276 lines
6.6 KiB
C
276 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright IBM Corp. 2004, 2010
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* Interface implementation for communication with the z/VM control program
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*
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* Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
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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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*
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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/compat.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/cma.h>
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#include <linux/mm.h>
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#include <asm/compat.h>
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#include <asm/cpcmd.h>
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#include <asm/debug.h>
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#include <asm/vmcp.h>
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struct vmcp_session {
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char *response;
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unsigned int bufsize;
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unsigned int cma_alloc : 1;
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int resp_size;
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int resp_code;
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struct mutex mutex;
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};
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static debug_info_t *vmcp_debug;
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static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024;
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static struct cma *vmcp_cma;
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static int __init early_parse_vmcp_cma(char *p)
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{
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vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE);
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return 0;
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}
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early_param("vmcp_cma", early_parse_vmcp_cma);
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void __init vmcp_cma_reserve(void)
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{
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if (!MACHINE_IS_VM)
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return;
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cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma);
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}
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static void vmcp_response_alloc(struct vmcp_session *session)
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{
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struct page *page = NULL;
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int nr_pages, order;
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order = get_order(session->bufsize);
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nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
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/*
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* For anything below order 3 allocations rely on the buddy
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* allocator. If such low-order allocations can't be handled
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* anymore the system won't work anyway.
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*/
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if (order > 2)
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page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL);
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if (page) {
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session->response = (char *)page_to_phys(page);
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session->cma_alloc = 1;
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return;
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}
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session->response = (char *)__get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, order);
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}
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static void vmcp_response_free(struct vmcp_session *session)
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{
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int nr_pages, order;
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struct page *page;
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if (!session->response)
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return;
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order = get_order(session->bufsize);
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nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
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if (session->cma_alloc) {
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page = phys_to_page((unsigned long)session->response);
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cma_release(vmcp_cma, page, nr_pages);
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session->cma_alloc = 0;
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} else {
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free_pages((unsigned long)session->response, order);
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}
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session->response = NULL;
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}
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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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mutex_init(&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 = file->private_data;
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file->private_data = NULL;
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vmcp_response_free(session);
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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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ssize_t ret;
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size_t size;
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struct vmcp_session *session;
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session = file->private_data;
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if (mutex_lock_interruptible(&session->mutex))
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return -ERESTARTSYS;
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if (!session->response) {
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mutex_unlock(&session->mutex);
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return 0;
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}
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size = min_t(size_t, session->resp_size, session->bufsize);
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ret = simple_read_from_buffer(buff, count, ppos,
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session->response, size);
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mutex_unlock(&session->mutex);
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return ret;
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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 = memdup_user_nul(buff, count);
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if (IS_ERR(cmd))
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return PTR_ERR(cmd);
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session = file->private_data;
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if (mutex_lock_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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vmcp_response_alloc(session);
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if (!session->response) {
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mutex_unlock(&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, session->bufsize,
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&session->resp_code);
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mutex_unlock(&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 ret = -ENOTTY;
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int __user *argp;
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session = file->private_data;
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if (is_compat_task())
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argp = compat_ptr(arg);
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else
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argp = (int __user *)arg;
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if (mutex_lock_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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ret = put_user(session->resp_code, argp);
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break;
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case VMCP_SETBUF:
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vmcp_response_free(session);
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ret = get_user(session->bufsize, argp);
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if (ret)
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session->bufsize = PAGE_SIZE;
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if (!session->bufsize || get_order(session->bufsize) > 8) {
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session->bufsize = PAGE_SIZE;
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ret = -EINVAL;
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}
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break;
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case VMCP_GETSIZE:
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ret = put_user(session->resp_size, argp);
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break;
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default:
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break;
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}
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mutex_unlock(&session->mutex);
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return ret;
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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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.write = vmcp_write,
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.unlocked_ioctl = vmcp_ioctl,
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.compat_ioctl = vmcp_ioctl,
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.llseek = no_llseek,
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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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return 0;
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vmcp_debug = debug_register("vmcp", 1, 1, 240);
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if (!vmcp_debug)
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return -ENOMEM;
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ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);
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if (ret) {
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debug_unregister(vmcp_debug);
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return ret;
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}
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ret = misc_register(&vmcp_dev);
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if (ret)
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debug_unregister(vmcp_debug);
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return ret;
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}
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device_initcall(vmcp_init);
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