Orange Pi5 kernel

// 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)
{
<------>if (!p)
<------><------>return 1;
<------>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);