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, 181 insertions, 0 deletions

diff --git a/drivers/soc/apple/apple-pmgr-misc.c b/drivers/soc/apple/apple-pmgr-misc.c
new file mode 100644
index 000000000..7db29f7de
--- /dev/null
+++ b/drivers/soc/apple/apple-pmgr-misc.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SoC PMGR device power state driver
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define APPLE_CLKGEN_PSTATE 0
+#define APPLE_CLKGEN_PSTATE_DESIRED GENMASK(3, 0)
+
+#define DCS_DEV_PSTATE_MIN_T600X 7
+#define SYS_DEV_PSTATE_SUSPEND 1
+
+enum sys_device {
+	DEV_FABRIC,
+	DEV_DCS,
+	DEV_MAX,
+};
+
+struct apple_pmgr_sys_device {
+	void __iomem *base;
+	u32 active_state;
+	u32 suspend_state;
+};
+
+struct apple_pmgr_misc_hw {
+	u32 dev_min_ps[DEV_MAX];
+};
+
+struct apple_pmgr_misc {
+	struct device *dev;
+	struct apple_pmgr_sys_device devices[DEV_MAX];
+};
+
+static void apple_pmgr_sys_dev_set_pstate(struct apple_pmgr_misc *misc,
+					  enum sys_device dev, bool active)
+{
+	u32 pstate;
+	u32 val;
+
+	if (!misc->devices[dev].base)
+		return;
+
+	if (active)
+		pstate = misc->devices[dev].active_state;
+	else
+		pstate = misc->devices[dev].suspend_state;
+
+	dev_dbg(misc->dev, "set %d ps to pstate %d\n", dev, pstate);
+
+	val = readl_relaxed(misc->devices[dev].base + APPLE_CLKGEN_PSTATE);
+	FIELD_MODIFY(APPLE_CLKGEN_PSTATE_DESIRED, &val, pstate);
+	writel_relaxed(val, misc->devices[dev].base + APPLE_CLKGEN_PSTATE);
+}
+
+static int __maybe_unused apple_pmgr_misc_suspend_noirq(struct device *dev)
+{
+	struct apple_pmgr_misc *misc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < DEV_MAX; i++)
+		apple_pmgr_sys_dev_set_pstate(misc, i, false);
+
+	return 0;
+}
+
+static int __maybe_unused apple_pmgr_misc_resume_noirq(struct device *dev)
+{
+	struct apple_pmgr_misc *misc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < DEV_MAX; i++)
+		apple_pmgr_sys_dev_set_pstate(misc, i, true);
+
+	return 0;
+}
+
+static int apple_pmgr_init_device(struct apple_pmgr_misc *misc,
+				  const struct apple_pmgr_misc_hw *hw,
+				  enum sys_device dev,
+				  const char *device_name)
+{
+	void __iomem *base;
+	char name[32];
+	u32 val;
+
+	snprintf(name, sizeof(name), "%s-ps", device_name);
+
+	base = devm_platform_ioremap_resource_byname(
+		to_platform_device(misc->dev), name);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	val = readl_relaxed(base + APPLE_CLKGEN_PSTATE);
+
+	misc->devices[dev].base = base;
+	misc->devices[dev].active_state =
+		FIELD_GET(APPLE_CLKGEN_PSTATE_DESIRED, val);
+	misc->devices[dev].suspend_state = hw->dev_min_ps[dev];
+
+	return 0;
+}
+
+static int apple_pmgr_misc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct apple_pmgr_misc_hw *hw;
+	struct apple_pmgr_misc *misc;
+	int ret;
+
+	misc = devm_kzalloc(dev, sizeof(*misc), GFP_KERNEL);
+	if (!misc)
+		return -ENOMEM;
+
+	misc->dev = dev;
+	hw = of_device_get_match_data(dev);
+	if (!hw)
+		return -EINVAL;
+
+	ret = apple_pmgr_init_device(misc, hw, DEV_FABRIC, "fabric");
+	if (ret)
+		return ret;
+
+	ret = apple_pmgr_init_device(misc, hw, DEV_DCS, "dcs");
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, misc);
+
+	return 0;
+}
+
+static const struct apple_pmgr_misc_hw apple_pmgr_misc_hw_t600x = {
+	.dev_min_ps = {
+		[DEV_FABRIC] = SYS_DEV_PSTATE_SUSPEND,
+		[DEV_DCS] = DCS_DEV_PSTATE_MIN_T600X,
+	},
+};
+
+static const struct apple_pmgr_misc_hw apple_pmgr_misc_hw_t602x = {
+	.dev_min_ps = {
+		[DEV_FABRIC] = SYS_DEV_PSTATE_SUSPEND,
+		[DEV_DCS] = SYS_DEV_PSTATE_SUSPEND,
+	},
+};
+
+static const struct of_device_id apple_pmgr_misc_of_match[] = {
+	{ .compatible = "apple,t6000-pmgr-misc", .data = &apple_pmgr_misc_hw_t600x },
+	{ .compatible = "apple,t6020-pmgr-misc", .data = &apple_pmgr_misc_hw_t602x },
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, apple_pmgr_misc_of_match);
+
+static const struct dev_pm_ops apple_pmgr_misc_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(apple_pmgr_misc_suspend_noirq,
+				      apple_pmgr_misc_resume_noirq)
+};
+
+static struct platform_driver apple_pmgr_misc_driver = {
+	.probe = apple_pmgr_misc_probe,
+	.driver = {
+		.name = "apple-pmgr-misc",
+		.of_match_table = apple_pmgr_misc_of_match,
+		.pm = pm_ptr(&apple_pmgr_misc_pm_ops),
+	},
+};
+
+MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
+MODULE_DESCRIPTION("PMGR misc driver for Apple SoCs");
+MODULE_LICENSE("GPL");
+
+module_platform_driver(apple_pmgr_misc_driver);