| /* |
| * Driver giving user-space access to the kernel's xenbus connection |
| * to xenstore. |
| * |
| * Copyright (c) 2005, Christian Limpach |
| * Copyright (c) 2005, Rusty Russell, IBM Corporation |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License version 2 |
| * as published by the Free Software Foundation; or, when distributed |
| * separately from the Linux kernel or incorporated into other |
| * software packages, subject to the following license: |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this source file (the "Software"), to deal in the Software without |
| * restriction, including without limitation the rights to use, copy, modify, |
| * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, subject to |
| * the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| * IN THE SOFTWARE. |
| * |
| * Changes: |
| * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem |
| * and /proc/xen compatibility mount point. |
| * Turned xenfs into a loadable module. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/kernel.h> |
| #include <linux/errno.h> |
| #include <linux/uio.h> |
| #include <linux/notifier.h> |
| #include <linux/wait.h> |
| #include <linux/fs.h> |
| #include <linux/poll.h> |
| #include <linux/mutex.h> |
| #include <linux/sched.h> |
| #include <linux/spinlock.h> |
| #include <linux/mount.h> |
| #include <linux/pagemap.h> |
| #include <linux/uaccess.h> |
| #include <linux/init.h> |
| #include <linux/namei.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/miscdevice.h> |
| |
| #include <xen/xenbus.h> |
| #include <xen/xen.h> |
| #include <asm/xen/hypervisor.h> |
| |
| #include "xenbus.h" |
| |
| /* |
| * An element of a list of outstanding transactions, for which we're |
| * still waiting a reply. |
| */ |
| struct xenbus_transaction_holder { |
| struct list_head list; |
| struct xenbus_transaction handle; |
| }; |
| |
| /* |
| * A buffer of data on the queue. |
| */ |
| struct read_buffer { |
| struct list_head list; |
| unsigned int cons; |
| unsigned int len; |
| char msg[]; |
| }; |
| |
| struct xenbus_file_priv { |
| /* |
| * msgbuffer_mutex is held while partial requests are built up |
| * and complete requests are acted on. It therefore protects |
| * the "transactions" and "watches" lists, and the partial |
| * request length and buffer. |
| * |
| * reply_mutex protects the reply being built up to return to |
| * usermode. It nests inside msgbuffer_mutex but may be held |
| * alone during a watch callback. |
| */ |
| struct mutex msgbuffer_mutex; |
| |
| /* In-progress transactions */ |
| struct list_head transactions; |
| |
| /* Active watches. */ |
| struct list_head watches; |
| |
| /* Partial request. */ |
| unsigned int len; |
| union { |
| struct xsd_sockmsg msg; |
| char buffer[XENSTORE_PAYLOAD_MAX]; |
| } u; |
| |
| /* Response queue. */ |
| struct mutex reply_mutex; |
| struct list_head read_buffers; |
| wait_queue_head_t read_waitq; |
| |
| struct kref kref; |
| }; |
| |
| /* Read out any raw xenbus messages queued up. */ |
| static ssize_t xenbus_file_read(struct file *filp, |
| char __user *ubuf, |
| size_t len, loff_t *ppos) |
| { |
| struct xenbus_file_priv *u = filp->private_data; |
| struct read_buffer *rb; |
| unsigned i; |
| int ret; |
| |
| mutex_lock(&u->reply_mutex); |
| again: |
| while (list_empty(&u->read_buffers)) { |
| mutex_unlock(&u->reply_mutex); |
