Merge tag 'linux-kselftest-5.2-rc2' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6-microblaze.git] / drivers / acpi / custom_method.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * custom_method.c - debugfs interface for customizing ACPI control method
4  */
5
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>
12
13 #include "internal.h"
14
15 #define _COMPONENT              ACPI_SYSTEM_COMPONENT
16 ACPI_MODULE_NAME("custom_method");
17 MODULE_LICENSE("GPL");
18
19 static struct dentry *cm_dentry;
20
21 /* /sys/kernel/debug/acpi/custom_method */
22
23 static ssize_t cm_write(struct file *file, const char __user * user_buf,
24                         size_t count, loff_t *ppos)
25 {
26         static char *buf;
27         static u32 max_size;
28         static u32 uncopied_bytes;
29
30         struct acpi_table_header table;
31         acpi_status status;
32
33         if (!(*ppos)) {
34                 /* parse the table header to get the table length */
35                 if (count <= sizeof(struct acpi_table_header))
36                         return -EINVAL;
37                 if (copy_from_user(&table, user_buf,
38                                    sizeof(struct acpi_table_header)))
39                         return -EFAULT;
40                 uncopied_bytes = max_size = table.length;
41                 buf = kzalloc(max_size, GFP_KERNEL);
42                 if (!buf)
43                         return -ENOMEM;
44         }
45
46         if (buf == NULL)
47                 return -EINVAL;
48
49         if ((*ppos > max_size) ||
50             (*ppos + count > max_size) ||
51             (*ppos + count < count) ||
52             (count > uncopied_bytes))
53                 return -EINVAL;
54
55         if (copy_from_user(buf + (*ppos), user_buf, count)) {
56                 kfree(buf);
57                 buf = NULL;
58                 return -EFAULT;
59         }
60
61         uncopied_bytes -= count;
62         *ppos += count;
63
64         if (!uncopied_bytes) {
65                 status = acpi_install_method(buf);
66                 kfree(buf);
67                 buf = NULL;
68                 if (ACPI_FAILURE(status))
69                         return -EINVAL;
70                 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
71         }
72
73         return count;
74 }
75
76 static const struct file_operations cm_fops = {
77         .write = cm_write,
78         .llseek = default_llseek,
79 };
80
81 static int __init acpi_custom_method_init(void)
82 {
83         cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
84                                         acpi_debugfs_dir, NULL, &cm_fops);
85         return 0;
86 }
87
88 static void __exit acpi_custom_method_exit(void)
89 {
90         debugfs_remove(cm_dentry);
91 }
92
93 module_init(acpi_custom_method_init);
94 module_exit(acpi_custom_method_exit);