1/*
2 * custom_method.c - debugfs interface for customizing ACPI control method
3 */
4
5#include <linux/init.h>
6#include <linux/module.h>
7#include <linux/kernel.h>
8#include <linux/uaccess.h>
9#include <linux/debugfs.h>
10#include <linux/acpi.h>
11
12#include "internal.h"
13
14#define _COMPONENT ACPI_SYSTEM_COMPONENT
15ACPI_MODULE_NAME("custom_method");
16MODULE_LICENSE("GPL");
17
18static struct dentry *cm_dentry;
19
20/* /sys/kernel/debug/acpi/custom_method */
21
22static ssize_t cm_write(struct file *file, const char __user * user_buf,
23 size_t count, loff_t *ppos)
24{
25 static char *buf;
26 static u32 max_size;
27 static u32 uncopied_bytes;
28
29 struct acpi_table_header table;
30 acpi_status status;
31
32 if (!(*ppos)) {
33 /* parse the table header to get the table length */
34 if (count <= sizeof(struct acpi_table_header))
35 return -EINVAL;
36 if (copy_from_user(&table, user_buf,
37 sizeof(struct acpi_table_header)))
38 return -EFAULT;
39 uncopied_bytes = max_size = table.length;
40 buf = kzalloc(max_size, GFP_KERNEL);
41 if (!buf)
42 return -ENOMEM;
43 }
44
45 if (buf == NULL)
46 return -EINVAL;
47
48 if ((*ppos > max_size) ||
49 (*ppos + count > max_size) ||
50 (*ppos + count < count) ||
51 (count > uncopied_bytes))
52 return -EINVAL;
53
54 if (copy_from_user(buf + (*ppos), user_buf, count)) {
55 kfree(buf);
56 buf = NULL;
57 return -EFAULT;
58 }
59
60 uncopied_bytes -= count;
61 *ppos += count;
62
63 if (!uncopied_bytes) {
64 status = acpi_install_method(buf);
65 kfree(buf);
66 buf = NULL;
67 if (ACPI_FAILURE(status))
68 return -EINVAL;
69 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
70 }
71
72 return count;
73}
74
75static const struct file_operations cm_fops = {
76 .write = cm_write,
77 .llseek = default_llseek,
78};
79
80static int __init acpi_custom_method_init(void)
81{
82 cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
83 acpi_debugfs_dir, NULL, &cm_fops);
84 return 0;
85}
86
87static void __exit acpi_custom_method_exit(void)
88{
89 debugfs_remove(cm_dentry);
90}
91
92module_init(acpi_custom_method_init);
93module_exit(acpi_custom_method_exit);
94