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, 142 insertions, 0 deletions

diff --git a/drivers/phy/broadcom/phy-bcm-ns-usb2.c b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
new file mode 100644
index 000000000..c5d35031b
--- /dev/null
+++ b/drivers/phy/broadcom/phy-bcm-ns-usb2.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Broadcom Northstar USB 2.0 PHY Driver
+ *
+ * Copyright (C) 2016 Rafał Miłecki <zajec5@gmail.com>
+ */
+
+#include <linux/bcma/bcma.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct bcm_ns_usb2 {
+	struct device *dev;
+	struct clk *ref_clk;
+	struct phy *phy;
+	struct regmap *clkset;
+	void __iomem *base;
+};
+
+static int bcm_ns_usb2_phy_init(struct phy *phy)
+{
+	struct bcm_ns_usb2 *usb2 = phy_get_drvdata(phy);
+	struct device *dev = usb2->dev;
+	u32 ref_clk_rate, usb2ctl, usb_pll_ndiv, usb_pll_pdiv;
+	int err = 0;
+
+	err = clk_prepare_enable(usb2->ref_clk);
+	if (err < 0) {
+		dev_err(dev, "Failed to prepare ref clock: %d\n", err);
+		goto err_out;
+	}
+
+	ref_clk_rate = clk_get_rate(usb2->ref_clk);
+	if (!ref_clk_rate) {
+		dev_err(dev, "Failed to get ref clock rate\n");
+		err = -EINVAL;
+		goto err_clk_off;
+	}
+
+	usb2ctl = readl(usb2->base);
+
+	if (usb2ctl & BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK) {
+		usb_pll_pdiv = usb2ctl;
+		usb_pll_pdiv &= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_MASK;
+		usb_pll_pdiv >>= BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_PDIV_SHIFT;
+	} else {
+		usb_pll_pdiv = 1 << 3;
+	}
+
+	/* Calculate ndiv based on a solid 1920 MHz that is for USB2 PHY */
+	usb_pll_ndiv = (1920000000 * usb_pll_pdiv) / ref_clk_rate;
+
+	/* Unlock DMU PLL settings with some magic value */
+	regmap_write(usb2->clkset, 0, 0x0000ea68);
+
+	/* Write USB 2.0 PLL control setting */
+	usb2ctl &= ~BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_MASK;
+	usb2ctl |= usb_pll_ndiv << BCMA_DMU_CRU_USB2_CONTROL_USB_PLL_NDIV_SHIFT;
+
+	writel(usb2ctl, usb2->base);
+
+	/* Lock DMU PLL settings */
+	regmap_write(usb2->clkset, 0, 0x00000000);
+
+err_clk_off:
+	clk_disable_unprepare(usb2->ref_clk);
+err_out:
+	return err;
+}
+
+static const struct phy_ops ops = {
+	.init		= bcm_ns_usb2_phy_init,
+	.owner		= THIS_MODULE,
+};
+
+static int bcm_ns_usb2_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm_ns_usb2 *usb2;
+	struct phy_provider *phy_provider;
+
+	usb2 = devm_kzalloc(&pdev->dev, sizeof(*usb2), GFP_KERNEL);
+	if (!usb2)
+		return -ENOMEM;
+	usb2->dev = dev;
+
+	usb2->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(usb2->base)) {
+		dev_err(dev, "Failed to map control reg\n");
+		return PTR_ERR(usb2->base);
+	}
+
+	usb2->clkset = syscon_regmap_lookup_by_phandle(dev->of_node,
+						       "brcm,syscon-clkset");
+	if (IS_ERR(usb2->clkset)) {
+		dev_err(dev, "Failed to lookup clkset regmap\n");
+		return PTR_ERR(usb2->clkset);
+	}
+
+	usb2->ref_clk = devm_clk_get(dev, "phy-ref-clk");
+	if (IS_ERR(usb2->ref_clk)) {
+		dev_err_probe(dev, PTR_ERR(usb2->ref_clk), "failed to get ref clk\n");
+		return PTR_ERR(usb2->ref_clk);
+	}
+
+	usb2->phy = devm_phy_create(dev, NULL, &ops);
+	if (IS_ERR(usb2->phy))
+		return PTR_ERR(usb2->phy);
+
+	phy_set_drvdata(usb2->phy, usb2);
+	platform_set_drvdata(pdev, usb2);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id bcm_ns_usb2_id_table[] = {
+	{ .compatible = "brcm,ns-usb2-phy", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm_ns_usb2_id_table);
+
+static struct platform_driver bcm_ns_usb2_driver = {
+	.probe		= bcm_ns_usb2_probe,
+	.driver = {
+		.name = "bcm_ns_usb2",
+		.of_match_table = bcm_ns_usb2_id_table,
+	},
+};
+module_platform_driver(bcm_ns_usb2_driver);
+
+MODULE_DESCRIPTION("Broadcom Northstar USB 2.0 PHY Driver");
+MODULE_LICENSE("GPL v2");