/*
 * SCSI Block Commands (SBC) parsing and emulation.
 *
 * Copyright (c) 2002, 2003, 2004, 2005 PyX Technologies, Inc.
 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
 * Copyright (c) 2007-2010 Rising Tide Systems
 * Copyright (c) 2008-2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ratelimit.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>
#include <target/target_core_fabric.h>

#include "target_core_internal.h"
#include "target_core_ua.h"


static int sbc_emulate_readcapacity(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf;
        unsigned long long blocks_long = dev->transport->get_blocks(dev);
        u32 blocks;

        if (blocks_long >= 0x00000000ffffffff)
                blocks = 0xffffffff;
        else
                blocks = (u32)blocks_long;

        buf = transport_kmap_data_sg(cmd);

        buf[0] = (blocks >> 24) & 0xff;
        buf[1] = (blocks >> 16) & 0xff;
        buf[2] = (blocks >> 8) & 0xff;
        buf[3] = blocks & 0xff;
        buf[4] = (dev->se_sub_dev->se_dev_attrib.block_size >> 24) & 0xff;
        buf[5] = (dev->se_sub_dev->se_dev_attrib.block_size >> 16) & 0xff;
        buf[6] = (dev->se_sub_dev->se_dev_attrib.block_size >> 8) & 0xff;
        buf[7] = dev->se_sub_dev->se_dev_attrib.block_size & 0xff;

        transport_kunmap_data_sg(cmd);

        target_complete_cmd(cmd, GOOD);
        return 0;
}

static int sbc_emulate_readcapacity_16(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf;
        unsigned long long blocks = dev->transport->get_blocks(dev);

        buf = transport_kmap_data_sg(cmd);

        buf[0] = (blocks >> 56) & 0xff;
        buf[1] = (blocks >> 48) & 0xff;
        buf[2] = (blocks >> 40) & 0xff;
        buf[3] = (blocks >> 32) & 0xff;
        buf[4] = (blocks >> 24) & 0xff;
        buf[5] = (blocks >> 16) & 0xff;
        buf[6] = (blocks >> 8) & 0xff;
        buf[7] = blocks & 0xff;
        buf[8] = (dev->se_sub_dev->se_dev_attrib.block_size >> 24) & 0xff;
        buf[9] = (dev->se_sub_dev->se_dev_attrib.block_size >> 16) & 0xff;
        buf[10] = (dev->se_sub_dev->se_dev_attrib.block_size >> 8) & 0xff;
        buf[11] = dev->se_sub_dev->se_dev_attrib.block_size & 0xff;
        /*
         * Set Thin Provisioning Enable bit following sbc3r22 in section
         * READ CAPACITY (16) byte 14 if emulate_tpu or emulate_tpws is enabled.
         */
        if (dev->se_sub_dev->se_dev_attrib.emulate_tpu || dev->se_sub_dev->se_dev_attrib.emulate_tpws)
                buf[14] = 0x80;

        transport_kunmap_data_sg(cmd);

        target_complete_cmd(cmd, GOOD);
        return 0;
}

int spc_get_write_same_sectors(struct se_cmd *cmd)
{
        u32 num_blocks;

        if (cmd->t_task_cdb[0] == WRITE_SAME)
                num_blocks = get_unaligned_be16(&cmd->t_task_cdb[7]);
        else if (cmd->t_task_cdb[0] == WRITE_SAME_16)
                num_blocks = get_unaligned_be32(&cmd->t_task_cdb[10]);
        else /* WRITE_SAME_32 via VARIABLE_LENGTH_CMD */
                num_blocks = get_unaligned_be32(&cmd->t_task_cdb[28]);

