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, 481 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
new file mode 100644
index 000000000..dc398c6b7
--- /dev/null
+++ b/drivers/ptp/ptp_sysfs.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PTP 1588 clock support - sysfs interface.
+ *
+ * Copyright (C) 2010 OMICRON electronics GmbH
+ * Copyright 2021 NXP
+ */
+#include <linux/capability.h>
+#include <linux/slab.h>
+
+#include "ptp_private.h"
+
+static ssize_t clock_name_show(struct device *dev,
+			       struct device_attribute *attr, char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	return sysfs_emit(page, "%s\n", ptp->info->name);
+}
+static DEVICE_ATTR_RO(clock_name);
+
+static ssize_t max_phase_adjustment_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+
+	return sysfs_emit(page, "%d\n", ptp->info->getmaxphase(ptp->info));
+}
+static DEVICE_ATTR_RO(max_phase_adjustment);
+
+#define PTP_SHOW_INT(name, var)						\
+static ssize_t var##_show(struct device *dev,				\
+			   struct device_attribute *attr, char *page)	\
+{									\
+	struct ptp_clock *ptp = dev_get_drvdata(dev);			\
+	return sysfs_emit(page, "%d\n", ptp->info->var);	\
+}									\
+static DEVICE_ATTR(name, 0444, var##_show, NULL);
+
+PTP_SHOW_INT(max_adjustment, max_adj);
+PTP_SHOW_INT(n_alarms, n_alarm);
+PTP_SHOW_INT(n_external_timestamps, n_ext_ts);
+PTP_SHOW_INT(n_periodic_outputs, n_per_out);
+PTP_SHOW_INT(n_programmable_pins, n_pins);
+PTP_SHOW_INT(pps_available, pps);
+
+static ssize_t extts_enable_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *ops = ptp->info;
+	struct ptp_clock_request req = { .type = PTP_CLK_REQ_EXTTS };
+	int cnt, enable;
+	int err = -EINVAL;
+
+	cnt = sscanf(buf, "%u %d", &req.extts.index, &enable);
+	if (cnt != 2)
+		goto out;
+	if (req.extts.index >= ops->n_ext_ts)
+		goto out;
+
+	err = ops->enable(ops, &req, enable ? 1 : 0);
+	if (err)
+		goto out;
+
+	return count;
+out:
+	return err;
+}
+static DEVICE_ATTR(extts_enable, 0220, NULL, extts_enable_store);
+
+static ssize_t extts_fifo_show(struct device *dev,
+			       struct device_attribute *attr, char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct timestamp_event_queue *queue;
+	struct ptp_extts_event event;
+	unsigned long flags;
+	size_t qcnt;
+	int cnt = 0;
+
+	cnt = list_count_nodes(&ptp->tsevqs);
+	if (cnt <= 0)
+		goto out;
+
+	/* The sysfs fifo will always draw from the fist queue */
+	queue = list_first_entry(&ptp->tsevqs, struct timestamp_event_queue,
+				 qlist);
+
+	memset(&event, 0, sizeof(event));
+	spin_lock_irqsave(&queue->lock, flags);
+	qcnt = queue_cnt(queue);
+	if (qcnt) {
+		event = queue->buf[queue->head];
+		/* Paired with READ_ONCE() in queue_cnt() */
+		WRITE_ONCE(queue->head, (queue->head + 1) % PTP_MAX_TIMESTAMPS);
+	}
+	spin_unlock_irqrestore(&queue->lock, flags);
+
+	if (!qcnt)
+		goto out;
+
+	cnt = sysfs_emit(page, "%u %lld %u\n",
+			 event.index, event.t.sec, event.t.nsec);
+out:
+	return cnt;
+}
+static DEVICE_ATTR(fifo, 0444, extts_fifo_show, NULL);
+
+static ssize_t period_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *ops = ptp->info;
+	struct ptp_clock_request req = { .type = PTP_CLK_REQ_PEROUT };
+	int cnt, enable, err = -EINVAL;
+
+	cnt = sscanf(buf, "%u %lld %u %lld %u", &req.perout.index,
+		     &req.perout.start.sec, &req.perout.start.nsec,
+		     &req.perout.period.sec, &req.perout.period.nsec);
+	if (cnt != 5)
+		goto out;
+	if (req.perout.index >= ops->n_per_out)
+		goto out;
+
+	enable = req.perout.period.sec || req.perout.period.nsec;
+	err = ops->enable(ops, &req, enable);
+	if (err)
+		goto out;
+
+	return count;
+out:
+	return err;
+}
+static DEVICE_ATTR(period, 0220, NULL, period_store);
+
+static ssize_t pps_enable_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *ops = ptp->info;
