linux/drivers/s390/char/vmcp.c
Heiko Carstens f73a2b03c5 [S390] vmcp: disallow modular build
Change the tristate Kbuild option into a bool option so that the module
is either builtin or not available at all.
There have been too many cases where people were missing the 'vmcp'
device node and unable to send z/VM CP commands. So let's make sure
that on distros it will always be present.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2010-05-17 10:00:15 +02:00

211 lines
5.1 KiB
C

/*
* 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,
};
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);