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d54b1fdb1d
Many struct file_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
222 lines
5.6 KiB
C
222 lines
5.6 KiB
C
/*
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* Copyright (C) 2004,2005 IBM Corporation
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* Interface implementation for communication with the z/VM control program
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* Author(s): Christian Borntraeger <cborntra@de.ibm.com>
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*
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*
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* z/VMs CP offers the possibility to issue commands via the diagnose code 8
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* this driver implements a character device that issues these commands and
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* returns the answer of CP.
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* The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <asm/cpcmd.h>
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#include <asm/debug.h>
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#include <asm/uaccess.h>
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#include "vmcp.h"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Borntraeger <cborntra@de.ibm.com>");
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MODULE_DESCRIPTION("z/VM CP interface");
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static debug_info_t *vmcp_debug;
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static int vmcp_open(struct inode *inode, struct file *file)
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{
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struct vmcp_session *session;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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session = kmalloc(sizeof(*session), GFP_KERNEL);
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if (!session)
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return -ENOMEM;
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session->bufsize = PAGE_SIZE;
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session->response = NULL;
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session->resp_size = 0;
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init_MUTEX(&session->mutex);
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file->private_data = session;
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return nonseekable_open(inode, file);
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}
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static int vmcp_release(struct inode *inode, struct file *file)
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{
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struct vmcp_session *session;
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session = (struct vmcp_session *)file->private_data;
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file->private_data = NULL;
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free_pages((unsigned long)session->response, get_order(session->bufsize));
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kfree(session);
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return 0;
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}
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static ssize_t
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vmcp_read(struct file *file, char __user * buff, size_t count, loff_t * ppos)
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{
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size_t tocopy;
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struct vmcp_session *session;
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session = (struct vmcp_session *)file->private_data;
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if (down_interruptible(&session->mutex))
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return -ERESTARTSYS;
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if (!session->response) {
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up(&session->mutex);
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return 0;
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}
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if (*ppos > session->resp_size) {
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up(&session->mutex);
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return 0;
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}
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tocopy = min(session->resp_size - (size_t) (*ppos), count);
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tocopy = min(tocopy,session->bufsize - (size_t) (*ppos));
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if (copy_to_user(buff, session->response + (*ppos), tocopy)) {
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up(&session->mutex);
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return -EFAULT;
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}
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up(&session->mutex);
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*ppos += tocopy;
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return tocopy;
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}
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static ssize_t
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vmcp_write(struct file *file, const char __user * buff, size_t count,
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loff_t * ppos)
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{
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char *cmd;
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struct vmcp_session *session;
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if (count > 240)
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return -EINVAL;
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cmd = kmalloc(count + 1, GFP_KERNEL);
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if (!cmd)
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return -ENOMEM;
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if (copy_from_user(cmd, buff, count)) {
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kfree(cmd);
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return -EFAULT;
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}
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cmd[count] = '\0';
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session = (struct vmcp_session *)file->private_data;
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if (down_interruptible(&session->mutex)) {
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kfree(cmd);
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return -ERESTARTSYS;
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}
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if (!session->response)
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session->response = (char *)__get_free_pages(GFP_KERNEL
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| __GFP_REPEAT | GFP_DMA,
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get_order(session->bufsize));
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if (!session->response) {
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up(&session->mutex);
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kfree(cmd);
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return -ENOMEM;
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}
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debug_text_event(vmcp_debug, 1, cmd);
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session->resp_size = cpcmd(cmd, session->response,
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session->bufsize,
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&session->resp_code);
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up(&session->mutex);
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kfree(cmd);
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*ppos = 0; /* reset the file pointer after a command */
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return count;
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}
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/*
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* These ioctls are available, as the semantics of the diagnose 8 call
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* does not fit very well into a Linux call. Diagnose X'08' is described in
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* CP Programming Services SC24-6084-00
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*
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* VMCP_GETCODE: gives the CP return code back to user space
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* VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8
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* expects adjacent pages in real storage and to make matters worse, we
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* dont know the size of the response. Therefore we default to PAGESIZE and
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* let userspace to change the response size, if userspace expects a bigger
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* response
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*/
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static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct vmcp_session *session;
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int temp;
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session = (struct vmcp_session *)file->private_data;
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if (down_interruptible(&session->mutex))
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return -ERESTARTSYS;
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switch (cmd) {
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case VMCP_GETCODE:
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temp = session->resp_code;
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up(&session->mutex);
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return put_user(temp, (int __user *)arg);
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case VMCP_SETBUF:
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free_pages((unsigned long)session->response,
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get_order(session->bufsize));
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session->response=NULL;
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temp = get_user(session->bufsize, (int __user *)arg);
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if (get_order(session->bufsize) > 8) {
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session->bufsize = PAGE_SIZE;
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temp = -EINVAL;
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}
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up(&session->mutex);
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return temp;
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case VMCP_GETSIZE:
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temp = session->resp_size;
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up(&session->mutex);
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return put_user(temp, (int __user *)arg);
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default:
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up(&session->mutex);
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return -ENOIOCTLCMD;
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}
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}
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static const struct file_operations vmcp_fops = {
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.owner = THIS_MODULE,
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.open = &vmcp_open,
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.release = &vmcp_release,
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.read = &vmcp_read,
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.llseek = &no_llseek,
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.write = &vmcp_write,
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.unlocked_ioctl = &vmcp_ioctl,
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.compat_ioctl = &vmcp_ioctl
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};
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static struct miscdevice vmcp_dev = {
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.name = "vmcp",
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.minor = MISC_DYNAMIC_MINOR,
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.fops = &vmcp_fops,
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};
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static int __init vmcp_init(void)
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{
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int ret;
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if (!MACHINE_IS_VM) {
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printk(KERN_WARNING
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"z/VM CP interface is only available under z/VM\n");
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return -ENODEV;
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}
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ret = misc_register(&vmcp_dev);
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if (!ret)
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printk(KERN_INFO "z/VM CP interface loaded\n");
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else
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printk(KERN_WARNING
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"z/VM CP interface not loaded. Could not register misc device.\n");
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vmcp_debug = debug_register("vmcp", 1, 1, 240);
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debug_register_view(vmcp_debug, &debug_hex_ascii_view);
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return ret;
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}
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static void __exit vmcp_exit(void)
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{
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WARN_ON(misc_deregister(&vmcp_dev) != 0);
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debug_unregister(vmcp_debug);
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printk(KERN_INFO "z/VM CP interface unloaded.\n");
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}
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module_init(vmcp_init);
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module_exit(vmcp_exit);
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