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, 76 insertions, 0 deletions

diff --git a/tools/perf/util/block-range.h b/tools/perf/util/block-range.h
new file mode 100644
index 000000000..ec0fb534b
--- /dev/null
+++ b/tools/perf/util/block-range.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_BLOCK_RANGE_H
+#define __PERF_BLOCK_RANGE_H
+
+#include <stdbool.h>
+#include <linux/rbtree.h>
+#include <linux/types.h>
+
+struct symbol;
+
+/*
+ * struct block_range - non-overlapping parts of basic blocks
+ * @node:	treenode
+ * @start:	inclusive start of range
+ * @end:	inclusive end of range
+ * @is_target:	@start is a jump target
+ * @is_branch:	@end is a branch instruction
+ * @coverage:	number of blocks that cover this range
+ * @taken:	number of times the branch is taken (requires @is_branch)
+ * @pred:	number of times the taken branch was predicted
+ */
+struct block_range {
+	struct rb_node node;
+
+	struct symbol *sym;
+
+	u64 start;
+	u64 end;
+
+	int is_target, is_branch;
+
+	u64 coverage;
+	u64 entry;
+	u64 taken;
+	u64 pred;
+};
+
+static inline struct block_range *block_range__next(struct block_range *br)
+{
+	struct rb_node *n = rb_next(&br->node);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct block_range, node);
+}
+
+struct block_range_iter {
+	struct block_range *start;
+	struct block_range *end;
+};
+
+static inline struct block_range *block_range_iter(struct block_range_iter *iter)
+{
+	return iter->start;
+}
+
+static inline bool block_range_iter__next(struct block_range_iter *iter)
+{
+	if (iter->start == iter->end)
+		return false;
+
+	iter->start = block_range__next(iter->start);
+	return true;
+}
+
+static inline bool block_range_iter__valid(struct block_range_iter *iter)
+{
+	if (!iter->start || !iter->end)
+		return false;
+	return true;
+}
+
+extern struct block_range *block_range__find(u64 addr);
+extern struct block_range_iter block_range__create(u64 start, u64 end);
+extern double block_range__coverage(struct block_range *br);
+
+#endif /* __PERF_BLOCK_RANGE_H */