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, 237 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-rtd119x.c b/drivers/rtc/rtc-rtd119x.c
new file mode 100644
index 000000000..85a138db8
--- /dev/null
+++ b/drivers/rtc/rtc-rtd119x.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Realtek RTD129x RTC
+ *
+ * Copyright (c) 2017 Andreas Färber
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spinlock.h>
+
+#define RTD_RTCSEC		0x00
+#define RTD_RTCMIN		0x04
+#define RTD_RTCHR		0x08
+#define RTD_RTCDATE1		0x0c
+#define RTD_RTCDATE2		0x10
+#define RTD_RTCACR		0x28
+#define RTD_RTCEN		0x2c
+#define RTD_RTCCR		0x30
+
+#define RTD_RTCSEC_RTCSEC_MASK		0x7f
+
+#define RTD_RTCMIN_RTCMIN_MASK		0x3f
+
+#define RTD_RTCHR_RTCHR_MASK		0x1f
+
+#define RTD_RTCDATE1_RTCDATE1_MASK	0xff
+
+#define RTD_RTCDATE2_RTCDATE2_MASK	0x7f
+
+#define RTD_RTCACR_RTCPWR		BIT(7)
+
+#define RTD_RTCEN_RTCEN_MASK		0xff
+
+#define RTD_RTCCR_RTCRST		BIT(6)
+
+struct rtd119x_rtc {
+	void __iomem *base;
+	struct clk *clk;
+	struct rtc_device *rtcdev;
+	unsigned int base_year;
+};
+
+static inline int rtd119x_rtc_days_in_year(int year)
+{
+	return 365 + (is_leap_year(year) ? 1 : 0);
+}
+
+static void rtd119x_rtc_reset(struct device *dev)
+{
+	struct rtd119x_rtc *data = dev_get_drvdata(dev);
+	u32 val;
+
+	val = readl_relaxed(data->base + RTD_RTCCR);
+	val |= RTD_RTCCR_RTCRST;
+	writel_relaxed(val, data->base + RTD_RTCCR);
+
+	val &= ~RTD_RTCCR_RTCRST;
+	writel(val, data->base + RTD_RTCCR);
+}
+
+static void rtd119x_rtc_set_enabled(struct device *dev, bool enable)
+{
+	struct rtd119x_rtc *data = dev_get_drvdata(dev);
+	u32 val;
+
+	val = readl_relaxed(data->base + RTD_RTCEN);
+	if (enable) {
+		if ((val & RTD_RTCEN_RTCEN_MASK) == 0x5a)
+			return;
+		writel_relaxed(0x5a, data->base + RTD_RTCEN);
+	} else {
+		writel_relaxed(0, data->base + RTD_RTCEN);
+	}
+}
+
+static int rtd119x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtd119x_rtc *data = dev_get_drvdata(dev);
+	s32 day;
+	u32 sec;
+	unsigned int year;
+	int tries = 0;
+
+	while (true) {
+		tm->tm_sec = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
+		tm->tm_min  = readl_relaxed(data->base + RTD_RTCMIN) & RTD_RTCMIN_RTCMIN_MASK;
+		tm->tm_hour = readl_relaxed(data->base + RTD_RTCHR) & RTD_RTCHR_RTCHR_MASK;
+		day  =  readl_relaxed(data->base + RTD_RTCDATE1) & RTD_RTCDATE1_RTCDATE1_MASK;
+		day |= (readl_relaxed(data->base + RTD_RTCDATE2) & RTD_RTCDATE2_RTCDATE2_MASK) << 8;
+		sec  = (readl_relaxed(data->base + RTD_RTCSEC) & RTD_RTCSEC_RTCSEC_MASK) >> 1;
+		tries++;
+
+		if (sec == tm->tm_sec)
+			break;
+
+		if (tries >= 3)
+			return -EINVAL;
+	}
+	if (tries > 1)
+		dev_dbg(dev, "%s: needed %i tries\n", __func__, tries);
+
+	year = data->base_year;
+	while (day >= rtd119x_rtc_days_in_year(year)) {
+		day -= rtd119x_rtc_days_in_year(year);
+		year++;
+	}
+	tm->tm_year = year - 1900;
+	tm->tm_yday = day;
+
+	tm->tm_mon = 0;
+	while (day >= rtc_month_days(tm->tm_mon, year)) {
