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, 215 insertions, 0 deletions

diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
new file mode 100644
index 000000000..cb0cb374b
--- /dev/null
+++ b/drivers/of/pdt.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* pdt.c: OF PROM device tree support code.
+ *
+ * Paul Mackerras	August 1996.
+ * Copyright (C) 1996-2005 Paul Mackerras.
+ *
+ *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
+ *    {engebret|bergner}@us.ibm.com
+ *
+ *  Adapted for sparc by David S. Miller davem@davemloft.net
+ *  Adapted for multiple architectures by Andres Salomon <dilinger@queued.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_pdt.h>
+
+#include "of_private.h"
+
+static struct of_pdt_ops *of_pdt_prom_ops __initdata;
+
+#if defined(CONFIG_SPARC)
+unsigned int of_pdt_unique_id __initdata;
+
+#define of_pdt_incr_unique_id(p) do { \
+	(p)->unique_id = of_pdt_unique_id++; \
+} while (0)
+
+static char * __init of_pdt_build_full_name(struct device_node *dp)
+{
+	return build_path_component(dp);
+}
+
+#else /* CONFIG_SPARC */
+
+static inline void of_pdt_incr_unique_id(void *p) { }
+static inline void irq_trans_init(struct device_node *dp) { }
+
+static char * __init of_pdt_build_full_name(struct device_node *dp)
+{
+	static int failsafe_id = 0; /* for generating unique names on failure */
+	const char *name;
+	char path[256];
+	char *buf;
+	int len;
+
+	if (!of_pdt_prom_ops->pkg2path(dp->phandle, path, sizeof(path), &len)) {
+		name = kbasename(path);
+		buf = prom_early_alloc(strlen(name) + 1);
+		strcpy(buf, name);
+		return buf;
+	}
+
+	name = of_get_property(dp, "name", &len);
+	buf = prom_early_alloc(len + 16);
+	sprintf(buf, "%s@unknown%i", name, failsafe_id++);
+	pr_err("%s: pkg2path failed; assigning %s\n", __func__, buf);
+	return buf;
+}
+
+#endif /* !CONFIG_SPARC */
+
+static struct property * __init of_pdt_build_one_prop(phandle node, char *prev,
+					       char *special_name,
+					       void *special_val,
+					       int special_len)
+{
+	static struct property *tmp = NULL;
+	struct property *p;
+	int err;
+
+	if (tmp) {
+		p = tmp;
+		memset(p, 0, sizeof(*p) + 32);
+		tmp = NULL;
+	} else {
+		p = prom_early_alloc(sizeof(struct property) + 32);
+		of_pdt_incr_unique_id(p);
+	}
+
+	p->name = (char *) (p + 1);
+	if (special_name) {
+		strcpy(p->name, special_name);
+		p->length = special_len;
+		p->value = prom_early_alloc(special_len);
+		memcpy(p->value, special_val, special_len);
+	} else {
+		err = of_pdt_prom_ops->nextprop(node, prev, p->name);
+		if (err) {
+			tmp = p;
+			return NULL;
+		}
+		p->length = of_pdt_prom_ops->getproplen(node, p->name);
+		if (p->length <= 0) {
+			p->length = 0;
+		} else {
+			int len;
+
+			p->value = prom_early_alloc(p->length + 1);
+			len = of_pdt_prom_ops->getproperty(node, p->name,
+					p->value, p->length);
+			if (len <= 0)
+				p->length = 0;
+			((unsigned char *)p->value)[p->length] = '\0';
+		}
+	}
+	return p;
+}
+
+static struct property * __init of_pdt_build_prop_list(phandle node)
+{
+	struct property *head, *tail;
+
+	head = tail = of_pdt_build_one_prop(node, NULL,
+				     ".node", &node, sizeof(node));
+
+	tail->next = of_pdt_build_one_prop(node, NULL, NULL, NULL, 0);
+	tail = tail->next;
+	while(tail) {
+		tail->next = of_pdt_build_one_prop(node, tail->name,
+					    NULL, NULL, 0);
+		tail = tail->next;
+	}
+
+	return head;
+}
+
+static char * __init of_pdt_get_one_property(phandle node, const char *name)
+{
+	char *buf = "<NULL>";
+	int len;
+
+	len = of_pdt_prom_ops->getproplen(node, name);
+	if (len > 0) {
+		buf = prom_early_alloc(len);
+		len = of_pdt_prom_ops->getproperty(node, name, buf, len);
+	}
+
+	return buf;
+}
+
+static struct device_node * __init of_pdt_create_node(phandle node,
+						    struct device_node *parent)
+{
+	struct device_node *dp;
+
+	if (!node)
+		return NULL;
+
+	dp = prom_early_alloc(sizeof(*dp));
+	of_node_init(dp);
+	of_pdt_incr_unique_id(dp);
+	dp->parent = parent;
+
+	dp->name = of_pdt_get_one_property(node, "name");
+	dp->phandle = node;
+
+	dp->properties = of_pdt_build_prop_list(node);
+
+	dp->full_name = of_pdt_build_full_name(dp);
+
+	irq_trans_init(dp);
+
+	return dp;
+}
+
+static struct device_node * __init of_pdt_build_tree(struct device_node *parent,
+						   phandle node)
+{
+	struct device_node *ret = NULL, *prev_sibling = NULL;
+	struct device_node *dp;
+
+	while (1) {
+		dp = of_pdt_create_node(node, parent);
+		if (!dp)
+			break;
+
+		if (prev_sibling)
+			prev_sibling->sibling = dp;
+
+		if (!ret)
+			ret = dp;
+		prev_sibling = dp;
+
+		dp->child = of_pdt_build_tree(dp, of_pdt_prom_ops->getchild(node));
+
+		node = of_pdt_prom_ops->getsibling(node);
+	}
+
+	return ret;
+}
+
+static void * __init kernel_tree_alloc(u64 size, u64 align)
+{
+	return prom_early_alloc(size);
+}
+
+void __init of_pdt_build_devicetree(phandle root_node, struct of_pdt_ops *ops)
+{
+	BUG_ON(!ops);
+	of_pdt_prom_ops = ops;
+
+	of_root = of_pdt_create_node(root_node, NULL);
+	of_root->full_name = "/";
+
+	of_root->child = of_pdt_build_tree(of_root,
+				of_pdt_prom_ops->getchild(of_root->phandle));
+
+	/* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
+	of_alias_scan(kernel_tree_alloc);
+}