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, 306 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c
new file mode 100644
index 000000000..84cb527f5
--- /dev/null
+++ b/drivers/ptp/ptp_vclock.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PTP virtual clock driver
+ *
+ * Copyright 2021 NXP
+ */
+#include <linux/slab.h>
+#include <linux/hashtable.h>
+#include "ptp_private.h"
+
+#define PTP_VCLOCK_CC_SHIFT		31
+#define PTP_VCLOCK_CC_MULT		(1 << PTP_VCLOCK_CC_SHIFT)
+#define PTP_VCLOCK_FADJ_SHIFT		9
+#define PTP_VCLOCK_FADJ_DENOMINATOR	15625ULL
+#define PTP_VCLOCK_REFRESH_INTERVAL	(HZ * 2)
+
+/* protects vclock_hash addition/deletion */
+static DEFINE_SPINLOCK(vclock_hash_lock);
+
+static DEFINE_READ_MOSTLY_HASHTABLE(vclock_hash, 8);
+
+DEFINE_STATIC_SRCU(vclock_srcu);
+
+static void ptp_vclock_hash_add(struct ptp_vclock *vclock)
+{
+	spin_lock(&vclock_hash_lock);
+
+	hlist_add_head_rcu(&vclock->vclock_hash_node,
+			   &vclock_hash[vclock->clock->index % HASH_SIZE(vclock_hash)]);
+
+	spin_unlock(&vclock_hash_lock);
+}
+
+static void ptp_vclock_hash_del(struct ptp_vclock *vclock)
+{
+	spin_lock(&vclock_hash_lock);
+
+	hlist_del_init_rcu(&vclock->vclock_hash_node);
+
+	spin_unlock(&vclock_hash_lock);
+
+	synchronize_srcu(&vclock_srcu);
+}
+
+static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	s64 adj;
+
+	adj = (s64)scaled_ppm << PTP_VCLOCK_FADJ_SHIFT;
+	adj = div_s64(adj, PTP_VCLOCK_FADJ_DENOMINATOR);
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	timecounter_read(&vclock->tc);
+	vclock->cc.mult = PTP_VCLOCK_CC_MULT + adj;
+	mutex_unlock(&vclock->lock);
+
+	return 0;
+}
+
+static int ptp_vclock_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	timecounter_adjtime(&vclock->tc, delta);
+	mutex_unlock(&vclock->lock);
+
+	return 0;
+}
+
+static int ptp_vclock_gettime(struct ptp_clock_info *ptp,
+			      struct timespec64 *ts)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	u64 ns;
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	ns = timecounter_read(&vclock->tc);
+	mutex_unlock(&vclock->lock);
+	*ts = ns_to_timespec64(ns);
+
+	return 0;
+}
+
+static int ptp_vclock_gettimex(struct ptp_clock_info *ptp,
+			       struct timespec64 *ts,
+			       struct ptp_system_timestamp *sts)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	struct ptp_clock *pptp = vclock->pclock;
+	struct timespec64 pts;
+	int err;
+	u64 ns;
+
+	err = pptp->info->getcyclesx64(pptp->info, &pts, sts);
+	if (err)
+		return err;
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	ns = timecounter_cyc2time(&vclock->tc, timespec64_to_ns(&pts));
+	mutex_unlock(&vclock->lock);
+
+	*ts = ns_to_timespec64(ns);
+
+	return 0;
+}
+
+static int ptp_vclock_settime(struct ptp_clock_info *ptp,
+			      const struct timespec64 *ts)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	u64 ns = timespec64_to_ns(ts);
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	timecounter_init(&vclock->tc, &vclock->cc, ns);
+	mutex_unlock(&vclock->lock);
+
+	return 0;
+}
+
+static int ptp_vclock_getcrosststamp(struct ptp_clock_info *ptp,
+				     struct system_device_crosststamp *xtstamp)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	struct ptp_clock *pptp = vclock->pclock;
+	int err;
+	u64 ns;
+
+	err = pptp->info->getcrosscycles(pptp->info, xtstamp);
+	if (err)
+		return err;
+
+	if (mutex_lock_interruptible(&vclock->lock))
+		return -EINTR;
+	ns = timecounter_cyc2time(&vclock->tc, ktime_to_ns(xtstamp->device));
+	mutex_unlock(&vclock->lock);
+
+	xtstamp->device = ns_to_ktime(ns);
+
+	return 0;
+}
+
+static long ptp_vclock_refresh(struct ptp_clock_info *ptp)
+{
+	struct ptp_vclock *vclock = info_to_vclock(ptp);
+	struct timespec64 ts;