| if (filp->f_flags & O_NONBLOCK) |
| return -EAGAIN; |
| |
| ret = wait_event_interruptible(u->read_waitq, |
| !list_empty(&u->read_buffers)); |
| if (ret) |
| return ret; |
| mutex_lock(&u->reply_mutex); |
| } |
| |
| rb = list_entry(u->read_buffers.next, struct read_buffer, list); |
| i = 0; |
| while (i < len) { |
| unsigned sz = min((unsigned)len - i, rb->len - rb->cons); |
| |
| ret = copy_to_user(ubuf + i, &rb->msg[rb->cons], sz); |
| |
| i += sz - ret; |
| rb->cons += sz - ret; |
| |
| if (ret != 0) { |
| if (i == 0) |
| i = -EFAULT; |
| goto out; |
| } |
| |
| /* Clear out buffer if it has been consumed */ |
| if (rb->cons == rb->len) { |
| list_del(&rb->list); |
| kfree(rb); |
| if (list_empty(&u->read_buffers)) |
| break; |
| rb = list_entry(u->read_buffers.next, |
| struct read_buffer, list); |
| } |
| } |
| if (i == 0) |
| goto again; |
| |
| out: |
| mutex_unlock(&u->reply_mutex); |
| return i; |
| } |
| |
| /* |
| * Add a buffer to the queue. Caller must hold the appropriate lock |
| * if the queue is not local. (Commonly the caller will build up |
| * multiple queued buffers on a temporary local list, and then add it |
| * to the appropriate list under lock once all the buffers have een |
| * successfully allocated.) |
| */ |
| static int queue_reply(struct list_head *queue, const void *data, size_t len) |
| { |
| struct read_buffer *rb; |
| |
| if (len == 0) |
| return 0; |
| if (len > XENSTORE_PAYLOAD_MAX) |
| return -EINVAL; |
| |
| rb = kmalloc(sizeof(*rb) + len, GFP_KERNEL); |
| if (rb == NULL) |
| return -ENOMEM; |
| |
| rb->cons = 0; |
| rb->len = len; |
| |
| memcpy(rb->msg, data, len); |
| |
| list_add_tail(&rb->list, queue); |
| return 0; |
| } |
| |
| /* |
| * Free all the read_buffer s on a list. |
| * Caller must have sole reference to list. |
| */ |
| static void queue_cleanup(struct list_head *list) |
| { |
| struct read_buffer *rb; |
| |
| while (!list_empty(list)) { |
| rb = list_entry(list->next, struct read_buffer, list); |
| list_del(list->next); |
| kfree(rb); |
| } |
| } |
| |
| struct watch_adapter { |
| struct list_head list; |
| struct xenbus_watch watch; |
| struct xenbus_file_priv *dev_data; |
| char *token; |
| }; |
| |
| static void free_watch_adapter(struct watch_adapter *watch) |
| { |
| kfree(watch->watch.node); |
| kfree(watch->token); |
| kfree(watch); |
| } |
| |
| static struct watch_adapter *alloc_watch_adapter(const char *path, |
| const char *token) |
| { |
| struct watch_adapter *watch; |
| |
| watch = kzalloc(sizeof(*watch), GFP_KERNEL); |
| if (watch == NULL) |
| goto out_fail; |
| |
| watch->watch.node = kstrdup(path, GFP_KERNEL); |
| if (watch->watch.node == NULL) |
| goto out_free; |
| |
| watch->token = kstrdup(token, GFP_KERNEL); |
| if (watch->token == NULL) |
| goto out_free; |
| |
| return watch; |
| |
| out_free: |
| free_watch_adapter(watch); |
| |
| out_fail: |
| return NULL; |
| } |
| |
| static void watch_fired(struct xenbus_watch *watch, |
| const char *path, |
| const char *token) |
| { |
| struct watch_adapter *adap; |
| struct xsd_sockmsg hdr; |
| const char *token_caller; |
| int path_len, tok_len, body_len; |
| int ret; |
| LIST_HEAD(staging_q); |
| |
| adap = container_of(watch, struct watch_adapter, watch); |
| |
| token_caller = adap->token; |
| |
| path_len = strlen(path) + 1; |
| tok_len = strlen(token_caller) + 1; |
| body_len = path_len + tok_len; |
