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, 160 insertions, 0 deletions

diff --git a/drivers/power/reset/arm-versatile-reboot.c b/drivers/power/reset/arm-versatile-reboot.c
new file mode 100644
index 000000000..c7624d761
--- /dev/null
+++ b/drivers/power/reset/arm-versatile-reboot.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ *
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <linux/init.h>
+#include <linux/mfd/syscon.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+
+#define INTEGRATOR_HDR_CTRL_OFFSET	0x0C
+#define INTEGRATOR_HDR_LOCK_OFFSET	0x14
+#define INTEGRATOR_CM_CTRL_RESET	(1 << 3)
+
+#define VERSATILE_SYS_LOCK_OFFSET	0x20
+#define VERSATILE_SYS_RESETCTL_OFFSET	0x40
+
+/* Magic unlocking token used on all Versatile boards */
+#define VERSATILE_LOCK_VAL		0xA05F
+
+/*
+ * We detect the different syscon types from the compatible strings.
+ */
+enum versatile_reboot {
+	INTEGRATOR_REBOOT_CM,
+	VERSATILE_REBOOT_CM,
+	REALVIEW_REBOOT_EB,
+	REALVIEW_REBOOT_PB1176,
+	REALVIEW_REBOOT_PB11MP,
+	REALVIEW_REBOOT_PBA8,
+	REALVIEW_REBOOT_PBX,
+};
+
+/* Pointer to the system controller */
+static struct regmap *syscon_regmap;
+static enum versatile_reboot versatile_reboot_type;
+
+static const struct of_device_id versatile_reboot_of_match[] = {
+	{
+		.compatible = "arm,core-module-integrator",
+		.data = (void *)INTEGRATOR_REBOOT_CM
+	},
+	{
+		.compatible = "arm,core-module-versatile",
+		.data = (void *)VERSATILE_REBOOT_CM,
+	},
+	{
+		.compatible = "arm,realview-eb-syscon",
+		.data = (void *)REALVIEW_REBOOT_EB,
+	},
+	{
+		.compatible = "arm,realview-pb1176-syscon",
+		.data = (void *)REALVIEW_REBOOT_PB1176,
+	},
+	{
+		.compatible = "arm,realview-pb11mp-syscon",
+		.data = (void *)REALVIEW_REBOOT_PB11MP,
+	},
+	{
+		.compatible = "arm,realview-pba8-syscon",
+		.data = (void *)REALVIEW_REBOOT_PBA8,
+	},
+	{
+		.compatible = "arm,realview-pbx-syscon",
+		.data = (void *)REALVIEW_REBOOT_PBX,
+	},
+	{},
+};
+
+static int versatile_reboot(struct notifier_block *this, unsigned long mode,
+			    void *cmd)
+{
+	/* Unlock the reset register */
+	/* Then hit reset on the different machines */
+	switch (versatile_reboot_type) {
+	case INTEGRATOR_REBOOT_CM:
+		regmap_write(syscon_regmap, INTEGRATOR_HDR_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_update_bits(syscon_regmap,
+				   INTEGRATOR_HDR_CTRL_OFFSET,
+				   INTEGRATOR_CM_CTRL_RESET,
+				   INTEGRATOR_CM_CTRL_RESET);
+		break;
+	case VERSATILE_REBOOT_CM:
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_update_bits(syscon_regmap,
+				   VERSATILE_SYS_RESETCTL_OFFSET,
+				   0x0107,
+				   0x0105);
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     0);
+		break;
+	case REALVIEW_REBOOT_EB:
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_write(syscon_regmap,
+			     VERSATILE_SYS_RESETCTL_OFFSET, 0x0008);
+		break;
+	case REALVIEW_REBOOT_PB1176:
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_write(syscon_regmap,
+			     VERSATILE_SYS_RESETCTL_OFFSET, 0x0100);
+		break;
+	case REALVIEW_REBOOT_PB11MP:
+	case REALVIEW_REBOOT_PBA8:
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_write(syscon_regmap, VERSATILE_SYS_RESETCTL_OFFSET,
+			     0x0000);
+		regmap_write(syscon_regmap, VERSATILE_SYS_RESETCTL_OFFSET,
+			     0x0004);
+		break;
+	case REALVIEW_REBOOT_PBX:
+		regmap_write(syscon_regmap, VERSATILE_SYS_LOCK_OFFSET,
+			     VERSATILE_LOCK_VAL);
+		regmap_write(syscon_regmap, VERSATILE_SYS_RESETCTL_OFFSET,
+			     0x00f0);
+		regmap_write(syscon_regmap, VERSATILE_SYS_RESETCTL_OFFSET,
+			     0x00f4);
+		break;
+	}
+	dsb();
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block versatile_reboot_nb = {
+	.notifier_call = versatile_reboot,
+	.priority = 192,
+};
+
+static int __init versatile_reboot_probe(void)
+{
+	const struct of_device_id *reboot_id;
+	struct device_node *np;
+	int err;
+
+	np = of_find_matching_node_and_match(NULL, versatile_reboot_of_match,
+						 &reboot_id);
+	if (!np)
+		return -ENODEV;
+	versatile_reboot_type = (enum versatile_reboot)reboot_id->data;
+
+	syscon_regmap = syscon_node_to_regmap(np);
+	of_node_put(np);
+	if (IS_ERR(syscon_regmap))
+		return PTR_ERR(syscon_regmap);
+
+	err = register_restart_handler(&versatile_reboot_nb);
+	if (err)
+		return err;
+
+	pr_info("versatile reboot driver registered\n");
+	return 0;
+}
+device_initcall(versatile_reboot_probe);