drivers/s390/char/sclp_ctl.c

   1 /*
   2  * IOCTL interface for SCLP
   3  *
   4  * Copyright IBM Corp. 2012
   5  *
   6  * Author: Michael Holzheu <holzheu@linux.vnet.ibm.com>
   7  */
   8
   9 #include <linux/compat.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/miscdevice.h>
  12 #include <linux/gfp.h>
  13 #include <linux/module.h>
  14 #include <linux/ioctl.h>
  15 #include <linux/fs.h>
  16 #include <asm/compat.h>
  17 #include <asm/sclp_ctl.h>
  18 #include <asm/sclp.h>
  19
  20 #include "sclp.h"
  21
  22 /*
  23  * Supported command words
  24  */
  25 static unsigned int sclp_ctl_sccb_wlist[] = {
  26         0x00400002,
  27         0x00410002,
  28 };
  29
  30 /*
  31  * Check if command word is supported
  32  */
  33 static int sclp_ctl_cmdw_supported(unsigned int cmdw)
  34 {
  35         int i;
  36
  37         for (i = 0; i < ARRAY_SIZE(sclp_ctl_sccb_wlist); i++) {
  38                 if (cmdw == sclp_ctl_sccb_wlist[i])
  39                         return 1;
  40         }
  41         return 0;
  42 }
  43
  44 static void __user *u64_to_uptr(u64 value)
  45 {
  46         if (is_compat_task())
  47                 return compat_ptr(value);
  48         else
  49                 return (void __user *)(unsigned long)value;
  50 }
  51
  52 /*
  53  * Start SCLP request
  54  */
  55 static int sclp_ctl_ioctl_sccb(void __user *user_area)
  56 {
  57         struct sclp_ctl_sccb ctl_sccb;
  58         struct sccb_header *sccb;
  59         int rc;
  60
  61         if (copy_from_user(&ctl_sccb, user_area, sizeof(ctl_sccb)))
  62                 return -EFAULT;
  63         if (!sclp_ctl_cmdw_supported(ctl_sccb.cmdw))
  64                 return -EOPNOTSUPP;
  65         sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
  66         if (!sccb)
  67                 return -ENOMEM;
  68         if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sizeof(*sccb))) {
  69                 rc = -EFAULT;
  70                 goto out_free;
  71         }
  72         if (sccb->length > PAGE_SIZE || sccb->length < 8)
  73                 return -EINVAL;
  74         if (copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), sccb->length)) {
  75                 rc = -EFAULT;
  76                 goto out_free;
  77         }
  78         rc = sclp_sync_request(ctl_sccb.cmdw, sccb);
  79         if (rc)
  80                 goto out_free;
  81         if (copy_to_user(u64_to_uptr(ctl_sccb.sccb), sccb, sccb->length))
  82                 rc = -EFAULT;
  83 out_free:
  84         free_page((unsigned long) sccb);
  85         return rc;
  86 }
  87
  88 /*
  89  * SCLP SCCB ioctl function
  90  */
  91 static long sclp_ctl_ioctl(struct file *filp, unsigned int cmd,
  92                            unsigned long arg)
  93 {
  94         void __user *argp;
  95
  96         if (is_compat_task())
  97                 argp = compat_ptr(arg);
  98         else
  99                 argp = (void __user *) arg;
 100         switch (cmd) {
 101         case SCLP_CTL_SCCB:
 102                 return sclp_ctl_ioctl_sccb(argp);
 103         default: /* unknown ioctl number */
 104                 return -ENOTTY;
 105         }
 106 }
 107
 108 /*
 109  * File operations
 110  */
 111 static const struct file_operations sclp_ctl_fops = {
 112         .owner = THIS_MODULE,
 113         .open = nonseekable_open,
 114         .unlocked_ioctl = sclp_ctl_ioctl,
 115         .compat_ioctl = sclp_ctl_ioctl,
 116         .llseek = no_llseek,
 117 };
 118
 119 /*
 120  * Misc device definition
 121  */
 122 static struct miscdevice sclp_ctl_device = {
 123         .minor = MISC_DYNAMIC_MINOR,
 124         .name = "sclp",
 125         .fops = &sclp_ctl_fops,
 126 };
 127
 128 /*
 129  * Register sclp_ctl misc device
 130  */
 131 static int __init sclp_ctl_init(void)
 132 {
 133         return misc_register(&sclp_ctl_device);
 134 }
 135 module_init(sclp_ctl_init);
 136
 137 /*
 138  * Deregister sclp_ctl misc device
 139  */
 140 static void __exit sclp_ctl_exit(void)
 141 {
 142         misc_deregister(&sclp_ctl_device);
 143 }
 144 module_exit(sclp_ctl_exit);