| |
| hdr.type = XS_WATCH_EVENT; |
| hdr.len = body_len; |
| |
| mutex_lock(&adap->dev_data->reply_mutex); |
| |
| ret = queue_reply(&staging_q, &hdr, sizeof(hdr)); |
| if (!ret) |
| ret = queue_reply(&staging_q, path, path_len); |
| if (!ret) |
| ret = queue_reply(&staging_q, token_caller, tok_len); |
| |
| if (!ret) { |
| /* success: pass reply list onto watcher */ |
| list_splice_tail(&staging_q, &adap->dev_data->read_buffers); |
| wake_up(&adap->dev_data->read_waitq); |
| } else |
| queue_cleanup(&staging_q); |
| |
| mutex_unlock(&adap->dev_data->reply_mutex); |
| } |
| |
| static void xenbus_file_free(struct kref *kref) |
| { |
| struct xenbus_file_priv *u; |
| struct xenbus_transaction_holder *trans, *tmp; |
| struct watch_adapter *watch, *tmp_watch; |
| struct read_buffer *rb, *tmp_rb; |
| |
| u = container_of(kref, struct xenbus_file_priv, kref); |
| |
| /* |
| * No need for locking here because there are no other users, |
| * by definition. |
| */ |
| |
| list_for_each_entry_safe(trans, tmp, &u->transactions, list) { |
| xenbus_transaction_end(trans->handle, 1); |
| list_del(&trans->list); |
| kfree(trans); |
| } |
| |
| list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) { |
| unregister_xenbus_watch(&watch->watch); |
| list_del(&watch->list); |
| free_watch_adapter(watch); |
| } |
| |
| list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) { |
| list_del(&rb->list); |
| kfree(rb); |
| } |
| kfree(u); |
| } |
| |
| static struct xenbus_transaction_holder *xenbus_get_transaction( |
| struct xenbus_file_priv *u, uint32_t tx_id) |
| { |
| struct xenbus_transaction_holder *trans; |
| |
| list_for_each_entry(trans, &u->transactions, list) |
| if (trans->handle.id == tx_id) |
| return trans; |
| |
| return NULL; |
| } |
| |
| void xenbus_dev_queue_reply(struct xb_req_data *req) |
| { |
| struct xenbus_file_priv *u = req->par; |
| struct xenbus_transaction_holder *trans = NULL; |
| int rc; |
| LIST_HEAD(staging_q); |
| |
| xs_request_exit(req); |
| |
| mutex_lock(&u->msgbuffer_mutex); |
| |
| if (req->type == XS_TRANSACTION_START) { |
| trans = xenbus_get_transaction(u, 0); |
| if (WARN_ON(!trans)) |
| goto out; |
| if (req->msg.type == XS_ERROR) { |
| list_del(&trans->list); |
| kfree(trans); |
| } else { |
| rc = kstrtou32(req->body, 10, &trans->handle.id); |
| if (WARN_ON(rc)) |
| goto out; |
| } |
| } else if (req->msg.type == XS_TRANSACTION_END) { |
| trans = xenbus_get_transaction(u, req->msg.tx_id); |
| if (WARN_ON(!trans)) |
| goto out; |
| list_del(&trans->list); |
| kfree(trans); |
| } |
| |
| mutex_unlock(&u->msgbuffer_mutex); |
| |
| mutex_lock(&u->reply_mutex); |
| rc = queue_reply(&staging_q, &req->msg, sizeof(req->msg)); |
| if (!rc) |
| rc = queue_reply(&staging_q, req->body, req->msg.len); |
| if (!rc) { |
| list_splice_tail(&staging_q, &u->read_buffers); |
| wake_up(&u->read_waitq); |
| } else { |
| queue_cleanup(&staging_q); |
| } |
| mutex_unlock(&u->reply_mutex); |
| |
| kfree(req->body); |
| kfree(req); |
| |
| kref_put(&u->kref, xenbus_file_free); |
| |
| return; |
| |
| out: |
| mutex_unlock(&u->msgbuffer_mutex); |
| } |
| |
| static int xenbus_command_reply(struct xenbus_file_priv *u, |
| unsigned int msg_type, const char *reply) |
| { |
| struct { |
| struct xsd_sockmsg hdr; |
| const char body[16]; |
| } msg; |
| int rc; |
| |
| msg.hdr = u->u.msg; |
| msg.hdr.type = msg_type; |
