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/clocksource/timer-imx-sysctr.c b/drivers/clocksource/timer-imx-sysctr.c
new file mode 100644
index 000000000..dfbd77950
--- /dev/null
+++ b/drivers/clocksource/timer-imx-sysctr.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2017-2019 NXP
+
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/slab.h>
+
+#include "timer-of.h"
+
+#define CMP_OFFSET	0x10000
+#define RD_OFFSET	0x20000
+
+#define CNTCV_LO	0x8
+#define CNTCV_HI	0xc
+#define CMPCV_LO	(CMP_OFFSET + 0x20)
+#define CMPCV_HI	(CMP_OFFSET + 0x24)
+#define CMPCR		(CMP_OFFSET + 0x2c)
+#define CNTCV_LO_IMX95	(RD_OFFSET + 0x8)
+#define CNTCV_HI_IMX95	(RD_OFFSET + 0xc)
+
+#define SYS_CTR_EN		0x1
+#define SYS_CTR_IRQ_MASK	0x2
+
+#define SYS_CTR_CLK_DIV		0x3
+
+struct sysctr_private {
+	u32 cmpcr;
+	u32 lo_off;
+	u32 hi_off;
+};
+
+static void sysctr_timer_enable(struct clock_event_device *evt, bool enable)
+{
+	struct timer_of *to = to_timer_of(evt);
+	struct sysctr_private *priv = to->private_data;
+	void __iomem *base = timer_of_base(to);
+
+	writel(enable ? priv->cmpcr | SYS_CTR_EN : priv->cmpcr, base + CMPCR);
+}
+
+static void sysctr_irq_acknowledge(struct clock_event_device *evt)
+{
+	/*
+	 * clear the enable bit(EN =0) will clear
+	 * the status bit(ISTAT = 0), then the interrupt
+	 * signal will be negated(acknowledged).
+	 */
+	sysctr_timer_enable(evt, false);
+}
+
+static inline u64 sysctr_read_counter(struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	struct sysctr_private *priv = to->private_data;
+	void __iomem *base = timer_of_base(to);
+	u32 cnt_hi, tmp_hi, cnt_lo;
+
+	do {
+		cnt_hi = readl_relaxed(base + priv->hi_off);
+		cnt_lo = readl_relaxed(base + priv->lo_off);
+		tmp_hi = readl_relaxed(base + priv->hi_off);
+	} while (tmp_hi != cnt_hi);
+
+	return  ((u64) cnt_hi << 32) | cnt_lo;
+}
+
+static int sysctr_set_next_event(unsigned long delta,
+				 struct clock_event_device *evt)
+{
+	struct timer_of *to = to_timer_of(evt);
+	void __iomem *base = timer_of_base(to);
+	u32 cmp_hi, cmp_lo;
+	u64 next;
+
+	sysctr_timer_enable(evt, false);
+
+	next = sysctr_read_counter(evt);
+
+	next += delta;
+
+	cmp_hi = (next >> 32) & 0x00fffff;
+	cmp_lo = next & 0xffffffff;
+
+	writel_relaxed(cmp_hi, base + CMPCV_HI);
+	writel_relaxed(cmp_lo, base + CMPCV_LO);
+
+	sysctr_timer_enable(evt, true);
+
+	return 0;
+}
+
+static int sysctr_set_state_oneshot(struct clock_event_device *evt)
+{
+	return 0;
+}
+
+static int sysctr_set_state_shutdown(struct clock_event_device *evt)
+{
+	sysctr_timer_enable(evt, false);
+
+	return 0;
+}
+
+static irqreturn_t sysctr_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+
+	sysctr_irq_acknowledge(evt);
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct timer_of to_sysctr = {
+	.flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE,
+	.clkevt = {
+		.name			= "i.MX system counter timer",
+		.features		= CLOCK_EVT_FEAT_ONESHOT |
+						CLOCK_EVT_FEAT_DYNIRQ,
+		.set_state_oneshot	= sysctr_set_state_oneshot,
+		.set_next_event		= sysctr_set_next_event,
+		.set_state_shutdown	= sysctr_set_state_shutdown,
+		.rating			= 200,
+	},
+	.of_irq = {
+		.handler		= sysctr_timer_interrupt,
+		.flags			= IRQF_TIMER,
+	},
+	.of_clk = {
+		.name = "per",
+	},
+};
+
+static int __init __sysctr_timer_init(struct device_node *np)
+{
+	struct sysctr_private *priv;
+	void __iomem *base;
+	int ret;
+
+	priv = kzalloc_obj(struct sysctr_private);
+	if (!priv)
+		return -ENOMEM;
+
+	ret = timer_of_init(np, &to_sysctr);
+	if (ret) {
+		kfree(priv);
+		return ret;
+	}
+
+	if (!of_property_read_bool(np, "nxp,no-divider")) {
+		/* system counter clock is divided by 3 internally */
+		to_sysctr.of_clk.rate /= SYS_CTR_CLK_DIV;
+	}
+
+	to_sysctr.clkevt.cpumask = cpu_possible_mask;
+	to_sysctr.private_data = priv;
+
+	base = timer_of_base(&to_sysctr);
+	priv->cmpcr = readl(base + CMPCR) & ~SYS_CTR_EN;
+
+	return 0;
+}
+
+static int __init sysctr_timer_init(struct device_node *np)
+{
+	struct sysctr_private *priv;
+	int ret;
+
+	ret = __sysctr_timer_init(np);
+	if (ret)
+		return ret;
+
+	priv = to_sysctr.private_data;
+	priv->lo_off = CNTCV_LO;
+	priv->hi_off = CNTCV_HI;
+
+	clockevents_config_and_register(&to_sysctr.clkevt,
+					timer_of_rate(&to_sysctr),
+					0xff, 0x7fffffff);
+
+	return 0;
+}
+
+static int __init sysctr_timer_imx95_init(struct device_node *np)
+{
+	struct sysctr_private *priv;
+	int ret;
+
+	ret = __sysctr_timer_init(np);
+	if (ret)
+		return ret;
+
+	priv = to_sysctr.private_data;
+	priv->lo_off = CNTCV_LO_IMX95;
+	priv->hi_off = CNTCV_HI_IMX95;
+
+	clockevents_config_and_register(&to_sysctr.clkevt,
+					timer_of_rate(&to_sysctr),
+					0xff, 0x7fffffff);
+
+	return 0;
+}
+
+TIMER_OF_DECLARE(sysctr_timer, "nxp,sysctr-timer", sysctr_timer_init);
+TIMER_OF_DECLARE(sysctr_timer_imx95, "nxp,imx95-sysctr-timer", sysctr_timer_imx95_init);