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, 380 insertions, 0 deletions

diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
new file mode 100644
index 000000000..6b5ffe81f
--- /dev/null
+++ b/tools/perf/util/debug.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0
+/* For general debugging purposes */
+
+#include <inttypes.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <api/debug.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+#include <sys/time.h>
+#ifdef HAVE_BACKTRACE_SUPPORT
+#include <execinfo.h>
+#endif
+#include "addr_location.h"
+#include "color.h"
+#include "debug.h"
+#include "env.h"
+#include "event.h"
+#include "machine.h"
+#include "map.h"
+#include "print_binary.h"
+#include "srcline.h"
+#include "symbol.h"
+#include "synthetic-events.h"
+#include "target.h"
+#include "thread.h"
+#include "trace-event.h"
+#include "ui/helpline.h"
+#include "ui/ui.h"
+#include "util/parse-sublevel-options.h"
+
+#include <linux/ctype.h>
+
+#ifdef HAVE_LIBTRACEEVENT
+#include <event-parse.h>
+#else
+#define LIBTRACEEVENT_VERSION 0
+#endif
+
+int verbose;
+int debug_kmaps;
+int debug_peo_args;
+bool dump_trace = false, quiet = false;
+int debug_ordered_events;
+static int redirect_to_stderr;
+int debug_data_convert;
+static FILE *_debug_file;
+static bool debug_display_time;
+int debug_type_profile;
+
+FILE *debug_file(void)
+{
+	if (!_debug_file) {
+		debug_set_file(stderr);
+		pr_warning_once("debug_file not set");
+	}
+	return _debug_file;
+}
+
+void debug_set_file(FILE *file)
+{
+	_debug_file = file;
+}
+
+void debug_set_display_time(bool set)
+{
+	debug_display_time = set;
+}
+
+static int fprintf_time(FILE *file)
+{
+	struct timeval tod;
+	struct tm ltime;
+	char date[64];
+
+	if (!debug_display_time)
+		return 0;
+
+	if (gettimeofday(&tod, NULL) != 0)
+		return 0;
+
+	if (localtime_r(&tod.tv_sec, &ltime) == NULL)
+		return 0;
+
+	strftime(date, sizeof(date),  "%F %H:%M:%S", &ltime);
+	return fprintf(file, "[%s.%06lu] ", date, (long)tod.tv_usec);
+}
+
+int veprintf(int level, int var, const char *fmt, va_list args)
+{
+	int ret = 0;
+
+	if (var >= level) {
+		if (use_browser >= 1 && !redirect_to_stderr) {
+			ui_helpline__vshow(fmt, args);
+		} else {
+			ret = fprintf_time(debug_file());
+			ret += vfprintf(debug_file(), fmt, args);
+		}
+	}
+
+	return ret;
+}
+
+int eprintf(int level, int var, const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = veprintf(level, var, fmt, args);
+	va_end(args);
+
+	return ret;
+}
+
+static int veprintf_time(u64 t, const char *fmt, va_list args)
+{
+	int ret = 0;
+	u64 secs, usecs, nsecs = t;
+
+	secs   = nsecs / NSEC_PER_SEC;
+	nsecs -= secs  * NSEC_PER_SEC;
+	usecs  = nsecs / NSEC_PER_USEC;
+
+	ret = fprintf(debug_file(), "[%13" PRIu64 ".%06" PRIu64 "] ", secs, usecs);
+	ret += vfprintf(debug_file(), fmt, args);
+	return ret;
+}
+
+int eprintf_time(int level, int var, u64 t, const char *fmt, ...)
+{
+	int ret = 0;
+	va_list args;
+
+	if (var >= level) {
+		va_start(args, fmt);
+		ret = veprintf_time(t, fmt, args);
+		va_end(args);
+	}
+
+	return ret;
+}
+
+/*
+ * Overloading libtraceevent standard info print
+ * function, display with -v in perf.
+ */
+void pr_stat(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	veprintf(1, verbose, fmt, args);
+	va_end(args);
+	eprintf(1, verbose, "\n");
+}
+
+int dump_printf(const char *fmt, ...)