| msg.hdr.len = strlen(reply) + 1; |
| if (msg.hdr.len > sizeof(msg.body)) |
| return -E2BIG; |
| |
| mutex_lock(&u->reply_mutex); |
| rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len); |
| wake_up(&u->read_waitq); |
| mutex_unlock(&u->reply_mutex); |
| |
| if (!rc) |
| kref_put(&u->kref, xenbus_file_free); |
| |
| return rc; |
| } |
| |
| static int xenbus_write_transaction(unsigned msg_type, |
| struct xenbus_file_priv *u) |
| { |
| int rc; |
| struct xenbus_transaction_holder *trans = NULL; |
| |
| if (msg_type == XS_TRANSACTION_START) { |
| trans = kzalloc(sizeof(*trans), GFP_KERNEL); |
| if (!trans) { |
| rc = -ENOMEM; |
| goto out; |
| } |
| list_add(&trans->list, &u->transactions); |
| } else if (u->u.msg.tx_id != 0 && |
| !xenbus_get_transaction(u, u->u.msg.tx_id)) |
| return xenbus_command_reply(u, XS_ERROR, "ENOENT"); |
| |
| rc = xenbus_dev_request_and_reply(&u->u.msg, u); |
| if (rc && trans) { |
| list_del(&trans->list); |
| kfree(trans); |
| } |
| |
| out: |
| return rc; |
| } |
| |
| static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u) |
| { |
| struct watch_adapter *watch; |
| char *path, *token; |
| int err, rc; |
| LIST_HEAD(staging_q); |
| |
| path = u->u.buffer + sizeof(u->u.msg); |
| token = memchr(path, 0, u->u.msg.len); |
| if (token == NULL) { |
| rc = xenbus_command_reply(u, XS_ERROR, "EINVAL"); |
| goto out; |
| } |
| token++; |
| if (memchr(token, 0, u->u.msg.len - (token - path)) == NULL) { |
| rc = xenbus_command_reply(u, XS_ERROR, "EINVAL"); |
| goto out; |
| } |
| |
| if (msg_type == XS_WATCH) { |
| watch = alloc_watch_adapter(path, token); |
| if (watch == NULL) { |
| rc = -ENOMEM; |
| goto out; |
| } |
| |
| watch->watch.callback = watch_fired; |
| watch->dev_data = u; |
| |
| err = register_xenbus_watch(&watch->watch); |
| if (err) { |
| free_watch_adapter(watch); |
| rc = err; |
| goto out; |
| } |
| list_add(&watch->list, &u->watches); |
| } else { |
| list_for_each_entry(watch, &u->watches, list) { |
| if (!strcmp(watch->token, token) && |
| !strcmp(watch->watch.node, path)) { |
| unregister_xenbus_watch(&watch->watch); |
| list_del(&watch->list); |
| free_watch_adapter(watch); |
| break; |
| } |
| } |
| } |
| |
| /* Success. Synthesize a reply to say all is OK. */ |
| rc = xenbus_command_reply(u, msg_type, "OK"); |
| |
| out: |
| return rc; |
| } |
| |
| static ssize_t xenbus_file_write(struct file *filp, |
| const char __user *ubuf, |
| size_t len, loff_t *ppos) |
| { |
| struct xenbus_file_priv *u = filp->private_data; |
| uint32_t msg_type; |
| int rc = len; |
| int ret; |
| LIST_HEAD(staging_q); |
| |
| /* |
| * We're expecting usermode to be writing properly formed |
| * xenbus messages. If they write an incomplete message we |
| * buffer it up. Once it is complete, we act on it. |
| */ |
| |
| /* |
| * Make sure concurrent writers can't stomp all over each |
| * other's messages and make a mess of our partial message |
| * buffer. We don't make any attemppt to stop multiple |
| * writers from making a mess of each other's incomplete |
| * messages; we're just trying to guarantee our own internal |
| * consistency and make sure that single writes are handled |
| * atomically. |
| */ |
| mutex_lock(&u->msgbuffer_mutex); |
| |
| /* Get this out of the way early to avoid confusion */ |
| if (len == 0) |
| goto out; |
| |
| /* Can't write a xenbus message larger we can buffer */ |
