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, 147 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-amdpt.c b/drivers/gpio/gpio-amdpt.c
new file mode 100644
index 000000000..8458a6949
--- /dev/null
+++ b/drivers/gpio/gpio-amdpt.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Promontory GPIO driver
+ *
+ * Copyright (C) 2015 ASMedia Technology Inc.
+ * Author: YD Tseng <yd_tseng@asmedia.com.tw>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/generic.h>
+#include <linux/spinlock.h>
+#include <linux/acpi.h>
+#include <linux/platform_device.h>
+
+#define PT_TOTAL_GPIO 8
+#define PT_TOTAL_GPIO_EX 24
+
+/* PCI-E MMIO register offsets */
+#define PT_DIRECTION_REG   0x00
+#define PT_INPUTDATA_REG   0x04
+#define PT_OUTPUTDATA_REG  0x08
+#define PT_CLOCKRATE_REG   0x0C
+#define PT_SYNC_REG        0x28
+
+struct pt_gpio_chip {
+	struct gpio_generic_chip chip;
+	void __iomem             *reg_base;
+};
+
+static int pt_gpio_request(struct gpio_chip *gc, unsigned offset)
+{
+	struct gpio_generic_chip *gen_gc = to_gpio_generic_chip(gc);
+	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
+	u32 using_pins;
+
+	dev_dbg(gc->parent, "pt_gpio_request offset=%x\n", offset);
+
+	guard(gpio_generic_lock_irqsave)(gen_gc);
+
+	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
+	if (using_pins & BIT(offset)) {
+		dev_warn(gc->parent, "PT GPIO pin %x reconfigured\n",
+			 offset);
+		return -EINVAL;
+	}
+
+	writel(using_pins | BIT(offset), pt_gpio->reg_base + PT_SYNC_REG);
+
+	return 0;
+}
+
+static void pt_gpio_free(struct gpio_chip *gc, unsigned offset)
+{
+	struct gpio_generic_chip *gen_gc = to_gpio_generic_chip(gc);
+	struct pt_gpio_chip *pt_gpio = gpiochip_get_data(gc);
+	u32 using_pins;
+
+	guard(gpio_generic_lock_irqsave)(gen_gc);
+
+	using_pins = readl(pt_gpio->reg_base + PT_SYNC_REG);
+	using_pins &= ~BIT(offset);
+	writel(using_pins, pt_gpio->reg_base + PT_SYNC_REG);
+
+	dev_dbg(gc->parent, "pt_gpio_free offset=%x\n", offset);
+}
+
+static int pt_gpio_probe(struct platform_device *pdev)
+{
+	struct gpio_generic_chip_config config;
+	struct device *dev = &pdev->dev;
+	struct pt_gpio_chip *pt_gpio;
+	int ret = 0;
+
+	if (!ACPI_COMPANION(dev)) {
+		dev_err(dev, "PT GPIO device node not found\n");
+		return -ENODEV;
+	}
+
+	pt_gpio = devm_kzalloc(dev, sizeof(struct pt_gpio_chip), GFP_KERNEL);
+	if (!pt_gpio)
+		return -ENOMEM;
+
+	pt_gpio->reg_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pt_gpio->reg_base)) {
+		dev_err(dev, "Failed to map MMIO resource for PT GPIO.\n");
+		return PTR_ERR(pt_gpio->reg_base);
+	}
+
+	config = (struct gpio_generic_chip_config) {
+		.dev = dev,
+		.sz = 4,
+		.dat = pt_gpio->reg_base + PT_INPUTDATA_REG,
+		.set = pt_gpio->reg_base + PT_OUTPUTDATA_REG,
+		.dirout = pt_gpio->reg_base + PT_DIRECTION_REG,
+		.flags = GPIO_GENERIC_READ_OUTPUT_REG_SET,
+	};
+
+	ret = gpio_generic_chip_init(&pt_gpio->chip, &config);
+	if (ret) {
+		dev_err(dev, "failed to initialize the generic GPIO chip\n");
+		return ret;
+	}
+
+	pt_gpio->chip.gc.owner = THIS_MODULE;
+	pt_gpio->chip.gc.request = pt_gpio_request;
+	pt_gpio->chip.gc.free = pt_gpio_free;
+	pt_gpio->chip.gc.ngpio = (uintptr_t)device_get_match_data(dev);
+
+	ret = devm_gpiochip_add_data(dev, &pt_gpio->chip.gc, pt_gpio);
+	if (ret) {
+		dev_err(dev, "Failed to register GPIO lib\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pt_gpio);
+
+	/* initialize register setting */
+	writel(0, pt_gpio->reg_base + PT_SYNC_REG);
+	writel(0, pt_gpio->reg_base + PT_CLOCKRATE_REG);
+
+	dev_dbg(dev, "PT GPIO driver loaded\n");
+	return ret;
+}
+
+static const struct acpi_device_id pt_gpio_acpi_match[] = {
+	{ "AMDF030", PT_TOTAL_GPIO },
+	{ "AMDIF030", PT_TOTAL_GPIO },
+	{ "AMDIF031", PT_TOTAL_GPIO_EX },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, pt_gpio_acpi_match);
+
+static struct platform_driver pt_gpio_driver = {
+	.driver = {
+		.name = "pt-gpio",
+		.acpi_match_table = ACPI_PTR(pt_gpio_acpi_match),
+	},
+	.probe = pt_gpio_probe,
+};
+
+module_platform_driver(pt_gpio_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("YD Tseng <yd_tseng@asmedia.com.tw>");
+MODULE_DESCRIPTION("AMD Promontory GPIO Driver");