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, 213 insertions, 0 deletions

diff --git a/drivers/acpi/nvs.c b/drivers/acpi/nvs.c
new file mode 100644
index 000000000..12aee4102
--- /dev/null
+++ b/drivers/acpi/nvs.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * nvs.c - Routines for saving and restoring ACPI NVS memory region
+ *
+ * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ */
+
+#define pr_fmt(fmt) "ACPI: PM: " fmt
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+
+#include "internal.h"
+
+/* ACPI NVS regions, APEI may use it */
+
+struct nvs_region {
+	__u64 phys_start;
+	__u64 size;
+	struct list_head node;
+};
+
+static LIST_HEAD(nvs_region_list);
+
+#ifdef CONFIG_ACPI_SLEEP
+static int suspend_nvs_register(unsigned long start, unsigned long size);
+#else
+static inline int suspend_nvs_register(unsigned long a, unsigned long b)
+{
+	return 0;
+}
+#endif
+
+int acpi_nvs_register(__u64 start, __u64 size)
+{
+	struct nvs_region *region;
+
+	region = kmalloc_obj(*region);
+	if (!region)
+		return -ENOMEM;
+	region->phys_start = start;
+	region->size = size;
+	list_add_tail(&region->node, &nvs_region_list);
+
+	return suspend_nvs_register(start, size);
+}
+
+int acpi_nvs_for_each_region(int (*func)(__u64 start, __u64 size, void *data),
+			     void *data)
+{
+	int rc;
+	struct nvs_region *region;
+
+	list_for_each_entry(region, &nvs_region_list, node) {
+		rc = func(region->phys_start, region->size, data);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+
+#ifdef CONFIG_ACPI_SLEEP
+/*
+ * Platforms, like ACPI, may want us to save some memory used by them during
+ * suspend and to restore the contents of this memory during the subsequent
+ * resume.  The code below implements a mechanism allowing us to do that.
+ */
+
+struct nvs_page {
+	unsigned long phys_start;
+	unsigned int size;
+	void *kaddr;
+	void *data;
+	bool unmap;
+	struct list_head node;
+};
+
+static LIST_HEAD(nvs_list);
+
+/**
+ * suspend_nvs_register - register platform NVS memory region to save
+ * @start: Physical address of the region.
+ * @size: Size of the region.
+ *
+ * The NVS region need not be page-aligned (both ends) and we arrange
+ * things so that the data from page-aligned addresses in this region will
+ * be copied into separate RAM pages.
+ */
+static int suspend_nvs_register(unsigned long start, unsigned long size)
+{
+	struct nvs_page *entry, *next;
+
+	pr_info("Registering ACPI NVS region [mem %#010lx-%#010lx] (%ld bytes)\n",
+		start, start + size - 1, size);
+
+	while (size > 0) {
+		unsigned int nr_bytes;
+
+		entry = kzalloc_obj(struct nvs_page);
+		if (!entry)
+			goto Error;
+
+		list_add_tail(&entry->node, &nvs_list);
+		entry->phys_start = start;
+		nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
+		entry->size = (size < nr_bytes) ? size : nr_bytes;
+
+		start += entry->size;
+		size -= entry->size;
+	}
+	return 0;
+
+ Error:
+	list_for_each_entry_safe(entry, next, &nvs_list, node) {
+		list_del(&entry->node);
+		kfree(entry);
+	}
+	return -ENOMEM;
+}
+
+/**
+ * suspend_nvs_free - free data pages allocated for saving NVS regions
+ */
+void suspend_nvs_free(void)
+{
+	struct nvs_page *entry;
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data) {
+			kfree(entry->data);
+			entry->data = NULL;
+			if (entry->kaddr) {
+				if (entry->unmap) {
+					iounmap(entry->kaddr);
+					entry->unmap = false;
+				} else {
+					acpi_os_unmap_iomem(entry->kaddr,
+							    entry->size);
+				}
+				entry->kaddr = NULL;
+			}
+		}
+}
+
+/**
+ * suspend_nvs_alloc - allocate memory necessary for saving NVS regions
+ */
+int suspend_nvs_alloc(void)
+{
+	struct nvs_page *entry;
+
+	list_for_each_entry(entry, &nvs_list, node) {
+		entry->data = kmalloc(PAGE_SIZE, GFP_KERNEL);
+		if (!entry->data) {
+			suspend_nvs_free();
+			return -ENOMEM;
+		}
+	}
+	return 0;
+}
+
+/**
+ * suspend_nvs_save - save NVS memory regions
+ */
+int suspend_nvs_save(void)
+{
+	struct nvs_page *entry;
+
+	pr_info("Saving platform NVS memory\n");
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data) {
+			unsigned long phys = entry->phys_start;
+			unsigned int size = entry->size;
+
+			entry->kaddr = acpi_os_get_iomem(phys, size);
+			if (!entry->kaddr) {
+				entry->kaddr = acpi_os_ioremap(phys, size);
+				entry->unmap = !!entry->kaddr;
+			}
+			if (!entry->kaddr) {
+				suspend_nvs_free();
+				return -ENOMEM;
+			}
+			memcpy(entry->data, entry->kaddr, entry->size);
+		}
+
+	return 0;
+}
+
+/**
+ * suspend_nvs_restore - restore NVS memory regions
+ *
+ * This function is going to be called with interrupts disabled, so it
+ * cannot iounmap the virtual addresses used to access the NVS region.
+ */
+void suspend_nvs_restore(void)
+{
+	struct nvs_page *entry;
+
+	pr_info("Restoring platform NVS memory\n");
+
+	list_for_each_entry(entry, &nvs_list, node)
+		if (entry->data)
+			memcpy(entry->kaddr, entry->data, entry->size);
+}
+#endif