        /*
         * Use the explicit range when non zero is supplied, otherwise calculate
         * the remaining range based on ->get_blocks() - starting LBA.
         */
        if (num_blocks)
                return num_blocks;

        return cmd->se_dev->transport->get_blocks(cmd->se_dev) -
                cmd->t_task_lba + 1;
}
EXPORT_SYMBOL(spc_get_write_same_sectors);

static int sbc_emulate_verify(struct se_cmd *cmd)
{
        target_complete_cmd(cmd, GOOD);
        return 0;
}

static int sbc_emulate_noop(struct se_cmd *cmd)
{
        target_complete_cmd(cmd, GOOD);
        return 0;
}

static inline u32 sbc_get_size(struct se_cmd *cmd, u32 sectors)
{
        return cmd->se_dev->se_sub_dev->se_dev_attrib.block_size * sectors;
}

static int sbc_check_valid_sectors(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned long long end_lba;
        u32 sectors;

        sectors = cmd->data_length / dev->se_sub_dev->se_dev_attrib.block_size;
        end_lba = dev->transport->get_blocks(dev) + 1;

        if (cmd->t_task_lba + sectors > end_lba) {
                pr_err("target: lba %llu, sectors %u exceeds end lba %llu\n",
                        cmd->t_task_lba, sectors, end_lba);
                return -EINVAL;
        }

        return 0;
}

static inline u32 transport_get_sectors_6(unsigned char *cdb)
{
        /*
         * Use 8-bit sector value.  SBC-3 says:
         *
         *   A TRANSFER LENGTH field set to zero specifies that 256
         *   logical blocks shall be written.  Any other value
         *   specifies the number of logical blocks that shall be
         *   written.
         */
        return cdb[4] ? : 256;
}

static inline u32 transport_get_sectors_10(unsigned char *cdb)
{
        return (u32)(cdb[7] << 8) + cdb[8];
}

static inline u32 transport_get_sectors_12(unsigned char *cdb)
{
        return (u32)(cdb[6] << 24) + (cdb[7] << 16) + (cdb[8] << 8) + cdb[9];
}

static inline u32 transport_get_sectors_16(unsigned char *cdb)
{
        return (u32)(cdb[10] << 24) + (cdb[11] << 16) +
                    (cdb[12] << 8) + cdb[13];
}

/*
 * Used for VARIABLE_LENGTH_CDB WRITE_32 and READ_32 variants
 */
static inline u32 transport_get_sectors_32(unsigned char *cdb)
{
        return (u32)(cdb[28] << 24) + (cdb[29] << 16) +
                    (cdb[30] << 8) + cdb[31];

}

static inline u32 transport_lba_21(unsigned char *cdb)
{
        return ((cdb[1] & 0x1f) << 16) | (cdb[2] << 8) | cdb[3];
}

static inline u32 transport_lba_32(unsigned char *cdb)
{
        return (cdb[2] << 24) | (cdb[3] << 16) | (cdb[4] << 8) | cdb[5];
}

static inline unsigned long long transport_lba_64(unsigned char *cdb)
{
        unsigned int __v1, __v2;

        __v1 = (cdb[2] << 24) | (cdb[3] << 16) | (cdb[4] << 8) | cdb[5];
        __v2 = (cdb[6] << 24) | (cdb[7] << 16) | (cdb[8] << 8) | cdb[9];

        return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
}

/*
 * For VARIABLE_LENGTH_CDB w/ 32 byte extended CDBs
 */
static inline unsigned long long transport_lba_64_ext(unsigned char *cdb)
{
        unsigned int __v1, __v2;

        __v1 = (cdb[12] << 24) | (cdb[13] << 16) | (cdb[14] << 8) | cdb[15];
        __v2 = (cdb[16] << 24) | (cdb[17] << 16) | (cdb[18] << 8) | cdb[19];

        return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
}

static int sbc_write_same_supported(struct se_device *dev,
                unsigned char *flags)
{
        if ((flags[0] & 0x04) || (flags[0] & 0x02)) {
                pr_err("WRITE_SAME PBDATA and LBDATA"
                        " bits not supported for Block Discard"
                        " Emulation\n");
                return -ENOSYS;
        }