+	struct ptp_clock_request req = { .type = PTP_CLK_REQ_PPS };
+	int cnt, enable;
+	int err = -EINVAL;
+
+	if (!capable(CAP_SYS_TIME))
+		return -EPERM;
+
+	cnt = sscanf(buf, "%d", &enable);
+	if (cnt != 1)
+		goto out;
+
+	err = ops->enable(ops, &req, enable ? 1 : 0);
+	if (err)
+		goto out;
+
+	return count;
+out:
+	return err;
+}
+static DEVICE_ATTR(pps_enable, 0220, NULL, pps_enable_store);
+
+static int unregister_vclock(struct device *dev, void *data)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *info = ptp->info;
+	struct ptp_vclock *vclock;
+	u32 *num = data;
+
+	vclock = info_to_vclock(info);
+	dev_info(dev->parent, "delete virtual clock ptp%d\n",
+		 vclock->clock->index);
+
+	ptp_vclock_unregister(vclock);
+	(*num)--;
+
+	/* For break. Not error. */
+	if (*num == 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+static ssize_t n_vclocks_show(struct device *dev,
+			      struct device_attribute *attr, char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	ssize_t size;
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+		return -ERESTARTSYS;
+
+	size = sysfs_emit(page, "%u\n", ptp->n_vclocks);
+
+	mutex_unlock(&ptp->n_vclocks_mux);
+
+	return size;
+}
+
+static ssize_t n_vclocks_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_vclock *vclock;
+	int err = -EINVAL;
+	u32 num, i;
+
+	if (kstrtou32(buf, 0, &num))
+		return err;
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+		return -ERESTARTSYS;
+
+	if (num > ptp->max_vclocks) {
+		dev_err(dev, "max value is %d\n", ptp->max_vclocks);
+		goto out;
+	}
+
+	/* Need to create more vclocks */
+	if (num > ptp->n_vclocks) {
+		for (i = 0; i < num - ptp->n_vclocks; i++) {
+			vclock = ptp_vclock_register(ptp);
+			if (!vclock)
+				goto out;
+
+			*(ptp->vclock_index + ptp->n_vclocks + i) =
+				vclock->clock->index;
+
+			dev_info(dev, "new virtual clock ptp%d\n",
+				 vclock->clock->index);
+		}
+	}
+
+	/* Need to delete vclocks */
+	if (num < ptp->n_vclocks) {
+		i = ptp->n_vclocks - num;
+		device_for_each_child_reverse(dev, &i,
+					      unregister_vclock);
+
+		for (i = 1; i <= ptp->n_vclocks - num; i++)
+			*(ptp->vclock_index + ptp->n_vclocks - i) = -1;
+	}
+
+	/* Need to inform about changed physical clock behavior */
+	if (!ptp->has_cycles) {
+		if (num == 0)
+			dev_info(dev, "only physical clock in use now\n");
+		else
+			dev_info(dev, "guarantee physical clock free running\n");
+	}
+
+	ptp->n_vclocks = num;
+	mutex_unlock(&ptp->n_vclocks_mux);
+
+	return count;
+out:
+	mutex_unlock(&ptp->n_vclocks_mux);
+	return err;
+}
+static DEVICE_ATTR_RW(n_vclocks);
+
+static ssize_t max_vclocks_show(struct device *dev,
+				struct device_attribute *attr, char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	ssize_t size;
+
+	size = sysfs_emit(page, "%u\n", ptp->max_vclocks);
+
+	return size;
+}
+
+static ssize_t max_vclocks_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	unsigned int *vclock_index;
+	int err = -EINVAL;
+	size_t size;
+	u32 max;
+
+	if (kstrtou32(buf, 0, &max) || max == 0 || max > PTP_MAX_VCLOCKS_LIMIT)
+		return -EINVAL;
+
+	if (max == ptp->max_vclocks)
+		return count;
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux))
+		return -ERESTARTSYS;
+
+	if (max < ptp->n_vclocks)
+		goto out;
+
+	vclock_index = kcalloc(max, sizeof(int), GFP_KERNEL);
+	if (!vclock_index) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	size = sizeof(int) * ptp->n_vclocks;
+	memcpy(vclock_index, ptp->vclock_index, size);
+
+	kfree(ptp->vclock_index);
+	ptp->vclock_index = vclock_index;
+	ptp->max_vclocks = max;
+
+	mutex_unlock(&ptp->n_vclocks_mux);
+
+	return count;
+out:
+	mutex_unlock(&ptp->n_vclocks_mux);
+	return err;
+}
+static DEVICE_ATTR_RW(max_vclocks);
+
