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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 <acpi/acpi_drivers.h> |
11 | |
12 | #include "internal.h" |
13 | |
14 | #define _COMPONENT ACPI_SYSTEM_COMPONENT |
15 | ACPI_MODULE_NAME("custom_method"); |
16 | MODULE_LICENSE("GPL"); |
17 | |
18 | static struct dentry *cm_dentry; |
19 | |
20 | /* /sys/kernel/debug/acpi/custom_method */ |
21 | |
22 | static 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 | |
75 | static const struct file_operations cm_fops = { |
76 | .write = cm_write, |
77 | .llseek = default_llseek, |
78 | }; |
79 | |
80 | static int __init acpi_custom_method_init(void) |
81 | { |
82 | if (acpi_debugfs_dir == NULL) |
83 | return -ENOENT; |
84 | |
85 | cm_dentry = debugfs_create_file("custom_method", S_IWUSR, |
86 | acpi_debugfs_dir, NULL, &cm_fops); |
87 | if (cm_dentry == NULL) |
88 | return -ENODEV; |
89 | |
90 | return 0; |
91 | } |
92 | |
93 | static void __exit acpi_custom_method_exit(void) |
94 | { |
95 | if (cm_dentry) |
96 | debugfs_remove(cm_dentry); |
97 | } |
98 | |
99 | module_init(acpi_custom_method_init); |
100 | module_exit(acpi_custom_method_exit); |
101 |
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