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Diffstat (limited to '')
| -rw-r--r-- | drivers/tty/hvc/hvc_iucv.c | 1481 |
1 files changed, 1481 insertions, 0 deletions
diff --git a/drivers/tty/hvc/hvc_iucv.c b/drivers/tty/hvc/hvc_iucv.c new file mode 100644 index 000000000..796fbff62 --- /dev/null +++ b/drivers/tty/hvc/hvc_iucv.c @@ -0,0 +1,1481 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * z/VM IUCV hypervisor console (HVC) device driver + * + * This HVC device driver provides terminal access using + * z/VM IUCV communication paths. + * + * Copyright IBM Corp. 2008, 2013 + * + * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com> + */ +#define KMSG_COMPONENT "hvc_iucv" +#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt + +#include <linux/types.h> +#include <linux/slab.h> +#include <asm/ebcdic.h> +#include <linux/ctype.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/init.h> +#include <linux/mempool.h> +#include <linux/moduleparam.h> +#include <linux/tty.h> +#include <linux/wait.h> +#include <net/iucv/iucv.h> + +#include "hvc_console.h" + + +/* General device driver settings */ +#define HVC_IUCV_MAGIC 0xc9e4c3e5 +#define MAX_HVC_IUCV_LINES HVC_ALLOC_TTY_ADAPTERS +#define MEMPOOL_MIN_NR (PAGE_SIZE / sizeof(struct iucv_tty_buffer)/4) + +/* IUCV TTY message */ +#define MSG_VERSION 0x02 /* Message version */ +#define MSG_TYPE_ERROR 0x01 /* Error message */ +#define MSG_TYPE_TERMENV 0x02 /* Terminal environment variable */ +#define MSG_TYPE_TERMIOS 0x04 /* Terminal IO struct update */ +#define MSG_TYPE_WINSIZE 0x08 /* Terminal window size update */ +#define MSG_TYPE_DATA 0x10 /* Terminal data */ + +struct iucv_tty_msg { + u8 version; /* Message version */ + u8 type; /* Message type */ +#define MSG_MAX_DATALEN ((u16)(~0)) + u16 datalen; /* Payload length */ + u8 data[]; /* Payload buffer */ +} __attribute__((packed)); +#define MSG_SIZE(s) ((s) + offsetof(struct iucv_tty_msg, data)) + +enum iucv_state_t { + IUCV_DISCONN = 0, + IUCV_CONNECTED = 1, + IUCV_SEVERED = 2, +}; + +enum tty_state_t { + TTY_CLOSED = 0, + TTY_OPENED = 1, +}; + +struct hvc_iucv_private { + struct hvc_struct *hvc; /* HVC struct reference */ + u8 srv_name[8]; /* IUCV service name (ebcdic) */ + unsigned char is_console; /* Linux console usage flag */ + enum iucv_state_t iucv_state; /* IUCV connection status */ + enum tty_state_t tty_state; /* TTY status */ + struct iucv_path *path; /* IUCV path pointer */ + spinlock_t lock; /* hvc_iucv_private lock */ +#define SNDBUF_SIZE (PAGE_SIZE) /* must be < MSG_MAX_DATALEN */ + void *sndbuf; /* send buffer */ + size_t sndbuf_len; /* length of send buffer */ +#define QUEUE_SNDBUF_DELAY (HZ / 25) + struct delayed_work sndbuf_work; /* work: send iucv msg(s) */ + wait_queue_head_t sndbuf_waitq; /* wait for send completion */ + struct list_head tty_outqueue; /* outgoing IUCV messages */ + struct list_head tty_inqueue; /* incoming IUCV messages */ + struct device *dev; /* device structure */ + u8 info_path[16]; /* IUCV path info (dev attr) */ +}; + +struct iucv_tty_buffer { + struct list_head list; /* list pointer */ + struct iucv_message msg; /* store an IUCV message */ + size_t offset; /* data buffer offset */ + struct iucv_tty_msg *mbuf; /* buffer to store input/output data */ +}; + +/* IUCV callback handler */ +static int hvc_iucv_path_pending(struct iucv_path *, u8 *, u8 *); +static void hvc_iucv_path_severed(struct iucv_path *, u8 *); +static void hvc_iucv_msg_pending(struct iucv_path *, struct iucv_message *); +static void hvc_iucv_msg_complete(struct iucv_path *, struct iucv_message *); + + +/* Kernel module parameter: use one terminal device as default */ +static unsigned long hvc_iucv_devices = 1; + +/* Array of allocated hvc iucv tty lines... */ +static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES]; +#define IUCV_HVC_CON_IDX (0) +/* List of z/VM user ID filter entries (struct iucv_vmid_filter) */ +#define MAX_VMID_FILTER (500) +#define FILTER_WILDCARD_CHAR '*' +static size_t hvc_iucv_filter_size; +static void *hvc_iucv_filter; +static const char *hvc_iucv_filter_string; +static DEFINE_RWLOCK(hvc_iucv_filter_lock); + +/* Kmem cache and mempool for iucv_tty_buffer elements */ +static struct kmem_cache *hvc_iucv_buffer_cache; +static mempool_t *hvc_iucv_mempool; + +/* IUCV handler callback functions */ +static struct iucv_handler hvc_iucv_handler = { + .path_pending = hvc_iucv_path_pending, + .path_severed = hvc_iucv_path_severed, + .message_complete = hvc_iucv_msg_complete, + .message_pending = hvc_iucv_msg_pending, +}; + + +/** + * hvc_iucv_get_private() - Return a struct hvc_iucv_private instance. + * @num: The HVC virtual terminal number (vtermno) + * + * This function returns the struct hvc_iucv_private instance that corresponds + * to the HVC virtual terminal number specified as parameter @num. + */ +static struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num) +{ + if ((num < HVC_IUCV_MAGIC) || (num - HVC_IUCV_MAGIC > hvc_iucv_devices)) + return NULL; + return hvc_iucv_table[num - HVC_IUCV_MAGIC]; +} + +/** + * alloc_tty_buffer() - Return a new struct iucv_tty_buffer element. + * @size: Size of the internal buffer used to store data. + * @flags: Memory allocation flags passed to mempool. + * + * This function allocates a new struct iucv_tty_buffer element and, optionally, + * allocates an internal data buffer with the specified size @size. + * The internal data buffer is always allocated with