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276 lines
6.6 KiB
276 lines
6.6 KiB
// 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 <[email protected]> |
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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/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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if (!p) |
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return 1; |
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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, false); |
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if (page) { |
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session->response = (char *)page_to_virt(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 = virt_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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