LXR linux/drivers/acpi/custom

   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
  16ACPI_MODULE_NAME("custom_method");
  17MODULE_LICENSE("GPL");
  18
  19static struct dentry *cm_dentry;
  20
  21/* /sys/kernel/debug/acpi/custom_method */
  22
  23static 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                return -EINVAL;
  54
  55        if (copy_from_user(buf + (*ppos), user_buf, count)) {
  56                kfree(buf);
  57                buf = NULL;
  58                return -EFAULT;
  59        }
  60
  61        uncopied_bytes -= count;
  62        *ppos += count;
  63
  64        if (!uncopied_bytes) {
  65                status = acpi_install_method(buf);
  66                kfree(buf);
  67                buf = NULL;
  68                if (ACPI_FAILURE(status))
  69                        return -EINVAL;
  70                add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
  71        }
  72
  73        return count;
  74}
  75
  76static const struct file_operations cm_fops = {
  77        .write = cm_write,
  78        .llseek = default_llseek,
  79};
  80
  81static int __init acpi_custom_method_init(void)
  82{
  83        cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
  84                                        acpi_debugfs_dir, NULL, &cm_fops);
  85        return 0;
  86}
  87
  88static void __exit acpi_custom_method_exit(void)
  89{
  90        debugfs_remove(cm_dentry);
  91}
  92
  93module_init(acpi_custom_method_init);
  94module_exit(acpi_custom_method_exit);
  95