+static struct attribute *ptp_attrs[] = {
+	&dev_attr_clock_name.attr,
+
+	&dev_attr_max_adjustment.attr,
+	&dev_attr_max_phase_adjustment.attr,
+	&dev_attr_n_alarms.attr,
+	&dev_attr_n_external_timestamps.attr,
+	&dev_attr_n_periodic_outputs.attr,
+	&dev_attr_n_programmable_pins.attr,
+	&dev_attr_pps_available.attr,
+
+	&dev_attr_extts_enable.attr,
+	&dev_attr_fifo.attr,
+	&dev_attr_period.attr,
+	&dev_attr_pps_enable.attr,
+	&dev_attr_n_vclocks.attr,
+	&dev_attr_max_vclocks.attr,
+	NULL
+};
+
+static umode_t ptp_is_attribute_visible(struct kobject *kobj,
+					struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	struct ptp_clock_info *info = ptp->info;
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_extts_enable.attr ||
+	    attr == &dev_attr_fifo.attr) {
+		if (!info->n_ext_ts)
+			mode = 0;
+	} else if (attr == &dev_attr_period.attr) {
+		if (!info->n_per_out)
+			mode = 0;
+	} else if (attr == &dev_attr_pps_enable.attr) {
+		if (!info->pps)
+			mode = 0;
+	} else if (attr == &dev_attr_n_vclocks.attr ||
+		   attr == &dev_attr_max_vclocks.attr) {
+		if (ptp->is_virtual_clock)
+			mode = 0;
+	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
+		if (!info->adjphase || !info->getmaxphase)
+			mode = 0;
+	}
+
+	return mode;
+}
+
+static const struct attribute_group ptp_group = {
+	.is_visible	= ptp_is_attribute_visible,
+	.attrs		= ptp_attrs,
+};
+
+const struct attribute_group *ptp_groups[] = {
+	&ptp_group,
+	NULL
+};
+
+static int ptp_pin_name2index(struct ptp_clock *ptp, const char *name)
+{
+	int i;
+	for (i = 0; i < ptp->info->n_pins; i++) {
+		if (!strcmp(ptp->info->pin_config[i].name, name))
+			return i;
+	}
+	return -1;
+}
+
+static ssize_t ptp_pin_show(struct device *dev, struct device_attribute *attr,
+			    char *page)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	unsigned int func, chan;
+	int index;
+
+	index = ptp_pin_name2index(ptp, attr->attr.name);
+	if (index < 0)
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&ptp->pincfg_mux))
+		return -ERESTARTSYS;
+
+	func = ptp->info->pin_config[index].func;
+	chan = ptp->info->pin_config[index].chan;
+
+	mutex_unlock(&ptp->pincfg_mux);
+
+	return sysfs_emit(page, "%u %u\n", func, chan);
+}
+
+static ssize_t ptp_pin_store(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct ptp_clock *ptp = dev_get_drvdata(dev);
+	unsigned int func, chan;
+	int cnt, err, index;
+
+	cnt = sscanf(buf, "%u %u", &func, &chan);
+	if (cnt != 2)
+		return -EINVAL;
+
+	index = ptp_pin_name2index(ptp, attr->attr.name);
+	if (index < 0)
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&ptp->pincfg_mux))
+		return -ERESTARTSYS;
+	err = ptp_set_pinfunc(ptp, index, func, chan);
+	mutex_unlock(&ptp->pincfg_mux);
+	if (err)
+		return err;
+
+	return count;
+}
+
+int ptp_populate_pin_groups(struct ptp_clock *ptp)
+{
+	struct ptp_clock_info *info = ptp->info;
+	int err = -ENOMEM, i, n_pins = info->n_pins;
+
+	if (!n_pins)
+		return 0;
+
+	ptp->pin_dev_attr = kzalloc_objs(*ptp->pin_dev_attr, n_pins);
+	if (!ptp->pin_dev_attr)
+		goto no_dev_attr;
+
+	ptp->pin_attr = kzalloc_objs(*ptp->pin_attr, 1 + n_pins);
+	if (!ptp->pin_attr)
+		goto no_pin_attr;
+
+	for (i = 0; i < n_pins; i++) {
+		struct device_attribute *da = &ptp->pin_dev_attr[i];
+		sysfs_attr_init(&da->attr);
+		da->attr.name = info->pin_config[i].name;
+		da->attr.mode = 0644;
+		da->show = ptp_pin_show;
+		da->store = ptp_pin_store;
+		ptp->pin_attr[i] = &da->attr;
+	}
+
+	ptp->pin_attr_group.name = "pins";
+	ptp->pin_attr_group.attrs = ptp->pin_attr;
+
+	ptp->pin_attr_groups[0] = &ptp->pin_attr_group;
+
+	return 0;
+
+no_pin_attr:
+	kfree(ptp->pin_dev_attr);
+no_dev_attr:
+	return err;
+}
+
+void ptp_cleanup_pin_groups(struct ptp_clock *ptp)
+{
+	kfree(ptp->pin_attr);
+	kfree(ptp->pin_dev_attr);
+}