linux/drivers/s390/char/vmcp.c
Michael Holzheu 66a464dbc8 [PATCH] s390: debug feature changes
This patch changes the memory allocation method for the s390 debug feature.
Trace buffers had been allocated using the get_free_pages() function before.
Therefore it was not possible to get big memory areas in a running system due
to memory fragmentation.  Now the trace buffers are subdivided into several
subbuffers with pagesize.  Therefore it is now possible to allocate more
memory for the trace buffers and more trace records can be written.

In addition to that, dynamic specification of the size of the trace buffers is
implemented.  It is now possible to change the size of a trace buffer using a
new debugfs file instance.  When writing a number into this file, the trace
buffer size is changed to 'number * pagesize'.

In the past all the traces could be obtained from userspace by accessing files
in the "proc" filesystem.  Now with debugfs we have a new filesystem which
should be used for debugging purposes.  This patch moves the debug feature
from procfs to debugfs.

Since the interface of debug_register() changed, all device drivers, which use
the debug feature had to be adjusted.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:37 -07:00

220 lines
5.6 KiB
C

/*
* Copyright (C) 2004,2005 IBM Corporation
* Interface implementation for communication with the v/VM control program
* Author(s): Christian Borntraeger <cborntra@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/module.h>
#include <asm/cpcmd.h>
#include <asm/debug.h>
#include <asm/uaccess.h>
#include "vmcp.h"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Borntraeger <cborntra@de.ibm.com>");
MODULE_DESCRIPTION("z/VM CP interface");
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;
init_MUTEX(&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)
{
size_t tocopy;
struct vmcp_session *session;
session = (struct vmcp_session *)file->private_data;
if (down_interruptible(&session->mutex))
return -ERESTARTSYS;
if (!session->response) {
up(&session->mutex);
return 0;
}
if (*ppos > session->resp_size) {
up(&session->mutex);
return 0;
}
tocopy = min(session->resp_size - (size_t) (*ppos), count);
tocopy = min(tocopy,session->bufsize - (size_t) (*ppos));
if (copy_to_user(buff, session->response + (*ppos), tocopy)) {
up(&session->mutex);
return -EFAULT;
}
up(&session->mutex);
*ppos += tocopy;
return tocopy;
}
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 (down_interruptible(&session->mutex))
return -ERESTARTSYS;
if (!session->response)
session->response = (char *)__get_free_pages(GFP_KERNEL
| __GFP_REPEAT | GFP_DMA,
get_order(session->bufsize));
if (!session->response) {
up(&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);
up(&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 temp;
session = (struct vmcp_session *)file->private_data;
if (down_interruptible(&session->mutex))
return -ERESTARTSYS;
switch (cmd) {
case VMCP_GETCODE:
temp = session->resp_code;
up(&session->mutex);
return put_user(temp, (int __user *)arg);
case VMCP_SETBUF:
free_pages((unsigned long)session->response,
get_order(session->bufsize));
session->response=NULL;
temp = get_user(session->bufsize, (int __user *)arg);
if (get_order(session->bufsize) > 8) {
session->bufsize = PAGE_SIZE;
temp = -EINVAL;
}
up(&session->mutex);
return temp;
case VMCP_GETSIZE:
temp = session->resp_size;
up(&session->mutex);
return put_user(temp, (int __user *)arg);
default:
up(&session->mutex);
return -ENOIOCTLCMD;
}
}
static struct file_operations vmcp_fops = {
.owner = THIS_MODULE,
.open = &vmcp_open,
.release = &vmcp_release,
.read = &vmcp_read,
.llseek = &no_llseek,
.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) {
printk(KERN_WARNING
"z/VM CP interface is only available under z/VM\n");
return -ENODEV;
}
ret = misc_register(&vmcp_dev);
if (!ret)
printk(KERN_INFO "z/VM CP interface loaded\n");
else
printk(KERN_WARNING
"z/VM CP interface not loaded. Could not register misc device.\n");
vmcp_debug = debug_register("vmcp", 1, 1, 240);
debug_register_view(vmcp_debug, &debug_hex_ascii_view);
return ret;
}
static void __exit vmcp_exit(void)
{
WARN_ON(misc_deregister(&vmcp_dev) != 0);
debug_unregister(vmcp_debug);
printk(KERN_INFO "z/VM CP interface unloaded.\n");
}
module_init(vmcp_init);
module_exit(vmcp_exit);