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, 207 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-goldfish.c b/drivers/rtc/rtc-goldfish.c
new file mode 100644
index 000000000..53ec7173c
--- /dev/null
+++ b/drivers/rtc/rtc-goldfish.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0
+/* drivers/rtc/rtc-goldfish.c
+ *
+ * Copyright (C) 2007 Google, Inc.
+ * Copyright (C) 2017 Imagination Technologies Ltd.
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/goldfish.h>
+#include <clocksource/timer-goldfish.h>
+
+struct goldfish_rtc {
+	void __iomem *base;
+	int irq;
+	struct rtc_device *rtc;
+};
+
+static int goldfish_rtc_read_alarm(struct device *dev,
+				   struct rtc_wkalrm *alrm)
+{
+	u64 rtc_alarm;
+	u64 rtc_alarm_low;
+	u64 rtc_alarm_high;
+	void __iomem *base;
+	struct goldfish_rtc *rtcdrv;
+
+	rtcdrv = dev_get_drvdata(dev);
+	base = rtcdrv->base;
+
+	rtc_alarm_low = gf_ioread32(base + TIMER_ALARM_LOW);
+	rtc_alarm_high = gf_ioread32(base + TIMER_ALARM_HIGH);
+	rtc_alarm = (rtc_alarm_high << 32) | rtc_alarm_low;
+
+	do_div(rtc_alarm, NSEC_PER_SEC);
+	memset(alrm, 0, sizeof(struct rtc_wkalrm));
+
+	rtc_time64_to_tm(rtc_alarm, &alrm->time);
+
+	if (gf_ioread32(base + TIMER_ALARM_STATUS))
+		alrm->enabled = 1;
+	else
+		alrm->enabled = 0;
+
+	return 0;
+}
+
+static int goldfish_rtc_set_alarm(struct device *dev,
+				  struct rtc_wkalrm *alrm)
+{
+	struct goldfish_rtc *rtcdrv;
+	u64 rtc_alarm64;
+	u64 rtc_status_reg;
+	void __iomem *base;
+
+	rtcdrv = dev_get_drvdata(dev);
+	base = rtcdrv->base;
+
+	if (alrm->enabled) {
+		rtc_alarm64 = rtc_tm_to_time64(&alrm->time) * NSEC_PER_SEC;
+		gf_iowrite32((rtc_alarm64 >> 32), base + TIMER_ALARM_HIGH);
+		gf_iowrite32(rtc_alarm64, base + TIMER_ALARM_LOW);
+		gf_iowrite32(1, base + TIMER_IRQ_ENABLED);
+	} else {
+		/*
+		 * if this function was called with enabled=0
+		 * then it could mean that the application is
+		 * trying to cancel an ongoing alarm
+		 */
+		rtc_status_reg = gf_ioread32(base + TIMER_ALARM_STATUS);
+		if (rtc_status_reg)
+			gf_iowrite32(1, base + TIMER_CLEAR_ALARM);
+	}
+
+	return 0;
+}
+
+static int goldfish_rtc_alarm_irq_enable(struct device *dev,
+					 unsigned int enabled)
+{
+	void __iomem *base;
+	struct goldfish_rtc *rtcdrv;
+
+	rtcdrv = dev_get_drvdata(dev);
+	base = rtcdrv->base;
+
+	if (enabled)
+		gf_iowrite32(1, base + TIMER_IRQ_ENABLED);
+	else
+		gf_iowrite32(0, base + TIMER_IRQ_ENABLED);
+
+	return 0;
+}
+
+static irqreturn_t goldfish_rtc_interrupt(int irq, void *dev_id)
+{
+	struct goldfish_rtc *rtcdrv = dev_id;
+	void __iomem *base = rtcdrv->base;
+
+	gf_iowrite32(1, base + TIMER_CLEAR_INTERRUPT);
+
+	rtc_update_irq(rtcdrv->rtc, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static int goldfish_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct goldfish_rtc *rtcdrv;
+	void __iomem *base;
+	u64 time_high;
+	u64 time_low;
+	u64 time;
+
+	rtcdrv = dev_get_drvdata(dev);
+	base = rtcdrv->base;
+
+	time_low = gf_ioread32(base + TIMER_TIME_LOW);
+	time_high = gf_ioread32(base + TIMER_TIME_HIGH);
+	time = (time_high << 32) | time_low;
+
+	do_div(time, NSEC_PER_SEC);
+
+	rtc_time64_to_tm(time, tm);
+
+	return 0;
+}
+
+static int goldfish_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct goldfish_rtc *rtcdrv;
+	void __iomem *base;
+	u64 now64;
+
+	rtcdrv = dev_get_drvdata(dev);
+	base = rtcdrv->base;
+
+	now64 = rtc_tm_to_time64(tm) * NSEC_PER_SEC;
+	gf_iowrite32((now64 >> 32), base + TIMER_TIME_HIGH);
+	gf_iowrite32(now64, base + TIMER_TIME_LOW);
+
+	return 0;
+}
+
+static const struct rtc_class_ops goldfish_rtc_ops = {
+	.read_time	= goldfish_rtc_read_time,
+	.set_time	= goldfish_rtc_set_time,
+	.read_alarm	= goldfish_rtc_read_alarm,
+	.set_alarm	= goldfish_rtc_set_alarm,
+	.alarm_irq_enable = goldfish_rtc_alarm_irq_enable
+};
+
+static int goldfish_rtc_probe(struct platform_device *pdev)
+{
+	struct goldfish_rtc *rtcdrv;
+	int err;
+
+	rtcdrv = devm_kzalloc(&pdev->dev, sizeof(*rtcdrv), GFP_KERNEL);
+	if (!rtcdrv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, rtcdrv);
+	rtcdrv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rtcdrv->base))
+		return PTR_ERR(rtcdrv->base);
+
+	rtcdrv->irq = platform_get_irq(pdev, 0);
+	if (rtcdrv->irq < 0)
+		return -ENODEV;
+
+	rtcdrv->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtcdrv->rtc))
+		return PTR_ERR(rtcdrv->rtc);
+
+	rtcdrv->rtc->ops = &goldfish_rtc_ops;
+	rtcdrv->rtc->range_max = U64_MAX / NSEC_PER_SEC;
+
+	err = devm_request_irq(&pdev->dev, rtcdrv->irq,
+			       goldfish_rtc_interrupt,
+			       0, pdev->name, rtcdrv);
+	if (err)
+		return err;
+
+	return devm_rtc_register_device(rtcdrv->rtc);
+}
+
+static const struct of_device_id goldfish_rtc_of_match[] = {
+	{ .compatible = "google,goldfish-rtc", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, goldfish_rtc_of_match);
+
+static struct platform_driver goldfish_rtc = {
+	.probe = goldfish_rtc_probe,
+	.driver = {
+		.name = "goldfish_rtc",
+		.of_match_table = goldfish_rtc_of_match,
+	}
+};
+
+module_platform_driver(goldfish_rtc);
+
+MODULE_DESCRIPTION("Android Goldfish Real Time Clock driver");
+MODULE_LICENSE("GPL v2");