+{
+	va_list args;
+	int ret = 0;
+
+	if (dump_trace) {
+		va_start(args, fmt);
+		ret = vprintf(fmt, args);
+		va_end(args);
+	}
+
+	return ret;
+}
+
+static int trace_event_printer(enum binary_printer_ops op,
+			       unsigned int val, void *extra, FILE *fp)
+{
+	const char *color = PERF_COLOR_BLUE;
+	union perf_event *event = (union perf_event *)extra;
+	unsigned char ch = (unsigned char)val;
+	int printed = 0;
+
+	switch (op) {
+	case BINARY_PRINT_DATA_BEGIN:
+		printed += fprintf(fp, ".");
+		printed += color_fprintf(fp, color, "\n. ... raw event: size %d bytes\n",
+					 event->header.size);
+		break;
+	case BINARY_PRINT_LINE_BEGIN:
+		printed += fprintf(fp, ".");
+		break;
+	case BINARY_PRINT_ADDR:
+		printed += color_fprintf(fp, color, "  %04x: ", val);
+		break;
+	case BINARY_PRINT_NUM_DATA:
+		printed += color_fprintf(fp, color, " %02x", val);
+		break;
+	case BINARY_PRINT_NUM_PAD:
+		printed += color_fprintf(fp, color, "   ");
+		break;
+	case BINARY_PRINT_SEP:
+		printed += color_fprintf(fp, color, "  ");
+		break;
+	case BINARY_PRINT_CHAR_DATA:
+		printed += color_fprintf(fp, color, "%c",
+			      isprint(ch) && isascii(ch) ? ch : '.');
+		break;
+	case BINARY_PRINT_CHAR_PAD:
+		printed += color_fprintf(fp, color, " ");
+		break;
+	case BINARY_PRINT_LINE_END:
+		printed += color_fprintf(fp, color, "\n");
+		break;
+	case BINARY_PRINT_DATA_END:
+		printed += fprintf(fp, "\n");
+		break;
+	default:
+		break;
+	}
+
+	return printed;
+}
+
+void trace_event(union perf_event *event)
+{
+	unsigned char *raw_event = (void *)event;
+
+	if (!dump_trace)
+		return;
+
+	print_binary(raw_event, event->header.size, 16,
+		     trace_event_printer, event);
+}
+
+static struct sublevel_option debug_opts[] = {
+	{ .name = "verbose",		.value_ptr = &verbose },
+	{ .name = "ordered-events",	.value_ptr = &debug_ordered_events},
+	{ .name = "stderr",		.value_ptr = &redirect_to_stderr},
+	{ .name = "data-convert",	.value_ptr = &debug_data_convert },
+	{ .name = "perf-event-open",	.value_ptr = &debug_peo_args },
+	{ .name = "kmaps",		.value_ptr = &debug_kmaps },
+	{ .name = "type-profile",	.value_ptr = &debug_type_profile },
+	{ .name = NULL, }
+};
+
+int perf_debug_option(const char *str)
+{
+	int ret;
+
+	ret = perf_parse_sublevel_options(str, debug_opts);
+	if (ret)
+		return ret;
+
+	/* Allow only verbose value in range (0, 10), otherwise set 0. */
+	verbose = (verbose < 0) || (verbose > 10) ? 0 : verbose;
+
+#if LIBTRACEEVENT_VERSION >= MAKE_LIBTRACEEVENT_VERSION(1, 3, 0)
+	if (verbose == 1)
+		tep_set_loglevel(TEP_LOG_INFO);
+	else if (verbose == 2)
+		tep_set_loglevel(TEP_LOG_DEBUG);
+	else if (verbose >= 3)
+		tep_set_loglevel(TEP_LOG_ALL);
+#endif
+	return 0;
+}
+
+int perf_quiet_option(void)
+{
+	struct sublevel_option *opt = &debug_opts[0];
+
+	/* disable all debug messages */
+	while (opt->name) {
+		*opt->value_ptr = -1;
+		opt++;
+	}
+
+	/* For debug variables that are used as bool types, set to 0. */
+	redirect_to_stderr = 0;
+	debug_peo_args = 0;
+	debug_kmaps = 0;
+	debug_type_profile = 0;
+
+	return 0;
+}
+
+#define DEBUG_WRAPPER(__n, __l)				\
+static int pr_ ## __n ## _wrapper(const char *fmt, ...)	\
+{							\
+	va_list args;					\
+	int ret;					\
+							\
+	va_start(args, fmt);				\
+	ret = veprintf(__l, verbose, fmt, args);	\
+	va_end(args);					\
+	return ret;					\
+}
+
+DEBUG_WRAPPER(warning, 0);
+DEBUG_WRAPPER(debug, 1);
+
+void perf_debug_setup(void)
+{
+	debug_set_file(stderr);
+	libapi_set_print(pr_warning_wrapper, pr_warning_wrapper, pr_debug_wrapper);
+}
+
+void __dump_stack(FILE *file, void **stackdump, size_t stackdump_size)
+{
+	/* TODO: async safety. printf, malloc, etc. aren't safe inside a signal handler. */
+	pid_t pid = getpid();
+	struct machine *machine;
+	struct thread *thread = NULL;
+	struct perf_env host_env;
+
+	perf_env__init(&host_env);
+	machine = machine__new_live(&host_env, /*kernel_maps=*/false, pid);
+
+	if (machine)
+		thread = machine__find_thread(machine, pid, pid);
+
+#ifdef HAVE_BACKTRACE_SUPPORT
+	if (!machine || !thread) {
+		/*
+		 * Backtrace functions are async signal safe. Fall back on them
+		 * if machine/thread creation fails.
+		 */
+		backtrace_symbols_fd(stackdump, stackdump_size, fileno(file));
+		machine__delete(machine);
+		perf_env__exit(&host_env);
+		return;
+	}
+#endif
+
+	for (size_t i = 0; i < stackdump_size; i++) {
+		struct addr_location al;
+		u64 addr = (u64)(uintptr_t)stackdump[i];
+		bool printed = false;
+
+		addr_location__init(&al);
+		if (thread && thread__find_map(thread, PERF_RECORD_MISC_USER, addr, &al)) {
+			al.sym = map__find_symbol(al.map, al.addr);
+			if (al.sym) {
+				fprintf(file, "    #%zd %p in %s ", i, stackdump[i], al.sym->name);
+				printed = true;
+			}
+		}
+		if (!printed)
+			fprintf(file, "    #%zd %p ", i, stackdump[i]);
+
+		map__fprintf_srcline(al.map, al.addr, "", file);
+		fprintf(file, "\n");
+		addr_location__exit(&al);
+	}
+	thread__put(thread);
+	machine__delete(machine);
+	perf_env__exit(&host_env);
+}
+
+/* Obtain a backtrace and print it to stdout. */
+#ifdef HAVE_BACKTRACE_SUPPORT
+void dump_stack(void)
+{
+	void *stackdump[32];
+	size_t size = backtrace(stackdump, ARRAY_SIZE(stackdump));
+
+	__dump_stack(stdout, stackdump, size);
+}
+#else
+void dump_stack(void) {}
+#endif
+
+void sighandler_dump_stack(int sig)
+{
+	psignal(sig, "perf");
+	dump_stack();
+	signal(sig, SIG_DFL);
+	raise(sig);
+}