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 kfree(buf); 54 return -EINVAL; 55 } 56 57 if (copy_from_user(buf + (*ppos), user_buf, count)) { 58 kfree(buf); 59 buf = NULL; 60 return -EFAULT; 61 } 62 63 uncopied_bytes -= count; 64 *ppos += count; 65 66 if (!uncopied_bytes) { 67 status = acpi_install_method(buf); 68 kfree(buf); 69 buf = NULL; 70 if (ACPI_FAILURE(status)) 71 return -EINVAL; 72 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE); 73 } 74 75 kfree(buf); 76 return count; 77 } 78 79 static const struct file_operations cm_fops = { 80 .write = cm_write, 81 .llseek = default_llseek, 82 }; 83 84 static int __init acpi_custom_method_init(void) 85 { 86 cm_dentry = debugfs_create_file("custom_method", S_IWUSR, 87 acpi_debugfs_dir, NULL, &cm_fops); 88 return 0; 89 } 90 91 static void __exit acpi_custom_method_exit(void) 92 { 93 debugfs_remove(cm_dentry); 94 } 95 96 module_init(acpi_custom_method_init); 97 module_exit(acpi_custom_method_exit); 98