diff options
Diffstat (limited to 'kernel/drivers/s390/char/vmcp.c')
| -rw-r--r-- | kernel/drivers/s390/char/vmcp.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/kernel/drivers/s390/char/vmcp.c b/kernel/drivers/s390/char/vmcp.c new file mode 100644 index 000000000..0fdedadff --- /dev/null +++ b/kernel/drivers/s390/char/vmcp.c @@ -0,0 +1,213 @@ +/* + * 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/compat.h> +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/slab.h> +#include <linux/export.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 = 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 = 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 = 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); |