+
+	ptp_vclock_gettime(&vclock->info, &ts);
+
+	return PTP_VCLOCK_REFRESH_INTERVAL;
+}
+
+static void ptp_vclock_set_subclass(struct ptp_clock *ptp)
+{
+	lockdep_set_subclass(&ptp->clock.rwsem, PTP_LOCK_VIRTUAL);
+}
+
+static const struct ptp_clock_info ptp_vclock_info = {
+	.owner		= THIS_MODULE,
+	.name		= "ptp virtual clock",
+	.max_adj	= 500000000,
+	.adjfine	= ptp_vclock_adjfine,
+	.adjtime	= ptp_vclock_adjtime,
+	.settime64	= ptp_vclock_settime,
+	.do_aux_work	= ptp_vclock_refresh,
+};
+
+static u64 ptp_vclock_read(struct cyclecounter *cc)
+{
+	struct ptp_vclock *vclock = cc_to_vclock(cc);
+	struct ptp_clock *ptp = vclock->pclock;
+	struct timespec64 ts = {};
+
+	ptp->info->getcycles64(ptp->info, &ts);
+
+	return timespec64_to_ns(&ts);
+}
+
+static const struct cyclecounter ptp_vclock_cc = {
+	.read	= ptp_vclock_read,
+	.mask	= CYCLECOUNTER_MASK(32),
+	.mult	= PTP_VCLOCK_CC_MULT,
+	.shift	= PTP_VCLOCK_CC_SHIFT,
+};
+
+struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock)
+{
+	struct ptp_vclock *vclock;
+
+	vclock = kzalloc_obj(*vclock);
+	if (!vclock)
+		return NULL;
+
+	vclock->pclock = pclock;
+	vclock->info = ptp_vclock_info;
+	if (pclock->info->getcyclesx64)
+		vclock->info.gettimex64 = ptp_vclock_gettimex;
+	else
+		vclock->info.gettime64 = ptp_vclock_gettime;
+	if (pclock->info->getcrosscycles)
+		vclock->info.getcrosststamp = ptp_vclock_getcrosststamp;
+	vclock->cc = ptp_vclock_cc;
+
+	snprintf(vclock->info.name, PTP_CLOCK_NAME_LEN, "ptp%d_virt",
+		 pclock->index);
+
+	INIT_HLIST_NODE(&vclock->vclock_hash_node);
+
+	mutex_init(&vclock->lock);
+
+	vclock->clock = ptp_clock_register(&vclock->info, &pclock->dev);
+	if (IS_ERR_OR_NULL(vclock->clock)) {
+		kfree(vclock);
+		return NULL;
+	}
+
+	ptp_vclock_set_subclass(vclock->clock);
+
+	timecounter_init(&vclock->tc, &vclock->cc, 0);
+	ptp_schedule_worker(vclock->clock, PTP_VCLOCK_REFRESH_INTERVAL);
+
+	ptp_vclock_hash_add(vclock);
+
+	return vclock;
+}
+
+void ptp_vclock_unregister(struct ptp_vclock *vclock)
+{
+	ptp_vclock_hash_del(vclock);
+
+	ptp_clock_unregister(vclock->clock);
+	kfree(vclock);
+}
+
+#if IS_BUILTIN(CONFIG_PTP_1588_CLOCK)
+int ptp_get_vclocks_index(int pclock_index, int **vclock_index)
+{
+	char name[PTP_CLOCK_NAME_LEN] = "";
+	struct ptp_clock *ptp;
+	struct device *dev;
+	int num = 0;
+
+	if (pclock_index < 0)
+		return num;
+
+	snprintf(name, PTP_CLOCK_NAME_LEN, "ptp%d", pclock_index);
+	dev = class_find_device_by_name(&ptp_class, name);
+	if (!dev)
+		return num;
+
+	ptp = dev_get_drvdata(dev);
+
+	if (mutex_lock_interruptible(&ptp->n_vclocks_mux)) {
+		put_device(dev);
+		return num;
+	}
+
+	*vclock_index = kzalloc(sizeof(int) * ptp->n_vclocks, GFP_KERNEL);
+	if (!(*vclock_index))
+		goto out;
+
+	memcpy(*vclock_index, ptp->vclock_index, sizeof(int) * ptp->n_vclocks);
+	num = ptp->n_vclocks;
+out:
+	mutex_unlock(&ptp->n_vclocks_mux);
+	put_device(dev);
+	return num;
+}
+EXPORT_SYMBOL(ptp_get_vclocks_index);
+
+ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index)
+{
+	unsigned int hash = vclock_index % HASH_SIZE(vclock_hash);
+	struct ptp_vclock *vclock;
+	u64 vclock_ns = 0;
+	int srcu_idx;
+	u64 ns;
+
+	ns = ktime_to_ns(*hwtstamp);
+
+	srcu_idx = srcu_read_lock(&vclock_srcu);
+
+	hlist_for_each_entry_srcu(vclock, &vclock_hash[hash], vclock_hash_node,
+				  srcu_read_lock_held(&vclock_srcu)) {
+		if (vclock->clock->index != vclock_index)
+			continue;
+
+		if (mutex_lock_interruptible(&vclock->lock))
+			break;
+		vclock_ns = timecounter_cyc2time(&vclock->tc, ns);
+		mutex_unlock(&vclock->lock);
+		break;
+	}
+
+	srcu_read_unlock(&vclock_srcu, srcu_idx);
+
+	return ns_to_ktime(vclock_ns);
+}
+EXPORT_SYMBOL(ptp_convert_timestamp);
+#endif