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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright IBM Corp. 2004, 20104 * Interface implementation for communication with the z/VM control program5 *6 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>7 *8 * z/VMs CP offers the possibility to issue commands via the diagnose code 89 * this driver implements a character device that issues these commands and10 * returns the answer of CP.11 *12 * The idea of this driver is based on cpint from Neale Ferguson and #CP in CMS13 */14 15#include <linux/fs.h>16#include <linux/init.h>17#include <linux/compat.h>18#include <linux/kernel.h>19#include <linux/miscdevice.h>20#include <linux/slab.h>21#include <linux/uaccess.h>22#include <linux/export.h>23#include <linux/mutex.h>24#include <linux/cma.h>25#include <linux/mm.h>26#include <asm/cpcmd.h>27#include <asm/debug.h>28#include <asm/vmcp.h>29 30struct vmcp_session {31 char *response;32 unsigned int bufsize;33 unsigned int cma_alloc : 1;34 int resp_size;35 int resp_code;36 struct mutex mutex;37};38 39static debug_info_t *vmcp_debug;40 41static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024;42static struct cma *vmcp_cma;43 44static int __init early_parse_vmcp_cma(char *p)45{46 if (!p)47 return 1;48 vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE);49 return 0;50}51early_param("vmcp_cma", early_parse_vmcp_cma);52 53void __init vmcp_cma_reserve(void)54{55 if (!MACHINE_IS_VM)56 return;57 cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma);58}59 60static void vmcp_response_alloc(struct vmcp_session *session)61{62 struct page *page = NULL;63 int nr_pages, order;64 65 order = get_order(session->bufsize);66 nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;67 /*68 * For anything below order 3 allocations rely on the buddy69 * allocator. If such low-order allocations can't be handled70 * anymore the system won't work anyway.71 */72 if (order > 2)73 page = cma_alloc(vmcp_cma, nr_pages, 0, false);74 if (page) {75 session->response = (char *)page_to_virt(page);76 session->cma_alloc = 1;77 return;78 }79 session->response = (char *)__get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, order);80}81 82static void vmcp_response_free(struct vmcp_session *session)83{84 int nr_pages, order;85 struct page *page;86 87 if (!session->response)88 return;89 order = get_order(session->bufsize);90 nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;91 if (session->cma_alloc) {92 page = virt_to_page(session->response);93 cma_release(vmcp_cma, page, nr_pages);94 session->cma_alloc = 0;95 } else {96 free_pages((unsigned long)session->response, order);97 }98 session->response = NULL;99}100 101static int vmcp_open(struct inode *inode, struct file *file)102{103 struct vmcp_session *session;104 105 if (!capable(CAP_SYS_ADMIN))106 return -EPERM;107 108 session = kmalloc(sizeof(*session), GFP_KERNEL);109 if (!session)110 return -ENOMEM;111 112 session->bufsize = PAGE_SIZE;113 session->response = NULL;114 session->resp_size = 0;115 mutex_init(&session->mutex);116 file->private_data = session;117 return nonseekable_open(inode, file);118}119 120static int vmcp_release(struct inode *inode, struct file *file)121{122 struct vmcp_session *session;123 124 session = file->private_data;125 file->private_data = NULL;126 vmcp_response_free(session);127 kfree(session);128 return 0;129}130 131static ssize_t132vmcp_read(struct file *file, char __user *buff, size_t count, loff_t *ppos)133{134 ssize_t ret;135 size_t size;136 struct vmcp_session *session;137 138 session = file->private_data;139 if (mutex_lock_interruptible(&session->mutex))140 return -ERESTARTSYS;141 if (!session->response) {142 mutex_unlock(&session->mutex);143 return 0;144 }145 size = min_t(size_t, session->resp_size, session->bufsize);146 ret = simple_read_from_buffer(buff, count, ppos,147 session->response, size);148 149 mutex_unlock(&session->mutex);150 151 return ret;152}153 154static ssize_t155vmcp_write(struct file *file, const char __user *buff, size_t count,156 loff_t *ppos)157{158 char *cmd;159 struct vmcp_session *session;160 161 if (count > 240)162 return -EINVAL;163 cmd = memdup_user_nul(buff, count);164 if (IS_ERR(cmd))165 return PTR_ERR(cmd);166 session = file->private_data;167 if (mutex_lock_interruptible(&session->mutex)) {168 kfree(cmd);169 return -ERESTARTSYS;170 }171 if (!session->response)172 vmcp_response_alloc(session);173 if (!session->response) {174 mutex_unlock(&session->mutex);175 kfree(cmd);176 return -ENOMEM;177 }178 debug_text_event(vmcp_debug, 1, cmd);179 session->resp_size = cpcmd(cmd, session->response, session->bufsize,180 &session->resp_code);181 mutex_unlock(&session->mutex);182 kfree(cmd);183 *ppos = 0; /* reset the file pointer after a command */184 return count;185}186 187 188/*189 * These ioctls are available, as the semantics of the diagnose 8 call190 * does not fit very well into a Linux call. Diagnose X'08' is described in191 * CP Programming Services SC24-6084-00192 *193 * VMCP_GETCODE: gives the CP return code back to user space194 * VMCP_SETBUF: sets the response buffer for the next write call. diagnose 8195 * expects adjacent pages in real storage and to make matters worse, we196 * dont know the size of the response. Therefore we default to PAGESIZE and197 * let userspace to change the response size, if userspace expects a bigger198 * response199 */200static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)201{202 struct vmcp_session *session;203 int ret = -ENOTTY;204 int __user *argp;205 206 session = file->private_data;207 if (is_compat_task())208 argp = compat_ptr(arg);209 else210 argp = (int __user *)arg;211 if (mutex_lock_interruptible(&session->mutex))212 return -ERESTARTSYS;213 switch (cmd) {214 case VMCP_GETCODE:215 ret = put_user(session->resp_code, argp);216 break;217 case VMCP_SETBUF:218 vmcp_response_free(session);219 ret = get_user(session->bufsize, argp);220 if (ret)221 session->bufsize = PAGE_SIZE;222 if (!session->bufsize || get_order(session->bufsize) > 8) {223 session->bufsize = PAGE_SIZE;224 ret = -EINVAL;225 }226 break;227 case VMCP_GETSIZE:228 ret = put_user(session->resp_size, argp);229 break;230 default:231 break;232 }233 mutex_unlock(&session->mutex);234 return ret;235}236 237static const struct file_operations vmcp_fops = {238 .owner = THIS_MODULE,239 .open = vmcp_open,240 .release = vmcp_release,241 .read = vmcp_read,242 .write = vmcp_write,243 .unlocked_ioctl = vmcp_ioctl,244 .compat_ioctl = vmcp_ioctl,245};246 247static struct miscdevice vmcp_dev = {248 .name = "vmcp",249 .minor = MISC_DYNAMIC_MINOR,250 .fops = &vmcp_fops,251};252 253static int __init vmcp_init(void)254{255 int ret;256 257 if (!MACHINE_IS_VM)258 return 0;259 260 vmcp_debug = debug_register("vmcp", 1, 1, 240);261 if (!vmcp_debug)262 return -ENOMEM;263 264 ret = debug_register_view(vmcp_debug, &debug_hex_ascii_view);265 if (ret) {266 debug_unregister(vmcp_debug);267 return ret;268 }269 270 ret = misc_register(&vmcp_dev);271 if (ret)272 debug_unregister(vmcp_debug);273 return ret;274}275device_initcall(vmcp_init);276