lib/libcrc32c.c


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/* 
 * CRC32C
 *@Article{castagnoli-crc,
 * author =       { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
 * title =        {{Optimization of Cyclic Redundancy-Check Codes with 24
 *                 and 32 Parity Bits}},
 * journal =      IEEE Transactions on Communication,
 * year =         {1993},
 * volume =       {41},
 * number =       {6},
 * pages =        {},
 * month =        {June},
 *}
 * Used by the iSCSI driver, possibly others, and derived from the
 * the iscsi-crc.c module of the linux-iscsi driver at
 * http://linux-iscsi.sourceforge.net.
 *
 * Following the example of lib/crc32, this function is intended to be
 * flexible and useful for all users.  Modules that currently have their
 * own crc32c, but hopefully may be able to use this one are:
 *  net/sctp (please add all your doco to here if you change to
 *            use this one!)
 *  <endoflist>
 *
 * Copyright (c) 2004 Cisco Systems, Inc.
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 */

#include <crypto/hash.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>

static struct crypto_shash *tfm;

u32 crc32c(u32 crc, const void *address, unsigned int length)
{
	struct {
		struct shash_desc shash;
		char ctx[crypto_shash_descsize(tfm)];
	} desc;
	int err;

	desc.shash.tfm = tfm;
	desc.shash.flags = 0;
	*(u32 *)desc.ctx = crc;

	err = crypto_shash_update(&desc.shash, address, length);
	BUG_ON(err);

	return *(u32 *)desc.ctx;
}

EXPORT_SYMBOL(crc32c);

static int __init libcrc32c_mod_init(void)
{
	tfm = crypto_alloc_shash("crc32c", 0, 0);
	if (IS_ERR(tfm))
		return PTR_ERR(tfm);

	return 0;
}

static void __exit libcrc32c_mod_fini(void)
{
	crypto_free_shash(tfm);
}

module_init(libcrc32c_mod_init);
module_exit(libcrc32c_mod_fini);

MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
MODULE_LICENSE("GPL");
/*
 * 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[8], u8[16]);
static void hvc_iucv_path_severed(struct iucv_path *, u8[16]);
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;