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, 433 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-brcmstb-waketimer.c b/drivers/rtc/rtc-brcmstb-waketimer.c
new file mode 100644
index 000000000..55c15aad4
--- /dev/null
+++ b/drivers/rtc/rtc-brcmstb-waketimer.c
@@ -0,0 +1,433 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright © 2014-2023 Broadcom
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irqreturn.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/reboot.h>
+#include <linux/rtc.h>
+#include <linux/stat.h>
+#include <linux/suspend.h>
+
+struct brcmstb_waketmr {
+	struct rtc_device *rtc;
+	struct device *dev;
+	void __iomem *base;
+	unsigned int wake_irq;
+	unsigned int alarm_irq;
+	struct notifier_block reboot_notifier;
+	struct clk *clk;
+	u32 rate;
+	unsigned long rtc_alarm;
+	bool alarm_en;
+	bool alarm_expired;
+};
+
+#define BRCMSTB_WKTMR_EVENT		0x00
+#define  WKTMR_ALARM_EVENT		BIT(0)
+#define BRCMSTB_WKTMR_COUNTER		0x04
+#define BRCMSTB_WKTMR_ALARM		0x08
+#define BRCMSTB_WKTMR_PRESCALER		0x0C
+#define BRCMSTB_WKTMR_PRESCALER_VAL	0x10
+
+#define BRCMSTB_WKTMR_DEFAULT_FREQ	27000000
+
+static inline bool brcmstb_waketmr_is_pending(struct brcmstb_waketmr *timer)
+{
+	u32 reg;
+
+	reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
+	return !!(reg & WKTMR_ALARM_EVENT);
+}
+
+static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
+{
+	u32 reg;
+
+	if (timer->alarm_en && timer->alarm_irq)
+		disable_irq(timer->alarm_irq);
+	timer->alarm_en = false;
+	reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+	writel_relaxed(reg - 1, timer->base + BRCMSTB_WKTMR_ALARM);
+	writel_relaxed(WKTMR_ALARM_EVENT, timer->base + BRCMSTB_WKTMR_EVENT);
+	(void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
+	if (timer->alarm_expired) {
+		timer->alarm_expired = false;
+		/* maintain call balance */
+		enable_irq(timer->alarm_irq);
+	}
+}
+
+static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
+				      unsigned int secs)
+{
+	unsigned int now;
+
+	brcmstb_waketmr_clear_alarm(timer);
+
+	/* Make sure we are actually counting in seconds */
+	writel_relaxed(timer->rate, timer->base + BRCMSTB_WKTMR_PRESCALER);
+
+	writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
+	now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+
+	while ((int)(secs - now) <= 0 &&
+		!brcmstb_waketmr_is_pending(timer)) {
+		secs = now + 1;
+		writel_relaxed(secs, timer->base + BRCMSTB_WKTMR_ALARM);
+		now = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+	}
+}
+
+static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
+{
+	struct brcmstb_waketmr *timer = data;
+
+	if (!timer->alarm_irq)
+		pm_wakeup_event(timer->dev, 0);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t brcmstb_alarm_irq(int irq, void *data)
+{
+	struct brcmstb_waketmr *timer = data;
+
+	/* Ignore spurious interrupts */
+	if (!brcmstb_waketmr_is_pending(timer))
+		return IRQ_HANDLED;
+
+	if (timer->alarm_en) {
+		if (device_may_wakeup(timer->dev)) {
+			disable_irq_nosync(irq);
+			timer->alarm_expired = true;
+		} else {
+			writel_relaxed(WKTMR_ALARM_EVENT,
+				       timer->base + BRCMSTB_WKTMR_EVENT);
+		}
+		rtc_update_irq(timer->rtc, 1, RTC_IRQF | RTC_AF);
+	} else {
+		writel_relaxed(WKTMR_ALARM_EVENT,
+			       timer->base + BRCMSTB_WKTMR_EVENT);
+	}
+
+	return IRQ_HANDLED;
+}
+
+struct wktmr_time {
+	u32 sec;
+	u32 pre;
+};
+
+static void wktmr_read(struct brcmstb_waketmr *timer,
+		       struct wktmr_time *t)
+{
+	u32 tmp;
+
+	do {
+		t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+		tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
+	} while (tmp >= timer->rate);
+