GFP_DMA which is + * required for receiving and sending data with IUCV. + * Note: The total message size arises from the internal buffer size and the + * members of the iucv_tty_msg structure. + * The function returns NULL if memory allocation has failed. + */ +static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags) +{ + struct iucv_tty_buffer *bufp; + + bufp = mempool_alloc(hvc_iucv_mempool, flags); + if (!bufp) + return NULL; + memset(bufp, 0, sizeof(*bufp)); + + if (size > 0) { + bufp->msg.length = MSG_SIZE(size); + bufp->mbuf = kmalloc(bufp->msg.length, flags | GFP_DMA); + if (!bufp->mbuf) { + mempool_free(bufp, hvc_iucv_mempool); + return NULL; + } + bufp->mbuf->version = MSG_VERSION; + bufp->mbuf->type = MSG_TYPE_DATA; + bufp->mbuf->datalen = (u16) size; + } + return bufp; +} + +/** + * destroy_tty_buffer() - destroy struct iucv_tty_buffer element. + * @bufp: Pointer to a struct iucv_tty_buffer element, SHALL NOT be NULL. + */ +static void destroy_tty_buffer(struct iucv_tty_buffer *bufp) +{ + kfree(bufp->mbuf); + mempool_free(bufp, hvc_iucv_mempool); +} + +/** + * destroy_tty_buffer_list() - call destroy_tty_buffer() for each list element. + * @list: List containing struct iucv_tty_buffer elements. + */ +static void destroy_tty_buffer_list(struct list_head *list) +{ + struct iucv_tty_buffer *ent, *next; + + list_for_each_entry_safe(ent, next, list, list) { + list_del(&ent->list); + destroy_tty_buffer(ent); + } +} + +/** + * hvc_iucv_write() - Receive IUCV message & write data to HVC buffer. + * @priv: Pointer to struct hvc_iucv_private + * @buf: HVC buffer for writing received terminal data. + * @count: HVC buffer size. + * @has_more_data: Pointer to an int variable. + * + * The function picks up pending messages from the input queue and receives + * the message data that is then written to the specified buffer @buf. + * If the buffer size @count is less than the data message size, the + * message is kept on the input queue and @has_more_data is set to 1. + * If all message data has been written, the message is removed from + * the input queue. + * + * The function returns the number of bytes written to the terminal, zero if + * there are no pending data messages available or if there is no established + * IUCV path. + * If the IUCV path has been severed, then -EPIPE is returned to cause a + * hang up (that is issued by the HVC layer). + */ +static int hvc_iucv_write(struct hvc_iucv_private *priv, + char *buf, int count, int *has_more_data) +{ + struct iucv_tty_buffer *rb; + int written; + int rc; + + /* immediately return if there is no IUCV connection */ + if (priv->iucv_state == IUCV_DISCONN) + return 0; + + /* if the IUCV path has been severed, return -EPIPE to inform the + * HVC layer to hang up the tty device. */ + if (priv->iucv_state == IUCV_SEVERED) + return -EPIPE; + + /* check if there are pending messages */ + if (list_empty(&priv->tty_inqueue)) + return 0; + + /* receive an iucv message and flip data to the tty (ldisc) */ + rb = list_first_entry(&priv->tty_inqueue, struct iucv_tty_buffer, list); + + written = 0; + if (!rb->mbuf) { /* message not yet received ... */ + /* allocate mem to store msg data; if no memory is available + * then leave the buffer on the list and re-try later */ + rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC | GFP_DMA); + if (!rb->mbuf) + return -ENOMEM; + + rc = __iucv_message_receive(priv->path, &rb->msg, 0, + rb->mbuf, rb->msg.length, NULL); + switch (rc) { + case 0: /* Successful */ + break; + case 2: /* No message found */ + case 9: /* Message purged */ + break; + default: + written = -EIO; + } + /* remove buffer if an error has occurred or received data + * is not correct */ + if (rc || (rb->mbuf->version != MSG_VERSION) || + (rb->msg.length != MSG_SIZE(rb->mbuf->datalen))) + goto out_remove_buffer; + } + + switch (rb->mbuf->type) { + case MSG_TYPE_DATA: + written = min_t(int, rb->mbuf->datalen - rb->offset, count); + memcpy(buf, rb->mbuf->data + rb->offset, written); + if (written < (rb->mbuf->datalen - rb->offset)) { + rb->offset += written; + *has_more_data = 1; + goto out_written; + } + break; + + case MSG_TYPE_WINSIZE: + if (rb->mbuf->datalen != sizeof(struct winsize)) + break; + /* The caller must ensure that the hvc is locked, which + * is the case when called from hvc_iucv_get_chars() */ + __hvc_resize(priv->hvc, *((struct winsize *) rb->mbuf->data)); + break; + + case MSG_TYPE_ERROR: /* ignored ... */ + case MSG_TYPE_TERMENV: /* ignored ... */ + case MSG_TYPE_TERMIOS: /* ignored ... */ + break; + } + +out_remove_buffer: + list_del(&rb->list); + destroy_tty_buffer(rb); + *has_more_data = !list_empty(&priv->tty_inqueue); + +out_written: + return written; +} + +/** + * hvc_iucv_get_chars() - HVC get_chars operation. + * @vtermno: HVC virtual terminal number. + * @buf: Pointer to a buffer to store data + * @count: Size of buffer available for writing + * + * The HVC thread calls this method to read characters from the back-end. + * If an IUCV communication path has been established, pending IUCV messages + * are received and data is copied into buffer @buf up to @count bytes. + * + * Locking: The routine gets called under an irqsave() spinlock; and + * the routine locks the struct hvc_iucv_private->lock to call + * helper functions. + */ +static int hvc_iucv_get_chars(uint32_t vtermno, char *buf, int count) +{ + struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno); + int