drivers/acpi/debugfs.c

   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 int uncopied_bytes;
  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 = table.length;
  41                 buf = kzalloc(uncopied_bytes, GFP_KERNEL);
  42                 if (!buf)
  43                         return -ENOMEM;
  44         }
  45
  46         if (uncopied_bytes < count) {
  47                 kfree(buf);
  48                 return -EINVAL;
  49         }
  50
  51         if (copy_from_user(buf + (*ppos), user_buf, count)) {
  52                 kfree(buf);
  53                 return -EFAULT;
  54         }
  55
  56         uncopied_bytes -= count;
  57         *ppos += count;
  58
  59         if (!uncopied_bytes) {
  60                 status = acpi_install_method(buf);
  61                 kfree(buf);
  62                 if (ACPI_FAILURE(status))
  63                         return -EINVAL;
  64                 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
  65         }
  66
  67         return count;
  68 }
  69
  70 static const struct file_operations cm_fops = {
  71         .write = cm_write,
  72         .llseek = default_llseek,
  73 };
  74
  75 int __init acpi_debugfs_init(void)
  76 {
  77         struct dentry *acpi_dir, *cm_dentry;
  78
  79         acpi_dir = debugfs_create_dir("acpi", NULL);
  80         if (!acpi_dir)
  81                 goto err;
  82
  83         cm_dentry = debugfs_create_file("custom_method", S_IWUGO,
  84                                         acpi_dir, NULL, &cm_fops);
  85         if (!cm_dentry)
  86                 goto err;
  87
  88         return 0;
  89
  90 err:
  91         if (acpi_dir)
  92                 debugfs_remove(acpi_dir);
  93         return -EINVAL;
  94 }