        /*
         * Currently for the emulated case we only accept
         * tpws with the UNMAP=1 bit set.
         */
        if (!(flags[0] & 0x08)) {
                pr_err("WRITE_SAME w/o UNMAP bit not"
                        " supported for Block Discard Emulation\n");
                return -ENOSYS;
        }

        return 0;
}

static void xdreadwrite_callback(struct se_cmd *cmd)
{
        unsigned char *buf, *addr;
        struct scatterlist *sg;
        unsigned int offset;
        int i;
        int count;
        /*
         * From sbc3r22.pdf section 5.48 XDWRITEREAD (10) command
         *
         * 1) read the specified logical block(s);
         * 2) transfer logical blocks from the data-out buffer;
         * 3) XOR the logical blocks transferred from the data-out buffer with
         *    the logical blocks read, storing the resulting XOR data in a buffer;
         * 4) if the DISABLE WRITE bit is set to zero, then write the logical
         *    blocks transferred from the data-out buffer; and
         * 5) transfer the resulting XOR data to the data-in buffer.
         */
        buf = kmalloc(cmd->data_length, GFP_KERNEL);
        if (!buf) {
                pr_err("Unable to allocate xor_callback buf\n");
                return;
        }
        /*
         * Copy the scatterlist WRITE buffer located at cmd->t_data_sg
         * into the locally allocated *buf
         */
        sg_copy_to_buffer(cmd->t_data_sg,
                          cmd->t_data_nents,
                          buf,
                          cmd->data_length);

        /*
         * Now perform the XOR against the BIDI read memory located at
         * cmd->t_mem_bidi_list
         */

        offset = 0;
        for_each_sg(cmd->t_bidi_data_sg, sg, cmd->t_bidi_data_nents, count) {
                addr = kmap_atomic(sg_page(sg));
                if (!addr)
                        goto out;

                for (i = 0; i < sg->length; i++)
                        *(addr + sg->offset + i) ^= *(buf + offset + i);

                offset += sg->length;
                kunmap_atomic(addr);
        }

out:
        kfree(buf);
}

int sbc_parse_cdb(struct se_cmd *cmd, struct spc_ops *ops)
{
        struct se_subsystem_dev *su_dev = cmd->se_dev->se_sub_dev;
        struct se_device *dev = cmd->se_dev;
        unsigned char *cdb = cmd->t_task_cdb;
        unsigned int size;
        u32 sectors = 0;
        int ret;

        switch (cdb[0]) {
        case READ_6:
                sectors = transport_get_sectors_6(cdb);
                cmd->t_task_lba = transport_lba_21(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case READ_10:
                sectors = transport_get_sectors_10(cdb);
                cmd->t_task_lba = transport_lba_32(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case READ_12:
                sectors = transport_get_sectors_12(cdb);
                cmd->t_task_lba = transport_lba_32(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case READ_16:
                sectors = transport_get_sectors_16(cdb);
                cmd->t_task_lba = transport_lba_64(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case WRITE_6:
                sectors = transport_get_sectors_6(cdb);
                cmd->t_task_lba = transport_lba_21(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case WRITE_10:
        case WRITE_VERIFY:
                sectors = transport_get_sectors_10(cdb);
                cmd->t_task_lba = transport_lba_32(cdb);
                if (cdb[1] & 0x8)
                        cmd->se_cmd_flags |= SCF_FUA;
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case WRITE_12:
                sectors = transport_get_sectors_12(cdb);
                cmd->t_task_lba = transport_lba_32(cdb);
                if (cdb[1] & 0x8)
                        cmd->se_cmd_flags |= SCF_FUA;
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case WRITE_16:
                sectors = transport_get_sectors_16(cdb);
                cmd->t_task_lba = transport_lba_64(cdb);
                if (cdb[1] & 0x8)
                        cmd->se_cmd_flags |= SCF_FUA;
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
                cmd->execute_cmd = ops->execute_rw;
                break;
        case XDWRITEREAD_10:
                if ((cmd->data_direction != DMA_TO_DEVICE) ||
                    !(cmd->se_cmd_flags & SCF_BIDI))
                        goto out_invalid_cdb_field;
                sectors = transport_get_sectors_10(cdb);

                cmd->t_task_lba = transport_lba_32(cdb);
                cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;

