1 /* 2 * debugfs.c - ACPI debugfs interface to userspace. 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 #define _COMPONENT ACPI_SYSTEM_COMPONENT 13 ACPI_MODULE_NAME("debugfs"); 14 15 16 /* /sys/modules/acpi/parameters/aml_debug_output */ 17 18 module_param_named(aml_debug_output, acpi_gbl_enable_aml_debug_object, 19 bool, 0644); 20 MODULE_PARM_DESC(aml_debug_output, 21 "To enable/disable the ACPI Debug Object output."); 22 23 /* /sys/kernel/debug/acpi/custom_method */ 24 25 static ssize_t cm_write(struct file *file, const char __user * user_buf, 26 size_t count, loff_t *ppos) 27 { 28 static char *buf; 29 static u32 max_size; 30 static u32 uncopied_bytes; 31 32 struct acpi_table_header table; 33 acpi_status status; 34 35 if (!(*ppos)) { 36 /* parse the table header to get the table length */ 37 if (count <= sizeof(struct acpi_table_header)) 38 return -EINVAL; 39 if (copy_from_user(&table, user_buf, 40 sizeof(struct acpi_table_header))) 41 return -EFAULT; 42 uncopied_bytes = max_size = table.length; 43 buf = kzalloc(max_size, GFP_KERNEL); 44 if (!buf) 45 return -ENOMEM; 46 } 47 48 if (buf == NULL) 49 return -EINVAL; 50 51 if ((*ppos > max_size) || 52 (*ppos + count > max_size) || 53 (*ppos + count < count) || 54 (count > uncopied_bytes)) 55 return -EINVAL; 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); 73 } 74 75 return count; 76 } 77 78 static const struct file_operations cm_fops = { 79 .write = cm_write, 80 .llseek = default_llseek, 81 }; 82 83 int __init acpi_debugfs_init(void) 84 { 85 struct dentry *acpi_dir, *cm_dentry; 86 87 acpi_dir = debugfs_create_dir("acpi", NULL); 88 if (!acpi_dir) 89 goto err; 90 91 cm_dentry = debugfs_create_file("custom_method", S_IWUSR, 92 acpi_dir, NULL, &cm_fops); 93 if (!cm_dentry) 94 goto err; 95 96 return 0; 97 98 err: 99 if (acpi_dir) 100 debugfs_remove(acpi_dir); 101 return -EINVAL; 102 } 103