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, 193 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-am335x-control.c b/drivers/usb/phy/phy-am335x-control.c
new file mode 100644
index 000000000..ada508be0
--- /dev/null
+++ b/drivers/usb/phy/phy-am335x-control.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/usb/otg.h>
+#include "phy-am335x-control.h"
+
+struct am335x_control_usb {
+	struct device *dev;
+	void __iomem *phy_reg;
+	void __iomem *wkup;
+	spinlock_t lock;
+	struct phy_control phy_ctrl;
+};
+
+#define AM335X_USB0_CTRL		0x0
+#define AM335X_USB1_CTRL		0x8
+#define AM335x_USB_WKUP			0x0
+
+#define USBPHY_CM_PWRDN		(1 << 0)
+#define USBPHY_OTG_PWRDN	(1 << 1)
+#define USBPHY_OTGVDET_EN	(1 << 19)
+#define USBPHY_OTGSESSEND_EN	(1 << 20)
+
+#define AM335X_PHY0_WK_EN	(1 << 0)
+#define AM335X_PHY1_WK_EN	(1 << 8)
+
+static void am335x_phy_wkup(struct  phy_control *phy_ctrl, u32 id, bool on)
+{
+	struct am335x_control_usb *usb_ctrl;
+	u32 val;
+	u32 reg;
+
+	usb_ctrl = container_of(phy_ctrl, struct am335x_control_usb, phy_ctrl);
+
+	switch (id) {
+	case 0:
+		reg = AM335X_PHY0_WK_EN;
+		break;
+	case 1:
+		reg = AM335X_PHY1_WK_EN;
+		break;
+	default:
+		WARN_ON(1);
+		return;
+	}
+
+	spin_lock(&usb_ctrl->lock);
+	val = readl(usb_ctrl->wkup);
+
+	if (on)
+		val |= reg;
+	else
+		val &= ~reg;
+
+	writel(val, usb_ctrl->wkup);
+	spin_unlock(&usb_ctrl->lock);
+}
+
+static void am335x_phy_power(struct phy_control *phy_ctrl, u32 id,
+				enum usb_dr_mode dr_mode, bool on)
+{
+	struct am335x_control_usb *usb_ctrl;
+	u32 val;
+	u32 reg;
+
+	usb_ctrl = container_of(phy_ctrl, struct am335x_control_usb, phy_ctrl);
+
+	switch (id) {
+	case 0:
+		reg = AM335X_USB0_CTRL;
+		break;
+	case 1:
+		reg = AM335X_USB1_CTRL;
+		break;
+	default:
+		WARN_ON(1);
+		return;
+	}
+
+	val = readl(usb_ctrl->phy_reg + reg);
+	if (on) {
+		if (dr_mode == USB_DR_MODE_HOST) {
+			val &= ~(USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN |
+					USBPHY_OTGVDET_EN);
+			val |= USBPHY_OTGSESSEND_EN;
+		} else {
+			val &= ~(USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN);
+			val |= USBPHY_OTGVDET_EN | USBPHY_OTGSESSEND_EN;
+		}
+	} else {
+		val |= USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN;
+	}
+
+	writel(val, usb_ctrl->phy_reg + reg);
+
+	/*
+	 * Give the PHY ~1ms to complete the power up operation.
+	 * Tests have shown unstable behaviour if other USB PHY related
+	 * registers are written too shortly after such a transition.
+	 */
+	if (on)
+		mdelay(1);
+}
+
+static const struct phy_control ctrl_am335x = {
+	.phy_power = am335x_phy_power,
+	.phy_wkup = am335x_phy_wkup,
+};
+
+static const struct of_device_id omap_control_usb_id_table[] = {
+	{ .compatible = "ti,am335x-usb-ctrl-module", .data = &ctrl_am335x },
+	{}
+};
+MODULE_DEVICE_TABLE(of, omap_control_usb_id_table);
+
+static struct platform_driver am335x_control_driver;
+static int match(struct device *dev, const void *data)
+{
+	const struct device_node *node = (const struct device_node *)data;
+	return dev->of_node == node &&
+		dev->driver == &am335x_control_driver.driver;
+}
+
+struct phy_control *am335x_get_phy_control(struct device *dev)
+{
+	struct device_node *node;
+	struct am335x_control_usb *ctrl_usb;
+
+	node = of_parse_phandle(dev->of_node, "ti,ctrl_mod", 0);
+	if (!node)
+		return NULL;
+
+	dev = bus_find_device(&platform_bus_type, NULL, node, match);
+	of_node_put(node);
+	if (!dev)
+		return NULL;
+
+	ctrl_usb = dev_get_drvdata(dev);
+	put_device(dev);
+	if (!ctrl_usb)
+		return NULL;
+	return &ctrl_usb->phy_ctrl;
+}
+EXPORT_SYMBOL_GPL(am335x_get_phy_control);
+
+static int am335x_control_usb_probe(struct platform_device *pdev)
+{
+	struct am335x_control_usb *ctrl_usb;
+	const struct of_device_id *of_id;
+	const struct phy_control *phy_ctrl;
+
+	of_id = of_match_node(omap_control_usb_id_table, pdev->dev.of_node);
+	if (!of_id)
+		return -EINVAL;
+
+	phy_ctrl = of_id->data;
+
+	ctrl_usb = devm_kzalloc(&pdev->dev, sizeof(*ctrl_usb), GFP_KERNEL);
+	if (!ctrl_usb)
+		return -ENOMEM;
+
+	ctrl_usb->dev = &pdev->dev;
+
+	ctrl_usb->phy_reg = devm_platform_ioremap_resource_byname(pdev, "phy_ctrl");
+	if (IS_ERR(ctrl_usb->phy_reg))
+		return PTR_ERR(ctrl_usb->phy_reg);
+
+	ctrl_usb->wkup = devm_platform_ioremap_resource_byname(pdev, "wakeup");
+	if (IS_ERR(ctrl_usb->wkup))
+		return PTR_ERR(ctrl_usb->wkup);
+
+	spin_lock_init(&ctrl_usb->lock);
+	ctrl_usb->phy_ctrl = *phy_ctrl;
+
+	dev_set_drvdata(ctrl_usb->dev, ctrl_usb);
+	return 0;
+}
+
+static struct platform_driver am335x_control_driver = {
+	.probe		= am335x_control_usb_probe,
+	.driver		= {
+		.name	= "am335x-control-usb",
+		.of_match_table = omap_control_usb_id_table,
+	},
+};
+
+module_platform_driver(am335x_control_driver);
+MODULE_DESCRIPTION("AM335x USB PHY Control Driver");
+MODULE_LICENSE("GPL v2");