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, 253 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-qcom.c b/drivers/clocksource/timer-qcom.c
new file mode 100644
index 000000000..ddb1debe6
--- /dev/null
+++ b/drivers/clocksource/timer-qcom.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2007 Google, Inc.
+ * Copyright (c) 2009-2012,2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+
+#include <asm/delay.h>
+
+#define TIMER_MATCH_VAL			0x0000
+#define TIMER_COUNT_VAL			0x0004
+#define TIMER_ENABLE			0x0008
+#define TIMER_ENABLE_CLR_ON_MATCH_EN	BIT(1)
+#define TIMER_ENABLE_EN			BIT(0)
+#define TIMER_CLEAR			0x000C
+#define DGT_CLK_CTL			0x10
+#define DGT_CLK_CTL_DIV_4		0x3
+#define TIMER_STS_GPT0_CLR_PEND		BIT(10)
+
+#define GPT_HZ 32768
+
+static void __iomem *event_base;
+static void __iomem *sts_base;
+
+static irqreturn_t msm_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+	/* Stop the timer tick */
+	if (clockevent_state_oneshot(evt)) {
+		u32 ctrl = readl_relaxed(event_base + TIMER_ENABLE);
+		ctrl &= ~TIMER_ENABLE_EN;
+		writel_relaxed(ctrl, event_base + TIMER_ENABLE);
+	}
+	evt->event_handler(evt);
+	return IRQ_HANDLED;
+}
+
+static int msm_timer_set_next_event(unsigned long cycles,
+				    struct clock_event_device *evt)
+{
+	u32 ctrl = readl_relaxed(event_base + TIMER_ENABLE);
+
+	ctrl &= ~TIMER_ENABLE_EN;
+	writel_relaxed(ctrl, event_base + TIMER_ENABLE);
+
+	writel_relaxed(ctrl, event_base + TIMER_CLEAR);
+	writel_relaxed(cycles, event_base + TIMER_MATCH_VAL);
+
+	if (sts_base)
+		while (readl_relaxed(sts_base) & TIMER_STS_GPT0_CLR_PEND)
+			cpu_relax();
+
+	writel_relaxed(ctrl | TIMER_ENABLE_EN, event_base + TIMER_ENABLE);
+	return 0;
+}
+
+static int msm_timer_shutdown(struct clock_event_device *evt)
+{
+	u32 ctrl;
+
+	ctrl = readl_relaxed(event_base + TIMER_ENABLE);
+	ctrl &= ~(TIMER_ENABLE_EN | TIMER_ENABLE_CLR_ON_MATCH_EN);
+	writel_relaxed(ctrl, event_base + TIMER_ENABLE);
+	return 0;
+}
+
+static struct clock_event_device __percpu *msm_evt;
+
+static void __iomem *source_base;
+
+static notrace u64 msm_read_timer_count(struct clocksource *cs)
+{
+	return readl_relaxed(source_base + TIMER_COUNT_VAL);
+}
+
+static struct clocksource msm_clocksource = {
+	.name	= "dg_timer",
+	.rating	= 300,
+	.read	= msm_read_timer_count,
+	.mask	= CLOCKSOURCE_MASK(32),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int msm_timer_irq;
+static int msm_timer_has_ppi;
+
+static int msm_local_timer_starting_cpu(unsigned int cpu)
+{
+	struct clock_event_device *evt = per_cpu_ptr(msm_evt, cpu);
+	int err;
+
+	evt->irq = msm_timer_irq;
+	evt->name = "msm_timer";
+	evt->features = CLOCK_EVT_FEAT_ONESHOT;
+	evt->rating = 200;
+	evt->set_state_shutdown = msm_timer_shutdown;
+	evt->set_state_oneshot = msm_timer_shutdown;
+	evt->tick_resume = msm_timer_shutdown;
+	evt->set_next_event = msm_timer_set_next_event;
+	evt->cpumask = cpumask_of(cpu);
+
+	clockevents_config_and_register(evt, GPT_HZ, 4, 0xffffffff);
+
+	if (msm_timer_has_ppi) {
+		enable_percpu_irq(evt->irq, IRQ_TYPE_EDGE_RISING);
+	} else {
+		err = request_irq(evt->irq, msm_timer_interrupt,
+				IRQF_TIMER | IRQF_NOBALANCING |
