_STR_ALIGNED_SIZE - ret), xs);
+	else
+		ret = snprintf(str + pos, size - pos, " %s", xs);
+	if (ret < 0)
+		return ret;
+
+	return pos + ret;
+}
+
+int perf_sample__sprintf_flags(u32 flags, char *str, size_t sz)
+{
+	const char *chars = PERF_IP_FLAG_CHARS;
+	const size_t n = strlen(PERF_IP_FLAG_CHARS);
+	size_t i, pos = 0;
+	int ret;
+
+	ret = sample_flags_to_name(flags, str, sz);
+	if (ret > 0)
+		return ret;
+
+	for (i = 0; i < n; i++, flags >>= 1) {
+		if ((flags & 1) && pos < sz)
+			str[pos++] = chars[i];
+	}
+	for (; i < 32; i++, flags >>= 1) {
+		if ((flags & 1) && pos < sz)
+			str[pos++] = '?';
+	}
+	if (pos < sz)
+		str[pos] = 0;
+
+	return pos;
+}