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, 297 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-lpc24xx.c b/drivers/rtc/rtc-lpc24xx.c
new file mode 100644
index 000000000..a1266986d
--- /dev/null
+++ b/drivers/rtc/rtc-lpc24xx.c
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RTC driver for NXP LPC178x/18xx/43xx Real-Time Clock (RTC)
+ *
+ * Copyright (C) 2011 NXP Semiconductors
+ * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* LPC24xx RTC register offsets and bits */
+#define LPC24XX_ILR		0x00
+#define  LPC24XX_RTCCIF		BIT(0)
+#define  LPC24XX_RTCALF		BIT(1)
+#define LPC24XX_CTC		0x04
+#define LPC24XX_CCR		0x08
+#define  LPC24XX_CLKEN		BIT(0)
+#define  LPC178X_CCALEN		BIT(4)
+#define LPC24XX_CIIR		0x0c
+#define LPC24XX_AMR		0x10
+#define  LPC24XX_ALARM_DISABLE	0xff
+#define LPC24XX_CTIME0		0x14
+#define LPC24XX_CTIME1		0x18
+#define LPC24XX_CTIME2		0x1c
+#define LPC24XX_SEC		0x20
+#define LPC24XX_MIN		0x24
+#define LPC24XX_HOUR		0x28
+#define LPC24XX_DOM		0x2c
+#define LPC24XX_DOW		0x30
+#define LPC24XX_DOY		0x34
+#define LPC24XX_MONTH		0x38
+#define LPC24XX_YEAR		0x3c
+#define LPC24XX_ALSEC		0x60
+#define LPC24XX_ALMIN		0x64
+#define LPC24XX_ALHOUR		0x68
+#define LPC24XX_ALDOM		0x6c
+#define LPC24XX_ALDOW		0x70
+#define LPC24XX_ALDOY		0x74
+#define LPC24XX_ALMON		0x78
+#define LPC24XX_ALYEAR		0x7c
+
+/* Macros to read fields in consolidated time (CT) registers */
+#define CT0_SECS(x)		(((x) >> 0)  & 0x3f)
+#define CT0_MINS(x)		(((x) >> 8)  & 0x3f)
+#define CT0_HOURS(x)		(((x) >> 16) & 0x1f)
+#define CT0_DOW(x)		(((x) >> 24) & 0x07)
+#define CT1_DOM(x)		(((x) >> 0)  & 0x1f)
+#define CT1_MONTH(x)		(((x) >> 8)  & 0x0f)
+#define CT1_YEAR(x)		(((x) >> 16) & 0xfff)
+#define CT2_DOY(x)		(((x) >> 0)  & 0xfff)
+
+#define rtc_readl(dev, reg)		readl((dev)->rtc_base + (reg))
+#define rtc_writel(dev, reg, val)	writel((val), (dev)->rtc_base + (reg))
+
+struct lpc24xx_rtc {
+	void __iomem *rtc_base;
+	struct rtc_device *rtc;
+	struct clk *clk_rtc;
+	struct clk *clk_reg;
+};
+
+static int lpc24xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+
+	/* Disable RTC during update */
+	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);
+
+	rtc_writel(rtc, LPC24XX_SEC,	tm->tm_sec);
+	rtc_writel(rtc, LPC24XX_MIN,	tm->tm_min);
+	rtc_writel(rtc, LPC24XX_HOUR,	tm->tm_hour);
+	rtc_writel(rtc, LPC24XX_DOW,	tm->tm_wday);
+	rtc_writel(rtc, LPC24XX_DOM,	tm->tm_mday);
+	rtc_writel(rtc, LPC24XX_DOY,	tm->tm_yday);
+	rtc_writel(rtc, LPC24XX_MONTH,	tm->tm_mon);
+	rtc_writel(rtc, LPC24XX_YEAR,	tm->tm_year);
+
+	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);
+
+	return 0;
+}
+
+static int lpc24xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+	u32 ct0, ct1, ct2;
+
+	ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
+	ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
+	ct2 = rtc_readl(rtc, LPC24XX_CTIME2);
+
+	tm->tm_sec  = CT0_SECS(ct0);
+	tm->tm_min  = CT0_MINS(ct0);
+	tm->tm_hour = CT0_HOURS(ct0);
+	tm->tm_wday = CT0_DOW(ct0);
+	tm->tm_mon  = CT1_MONTH(ct1);
+	tm->tm_mday = CT1_DOM(ct1);
+	tm->tm_year = CT1_YEAR(ct1);
+	tm->tm_yday = CT2_DOY(ct2);
+
+	return 0;
+}
+
+static int lpc24xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &wkalrm->time;
+
+	tm->tm_sec  = rtc_readl(rtc, LPC24XX_ALSEC);
+	tm->tm_min  = rtc_readl(rtc, LPC24XX_ALMIN);
+	tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
+	tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
+	tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
+	tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
+	tm->tm_mon  = rtc_readl(rtc, LPC24XX_ALMON);
+	tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);
+
+	wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
+	wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);
+
+	return rtc_valid_tm(&wkalrm->time);
+}
+
+static int lpc24xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &wkalrm->time;
+
+	/* Disable alarm irq during update */
+	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+
+	rtc_writel(rtc, LPC24XX_ALSEC,  tm->tm_sec);
+	rtc_writel(rtc, LPC24XX_ALMIN,  tm->tm_min);
