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, 262 insertions, 0 deletions

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
new file mode 100644
index 000000000..c890e2a5b
--- /dev/null
+++ b/drivers/base/topology.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * driver/base/topology.c - Populate sysfs with cpu topology information
+ *
+ * Written by: Zhang Yanmin, Intel Corporation
+ *
+ * Copyright (C) 2006, Intel Corp.
+ *
+ * All rights reserved.
+ */
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/hardirq.h>
+#include <linux/topology.h>
+
+#define define_id_show_func(name, fmt)					\
+static ssize_t name##_show(struct device *dev,				\
+			   struct device_attribute *attr, char *buf)	\
+{									\
+	return sysfs_emit(buf, fmt "\n", topology_##name(dev->id));	\
+}
+
+#define define_siblings_read_func(name, mask)					\
+static ssize_t name##_read(struct file *file, struct kobject *kobj,		\
+			   const struct bin_attribute *attr, char *buf,		\
+			   loff_t off, size_t count)				\
+{										\
+	struct device *dev = kobj_to_dev(kobj);                                 \
+	cpumask_var_t mask;							\
+	ssize_t n;								\
+										\
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))				\
+		return -ENOMEM;							\
+										\
+	cpumask_copy(mask, topology_##mask(dev->id));				\
+	n = cpumap_print_bitmask_to_buf(buf, mask, off, count);			\
+	free_cpumask_var(mask);							\
+										\
+	return n;								\
+}										\
+										\
+static ssize_t name##_list_read(struct file *file, struct kobject *kobj,	\
+				const struct bin_attribute *attr, char *buf,	\
+				loff_t off, size_t count)			\
+{										\
+	struct device *dev = kobj_to_dev(kobj);					\
+	cpumask_var_t mask;							\
+	ssize_t n;								\
+										\
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))				\
+		return -ENOMEM;							\
+										\
+	cpumask_copy(mask, topology_##mask(dev->id));				\
+	n = cpumap_print_list_to_buf(buf, mask, off, count);			\
+	free_cpumask_var(mask);							\
+										\
+	return n;								\
+}
+
+define_id_show_func(physical_package_id, "%d");
+static DEVICE_ATTR_RO(physical_package_id);
+
+#ifdef TOPOLOGY_DIE_SYSFS
+define_id_show_func(die_id, "%d");
+static DEVICE_ATTR_RO(die_id);
+#endif
+
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+define_id_show_func(cluster_id, "%d");
+static DEVICE_ATTR_RO(cluster_id);
+#endif
+
+define_id_show_func(core_id, "%d");
+static DEVICE_ATTR_RO(core_id);
+
+define_id_show_func(ppin, "0x%llx");
+static DEVICE_ATTR_ADMIN_RO(ppin);
+
+define_siblings_read_func(thread_siblings, sibling_cpumask);
+static const BIN_ATTR_RO(thread_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(thread_siblings_list, CPULIST_FILE_MAX_BYTES);
+
+define_siblings_read_func(core_cpus, sibling_cpumask);
+static const BIN_ATTR_RO(core_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(core_cpus_list, CPULIST_FILE_MAX_BYTES);
+
+define_siblings_read_func(core_siblings, core_cpumask);
+static const BIN_ATTR_RO(core_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(core_siblings_list, CPULIST_FILE_MAX_BYTES);
+
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+define_siblings_read_func(cluster_cpus, cluster_cpumask);
+static const BIN_ATTR_RO(cluster_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(cluster_cpus_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+#ifdef TOPOLOGY_DIE_SYSFS
+define_siblings_read_func(die_cpus, die_cpumask);
+static const BIN_ATTR_RO(die_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(die_cpus_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+define_siblings_read_func(package_cpus, core_cpumask);
+static const BIN_ATTR_RO(package_cpus, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(package_cpus_list, CPULIST_FILE_MAX_BYTES);