+		day -= rtc_month_days(tm->tm_mon, year);
+		tm->tm_mon++;
+	}
+	tm->tm_mday = day + 1;
+
+	return 0;
+}
+
+static int rtd119x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtd119x_rtc *data = dev_get_drvdata(dev);
+	unsigned int day;
+	int i;
+
+	if (1900 + tm->tm_year < data->base_year)
+		return -EINVAL;
+
+	day = 0;
+	for (i = data->base_year; i < 1900 + tm->tm_year; i++)
+		day += rtd119x_rtc_days_in_year(i);
+
+	day += tm->tm_yday;
+	if (day > 0x7fff)
+		return -EINVAL;
+
+	rtd119x_rtc_set_enabled(dev, false);
+
+	writel_relaxed((tm->tm_sec << 1) & RTD_RTCSEC_RTCSEC_MASK, data->base + RTD_RTCSEC);
+	writel_relaxed(tm->tm_min & RTD_RTCMIN_RTCMIN_MASK, data->base + RTD_RTCMIN);
+	writel_relaxed(tm->tm_hour & RTD_RTCHR_RTCHR_MASK, data->base + RTD_RTCHR);
+	writel_relaxed(day & RTD_RTCDATE1_RTCDATE1_MASK, data->base + RTD_RTCDATE1);
+	writel_relaxed((day >> 8) & RTD_RTCDATE2_RTCDATE2_MASK, data->base + RTD_RTCDATE2);
+
+	rtd119x_rtc_set_enabled(dev, true);
+
+	return 0;
+}
+
+static const struct rtc_class_ops rtd119x_rtc_ops = {
+	.read_time	= rtd119x_rtc_read_time,
+	.set_time	= rtd119x_rtc_set_time,
+};
+
+static const struct of_device_id rtd119x_rtc_dt_ids[] = {
+	 { .compatible = "realtek,rtd1295-rtc" },
+	 { }
+};
+
+static int rtd119x_rtc_probe(struct platform_device *pdev)
+{
+	struct rtd119x_rtc *data;
+	u32 val;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, data);
+	data->base_year = 2014;
+
+	data->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(data->base))
+		return PTR_ERR(data->base);
+
+	data->clk = of_clk_get(pdev->dev.of_node, 0);
+	if (IS_ERR(data->clk))
+		return PTR_ERR(data->clk);
+
+	ret = clk_prepare_enable(data->clk);
+	if (ret) {
+		clk_put(data->clk);
+		return ret;
+	}
+
+	val = readl_relaxed(data->base + RTD_RTCACR);
+	if (!(val & RTD_RTCACR_RTCPWR)) {
+		writel_relaxed(RTD_RTCACR_RTCPWR, data->base + RTD_RTCACR);
+
+		rtd119x_rtc_reset(&pdev->dev);
+
+		writel_relaxed(0, data->base + RTD_RTCMIN);
+		writel_relaxed(0, data->base + RTD_RTCHR);
+		writel_relaxed(0, data->base + RTD_RTCDATE1);
+		writel_relaxed(0, data->base + RTD_RTCDATE2);
+	}
+
+	rtd119x_rtc_set_enabled(&pdev->dev, true);
+
+	data->rtcdev = devm_rtc_device_register(&pdev->dev, "rtc",
+						&rtd119x_rtc_ops, THIS_MODULE);
+	if (IS_ERR(data->rtcdev)) {
+		dev_err(&pdev->dev, "failed to register rtc device");
+		clk_disable_unprepare(data->clk);
+		clk_put(data->clk);
+		return PTR_ERR(data->rtcdev);
+	}
+
+	return 0;
+}
+
+static void rtd119x_rtc_remove(struct platform_device *pdev)
+{
+	struct rtd119x_rtc *data = platform_get_drvdata(pdev);
+
+	rtd119x_rtc_set_enabled(&pdev->dev, false);
+
+	clk_disable_unprepare(data->clk);
+	clk_put(data->clk);
+}
+
+static struct platform_driver rtd119x_rtc_driver = {
+	.probe = rtd119x_rtc_probe,
+	.remove = rtd119x_rtc_remove,
+	.driver = {
+		.name = "rtd1295-rtc",
+		.of_match_table	= rtd119x_rtc_dt_ids,
+	},
+};
+builtin_platform_driver(rtd119x_rtc_driver);