+	t->pre = timer->rate - tmp;
+}
+
+static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
+{
+	struct device *dev = timer->dev;
+	int ret;
+
+	if (device_may_wakeup(dev)) {
+		ret = enable_irq_wake(timer->wake_irq);
+		if (ret) {
+			dev_err(dev, "failed to enable wake-up interrupt\n");
+			return ret;
+		}
+		if (timer->alarm_en && timer->alarm_irq) {
+			ret = enable_irq_wake(timer->alarm_irq);
+			if (ret) {
+				dev_err(dev, "failed to enable rtc interrupt\n");
+				disable_irq_wake(timer->wake_irq);
+				return ret;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/* If enabled as a wakeup-source, arm the timer when powering off */
+static int brcmstb_waketmr_reboot(struct notifier_block *nb,
+		unsigned long action, void *data)
+{
+	struct brcmstb_waketmr *timer;
+
+	timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
+
+	/* Set timer for cold boot */
+	if (action == SYS_POWER_OFF)
+		brcmstb_waketmr_prepare_suspend(timer);
+
+	return NOTIFY_DONE;
+}
+
+static int brcmstb_waketmr_gettime(struct device *dev,
+				   struct rtc_time *tm)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+	struct wktmr_time now;
+
+	wktmr_read(timer, &now);
+
+	rtc_time64_to_tm(now.sec, tm);
+
+	return 0;
+}
+
+static int brcmstb_waketmr_settime(struct device *dev,
+				   struct rtc_time *tm)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+	time64_t sec;
+
+	sec = rtc_tm_to_time64(tm);
+
+	writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
+
+	return 0;
+}
+
+static int brcmstb_waketmr_getalarm(struct device *dev,
+				    struct rtc_wkalrm *alarm)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+	alarm->enabled = timer->alarm_en;
+	rtc_time64_to_tm(timer->rtc_alarm, &alarm->time);
+
+	alarm->pending = brcmstb_waketmr_is_pending(timer);
+
+	return 0;
+}
+
+static int brcmstb_waketmr_alarm_enable(struct device *dev,
+					unsigned int enabled)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+	if (enabled && !timer->alarm_en) {
+		if ((int)(readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER) -
+		    readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM)) >= 0 &&
+		    !brcmstb_waketmr_is_pending(timer))
+			return -EINVAL;
+		timer->alarm_en = true;
+		if (timer->alarm_irq) {
+			if (timer->alarm_expired) {
+				timer->alarm_expired = false;
+				/* maintain call balance */
+				enable_irq(timer->alarm_irq);
+			}
+			enable_irq(timer->alarm_irq);
+		}
+	} else if (!enabled && timer->alarm_en) {
+		if (timer->alarm_irq)
+			disable_irq(timer->alarm_irq);
+		timer->alarm_en = false;
+	}
+
+	return 0;
+}
+
+static int brcmstb_waketmr_setalarm(struct device *dev,
+				     struct rtc_wkalrm *alarm)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+	timer->rtc_alarm = rtc_tm_to_time64(&alarm->time);
+
+	brcmstb_waketmr_set_alarm(timer, timer->rtc_alarm);
+
+	return brcmstb_waketmr_alarm_enable(dev, alarm->enabled);
+}
+
+static const struct rtc_class_ops brcmstb_waketmr_ops = {
+	.read_time	= brcmstb_waketmr_gettime,
+	.set_time	= brcmstb_waketmr_settime,
+	.read_alarm	= brcmstb_waketmr_getalarm,
+	.set_alarm	= brcmstb_waketmr_setalarm,
+	.alarm_irq_enable = brcmstb_waketmr_alarm_enable,
+};
+
+static int brcmstb_waketmr_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct brcmstb_waketmr *timer;
+	int ret;
+
+	timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
+	if (!timer)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, timer);
+	timer->dev = dev;
+
+	timer->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(timer->base))
+		return PTR_ERR(timer->base);
+
+	timer->rtc = devm_rtc_allocate_device(dev);
+	if (IS_ERR(timer->rtc))
+		return PTR_ERR(timer->rtc);
+
+	/*