| if (len > sizeof(u->u.buffer) - u->len) { |
| /* On error, dump existing buffer */ |
| u->len = 0; |
| rc = -EINVAL; |
| goto out; |
| } |
| |
| ret = copy_from_user(u->u.buffer + u->len, ubuf, len); |
| |
| if (ret != 0) { |
| rc = -EFAULT; |
| goto out; |
| } |
| |
| /* Deal with a partial copy. */ |
| len -= ret; |
| rc = len; |
| |
| u->len += len; |
| |
| /* Return if we haven't got a full message yet */ |
| if (u->len < sizeof(u->u.msg)) |
| goto out; /* not even the header yet */ |
| |
| /* If we're expecting a message that's larger than we can |
| possibly send, dump what we have and return an error. */ |
| if ((sizeof(u->u.msg) + u->u.msg.len) > sizeof(u->u.buffer)) { |
| rc = -E2BIG; |
| u->len = 0; |
| goto out; |
| } |
| |
| if (u->len < (sizeof(u->u.msg) + u->u.msg.len)) |
| goto out; /* incomplete data portion */ |
| |
| /* |
| * OK, now we have a complete message. Do something with it. |
| */ |
| |
| kref_get(&u->kref); |
| |
| msg_type = u->u.msg.type; |
| |
| switch (msg_type) { |
| case XS_WATCH: |
| case XS_UNWATCH: |
| /* (Un)Ask for some path to be watched for changes */ |
| ret = xenbus_write_watch(msg_type, u); |
| break; |
| |
| default: |
| /* Send out a transaction */ |
| ret = xenbus_write_transaction(msg_type, u); |
| break; |
| } |
| if (ret != 0) { |
| rc = ret; |
| kref_put(&u->kref, xenbus_file_free); |
| } |
| |
| /* Buffered message consumed */ |
| u->len = 0; |
| |
| out: |
| mutex_unlock(&u->msgbuffer_mutex); |
| return rc; |
| } |
| |
| static int xenbus_file_open(struct inode *inode, struct file *filp) |
| { |
| struct xenbus_file_priv *u; |
| |
| if (xen_store_evtchn == 0) |
| return -ENOENT; |
| |
| nonseekable_open(inode, filp); |
| |
| filp->f_mode &= ~FMODE_ATOMIC_POS; /* cdev-style semantics */ |
| |
| u = kzalloc(sizeof(*u), GFP_KERNEL); |
| if (u == NULL) |
| return -ENOMEM; |
| |
| kref_init(&u->kref); |
| |
| INIT_LIST_HEAD(&u->transactions); |
| INIT_LIST_HEAD(&u->watches); |
| INIT_LIST_HEAD(&u->read_buffers); |
| init_waitqueue_head(&u->read_waitq); |
| |
| mutex_init(&u->reply_mutex); |
| mutex_init(&u->msgbuffer_mutex); |
| |
| filp->private_data = u; |
| |
| return 0; |
| } |
| |
| static int xenbus_file_release(struct inode *inode, struct file *filp) |
| { |
| struct xenbus_file_priv *u = filp->private_data; |
| |
| kref_put(&u->kref, xenbus_file_free); |
| |
| return 0; |
| } |
| |
| static __poll_t xenbus_file_poll(struct file *file, poll_table *wait) |
| { |
| struct xenbus_file_priv *u = file->private_data; |
| |
| poll_wait(file, &u->read_waitq, wait); |
| if (!list_empty(&u->read_buffers)) |
| return EPOLLIN | EPOLLRDNORM; |
| return 0; |
| } |
| |
| const struct file_operations xen_xenbus_fops = { |
| .read = xenbus_file_read, |
| .write = xenbus_file_write, |
| .open = xenbus_file_open, |
| .release = xenbus_file_release, |
| .poll = xenbus_file_poll, |
| .llseek = no_llseek, |
| }; |
| EXPORT_SYMBOL_GPL(xen_xenbus_fops); |
| |
| static struct miscdevice xenbus_dev = { |
| .minor = MISC_DYNAMIC_MINOR, |
| .name = "xen/xenbus", |
| .fops = &xen_xenbus_fops, |
| }; |
| |
| static int __init xenbus_init(void) |
| { |
| int err; |
| |
| if (!xen_domain()) |
| return -ENODEV; |
| |
| err = misc_register(&xenbus_dev); |
| if (err) |
| pr_err("Could not register xenbus frontend device\n"); |
| return err; |
| } |
| device_initcall(xenbus_init); |