+	rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
+	rtc_writel(rtc, LPC24XX_ALDOM,  tm->tm_mday);
+	rtc_writel(rtc, LPC24XX_ALDOW,  tm->tm_wday);
+	rtc_writel(rtc, LPC24XX_ALDOY,  tm->tm_yday);
+	rtc_writel(rtc, LPC24XX_ALMON,  tm->tm_mon);
+	rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);
+
+	if (wkalrm->enabled)
+		rtc_writel(rtc, LPC24XX_AMR, 0);
+
+	return 0;
+}
+
+static int lpc24xx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+
+	if (enable)
+		rtc_writel(rtc, LPC24XX_AMR, 0);
+	else
+		rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+
+	return 0;
+}
+
+static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *data)
+{
+	unsigned long events = RTC_IRQF;
+	struct lpc24xx_rtc *rtc = data;
+	u32 rtc_iir;
+
+	/* Check interrupt cause */
+	rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
+	if (rtc_iir & LPC24XX_RTCALF) {
+		events |= RTC_AF;
+		rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+	}
+
+	/* Clear interrupt status and report event */
+	rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
+	rtc_update_irq(rtc->rtc, 1, events);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops lpc24xx_rtc_ops = {
+	.read_time		= lpc24xx_rtc_read_time,
+	.set_time		= lpc24xx_rtc_set_time,
+	.read_alarm		= lpc24xx_rtc_read_alarm,
+	.set_alarm		= lpc24xx_rtc_set_alarm,
+	.alarm_irq_enable	= lpc24xx_rtc_alarm_irq_enable,
+};
+
+static int lpc24xx_rtc_probe(struct platform_device *pdev)
+{
+	struct lpc24xx_rtc *rtc;
+	int irq, ret;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	rtc->rtc_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rtc->rtc_base))
+		return PTR_ERR(rtc->rtc_base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
+	if (IS_ERR(rtc->clk_rtc)) {
+		dev_err(&pdev->dev, "error getting rtc clock\n");
+		return PTR_ERR(rtc->clk_rtc);
+	}
+
+	rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
+	if (IS_ERR(rtc->clk_reg)) {
+		dev_err(&pdev->dev, "error getting reg clock\n");
+		return PTR_ERR(rtc->clk_reg);
+	}
+
+	ret = clk_prepare_enable(rtc->clk_rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable rtc clock\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(rtc->clk_reg);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable reg clock\n");
+		goto disable_rtc_clk;
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	/* Clear any pending interrupts */
+	rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF | LPC24XX_RTCALF);
+
+	/* Enable RTC count */
+	rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);
+
+	ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
+			       pdev->name, rtc);
+	if (ret < 0) {
+		dev_warn(&pdev->dev, "can't request interrupt\n");
+		goto disable_clks;
+	}
+
+	rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc24xx-rtc",
+					    &lpc24xx_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc->rtc)) {
+		dev_err(&pdev->dev, "can't register rtc device\n");
+		ret = PTR_ERR(rtc->rtc);
+		goto disable_clks;
+	}
+
+	return 0;
+
+disable_clks:
+	clk_disable_unprepare(rtc->clk_reg);
+disable_rtc_clk:
+	clk_disable_unprepare(rtc->clk_rtc);
+	return ret;
+}
+
+static void lpc24xx_rtc_remove(struct platform_device *pdev)
+{
+	struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);
+
+	/* Ensure all interrupt sources are masked */
+	rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+	rtc_writel(rtc, LPC24XX_CIIR, 0);
+
+	rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);
+
+	clk_disable_unprepare(rtc->clk_rtc);
+	clk_disable_unprepare(rtc->clk_reg);
+}
+
+static const struct of_device_id lpc24xx_rtc_match[] = {
+	{ .compatible = "nxp,lpc1788-rtc" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);
+
+static struct platform_driver lpc24xx_rtc_driver = {
+	.probe	= lpc24xx_rtc_probe,
+	.remove = lpc24xx_rtc_remove,
+	.driver	= {
+		.name = "lpc24xx-rtc",
+		.of_match_table	= lpc24xx_rtc_match,
+	},
+};
+module_platform_driver(lpc24xx_rtc_driver);
+
+MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com>");
+MODULE_DESCRIPTION("RTC driver for the LPC178x/18xx/408x/43xx SoCs");
+MODULE_LICENSE("GPL");