                /*
                 * Setup BIDI XOR callback to be run after I/O completion.
                 */
                cmd->execute_cmd = ops->execute_rw;
                cmd->transport_complete_callback = &xdreadwrite_callback;
                if (cdb[1] & 0x8)
                        cmd->se_cmd_flags |= SCF_FUA;
                break;
        case VARIABLE_LENGTH_CMD:
        {
                u16 service_action = get_unaligned_be16(&cdb[8]);
                switch (service_action) {
                case XDWRITEREAD_32:
                        sectors = transport_get_sectors_32(cdb);

                        /*
                         * Use WRITE_32 and READ_32 opcodes for the emulated
                         * XDWRITE_READ_32 logic.
                         */
                        cmd->t_task_lba = transport_lba_64_ext(cdb);
                        cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;

                        /*
                         * Setup BIDI XOR callback to be run during after I/O
                         * completion.
                         */
                        cmd->execute_cmd = ops->execute_rw;
                        cmd->transport_complete_callback = &xdreadwrite_callback;
                        if (cdb[1] & 0x8)
                                cmd->se_cmd_flags |= SCF_FUA;
                        break;
                case WRITE_SAME_32:
                        if (!ops->execute_write_same)
                                goto out_unsupported_cdb;

                        sectors = transport_get_sectors_32(cdb);
                        if (!sectors) {
                                pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not"
                                       " supported\n");
                                goto out_invalid_cdb_field;
                        }

                        size = sbc_get_size(cmd, 1);
                        cmd->t_task_lba = get_unaligned_be64(&cdb[12]);

                        if (sbc_write_same_supported(dev, &cdb[10]) < 0)
                                goto out_unsupported_cdb;
                        cmd->execute_cmd = ops->execute_write_same;
                        break;
                default:
                        pr_err("VARIABLE_LENGTH_CMD service action"
                                " 0x%04x not supported\n", service_action);
                        goto out_unsupported_cdb;
                }
                break;
        }
        case READ_CAPACITY:
                size = READ_CAP_LEN;
                cmd->execute_cmd = sbc_emulate_readcapacity;
                break;
        case SERVICE_ACTION_IN:
                switch (cmd->t_task_cdb[1] & 0x1f) {
                case SAI_READ_CAPACITY_16:
                        cmd->execute_cmd = sbc_emulate_readcapacity_16;
                        break;
                default:
                        pr_err("Unsupported SA: 0x%02x\n",
                                cmd->t_task_cdb[1] & 0x1f);
                        goto out_invalid_cdb_field;
                }
                size = (cdb[10] << 24) | (cdb[11] << 16) |
                       (cdb[12] << 8) | cdb[13];
                break;
        case SYNCHRONIZE_CACHE:
        case SYNCHRONIZE_CACHE_16:
                if (!ops->execute_sync_cache)
                        goto out_unsupported_cdb;

                /*
                 * Extract LBA and range to be flushed for emulated SYNCHRONIZE_CACHE
                 */
                if (cdb[0] == SYNCHRONIZE_CACHE) {
                        sectors = transport_get_sectors_10(cdb);
                        cmd->t_task_lba = transport_lba_32(cdb);
                } else {
                        sectors = transport_get_sectors_16(cdb);
                        cmd->t_task_lba = transport_lba_64(cdb);
                }

                size = sbc_get_size(cmd, sectors);