written; + int has_more_data; + + if (count <= 0) + return 0; + + if (!priv) + return -ENODEV; + + spin_lock(&priv->lock); + has_more_data = 0; + written = hvc_iucv_write(priv, buf, count, &has_more_data); + spin_unlock(&priv->lock); + + /* if there are still messages on the queue... schedule another run */ + if (has_more_data) + hvc_kick(); + + return written; +} + +/** + * hvc_iucv_queue() - Buffer terminal data for sending. + * @priv: Pointer to struct hvc_iucv_private instance. + * @buf: Buffer containing data to send. + * @count: Size of buffer and amount of data to send. + * + * The function queues data for sending. To actually send the buffered data, + * a work queue function is scheduled (with QUEUE_SNDBUF_DELAY). + * The function returns the number of data bytes that has been buffered. + * + * If the device is not connected, data is ignored and the function returns + * @count. + * If the buffer is full, the function returns 0. + * If an existing IUCV communicaton path has been severed, -EPIPE is returned + * (that can be passed to HVC layer to cause a tty hangup). + */ +static int hvc_iucv_queue(struct hvc_iucv_private *priv, const char *buf, + int count) +{ + size_t len; + + if (priv->iucv_state == IUCV_DISCONN) + return count; /* ignore data */ + + if (priv->iucv_state == IUCV_SEVERED) + return -EPIPE; + + len = min_t(size_t, count, SNDBUF_SIZE - priv->sndbuf_len); + if (!len) + return 0; + + memcpy(priv->sndbuf + priv->sndbuf_len, buf, len); + priv->sndbuf_len += len; + + if (priv->iucv_state == IUCV_CONNECTED) + schedule_delayed_work(&priv->sndbuf_work, QUEUE_SNDBUF_DELAY); + + return len; +} + +/** + * hvc_iucv_send() - Send an IUCV message containing terminal data. + * @priv: Pointer to struct hvc_iucv_private instance. + * + * If an IUCV communication path has been established, the buffered output data + * is sent via an IUCV message and the number of bytes sent is returned. + * Returns 0 if there is no established IUCV communication path or + * -EPIPE if an existing IUCV communicaton path has been severed. + */ +static int hvc_iucv_send(struct hvc_iucv_private *priv) +{ + struct iucv_tty_buffer *sb; + int rc, len; + + if (priv->iucv_state == IUCV_SEVERED) + return -EPIPE; + + if (priv->iucv_state == IUCV_DISCONN) + return -EIO; + + if (!priv->sndbuf_len) + return 0; + + /* allocate internal buffer to store msg data and also compute total + * message length */ + sb = alloc_tty_buffer(priv->sndbuf_len, GFP_ATOMIC); + if (!sb) + return -ENOMEM; + + memcpy(sb->mbuf->data, priv->sndbuf, priv->sndbuf_len); + sb->mbuf->datalen = (u16) priv->sndbuf_len; + sb->msg.length = MSG_SIZE(sb->mbuf->datalen); + + list_add_tail(&sb->list, &priv->tty_outqueue); + + rc = __iucv_message_send(priv->path, &sb->msg, 0, 0, + (void *) sb->mbuf, sb->msg.length); + if (rc) { + /* drop the message here; however we might want to handle + * 0x03 (msg limit reached) by trying again... */ + list_del(&sb->list); + destroy_tty_buffer(sb); + } + len = priv->sndbuf_len; + priv->sndbuf_len = 0; + + return len; +} + +/** + * hvc_iucv_sndbuf_work() - Send buffered data over IUCV + * @work: Work structure. + * + * This work queue function sends buffered output data over IUCV and, + * if not all buffered data could be sent, reschedules itself. + */ +static void hvc_iucv_sndbuf_work(struct work_struct *work) +{ + struct hvc_iucv_private *priv; + + priv = container_of(work, struct hvc_iucv_private, sndbuf_work.work); + if (!priv) + return; + + spin_lock_bh(&priv->lock); + hvc_iucv_send(priv); + spin_unlock_bh(&priv->lock); +} + +/** + * hvc_iucv_put_chars() - HVC put_chars operation. + * @vtermno: HVC virtual terminal number. + * @buf: Pointer to an buffer to read data from + * @count: Size of buffer available for reading + * + * The HVC thread calls this method to write characters to the back-end. + * The function calls hvc_iucv_queue() to queue terminal data for sending. + * + * Locking: The method gets called under an irqsave() spinlock; and + * locks struct hvc_iucv_private->lock. + */ +static int hvc_iucv_put_chars(uint32_t vtermno, const char *buf, int count) +{ + struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno); + int queued; + + if (count <= 0) + return 0; + + if (!priv) + return -ENODEV; + + spin_lock(&priv->lock); + queued = hvc_iucv_queue(priv, buf, count); + spin_unlock(&priv->lock); + + return queued; +} + +/** + * hvc_iucv_notifier_add() - HVC notifier for opening a TTY for the first time. + * @hp: Pointer to the HVC device (struct hvc_struct) + * @id: Additional data (originally passed to hvc_alloc): the index of an struct + * hvc_iucv_private instance. + * + * The function sets the tty state to TTY_OPENED for the struct hvc_iucv_private + * instance that is derived from @id. Always returns 0. + * + * Locking: struct hvc_iucv_private->lock, spin_lock_bh + */ +static int hvc_iucv_notifier_add(struct hvc_struct *hp, int id) +{ + struct hvc_iucv_private *priv; + + priv = hvc_iucv_get_private(id); + if (!priv) + return 0; + + spin_lock_bh(&priv->lock); + priv->tty_state = TTY_OPENED; + spin_unlock_bh(&priv->lock); + + return 0; +} + +/** + * hvc_iucv_cleanup() - Clean up and reset a z/VM IUCV HVC instance. + * @priv: Pointer to the struct hvc_iucv_private instance. + */ +static void hvc_iucv_cleanup(struct hvc_iucv_private *priv) +{ + destroy_tty_buffer_list(&priv->tty_outqueue); + destroy_tty_buffer_list(&priv->tty_inqueue); + + priv->tty_state = TTY_CLOSED; + priv->iucv_state = IUCV_DISCONN; + + priv->sndbuf_len = 0; +} + +/** + * tty_outqueue_empty() - Test if the tty outq is empty + * @priv: Pointer to struct hvc_iucv_private instance. + */ +static inline int tty_outqueue_empty(struct hvc_iucv_private *priv) +{ + int rc; + + spin_lock_bh(&priv->lock); + rc = list_empty(&priv->tty_outqueue); + spin_unlock_bh(&priv->lock); + + return rc; +} + +/** + * flush_sndbuf_sync() - Flush send buffer and wait for completion + * @priv: Pointer to struct hvc_iucv_private instance. + * + * The routine cancels a pending sndbuf work, calls hvc_iucv_send() + * to flush any buffered terminal output data and waits for completion. + */ +static void flush_sndbuf_sync(struct hvc_iucv_private *priv) +{ + int sync_wait; + + cancel_delayed_work_sync(&priv->sndbuf_work); + + spin_lock_bh(&priv->lock); + hvc_iucv_send(priv); /* force sending buffered data */ + sync_wait = !list_empty(&priv->tty_outqueue); /* anything queued ? */ + spin_unlock_bh(&priv->lock); + + if (sync_wait) + wait_event_timeout(priv->sndbuf_waitq, + tty_outqueue_empty(priv), HZ/10); +} + +/** + * hvc_iucv_hangup() - Sever IUCV path and schedule hvc tty hang up + * @priv: Pointer to hvc_iucv_private structure + * + * This routine severs an existing IUCV communication path and hangs + * up the underlying HVC terminal device. + * The hang-up occurs only if an IUCV communication path is established; + * otherwise there is no need to hang up the terminal device. + * + * The IUCV HVC hang-up is separated into two steps: + * 1. After the IUCV path has been severed, the iucv_state is set to + * IUCV_SEVERED. + * 2. Later, when the HVC thread calls hvc_iucv_get_chars(), the + * IUCV_SEVERED state causes the tty hang-up in the HVC layer. + * + * If the tty has not yet been opened, clean up the hvc_iucv_private + * structure to allow re-connects. + * If the tty has been opened, let get_chars() return -EPIPE to signal + * the HVC layer to hang up the tty and, if so, wake up the HVC thread + * to call get_chars()... + * + * Special notes on hanging up a HVC terminal instantiated as console: + * Hang-up: 1. do_tty_hangup() replaces file ops (= hung_up_tty_fops) + * 2. do_tty_hangup() calls tty->ops->close() for console_filp + * => no hangup notifier is called by HVC (default) + * 2. hvc_close() returns because of tty_hung_up_p(filp) + * => no delete notifier is called! + * Finally, the back-end is not being notified, thus, the tty session is + * kept active (TTY_OPEN) to be ready for re-connects. + * + * Locking: spin_lock(&priv->lock) w/o disabling bh + */ +static void hvc_iucv_hangup(struct hvc_iucv_private *priv) +{ + struct iucv_path *path; + + path = NULL; + spin_lock(&priv->lock); + if (priv->iucv_state == IUCV_CONNECTED) { + path = priv->path; + priv->path = NULL; + priv->iucv_state = IUCV_SEVERED; + if (priv->tty_state == TTY_CLOSED) + hvc_iucv_cleanup(priv); + else + /* console is special (see above) */ + if (priv->is_console) { + hvc_iucv_cleanup(priv); + priv->tty_state = TTY_OPENED; + } else + hvc_kick(); + } + spin_unlock(&priv->lock); + + /* finally sever path (outside of priv->lock due to lock ordering) */ + if (path) { + iucv_path_sever(path, NULL); + iucv_path_free(path); + } +} + +/** + * hvc_iucv_notifier_hangup() - HVC notifier for TTY hangups. + * @hp: Pointer to the HVC device (struct hvc_struct) + * @id: Additional data (originally passed to hvc_alloc): + * the index of an struct hvc_iucv_private instance. + * + * This routine notifies the HVC back-end that a tty hangup (carrier loss, + * virtual or otherwise) has occurred. + * The z/VM IUCV HVC device driver ignores virtual hangups (vhangup()) + * to keep an existing IUCV communication path established. + * (Background: vhangup() is called from user space (by getty or login) to + * disable writing to the tty by other applications). + * If the tty has been opened and an established IUCV path has been severed + * (we caused the tty hangup), the function calls hvc_iucv_cleanup(). + * + * Locking: struct hvc_iucv_private->lock + */ +static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id) +{ + struct hvc_iucv_private *priv; + + priv = hvc_iucv_get_private(id); + if (!priv) + return; + + flush_sndbuf_sync(priv); + + spin_lock_bh(&priv->lock); + /* NOTE: If the hangup was scheduled by ourself (from the iucv + * path_servered callback [IUCV_SEVERED]), we have to clean up + * our structure and to set state to TTY_CLOSED. + * If the tty was hung up otherwise (e.g. vhangup()), then we + * ignore this hangup and keep an established IUCV path open... + * (...the reason is that we are not able to connect back to the + * client if we disconnect on hang up) */ + priv->tty_state = TTY_CLOSED; + + if (priv->iucv_state == IUCV_SEVERED) + hvc_iucv_cleanup(priv); + spin_unlock_bh(&priv->lock); +} + +/** + * hvc_iucv_dtr_rts() - HVC notifier for handling DTR/RTS + * @hp: Pointer the HVC device (struct hvc_struct) + * @raise: Non-zero to raise or zero to lower DTR/RTS lines + * + * This routine notifies the HVC back-end to raise or lower DTR/RTS + * lines. Raising DTR/RTS is ignored. Lowering DTR/RTS indicates to + * drop the IUCV connection (similar to hang up the modem). + */ +static void hvc_iucv_dtr_rts(struct hvc_struct *hp, int raise) +{ + struct hvc_iucv_private *priv; + struct iucv_path *path; + + /* Raising the DTR/RTS is ignored as IUCV connections can be + * established at any times. + */ + if (raise) + return; + + priv = hvc_iucv_get_private(hp->vtermno); + if (!priv) + return; + + /* Lowering the DTR/RTS lines disconnects an established IUCV + * connection. + */ + flush_sndbuf_sync(priv); + + spin_lock_bh(&priv->lock); + path = priv->path; /* save reference to IUCV path */ + priv->path = NULL; + priv->iucv_state = IUCV_DISCONN; + spin_unlock_bh(&priv->lock); + + /* Sever IUCV path outside of priv->lock due to lock ordering of: + * priv->lock <--> iucv_table_lock */ + if (path) { + iucv_path_sever(path, NULL); + iucv_path_free(path); + } +} + +/** + * hvc_iucv_notifier_del() - HVC notifier for closing a TTY for the last time. + * @hp: Pointer to the HVC device (struct hvc_struct) + * @id: Additional data (originally passed to hvc_alloc): + * the index of an struct hvc_iucv_private instance. + * + * This routine notifies the HVC back-end that the last tty device fd has been + * closed. The function cleans up tty resources. The clean-up of the IUCV + * connection is done in hvc_iucv_dtr_rts() and depends on the HUPCL termios + * control setting. + * + * Locking: struct hvc_iucv_private->lock + */ +static void hvc_iucv_notifier_del(struct hvc_struct *hp, int id) +{ + struct hvc_iucv_private *priv; + + priv = hvc_iucv_get_private(id); + if (!priv) + return; + + flush_sndbuf_sync(priv); + + spin_lock_bh(&priv->lock); + destroy_tty_buffer_list(&priv->tty_outqueue); + destroy_tty_buffer_list(&priv->tty_inqueue); + priv->tty_state = TTY_CLOSED; + priv->sndbuf_len = 0; + spin_unlock_bh(&priv->lock); +} + +/** + * hvc_iucv_filter_connreq() - Filter connection request based on z/VM user ID + * @ipvmid: Originating z/VM user ID (right padded with blanks) + * + * Returns 0 if the z/VM user ID that is specified with @ipvmid is permitted to + * connect, otherwise non-zero. + */ +static int hvc_iucv_filter_connreq(u8 ipvmid[8]) +{ + const char *wildcard, *filter_entry; + size_t i, len; + + /* Note: default policy is ACCEPT if no filter is set */ + if (!hvc_iucv_filter_size) + return 0; + + for (i = 0; i < hvc_iucv_filter_size; i++) { + filter_entry = hvc_iucv_filter + (8 * i); + + /* If a filter entry contains the filter wildcard character, + * reduce the length to match the leading portion of the user + * ID only (wildcard match). Characters following the wildcard + * are ignored. + */ + wildcard = strnchr(filter_entry, 8, FILTER_WILDCARD_CHAR); + len = (wildcard) ? wildcard - filter_entry : 8; + if (0 == memcmp(ipvmid, filter_entry, len)) + return 0; + } + return 1; +} + +/** + * hvc_iucv_path_pending() - IUCV handler to process a connection request. + * @path: Pending path (struct iucv_path) + * @ipvmid: z/VM system identifier of originator + * @ipuser: User specified data for this path + * (AF_IUCV: port/service name and originator port) + * + * The function uses the @ipuser data to determine if the pending path belongs + * to a terminal managed by this device driver. + * If the path belongs to this driver, ensure that the terminal is not accessed + * multiple times (only one connection to a terminal is allowed). + * If the terminal is not yet connected, the pending path is accepted and is + * associated to the appropriate struct hvc_iucv_private instance. + * + * Returns 0 if @path belongs to a terminal managed by the this device driver; + * otherwise returns -ENODEV in order to dispatch this path to other handlers. + * + * Locking: struct hvc_iucv_private->lock + */ +static int hvc_iucv_path_pending(struct iucv_path *path, u8 *ipvmid, + u8 *ipuser) +{ + struct hvc_iucv_private *priv, *tmp; + u8 wildcard[9] = "lnxhvc "; + int i, rc, find_unused; + u8 nuser_data[16]; + u8 vm_user_id[9]; + + ASCEBC(wildcard, sizeof(wildcard)); + find_unused = !memcmp(wildcard, ipuser, 8); + + /* First, check if the pending path request is managed by this + * IUCV handler: + * - find a disconnected device if ipuser contains the wildcard + * - find the device that matches the terminal ID in ipuser + */ + priv = NULL; + for (i = 0; i < hvc_iucv_devices; i++) { + tmp = hvc_iucv_table[i]; + if (!tmp) + continue; + + if (find_unused) { + spin_lock(&tmp->lock); + if (tmp->iucv_state == IUCV_DISCONN) + priv = tmp; + spin_unlock(&tmp->lock); + + } else if (!memcmp(tmp->srv_name, ipuser, 8)) + priv = tmp; + if (priv) + break; + } + if (!priv) + return -ENODEV; + + /* Enforce that ipvmid is allowed to connect to us */ + read_lock(&hvc_iucv_filter_lock); + rc = hvc_iucv_filter_connreq(ipvmid); + read_unlock(&hvc_iucv_filter_lock); + if (rc) { + iucv_path_sever(path, ipuser); + iucv_path_free(path); + memcpy(vm_user_id, ipvmid, 8); + vm_user_id[8] = 0; + pr_info("A connection request from z/VM user ID %s " + "was refused\n", vm_user_id); + return 0; + } + + spin_lock(&priv->lock); + + /* If the terminal is already connected or being severed, then sever + * this path to enforce that there is only ONE established communication + * path per terminal. */ + if (priv->iucv_state != IUCV_DISCONN) { + iucv_path_sever(path, ipuser); + iucv_path_free(path); + goto out_path_handled; + } + + /* accept path */ + memcpy(nuser_data, ipuser + 8, 8); /* remote service (for af_iucv) */ + memcpy(nuser_data + 8, ipuser, 8); /* local service (for af_iucv) */ + path->msglim = 0xffff; /* IUCV MSGLIMIT */ + path->flags &= ~IUCV_IPRMDATA; /* TODO: use IUCV_IPRMDATA */ + rc = iucv_path_accept(path, &hvc_iucv_handler, nuser_data, priv); + if (rc) { + iucv_path_sever(path, ipuser); + iucv_path_free(path); + goto