+
+#ifdef TOPOLOGY_BOOK_SYSFS
+define_id_show_func(book_id, "%d");
+static DEVICE_ATTR_RO(book_id);
+define_siblings_read_func(book_siblings, book_cpumask);
+static const BIN_ATTR_RO(book_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(book_siblings_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+#ifdef TOPOLOGY_DRAWER_SYSFS
+define_id_show_func(drawer_id, "%d");
+static DEVICE_ATTR_RO(drawer_id);
+define_siblings_read_func(drawer_siblings, drawer_cpumask);
+static const BIN_ATTR_RO(drawer_siblings, CPUMAP_FILE_MAX_BYTES);
+static const BIN_ATTR_RO(drawer_siblings_list, CPULIST_FILE_MAX_BYTES);
+#endif
+
+static const struct bin_attribute *const bin_attrs[] = {
+	&bin_attr_core_cpus,
+	&bin_attr_core_cpus_list,
+	&bin_attr_thread_siblings,
+	&bin_attr_thread_siblings_list,
+	&bin_attr_core_siblings,
+	&bin_attr_core_siblings_list,
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+	&bin_attr_cluster_cpus,
+	&bin_attr_cluster_cpus_list,
+#endif
+#ifdef TOPOLOGY_DIE_SYSFS
+	&bin_attr_die_cpus,
+	&bin_attr_die_cpus_list,
+#endif
+	&bin_attr_package_cpus,
+	&bin_attr_package_cpus_list,
+#ifdef TOPOLOGY_BOOK_SYSFS
+	&bin_attr_book_siblings,
+	&bin_attr_book_siblings_list,
+#endif
+#ifdef TOPOLOGY_DRAWER_SYSFS
+	&bin_attr_drawer_siblings,
+	&bin_attr_drawer_siblings_list,
+#endif
+	NULL
+};
+
+static struct attribute *default_attrs[] = {
+	&dev_attr_physical_package_id.attr,
+#ifdef TOPOLOGY_DIE_SYSFS
+	&dev_attr_die_id.attr,
+#endif
+#ifdef TOPOLOGY_CLUSTER_SYSFS
+	&dev_attr_cluster_id.attr,
+#endif
+	&dev_attr_core_id.attr,
+#ifdef TOPOLOGY_BOOK_SYSFS
+	&dev_attr_book_id.attr,
+#endif
+#ifdef TOPOLOGY_DRAWER_SYSFS
+	&dev_attr_drawer_id.attr,
+#endif
+	&dev_attr_ppin.attr,
+	NULL
+};
+
+static umode_t topology_is_visible(struct kobject *kobj,
+				   struct attribute *attr, int unused)
+{
+	if (attr == &dev_attr_ppin.attr && !topology_ppin(kobj_to_dev(kobj)->id))
+		return 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group topology_attr_group = {
+	.attrs = default_attrs,
+	.bin_attrs = bin_attrs,
+	.is_visible = topology_is_visible,
+	.name = "topology"
+};
+
+/* Add/Remove cpu_topology interface for CPU device */
+static int topology_add_dev(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	return sysfs_create_group(&dev->kobj, &topology_attr_group);
+}
+
+static int topology_remove_dev(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+
+	sysfs_remove_group(&dev->kobj, &topology_attr_group);
+	return 0;
+}
+
+static int __init topology_sysfs_init(void)
+{
+	return cpuhp_setup_state(CPUHP_TOPOLOGY_PREPARE,
+				 "base/topology:prepare", topology_add_dev,
+				 topology_remove_dev);
+}
+
+device_initcall(topology_sysfs_init);
+
+DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
+EXPORT_PER_CPU_SYMBOL_GPL(cpu_scale);
+
+void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
+{
+	per_cpu(cpu_scale, cpu) = capacity;
+}
+
+static ssize_t cpu_capacity_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+
+	return sysfs_emit(buf, "%lu\n", topology_get_cpu_scale(cpu->dev.id));
+}
+
+static DEVICE_ATTR_RO(cpu_capacity);
+
+static int cpu_capacity_sysctl_add(unsigned int cpu)
+{
+	struct device *cpu_dev = get_cpu_device(cpu);
+
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_create_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int cpu_capacity_sysctl_remove(unsigned int cpu)
+{
+	struct device *cpu_dev = get_cpu_device(cpu);
+
+	if (!cpu_dev)
+		return -ENOENT;
+
+	device_remove_file(cpu_dev, &dev_attr_cpu_capacity);
+
+	return 0;
+}
+
+static int register_cpu_capacity_sysctl(void)
+{
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "topology/cpu-capacity",
+			  cpu_capacity_sysctl_add, cpu_capacity_sysctl_remove);
+
+	return 0;
+}
+subsys_initcall(register_cpu_capacity_sysctl);