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 struct dentry *acpi_debugfs_dir;
  16 static struct dentry *cm_dentry;
  17
  18 /* /sys/kernel/debug/acpi/custom_method */
  19
  20 static ssize_t cm_write(struct file *file, const char __user * user_buf,
  21                         size_t count, loff_t *ppos)
  22 {
  23         static char *buf;
  24         static u32 max_size;
  25         static u32 uncopied_bytes;
  26
  27         struct acpi_table_header table;
  28         acpi_status status;
  29
  30         if (!(*ppos)) {
  31                 /* parse the table header to get the table length */
  32                 if (count <= sizeof(struct acpi_table_header))
  33                         return -EINVAL;
  34                 if (copy_from_user(&table, user_buf,
  35                                    sizeof(struct acpi_table_header)))
  36                         return -EFAULT;
  37                 uncopied_bytes = max_size = table.length;
  38                 buf = kzalloc(max_size, GFP_KERNEL);
  39                 if (!buf)
  40                         return -ENOMEM;
  41         }
  42
  43         if (buf == NULL)
  44                 return -EINVAL;
  45
  46         if ((*ppos > max_size) ||
  47             (*ppos + count > max_size) ||
  48             (*ppos + count < count) ||
  49             (count > uncopied_bytes))
  50                 return -EINVAL;
  51
  52         if (copy_from_user(buf + (*ppos), user_buf, count)) {
  53                 kfree(buf);
  54                 buf = NULL;
  55                 return -EFAULT;
  56         }
  57
  58         uncopied_bytes -= count;
  59         *ppos += count;
  60
  61         if (!uncopied_bytes) {
  62                 status = acpi_install_method(buf);
  63                 kfree(buf);
  64                 buf = NULL;
  65                 if (ACPI_FAILURE(status))
  66                         return -EINVAL;
  67                 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE);
  68         }
  69
  70         return count;
  71 }
  72
  73 static const struct file_operations cm_fops = {
  74         .write = cm_write,
  75         .llseek = default_llseek,
  76 };
  77
  78 static int __init acpi_custom_method_init(void)
  79 {
  80         if (!acpi_debugfs_dir)
  81                 return -ENOENT;
  82
  83         cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
  84                                         acpi_debugfs_dir, NULL, &cm_fops);
  85         if (!cm_dentry)
  86                 return -ENODEV;
  87
  88         return 0;
  89 }
  90
  91 void __init acpi_debugfs_init(void)
  92 {
  93         acpi_debugfs_dir = debugfs_create_dir("acpi", NULL);
  94
  95         acpi_custom_method_init();
  96 }