out_path_handled; + } + priv->path = path; + priv->iucv_state = IUCV_CONNECTED; + + /* store path information */ + memcpy(priv->info_path, ipvmid, 8); + memcpy(priv->info_path + 8, ipuser + 8, 8); + + /* flush buffered output data... */ + schedule_delayed_work(&priv->sndbuf_work, 5); + +out_path_handled: + spin_unlock(&priv->lock); + return 0; +} + +/** + * hvc_iucv_path_severed() - IUCV handler to process a path sever. + * @path: Pending path (struct iucv_path) + * @ipuser: User specified data for this path + * (AF_IUCV: port/service name and originator port) + * + * This function calls the hvc_iucv_hangup() function for the + * respective IUCV HVC terminal. + * + * Locking: struct hvc_iucv_private->lock + */ +static void hvc_iucv_path_severed(struct iucv_path *path, u8 *ipuser) +{ + struct hvc_iucv_private *priv = path->private; + + hvc_iucv_hangup(priv); +} + +/** + * hvc_iucv_msg_pending() - IUCV handler to process an incoming IUCV message. + * @path: Pending path (struct iucv_path) + * @msg: Pointer to the IUCV message + * + * The function puts an incoming message on the input queue for later + * processing (by hvc_iucv_get_chars() / hvc_iucv_write()). + * If the tty has not yet been opened, the message is rejected. + * + * Locking: struct hvc_iucv_private->lock + */ +static void hvc_iucv_msg_pending(struct iucv_path *path, + struct iucv_message *msg) +{ + struct hvc_iucv_private *priv = path->private; + struct iucv_tty_buffer *rb; + + /* reject messages that exceed max size of iucv_tty_msg->datalen */ + if (msg->length > MSG_SIZE(MSG_MAX_DATALEN)) { + iucv_message_reject(path, msg); + return; + } + + spin_lock(&priv->lock); + + /* reject messages if tty has not yet been opened */ + if (priv->tty_state == TTY_CLOSED) { + iucv_message_reject(path, msg); + goto unlock_return; + } + + /* allocate tty buffer to save iucv msg only */ + rb = alloc_tty_buffer(0, GFP_ATOMIC); + if (!rb) { + iucv_message_reject(path, msg); + goto unlock_return; /* -ENOMEM */ + } + rb->msg = *msg; + + list_add_tail(&rb->list, &priv->tty_inqueue); + + hvc_kick(); /* wake up hvc thread */ + +unlock_return: + spin_unlock(&priv->lock); +} + +/** + * hvc_iucv_msg_complete() - IUCV handler to process message completion + * @path: Pending path (struct iucv_path) + * @msg: Pointer to the IUCV message + * + * The function is called upon completion of message delivery to remove the + * message from the outqueue. Additional delivery information can be found + * msg->audit: rejected messages (0x040000 (IPADRJCT)), and + * purged messages (0x010000 (IPADPGNR)). + * + * Locking: struct hvc_iucv_private->lock + */ +static void hvc_iucv_msg_complete(struct iucv_path *path, + struct iucv_message *msg) +{ + struct hvc_iucv_private *priv = path->private; + struct iucv_tty_buffer *ent, *next; + LIST_HEAD(list_remove); + + spin_lock(&priv->lock); + list_for_each_entry_safe(ent, next, &priv->tty_outqueue, list) + if (ent->msg.id == msg->id) { + list_move(&ent->list, &list_remove); + break; + } + wake_up(&priv->sndbuf_waitq); + spin_unlock(&priv->lock); + destroy_tty_buffer_list(&list_remove); +} + +/** + * hvc_iucv_pm_freeze() - Freeze PM callback + * @dev: IUVC HVC terminal device + * + * Sever an established IUCV communication path and + * trigger a hang-up of the underlying HVC terminal. + */ +static int hvc_iucv_pm_freeze(struct device *dev) +{ + struct hvc_iucv_private *priv = dev_get_drvdata(dev); + + local_bh_disable(); + hvc_iucv_hangup(priv); + local_bh_enable(); + + return 0; +} + +/** + * hvc_iucv_pm_restore_thaw() - Thaw and restore PM callback + * @dev: IUVC HVC terminal device + * + * Wake up the HVC thread to trigger hang-up and respective + * HVC back-end notifier invocations. + */ +static int hvc_iucv_pm_restore_thaw(struct device *dev) +{ + hvc_kick(); + return 0; +} + +static ssize_t hvc_iucv_dev_termid_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct hvc_iucv_private *priv = dev_get_drvdata(dev); + size_t len; + + len = sizeof(priv->srv_name); + memcpy(buf, priv->srv_name, len); + EBCASC(buf, len); + buf[len++] = '\n'; + return len; +} + +static ssize_t hvc_iucv_dev_state_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct hvc_iucv_private *priv = dev_get_drvdata(dev); + return sprintf(buf, "%u:%u\n", priv->iucv_state, priv->tty_state); +} + +static ssize_t hvc_iucv_dev_peer_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct hvc_iucv_private *priv = dev_get_drvdata(dev); + char vmid[9], ipuser[9]; + + memset(vmid, 0, sizeof(vmid)); + memset(ipuser, 0, sizeof(ipuser)); + + spin_lock_bh(&priv->lock); + if (priv->iucv_state == IUCV_CONNECTED) { + memcpy(vmid, priv->info_path, 8); + memcpy(ipuser, priv->info_path + 8, 8); + } + spin_unlock_bh(&priv->lock); + EBCASC(ipuser, 8); + + return sprintf(buf, "%s:%s\n", vmid, ipuser); +} + + +/* HVC operations */ +static const struct hv_ops hvc_iucv_ops = { + .get_chars = hvc_iucv_get_chars, + .put_chars = hvc_iucv_put_chars, + .notifier_add = hvc_iucv_notifier_add, + .notifier_del = hvc_iucv_notifier_del, + .notifier_hangup = hvc_iucv_notifier_hangup, + .dtr_rts = hvc_iucv_dtr_rts, +}; + +/* Suspend / resume device operations */ +static const struct dev_pm_ops hvc_iucv_pm_ops = { + .freeze = hvc_iucv_pm_freeze, + .thaw = hvc_iucv_pm_restore_thaw, + .restore = hvc_iucv_pm_restore_thaw, +}; + +/* IUCV HVC device driver */ +static struct device_driver hvc_iucv_driver = { + .name = KMSG_COMPONENT, + .bus = &iucv_bus, + .pm = &hvc_iucv_pm_ops, +}; + +/* IUCV HVC device attributes */ +static DEVICE_ATTR(termid, 0640, hvc_iucv_dev_termid_show, NULL); +static DEVICE_ATTR(state, 0640, hvc_iucv_dev_state_show, NULL); +static DEVICE_ATTR(peer, 0640, hvc_iucv_dev_peer_show, NULL); +static struct attribute *hvc_iucv_dev_attrs[] = { + &dev_attr_termid.attr, + &dev_attr_state.attr, + &dev_attr_peer.attr, + NULL, +}; +static struct attribute_group hvc_iucv_dev_attr_group = { + .attrs = hvc_iucv_dev_attrs, +}; +static const struct attribute_group *hvc_iucv_dev_attr_groups[] = { + &hvc_iucv_dev_attr_group, + NULL, +}; + + +/** + * hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance + * @id: hvc_iucv_table index + * @is_console: Flag if the instance is used as Linux console + * + * This function allocates a new hvc_iucv_private structure and stores + * the instance in hvc_iucv_table at index @id. + * Returns 0 on success; otherwise non-zero. + */ +static int __init hvc_iucv_alloc(int id, unsigned int is_console) +{ + struct hvc_iucv_private *priv; + char name[9]; + int rc; + + priv = kzalloc(sizeof(struct hvc_iucv_private), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + spin_lock_init(&priv->lock); + INIT_LIST_HEAD(&priv->tty_outqueue); + INIT_LIST_HEAD(&priv->tty_inqueue); + INIT_DELAYED_WORK(&priv->sndbuf_work, hvc_iucv_sndbuf_work); + init_waitqueue_head(&priv->sndbuf_waitq); + + priv->sndbuf = (void *) get_zeroed_page(GFP_KERNEL); + if (!priv->sndbuf) { + kfree(priv); + return -ENOMEM; + } + + /* set console flag */ + priv->is_console = is_console; + + /* allocate hvc device */ + priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id, /* PAGE_SIZE */ + HVC_IUCV_MAGIC + id, &hvc_iucv_ops, 256); + if (IS_ERR(priv->hvc)) { + rc = PTR_ERR(priv->hvc); + goto out_error_hvc; + } + + /* notify HVC thread instead of using polling */ + priv->hvc->irq_requested = 1; + + /* setup iucv related information */ + snprintf(name, 9, "lnxhvc%-2d", id); + memcpy(priv->srv_name, name, 8); + ASCEBC(priv->srv_name, 8); + + /* create and setup device */ + priv->dev = kzalloc(sizeof(*priv->dev), GFP_KERNEL); + if (!priv->dev) { + rc = -ENOMEM; + goto out_error_dev; + } + dev_set_name(priv->dev, "hvc_iucv%d", id); + dev_set_drvdata(priv->dev, priv); + priv->dev->bus = &iucv_bus; + priv->dev->parent = iucv_root; + priv->dev->driver = &hvc_iucv_driver; + priv->dev->groups = hvc_iucv_dev_attr_groups; + priv->dev->release = (void (*)(struct device *)) kfree; + rc = device_register(priv->dev); + if (rc) { + put_device(priv->dev); + goto out_error_dev; + } + + hvc_iucv_table[id] = priv; + return 0; + +out_error_dev: + hvc_remove(priv->hvc); +out_error_hvc: + free_page((unsigned long) priv->sndbuf); + kfree(priv); + + return rc; +} + +/** + * hvc_iucv_destroy() - Destroy and free hvc_iucv_private instances + */ +static void __init hvc_iucv_destroy(struct hvc_iucv_private *priv) +{ + hvc_remove(priv->hvc); + device_unregister(priv->dev); + free_page((unsigned long) priv->sndbuf); + kfree(priv); +} + +/** + * hvc_iucv_parse_filter() - Parse filter for a single z/VM user ID + * @filter: String containing a comma-separated list of z/VM user IDs + * @dest: Location where to store the parsed z/VM user ID + */ +static const char *hvc_iucv_parse_filter(const char *filter, char *dest) +{ + const char *nextdelim, *residual; + size_t len; + + nextdelim = strchr(filter, ','); + if (nextdelim) { + len = nextdelim - filter; + residual = nextdelim + 1; + } else { + len = strlen(filter); + residual = filter + len; + } + + if (len == 0) + return ERR_PTR(-EINVAL); + + /* check for '\n' (if called from sysfs) */ + if (filter[len - 1] == '\n') + len--; + + /* prohibit filter entries containing the wildcard character only */ + if (len == 1 && *filter == FILTER_WILDCARD_CHAR) + return ERR_PTR(-EINVAL); + + if (len > 8) + return ERR_PTR(-EINVAL); + + /* pad with blanks and save upper case version of user ID */ + memset(dest, ' ', 8); + while (len--) + dest[len] = toupper(filter[len]); + return residual; +} + +/** + * hvc_iucv_setup_filter() - Set up z/VM user ID filter + * @filter: String consisting of a comma-separated list of z/VM user IDs + * + * The function parses the @filter string and creates an array containing + * the list of z/VM user ID filter entries. + * Return code 0 means success, -EINVAL if the filter is syntactically + * incorrect, -ENOMEM if there was not enough memory to allocate the + * filter list array, or -ENOSPC if too many z/VM user IDs have been specified. + */ +static int hvc_iucv_setup_filter(const char *val) +{ + const char *residual; + int err; + size_t size, count; + void *array, *old_filter; + + count = strlen(val); + if (count == 0 || (count == 1 && val[0] == '\n')) { + size = 0; + array = NULL; + goto out_replace_filter; /* clear filter */ + } + + /* count user IDs in order to allocate sufficient memory */ + size = 1; + residual = val; + while ((residual = strchr(residual, ',')) != NULL) { + residual++; + size++; + } + + /* check if the specified list exceeds the filter limit */ + if (size > MAX_VMID_FILTER) + return -ENOSPC; + + array = kcalloc(size, 8, GFP_KERNEL); + if (!array) + return -ENOMEM; + + count = size; + residual = val; + while (*residual && count) { + residual = hvc_iucv_parse_filter(residual, + array + ((size - count) * 8)); + if (IS_ERR(residual)) { + err = PTR_ERR(residual); + kfree(array); + goto out_err; + } + count--; + } + +out_replace_filter: + write_lock_bh(&hvc_iucv_filter_lock); + old_filter = hvc_iucv_filter; + hvc_iucv_filter_size = size; + hvc_iucv_filter = array; + write_unlock_bh(&hvc_iucv_filter_lock); + kfree(old_filter); + + err = 0; +out_err: + return err; +} + +/** + * param_set_vmidfilter() - Set z/VM user ID filter parameter + * @val: String consisting of a comma-separated list of z/VM user IDs + * @kp: Kernel parameter pointing to hvc_iucv_filter array + * + * The function sets up the z/VM user ID filter specified as comma-separated + * list of user IDs in @val. + * Note: If it is called early in the boot process, @val is stored and + * parsed later in hvc_iucv_init(). + */ +static int param_set_vmidfilter(const char *val, const struct kernel_param *kp) +{ + int rc; + + if (!MACHINE_IS_VM || !hvc_iucv_devices) + return -ENODEV; + + if (!val) + return -EINVAL; + + rc = 0; + if (slab_is_available()) + rc = hvc_iucv_setup_filter(val); + else + hvc_iucv_filter_string = val; /* defer... */ + return rc; +} + +/** + * param_get_vmidfilter() - Get z/VM user ID filter + * @buffer: Buffer to store z/VM user ID filter, + * (buffer size assumption PAGE_SIZE) + * @kp: Kernel parameter pointing to the hvc_iucv_filter array + * + * The function stores the filter as a comma-separated list of z/VM user IDs + * in @buffer. Typically, sysfs routines call this function for attr show. + */ +static int param_get_vmidfilter(char *buffer, const struct kernel_param *kp) +{ + int rc; + size_t index, len; + void *start, *end; + + if (!MACHINE_IS_VM || !hvc_iucv_devices) + return -ENODEV; + + rc = 0; + read_lock_bh(&hvc_iucv_filter_lock); + for (index = 0; index < hvc_iucv_filter_size; index++) { + start = hvc_iucv_filter + (8 * index); + end = memchr(start, ' ', 8); + len = (end) ? end - start : 8; + memcpy(buffer + rc, start, len); + rc += len; + buffer[rc++] = ','; + } + read_unlock_bh(&hvc_iucv_filter_lock); + if (rc) + buffer[--rc] = '\0'; /* replace last comma and update rc */ + return rc; +} + +#define param_check_vmidfilter(name, p) __param_check(name, p, void) + +static const struct kernel_param_ops param_ops_vmidfilter = { + .set = param_set_vmidfilter, + .get = param_get_vmidfilter, +}; + +/** + * hvc_iucv_init() - z/VM IUCV HVC device driver initialization + */ +static int __init hvc_iucv_init(void) +{ + int rc; + unsigned int i; + + if (!hvc_iucv_devices) + return -ENODEV; + + if (!MACHINE_IS_VM) { + pr_notice("The z/VM IUCV HVC device driver cannot " + "be used without z/VM\n"); + rc = -ENODEV; + goto out_error; + } + + if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) { + pr_err("%lu is not a valid value for the hvc_iucv= " + "kernel parameter\n", hvc_iucv_devices); + rc = -EINVAL; + goto out_error; + } + + /* register IUCV HVC device driver */ + rc = driver_register(&hvc_iucv_driver); + if (rc) + goto out_error; + + /* parse hvc_iucv_allow string and create z/VM user ID filter list */ + if (hvc_iucv_filter_string) { + rc = hvc_iucv_setup_filter(hvc_iucv_filter_string); + switch (rc) { + case 0: + break; + case -ENOMEM: + pr_err("Allocating memory failed with " + "reason code=%d\n", 3); + goto out_error; + case -EINVAL: + pr_err("hvc_iucv_allow= does not specify a valid " + "z/VM user ID list\n"); + goto out_error; + case -ENOSPC: + pr_err("hvc_iucv_allow= specifies too many " + "z/VM user IDs\n"); + goto out_error; + default: + goto out_error; + } + } + + hvc_iucv_buffer_cache = kmem_cache_create(KMSG_COMPONENT, + sizeof(struct iucv_tty_buffer), + 0, 0, NULL); + if (!hvc_iucv_buffer_cache) { + pr_err("Allocating memory failed with reason code=%d\n", 1); + rc = -ENOMEM; + goto out_error; + } + + hvc_iucv_mempool = mempool_create_slab_pool(MEMPOOL_MIN_NR, + hvc_iucv_buffer_cache); + if (!hvc_iucv_mempool) { + pr_err("Allocating memory failed with reason code=%d\n", 2); + kmem_cache_destroy(hvc_iucv_buffer_cache); + rc = -ENOMEM; + goto out_error; + } + + /* register the first terminal device as console + * (must be done before allocating hvc terminal devices) */ + rc = hvc_instantiate(HVC_IUCV_MAGIC, IUCV_HVC_CON_IDX, &hvc_iucv_ops); + if (rc) { + pr_err("Registering HVC terminal device as " + "Linux console failed\n"); + goto out_error_memory; + } + + /* allocate hvc_iucv_private structs */ + for (i = 0; i < hvc_iucv_devices; i++) { + rc = hvc_iucv_alloc(i, (i == IUCV_HVC_CON_IDX) ? 1 : 0); + if (rc) { + pr_err("Creating a new HVC terminal device " + "failed with error code=%d\n", rc); + goto out_error_hvc; + } + } + + /* register IUCV callback handler */ + rc = iucv_register(&hvc_iucv_handler, 0); + if (rc) { + pr_err("Registering IUCV handlers failed with error code=%d\n", + rc); + goto out_error_hvc; + } + + return 0; + +out_error_hvc: + for (i = 0; i < hvc_iucv_devices; i++) + if (hvc_iucv_table[i]) + hvc_iucv_destroy(hvc_iucv_table[i]); +out_error_memory: + mempool_destroy(hvc_iucv_mempool); + kmem_cache_destroy(hvc_iucv_buffer_cache); +out_error: + kfree(hvc_iucv_filter); + hvc_iucv_devices = 0; /* ensure that we do not provide any device */ + return rc; +} + +/** + * hvc_iucv_config() - Parsing of hvc_iucv= kernel command line parameter + * @val: Parameter value (numeric) + */ +static int __init hvc_iucv_config(char *val) +{ + if (kstrtoul(val, 10, &hvc_iucv_devices)) + pr_warn("hvc_iucv= invalid parameter value '%s'\n", val); + return 1; +} + + +device_initcall(hvc_iucv_init); +__setup("hvc_iucv=", hvc_iucv_config); +core_param(hvc_iucv_allow, hvc_iucv_filter, vmidfilter, 0640); |