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 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 cm_dentry = debugfs_create_file("custom_method", S_IWUSR, 83 acpi_debugfs_dir, NULL, &cm_fops); 84 return 0; 85 } 86 87 static void __exit acpi_custom_method_exit(void) 88 { 89 debugfs_remove(cm_dentry); 90 } 91 92 module_init(acpi_custom_method_init); 93 module_exit(acpi_custom_method_exit); 94