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, 127 insertions, 0 deletions

diff --git a/drivers/mfd/bcm2835-pm.c b/drivers/mfd/bcm2835-pm.c
new file mode 100644
index 000000000..9e8e3dcf4
--- /dev/null
+++ b/drivers/mfd/bcm2835-pm.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PM MFD driver for Broadcom BCM2835
+ *
+ * This driver binds to the PM block and creates the MFD device for
+ * the WDT and power drivers.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/bcm2835-pm.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+static const struct mfd_cell bcm2835_pm_devs[] = {
+	{ .name = "bcm2835-wdt" },
+};
+
+static const struct mfd_cell bcm2835_power_devs[] = {
+	{ .name = "bcm2835-power" },
+};
+
+static int bcm2835_pm_get_pdata(struct platform_device *pdev,
+				struct bcm2835_pm *pm)
+{
+	if (of_property_present(pm->dev->of_node, "reg-names")) {
+		struct resource *res;
+
+		pm->base = devm_platform_ioremap_resource_byname(pdev, "pm");
+		if (IS_ERR(pm->base))
+			return PTR_ERR(pm->base);
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "asb");
+		if (res) {
+			pm->asb = devm_ioremap_resource(&pdev->dev, res);
+			if (IS_ERR(pm->asb))
+				pm->asb = NULL;
+		}
+
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+						    "rpivid_asb");
+		if (res) {
+			pm->rpivid_asb = devm_ioremap_resource(&pdev->dev, res);
+			if (IS_ERR(pm->rpivid_asb))
+				pm->rpivid_asb = NULL;
+		}
+
+		return 0;
+	}
+
+	/* If no 'reg-names' property is found we can assume we're using old DTB. */
+	pm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pm->base))
+		return PTR_ERR(pm->base);
+
+	pm->asb = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(pm->asb))
+		pm->asb = NULL;
+
+	pm->rpivid_asb = devm_platform_ioremap_resource(pdev, 2);
+	if (IS_ERR(pm->rpivid_asb))
+		pm->rpivid_asb = NULL;
+
+	return 0;
+}
+
+static int bcm2835_pm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm2835_pm *pm;
+	int ret;
+
+	pm = devm_kzalloc(dev, sizeof(*pm), GFP_KERNEL);
+	if (!pm)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, pm);
+
+	pm->dev = dev;
+	pm->soc = (uintptr_t)device_get_match_data(dev);
+
+	ret = bcm2835_pm_get_pdata(pdev, pm);
+	if (ret)
+		return ret;
+
+	ret = devm_mfd_add_devices(dev, -1,
+				   bcm2835_pm_devs, ARRAY_SIZE(bcm2835_pm_devs),
+				   NULL, 0, NULL);
+	if (ret)
+		return ret;
+
+	/*
+	 * We'll use the presence of the AXI ASB regs in the
+	 * bcm2835-pm binding as the key for whether we can reference
+	 * the full PM register range and support power domains.
+	 */
+	if (pm->asb || pm->soc == BCM2835_PM_SOC_BCM2712)
+		return devm_mfd_add_devices(dev, -1, bcm2835_power_devs,
+					    ARRAY_SIZE(bcm2835_power_devs),
+					    NULL, 0, NULL);
+	return 0;
+}
+
+static const struct of_device_id bcm2835_pm_of_match[] = {
+	{ .compatible = "brcm,bcm2835-pm-wdt", },
+	{ .compatible = "brcm,bcm2835-pm", .data = (void *)BCM2835_PM_SOC_BCM2835 },
+	{ .compatible = "brcm,bcm2711-pm", .data = (void *)BCM2835_PM_SOC_BCM2711 },
+	{ .compatible = "brcm,bcm2712-pm", .data = (void *)BCM2835_PM_SOC_BCM2712 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_pm_of_match);
+
+static struct platform_driver bcm2835_pm_driver = {
+	.probe		= bcm2835_pm_probe,
+	.driver = {
+		.name =	"bcm2835-pm",
+		.of_match_table = bcm2835_pm_of_match,
+	},
+};
+module_platform_driver(bcm2835_pm_driver);
+
+MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
+MODULE_DESCRIPTION("Driver for Broadcom BCM2835 PM MFD");