1 // SPDX-License-Identifier: GPL-2.0-only
3 * custom_method.c - debugfs interface for customizing ACPI control method
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/kernel.h>
9 #include <linux/uaccess.h>
10 #include <linux/debugfs.h>
11 #include <linux/acpi.h>
15 #define _COMPONENT ACPI_SYSTEM_COMPONENT
16 ACPI_MODULE_NAME("custom_method");
17 MODULE_LICENSE("GPL");
19 static struct dentry *cm_dentry;
21 /* /sys/kernel/debug/acpi/custom_method */
23 static ssize_t cm_write(struct file *file, const char __user * user_buf,
24 size_t count, loff_t *ppos)
28 static u32 uncopied_bytes;
30 struct acpi_table_header table;
34 /* parse the table header to get the table length */
35 if (count <= sizeof(struct acpi_table_header))
37 if (copy_from_user(&table, user_buf,
38 sizeof(struct acpi_table_header)))
40 uncopied_bytes = max_size = table.length;
41 buf = kzalloc(max_size, GFP_KERNEL);
49 if ((*ppos > max_size) ||
50 (*ppos + count > max_size) ||
51 (*ppos + count < count) ||
52 (count > uncopied_bytes))
55 if (copy_from_user(buf + (*ppos), user_buf, count)) {
61 uncopied_bytes -= count;
64 if (!uncopied_bytes) {
65 status = acpi_install_method(buf);
68 if (ACPI_FAILURE(status))
70 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
76 static const struct file_operations cm_fops = {
78 .llseek = default_llseek,
81 static int __init acpi_custom_method_init(void)
83 cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
84 acpi_debugfs_dir, NULL, &cm_fops);
88 static void __exit acpi_custom_method_exit(void)
90 debugfs_remove(cm_dentry);
93 module_init(acpi_custom_method_init);
94 module_exit(acpi_custom_method_exit);