+	 * Set wakeup capability before requesting wakeup interrupt, so we can
+	 * process boot-time "wakeups" (e.g., from S5 soft-off)
+	 */
+	device_init_wakeup(dev, true);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return -ENODEV;
+	timer->wake_irq = (unsigned int)ret;
+
+	timer->clk = devm_clk_get(dev, NULL);
+	if (!IS_ERR(timer->clk)) {
+		ret = clk_prepare_enable(timer->clk);
+		if (ret)
+			return ret;
+		timer->rate = clk_get_rate(timer->clk);
+		if (!timer->rate)
+			timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
+	} else {
+		timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
+		timer->clk = NULL;
+	}
+
+	ret = devm_request_irq(dev, timer->wake_irq, brcmstb_waketmr_irq, 0,
+			       "brcmstb-waketimer", timer);
+	if (ret < 0)
+		goto err_clk;
+
+	brcmstb_waketmr_clear_alarm(timer);
+
+	/* Attempt to initialize non-wake irq */
+	ret = platform_get_irq(pdev, 1);
+	if (ret > 0) {
+		timer->alarm_irq = (unsigned int)ret;
+		ret = devm_request_irq(dev, timer->alarm_irq, brcmstb_alarm_irq,
+				       IRQF_NO_AUTOEN, "brcmstb-waketimer-rtc",
+				       timer);
+		if (ret < 0)
+			timer->alarm_irq = 0;
+	}
+
+	timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
+	register_reboot_notifier(&timer->reboot_notifier);
+
+	timer->rtc->ops = &brcmstb_waketmr_ops;
+	timer->rtc->range_max = U32_MAX;
+
+	ret = devm_rtc_register_device(timer->rtc);
+	if (ret)
+		goto err_notifier;
+
+	return 0;
+
+err_notifier:
+	unregister_reboot_notifier(&timer->reboot_notifier);
+
+err_clk:
+	clk_disable_unprepare(timer->clk);
+
+	return ret;
+}
+
+static void brcmstb_waketmr_remove(struct platform_device *pdev)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
+
+	unregister_reboot_notifier(&timer->reboot_notifier);
+	clk_disable_unprepare(timer->clk);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int brcmstb_waketmr_suspend(struct device *dev)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+	return brcmstb_waketmr_prepare_suspend(timer);
+}
+
+static int brcmstb_waketmr_suspend_noirq(struct device *dev)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+	/* Catch any alarms occurring prior to noirq */
+	if (timer->alarm_expired && device_may_wakeup(dev))
+		return -EBUSY;
+
+	return 0;
+}
+
+static int brcmstb_waketmr_resume(struct device *dev)
+{
+	struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+	int ret;
+
+	if (!device_may_wakeup(dev))
+		return 0;
+
+	ret = disable_irq_wake(timer->wake_irq);
+	if (timer->alarm_en && timer->alarm_irq)
+		disable_irq_wake(timer->alarm_irq);
+
+	brcmstb_waketmr_clear_alarm(timer);
+
+	return ret;
+}
+#else
+#define brcmstb_waketmr_suspend		NULL
+#define brcmstb_waketmr_suspend_noirq	NULL
+#define brcmstb_waketmr_resume		NULL
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops brcmstb_waketmr_pm_ops = {
+	.suspend	= brcmstb_waketmr_suspend,
+	.suspend_noirq	= brcmstb_waketmr_suspend_noirq,
+	.resume		= brcmstb_waketmr_resume,
+};
+
+static const __maybe_unused struct of_device_id brcmstb_waketmr_of_match[] = {
+	{ .compatible = "brcm,brcmstb-waketimer" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, brcmstb_waketmr_of_match);
+
+static struct platform_driver brcmstb_waketmr_driver = {
+	.probe			= brcmstb_waketmr_probe,
+	.remove			= brcmstb_waketmr_remove,
+	.driver = {
+		.name		= "brcmstb-waketimer",
+		.pm		= &brcmstb_waketmr_pm_ops,
+		.of_match_table	= of_match_ptr(brcmstb_waketmr_of_match),
+	}
+};
+module_platform_driver(brcmstb_waketmr_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Norris");
+MODULE_AUTHOR("Markus Mayer");
+MODULE_AUTHOR("Doug Berger");
+MODULE_DESCRIPTION("Wake-up timer driver for STB chips");