+				IRQF_TRIGGER_RISING, "gp_timer", evt);
+		if (err)
+			pr_err("request_irq failed\n");
+	}
+
+	return 0;
+}
+
+static int msm_local_timer_dying_cpu(unsigned int cpu)
+{
+	struct clock_event_device *evt = per_cpu_ptr(msm_evt, cpu);
+
+	disable_percpu_irq(evt->irq);
+	return 0;
+}
+
+static u64 notrace msm_sched_clock_read(void)
+{
+	return msm_clocksource.read(&msm_clocksource);
+}
+
+static unsigned long msm_read_current_timer(void)
+{
+	return msm_clocksource.read(&msm_clocksource);
+}
+
+static struct delay_timer msm_delay_timer = {
+	.read_current_timer = msm_read_current_timer,
+};
+
+static int __init msm_timer_init(u32 dgt_hz, int sched_bits, int irq,
+				  bool percpu)
+{
+	struct clocksource *cs = &msm_clocksource;
+	int res = 0;
+
+	msm_timer_irq = irq;
+	msm_timer_has_ppi = percpu;
+
+	msm_evt = alloc_percpu(struct clock_event_device);
+	if (!msm_evt) {
+		pr_err("memory allocation failed for clockevents\n");
+		goto err;
+	}
+
+	if (percpu)
+		res = request_percpu_irq(irq, msm_timer_interrupt,
+					 "gp_timer", msm_evt);
+
+	if (res) {
+		pr_err("request_percpu_irq failed\n");
+	} else {
+		/* Install and invoke hotplug callbacks */
+		res = cpuhp_setup_state(CPUHP_AP_QCOM_TIMER_STARTING,
+					"clockevents/qcom/timer:starting",
+					msm_local_timer_starting_cpu,
+					msm_local_timer_dying_cpu);
+		if (res) {
+			free_percpu_irq(irq, msm_evt);
+			goto err;
+		}
+	}
+
+err:
+	writel_relaxed(TIMER_ENABLE_EN, source_base + TIMER_ENABLE);
+	res = clocksource_register_hz(cs, dgt_hz);
+	if (res)
+		pr_err("clocksource_register failed\n");
+	sched_clock_register(msm_sched_clock_read, sched_bits, dgt_hz);
+	msm_delay_timer.freq = dgt_hz;
+	register_current_timer_delay(&msm_delay_timer);
+
+	return res;
+}
+
+static int __init msm_dt_timer_init(struct device_node *np)
+{
+	u32 freq;
+	int irq, ret;
+	struct resource res;
+	u32 percpu_offset;
+	void __iomem *base;
+	void __iomem *cpu0_base;
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_err("Failed to map event base\n");
+		return -ENXIO;
+	}
+
+	/* We use GPT0 for the clockevent */
+	irq = irq_of_parse_and_map(np, 1);
+	if (irq <= 0) {
+		pr_err("Can't get irq\n");
+		return -EINVAL;
+	}
+
+	/* We use CPU0's DGT for the clocksource */
+	if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
+		percpu_offset = 0;
+
+	ret = of_address_to_resource(np, 0, &res);
+	if (ret) {
+		pr_err("Failed to parse DGT resource\n");
+		return ret;
+	}
+
+	cpu0_base = ioremap(res.start + percpu_offset, resource_size(&res));
+	if (!cpu0_base) {
+		pr_err("Failed to map source base\n");
+		return -EINVAL;
+	}
+
+	if (of_property_read_u32(np, "clock-frequency", &freq)) {
+		iounmap(cpu0_base);
+		pr_err("Unknown frequency\n");
+		return -EINVAL;
+	}
+
+	event_base = base + 0x4;
+	sts_base = base + 0x88;
+	source_base = cpu0_base + 0x24;
+	freq /= 4;
+	writel_relaxed(DGT_CLK_CTL_DIV_4, source_base + DGT_CLK_CTL);
+
+	ret = msm_timer_init(freq, 32, irq, !!percpu_offset);
+	if (ret)
+		iounmap(cpu0_base);
+
+	return ret;
+}
+TIMER_OF_DECLARE(kpss_timer, "qcom,kpss-timer", msm_dt_timer_init);
+TIMER_OF_DECLARE(scss_timer, "qcom,scss-timer", msm_dt_timer_init);