drivers/s390/char/vmcp.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * 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/uaccess.h>
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/cma.h>
 #include <linux/mm.h>
 #include <asm/cpcmd.h>
 #include <asm/debug.h>
 #include <asm/vmcp.h>

 struct vmcp_session {
 	char *response;
 	unsigned int bufsize;
 	unsigned int cma_alloc : 1;
 	int resp_size;
 	int resp_code;
 	struct mutex mutex;
 };

 static debug_info_t *vmcp_debug;

 static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024;
 static struct cma *vmcp_cma;

 static int __init early_parse_vmcp_cma(char *p)
 {
 	vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE);
 	return 0;
 }
 early_param("vmcp_cma", early_parse_vmcp_cma);

 void __init vmcp_cma_reserve(void)
 {
 	if (!MACHINE_IS_VM)
 		return;
 	cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma);
 }

 static void vmcp_response_alloc(struct vmcp_session *session)
 {
 	struct page *page = NULL;
 	int nr_pages, order;

 	order = get_order(session->bufsize);
 	nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
 	/*
 	 * For anything below order 3 allocations rely on the buddy
 	 * allocator. If such low-order allocations can't be handled
 	 * anymore the system won't work anyway.
 	 */
 	if (order > 2)
 		page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL);
 	if (page) {
 		session->response = (char *)page_to_phys(page);
 		session->cma_alloc = 1;
 		return;
 	}
 	session->response = (char *)__get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, order);
 }

 static void vmcp_response_free(struct vmcp_session *session)
 {
 	int nr_pages, order;
 	struct page *page;

 	if (!session->response)
 		return;
 	order = get_order(session->bufsize);
 	nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
 	if (session->cma_alloc) {
 		page = phys_to_page((unsigned long)session->response);
 		cma_release(vmcp_cma, page, nr_pages);
 		session->cma_alloc = 0;
 	} else {
 		free_pages((unsigned long)session->response, order);
 	}
 	session->response = NULL;
 }

 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;
 	vmcp_response_free(session);
 	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 = memdup_user_nul(buff, count);
 	if (IS_ERR(cmd))
 		return PTR_ERR(cmd);
 	session = file->private_data;
 	if (mutex_lock_interruptible(&session->mutex)) {
 		kfree(cmd);
 		return -ERESTARTSYS;
 	}
 	if (!session->response)
 		vmcp_response_alloc(session);
 	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 ret = -ENOTTY;
 	int __user *argp;

 	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:
 		ret = put_user(session->resp_code, argp);
 		break;
 	case VMCP_SETBUF:
 		vmcp_response_free(session);
 		ret = get_user(session->bufsize, argp);
 		if (ret)
 			session->bufsize = PAGE_SIZE;
 		if (!session->bufsize || get_order(session->bufsize) > 8) {
 			session->bufsize = PAGE_SIZE;
 			ret = -EINVAL;
 		}
 		break;
 	case VMCP_GETSIZE:
 		ret = put_user(session->resp_size, argp);
 		break;
 	default:
 		break;
 	}
 	mutex_unlock(&session->mutex);
 	return ret;
 }

 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);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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/uaccess.h>
	#include <linux/export.h>
	#include <linux/mutex.h>
	#include <linux/cma.h>
	#include <linux/mm.h>
	#include <asm/cpcmd.h>
	#include <asm/debug.h>
	#include <asm/vmcp.h>

	struct vmcp_session {
	char *response;
	unsigned int bufsize;
	unsigned int cma_alloc : 1;
	int resp_size;
	int resp_code;
	struct mutex mutex;
	};

	static debug_info_t *vmcp_debug;

	static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024;
	static struct cma *vmcp_cma;

	static int __init early_parse_vmcp_cma(char *p)
	{
	vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE);
	return 0;
	}
	early_param("vmcp_cma", early_parse_vmcp_cma);

	void __init vmcp_cma_reserve(void)
	{
	if (!MACHINE_IS_VM)
	return;
	cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma);
	}

	static void vmcp_response_alloc(struct vmcp_session *session)
	{
	struct page *page = NULL;
	int nr_pages, order;

	order = get_order(session->bufsize);
	nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
	/*
	* For anything below order 3 allocations rely on the buddy
	* allocator. If such low-order allocations can't be handled
	* anymore the system won't work anyway.
	*/
	if (order > 2)
	page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL);
	if (page) {
	session->response = (char *)page_to_phys(page);
	session->cma_alloc = 1;
	return;
	}
	session->response = (char *)__get_free_pages(GFP_KERNEL \| __GFP_RETRY_MAYFAIL, order);
	}

	static void vmcp_response_free(struct vmcp_session *session)
	{
	int nr_pages, order;
	struct page *page;

	if (!session->response)
	return;
	order = get_order(session->bufsize);
	nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
	if (session->cma_alloc) {
	page = phys_to_page((unsigned long)session->response);
	cma_release(vmcp_cma, page, nr_pages);
	session->cma_alloc = 0;
	} else {
	free_pages((unsigned long)session->response, order);
	}
	session->response = NULL;
	}

	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;
	vmcp_response_free(session);
	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 = memdup_user_nul(buff, count);
	if (IS_ERR(cmd))
	return PTR_ERR(cmd);
	session = file->private_data;
	if (mutex_lock_interruptible(&session->mutex)) {
	kfree(cmd);
	return -ERESTARTSYS;
	}
	if (!session->response)
	vmcp_response_alloc(session);
	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 ret = -ENOTTY;
	int __user *argp;

	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:
	ret = put_user(session->resp_code, argp);
	break;
	case VMCP_SETBUF:
	vmcp_response_free(session);
	ret = get_user(session->bufsize, argp);
	if (ret)
	session->bufsize = PAGE_SIZE;
	if (!session->bufsize \|\| get_order(session->bufsize) > 8) {
	session->bufsize = PAGE_SIZE;
	ret = -EINVAL;
	}
	break;
	case VMCP_GETSIZE:
	ret = put_user(session->resp_size, argp);
	break;
	default:
	break;
	}
	mutex_unlock(&session->mutex);
	return ret;
	}

	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);