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, 199 insertions, 0 deletions

diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
new file mode 100644
index 000000000..71905ede0
--- /dev/null
+++ b/tools/perf/util/probe-event.h
@@ -0,0 +1,199 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PROBE_EVENT_H
+#define _PROBE_EVENT_H
+
+#include <linux/compiler.h>
+#include <stdbool.h>
+
+struct intlist;
+struct nsinfo;
+
+/* Probe related configurations */
+struct probe_conf {
+	bool	show_ext_vars;
+	bool	show_location_range;
+	bool	force_add;
+	bool	no_inlines;
+	bool	cache;
+	bool	bootconfig;
+	int	max_probes;
+	unsigned long	magic_num;
+};
+extern struct probe_conf probe_conf;
+extern bool probe_event_dry_run;
+
+#define DEFAULT_PROBE_MAGIC_NUM	0xdeade12d	/* u32: 3735937325 */
+
+struct symbol;
+
+/* kprobe-tracer and uprobe-tracer tracing point */
+struct probe_trace_point {
+	char		*realname;	/* function real name (if needed) */
+	char		*symbol;	/* Base symbol */
+	char		*module;	/* Module name */
+	unsigned long	offset;		/* Offset from symbol */
+	unsigned long	ref_ctr_offset;	/* SDT reference counter offset */
+	u64		address;	/* Actual address of the trace point */
+	bool		retprobe;	/* Return probe flag */
+};
+
+/* probe-tracer tracing argument referencing offset */
+struct probe_trace_arg_ref {
+	struct probe_trace_arg_ref	*next;	/* Next reference */
+	long				offset;	/* Offset value */
+	bool				user_access;	/* User-memory access */
+};
+
+/* kprobe-tracer and uprobe-tracer tracing argument */
+struct probe_trace_arg {
+	char				*name;	/* Argument name */
+	char				*value;	/* Base value */
+	char				*type;	/* Type name */
+	struct probe_trace_arg_ref	*ref;	/* Referencing offset */
+};
+
+/* kprobe-tracer and uprobe-tracer tracing event (point + arg) */
+struct probe_trace_event {
+	char				*event;	/* Event name */
+	char				*group;	/* Group name */
+	struct probe_trace_point	point;	/* Trace point */
+	int				nargs;	/* Number of args */
+	int				lang;	/* Dwarf language code */
+	bool				uprobes;	/* uprobes only */
+	struct probe_trace_arg		*args;	/* Arguments */
+};
+
+/* Perf probe probing point */
+struct perf_probe_point {
+	char		*file;		/* File path */
+	char		*function;	/* Function name */
+	int		line;		/* Line number */
+	bool		retprobe;	/* Return probe flag */
+	char		*lazy_line;	/* Lazy matching pattern */
+	unsigned long	offset;		/* Offset from function entry */
+	u64		abs_address;	/* Absolute address of the point */
+};
+
+/* Perf probe probing argument field chain */
+struct perf_probe_arg_field {
+	struct perf_probe_arg_field	*next;	/* Next field */
+	char				*name;	/* Name of the field */
+	long				index;	/* Array index number */
+	bool				ref;	/* Referencing flag */
+};
+
+/* Perf probe probing argument */
+struct perf_probe_arg {
+	char				*name;	/* Argument name */
+	char				*var;	/* Variable name */
+	char				*type;	/* Type name */
+	struct perf_probe_arg_field	*field;	/* Structure fields */
+	bool				user_access;	/* User-memory access */
+};
+
+/* Perf probe probing event (point + arg) */
+struct perf_probe_event {
+	char			*event;	/* Event name */
+	char			*group;	/* Group name */
+	struct perf_probe_point	point;	/* Probe point */
+	int			nargs;	/* Number of arguments */
+	bool			sdt;	/* SDT/cached event flag */
+	bool			uprobes;	/* Uprobe event flag */
+	char			*target;	/* Target binary */
+	struct perf_probe_arg	*args;	/* Arguments */
+	struct probe_trace_event *tevs;
+	int			ntevs;
+	struct nsinfo		*nsi;	/* Target namespace */
+};
+
+/* Line range */
+struct line_range {
+	char			*file;		/* File name */
+	char			*function;	/* Function name */
+	int			start;		/* Start line number */
+	int			end;		/* End line number */
+	int			offset;		/* Start line offset */
+	char			*path;		/* Real path name */
+	char			*comp_dir;	/* Compile directory */
+	struct intlist		*line_list;	/* Visible lines */
+};
+
+struct strlist;
+
+/* List of variables */
+struct variable_list {
+	struct probe_trace_point	point;	/* Actual probepoint */
+	struct strlist			*vars;	/* Available variables */
+};
+
+struct map;
+int init_probe_symbol_maps(bool user_only);
+void exit_probe_symbol_maps(void);
+
+/* Command string to events */
+int parse_perf_probe_command(const char *cmd, struct perf_probe_event *pev);
+int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev);
+
+/* Events to command string */
+char *synthesize_perf_probe_command(struct perf_probe_event *pev);
+char *synthesize_probe_trace_command(struct probe_trace_event *tev);
+char *synthesize_perf_probe_arg(struct perf_probe_arg *pa);
+
+int perf_probe_event__copy(struct perf_probe_event *dst,
+			   struct perf_probe_event *src);
+
+bool perf_probe_with_var(struct perf_probe_event *pev);
+
+/* Check the perf_probe_event needs debuginfo */
+bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);
+
+/* Release event contents */
+void clear_perf_probe_event(struct perf_probe_event *pev);
+void clear_probe_trace_event(struct probe_trace_event *tev);
+
+/* Command string to line-range */
+int parse_line_range_desc(const char *cmd, struct line_range *lr);
+
+/* Release line range members */
+void line_range__clear(struct line_range *lr);
+
+/* Initialize line range */
+int line_range__init(struct line_range *lr);
+
+int convert_perf_probe_events(struct perf_probe_event *pevs, int npevs);
+int apply_perf_probe_events(struct perf_probe_event *pevs, int npevs);
+int show_probe_trace_events(struct perf_probe_event *pevs, int npevs);
+int show_bootconfig_events(struct perf_probe_event *pevs, int npevs);
+void cleanup_perf_probe_events(struct perf_probe_event *pevs, int npevs);
+
+struct strfilter;
+
+int show_perf_probe_event(const char *group, const char *event,
+			  struct perf_probe_event *pev,
+			  const char *module, bool use_stdout);
+int show_perf_probe_events(struct strfilter *filter);
+int show_line_range(struct line_range *lr, const char *module,
+		    struct nsinfo *nsi, bool user);
+int show_available_vars(struct perf_probe_event *pevs, int npevs,
+			struct strfilter *filter);
+int show_available_funcs(const char *module, struct nsinfo *nsi,
+			 struct strfilter *filter, bool user);
+void arch__fix_tev_from_maps(struct perf_probe_event *pev,
+			     struct probe_trace_event *tev, struct map *map,
+			     struct symbol *sym);
+
+/* If there is no space to write, returns -E2BIG. */
+int e_snprintf(char *str, size_t size, const char *format, ...) __printf(3, 4);
+
+/* Maximum index number of event-name postfix */
+#define MAX_EVENT_INDEX	1024
+
+int copy_to_probe_trace_arg(struct probe_trace_arg *tvar,
+			    struct perf_probe_arg *pvar);
+
+struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user);
+
+void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
+					   int ntevs);
+
+#endif /*_PROBE_EVENT_H */