                /*
                 * Check to ensure that LBA + Range does not exceed past end of
                 * device for IBLOCK and FILEIO ->do_sync_cache() backend calls
                 */
                if (cmd->t_task_lba || sectors) {
                        if (sbc_check_valid_sectors(cmd) < 0)
                                goto out_invalid_cdb_field;
                }
                cmd->execute_cmd = ops->execute_sync_cache;
                break;
        case UNMAP:
                if (!ops->execute_unmap)
                        goto out_unsupported_cdb;

                size = get_unaligned_be16(&cdb[7]);
                cmd->execute_cmd = ops->execute_unmap;
                break;
        case WRITE_SAME_16:
                if (!ops->execute_write_same)
                        goto out_unsupported_cdb;

                sectors = transport_get_sectors_16(cdb);
                if (!sectors) {
                        pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not supported\n");
                        goto out_invalid_cdb_field;
                }

                size = sbc_get_size(cmd, 1);
                cmd->t_task_lba = get_unaligned_be64(&cdb[2]);

                if (sbc_write_same_supported(dev, &cdb[1]) < 0)
                        goto out_unsupported_cdb;
                cmd->execute_cmd = ops->execute_write_same;
                break;
        case WRITE_SAME:
                if (!ops->execute_write_same)
                        goto out_unsupported_cdb;

                sectors = transport_get_sectors_10(cdb);
                if (!sectors) {
                        pr_err("WSNZ=1, WRITE_SAME w/sectors=0 not supported\n");
                        goto out_invalid_cdb_field;
                }

                size = sbc_get_size(cmd, 1);
                cmd->t_task_lba = get_unaligned_be32(&cdb[2]);

                /*
                 * Follow sbcr26 with WRITE_SAME (10) and check for the existence
                 * of byte 1 bit 3 UNMAP instead of original reserved field
                 */
                if (sbc_write_same_supported(dev, &cdb[1]) < 0)
                        goto out_unsupported_cdb;
                cmd->execute_cmd = ops->execute_write_same;
                break;
        case VERIFY:
                size = 0;
                cmd->execute_cmd = sbc_emulate_verify;
                break;
        case REZERO_UNIT:
        case SEEK_6:
        case SEEK_10:
                /*
                 * There are still clients out there which use these old SCSI-2
                 * commands. This mainly happens when running VMs with legacy
                 * guest systems, connected via SCSI command pass-through to
                 * iSCSI targets. Make them happy and return status GOOD.
                 */
                size = 0;
                cmd->execute_cmd = sbc_emulate_noop;
                break;
        default:
                ret = spc_parse_cdb(cmd, &size);
                if (ret)
                        return ret;
        }

        /* reject any command that we don't have a handler for */
        if (!(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) && !cmd->execute_cmd)
                goto out_unsupported_cdb;

        if (cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
                unsigned long long end_lba;

                if (sectors > su_dev->se_dev_attrib.fabric_max_sectors) {
                        printk_ratelimited(KERN_ERR "SCSI OP %02xh with too"
                                " big sectors %u exceeds fabric_max_sectors:"
                                " %u\n", cdb[0], sectors,
                                su_dev->se_dev_attrib.fabric_max_sectors);
                        goto out_invalid_cdb_field;
                }
                if (sectors > su_dev->se_dev_attrib.hw_max_sectors) {
                        printk_ratelimited(KERN_ERR "SCSI OP %02xh with too"
                                " big sectors %u exceeds backend hw_max_sectors:"
                                " %u\n", cdb[0], sectors,
                                su_dev->se_dev_attrib.hw_max_sectors);
                        goto out_invalid_cdb_field;
                }

                end_lba = dev->transport->get_blocks(dev) + 1;
                if (cmd->t_task_lba + sectors > end_lba) {
                        pr_err("cmd exceeds last lba %llu "
                                "(lba %llu, sectors %u)\n",
                                end_lba, cmd->t_task_lba, sectors);
                        goto out_invalid_cdb_field;
                }

                size = sbc_get_size(cmd, sectors);
        }

        ret = target_cmd_size_check(cmd, size);
        if (ret < 0)
                return ret;

        return 0;

out_unsupported_cdb:
        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
        cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
        return -EINVAL;
out_invalid_cdb_field:
        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
        cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
        return -EINVAL;
}
EXPORT_SYMBOL(sbc_parse_cdb);