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, 88 insertions, 0 deletions

diff --git a/tools/perf/util/maps.h b/tools/perf/util/maps.h
new file mode 100644
index 000000000..4ec9b7453
--- /dev/null
+++ b/tools/perf/util/maps.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_MAPS_H
+#define __PERF_MAPS_H
+
+#include <linux/refcount.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <linux/types.h>
+
+struct ref_reloc_sym;
+struct machine;
+struct map;
+struct maps;
+
+#define KMAP_NAME_LEN 256
+
+struct kmap {
+	struct ref_reloc_sym *ref_reloc_sym;
+	struct maps	     *kmaps;
+	char		     name[KMAP_NAME_LEN];
+};
+
+struct maps *maps__new(struct machine *machine);
+bool maps__empty(struct maps *maps);
+int maps__copy_from(struct maps *maps, struct maps *parent);
+
+struct maps *maps__get(struct maps *maps);
+void maps__put(struct maps *maps);
+
+static inline void __maps__zput(struct maps **map)
+{
+	maps__put(*map);
+	*map = NULL;
+}
+
+#define maps__zput(map) __maps__zput(&map)
+
+bool maps__equal(struct maps *a, struct maps *b);
+
+/* Iterate over map calling cb for each entry. */
+int maps__for_each_map(struct maps *maps, int (*cb)(struct map *map, void *data), void *data);
+/* Iterate over map removing an entry if cb returns true. */
+void maps__remove_maps(struct maps *maps, bool (*cb)(struct map *map, void *data), void *data);
+
+struct machine *maps__machine(const struct maps *maps);
+unsigned int maps__nr_maps(const struct maps *maps); /* Test only. */
+refcount_t *maps__refcnt(struct maps *maps); /* Test only. */
+
+#ifdef HAVE_LIBUNWIND_SUPPORT
+void *maps__addr_space(const struct maps *maps);
+void maps__set_addr_space(struct maps *maps, void *addr_space);
+uint16_t maps__e_machine(const struct maps *maps);
+void maps__set_e_machine(struct maps *maps, uint16_t e_machine);
+#endif
+#ifdef HAVE_LIBDW_SUPPORT
+void *maps__libdw_addr_space_dwfl(const struct maps *maps);
+void maps__set_libdw_addr_space_dwfl(struct maps *maps, void *dwfl);
+#endif
+
+size_t maps__fprintf(struct maps *maps, FILE *fp);
+
+int maps__load_maps(struct maps *maps);
+int maps__insert(struct maps *maps, struct map *map);
+void maps__remove(struct maps *maps, struct map *map);
+int maps__mutate_mapping(struct maps *maps, struct map *map,
+			 int (*mutate_cb)(struct map *map, void *data), void *data);
+
+struct map *maps__find(struct maps *maps, u64 addr);
+struct symbol *maps__find_symbol(struct maps *maps, u64 addr, struct map **mapp);
+struct symbol *maps__find_symbol_by_name(struct maps *maps, const char *name, struct map **mapp);
+
+struct addr_map_symbol;
+
+int maps__find_ams(struct maps *maps, struct addr_map_symbol *ams);
+
+int maps__fixup_overlap_and_insert(struct maps *maps, struct map *new);
+
+struct map *maps__find_by_name(struct maps *maps, const char *name);
+
+struct map *maps__find_next_entry(struct maps *maps, struct map *map);
+
+int maps__merge_in(struct maps *kmaps, struct map *new_map);
+
+void maps__fixup_end(struct maps *maps);
+
+void maps__load_first(struct maps *maps);
+
+#endif // __PERF_MAPS_H