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/*
* Copyright IBM Corp. 2004,2010
* Interface implementation for communication with the z/VM control program
*
* Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
*
* z/VMs CP offers the possibility to issue commands via the diagnose code 8
* this driver implements a character device that issues these commands and
* returns the answer of CP.
*
* The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <asm/compat.h>
#include <asm/cpcmd.h>
#include <asm/debug.h>
#include <asm/uaccess.h>
#include "vmcp.h"
static debug_info_t *vmcp_debug;
static int vmcp_open(struct inode *inode, struct file *file)
{
struct vmcp_session *session;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
session = kmalloc(sizeof(*session), GFP_KERNEL);
if (!session)
return -ENOMEM;
session->bufsize = PAGE_SIZE;
session->response = NULL;
session->resp_size = 0;
mutex_init(&session->mutex);
file->private_data = session;
return nonseekable_open(inode, file);
}
static int vmcp_release(struct inode *inode, struct file *file)
{
struct vmcp_session *session;
session = (struct vmcp_session *)file->private_data;
file->private_data = NULL;
free_pages((unsigned long)session->response, get_order(session->bufsize));
kfree(session);
return 0;
}
static ssize_t
vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)
{
ssize_t ret;
size_t size;
struct vmcp_session *session;
session = file->private_data;
if (mutex_lock_interruptible(&session->mutex))
return -ERESTARTSYS;
if (!session->response) {
mutex_unlock(&session->mutex);
return 0;
}
size = min_t(size_t, session->resp_size, session->bufsize);
ret = simple_read_from_buffer(buff, count, ppos,
session->response, size);
mutex_unlock(&session->mutex);
return ret;
}
static ssize_t
vmcp_write(struct file *file, const char __user *buff, size_t count,
loff_t *ppos)
{
char *cmd;
struct vmcp_session *session;
if (count > 240)
return -EINVAL;
cmd = kmalloc(count + 1, GFP_KERNEL);
if (!cmd)
return -ENOMEM;
if (copy_from_user(cmd, buff, count)) {
kfree(cmd);
return -EFAULT;
}
cmd[count] = '\0';
session = (struct vmcp_session *)file->private_data;
if (mutex_lock_interruptible(&session->mutex)) {
kfree(cmd);
return -ERESTARTSYS;
}
if (!session->response)
session->response = (char *)__get_free_pages(GFP_KERNEL
| __GFP_REPEAT | GFP_DMA,
get_order(session->bufsize));
if (!session->response) {
mutex_unlock(&session->mutex);
kfree(cmd);
return -ENOMEM;
}
debug_text_event(vmcp_debug, 1, cmd);
session->resp_size = cpcmd(cmd, session->response, session->bufsize,
&session->resp_code);
mutex_unlock(&session->mutex);
kfree(cmd);
*ppos = 0; /* reset the file pointer after a command */
return count;
}
/*
* These ioctls are available, as the semantics of the diagnose 8 call
* does not fit very well into a Linux call. Diagnose X'08' is described in
* CP Programming Services SC24-6084-00
*
* VMCP_GETCODE: gives the CP return code back to user space
* VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
* expects adjacent pages in real storage and to make matters worse, we
* dont know the size of the response. Therefore we default to PAGESIZE and
* let userspace to change the response size, if userspace expects a bigger
* response
*/
static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct vmcp_session *session;
int __user *argp;
int temp;
session = (struct vmcp_session *)file->private_data;
if (is_compat_task())
argp = compat_ptr(arg);
else
argp = (int __user *)arg;
if (mutex_lock_interruptible(&session->mutex))
return -ERESTARTSYS;
switch (cmd) {
case VMCP_GETCODE:
temp = session->resp_code;
mutex_unlock(&session->mutex);
return put_user(temp, argp);
case VMCP_SETBUF:
free_pages((unsigned long)session->response,
get_order(session->bufsize));
session->response=NULL;
temp = get_user(session->bufsize, argp);
if (get_order(session->bufsize) > 8) {
session->bufsize = PAGE_SIZE;
temp = -EINVAL;
}
mutex_unlock(&session->mutex);
return temp;
case VMCP_GETSIZE:
temp = session->resp_size;
mutex_unlock(&session->mutex);
return put_user(temp, argp);
default:
mutex_unlock(&session->mutex);
return -ENOIOCTLCMD;
}
}
static const struct file_operations vmcp_fops = {
.owner = THIS_MODULE,
.open = vmcp_open,
.release = vmcp_release,
.read = vmcp_read,
.write = vmcp_write,
.unlocked_ioctl = vmcp_ioctl,
.compat_ioctl = vmcp_ioctl,
.llseek = no_llseek,
};
static struct miscdevice vmcp_dev = {
.name = "vmcp",
.minor = MISC_DYNAMIC_MINOR,
.fops = &vmcp_fops,
};
static int __init vmcp_init(void)
{
int ret;
if (!MACHINE_IS_VM)
return 0;
vmcp_debug = debug_register("vmcp", 1, 1, 240);
if (!vmcp_debug)
return -ENOMEM;
ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
if (ret) {
debug_unregister(vmcp_debug);
return ret;
}
ret = misc_register(&vmcp_dev);
if (ret)
debug_unregister(vmcp_debug);
return ret;
}
device_initcall(vmcp_init);
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