redboot.c

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/*
 * Parse RedBoot-style Flash Image System (FIS) tables and
 * produce a Linux partition array to match.
 *
 * Copyright © 2001      Red Hat UK Limited
 * Copyright © 2001-2010 David Woodhouse <[email protected]>
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/vmalloc.h>

#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/module.h>

struct fis_image_desc {
    unsigned char name[16];      // Null terminated name
    uint32_t      flash_base;    // Address within FLASH of image
    uint32_t      mem_base;      // Address in memory where it executes
    uint32_t      size;          // Length of image
    uint32_t      entry_point;   // Execution entry point
    uint32_t      data_length;   // Length of actual data
    unsigned char _pad[256-(16+7*sizeof(uint32_t))];
    uint32_t      desc_cksum;    // Checksum over image descriptor
    uint32_t      file_cksum;    // Checksum over image data
};

struct fis_list {
    struct fis_image_desc *img;
    struct fis_list *next;
};

static int directory = CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK;
module_param(directory, int, 0);

static inline int redboot_checksum(struct fis_image_desc *img)
{
    /* RedBoot doesn't actually write the desc_cksum field yet AFAICT */
    return 1;
}

static int parse_redboot_partitions(struct mtd_info *master,
                    struct mtd_partition **pparts,
                    struct mtd_part_parser_data *data)
{
    int nrparts = 0;
    struct fis_image_desc *buf;
    struct mtd_partition *parts;
    struct fis_list *fl = NULL, *tmp_fl;
    int ret, i;
    size_t retlen;
    char *names;
    char *nullname;
    int namelen = 0;
    int nulllen = 0;
    int numslots;
    unsigned long offset;
#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
    static char nullstring[] = "unallocated";
#endif

    if ( directory < 0 ) {
        offset = master->size + directory * master->erasesize;
        while (mtd_block_isbad(master, offset)) {
            if (!offset) {
            nogood:
                printk(KERN_NOTICE "Failed to find a non-bad block to check for RedBoot partition table\n");
                return -EIO;
            }
            offset -= master->erasesize;
        }
    } else {
        offset = directory * master->erasesize;
        while (mtd_block_isbad(master, offset)) {
            offset += master->erasesize;
            if (offset == master->size)
                goto nogood;
        }
    }
    buf = vmalloc(master->erasesize);

    if (!buf)
        return -ENOMEM;

    printk(KERN_NOTICE "Searching for RedBoot partition table in %s at offset 0x%lx\n",
           master->name, offset);

    ret = mtd_read(master, offset, master->erasesize, &retlen,
               (void *)buf);

    if (ret)
        goto out;

    if (retlen != master->erasesize) {
        ret = -EIO;
        goto out;
    }

    numslots = (master->erasesize / sizeof(struct fis_image_desc));
    for (i = 0; i < numslots; i++) {
        if (!memcmp(buf[i].name, "FIS directory", 14)) {
            /* This is apparently the FIS directory entry for the
             * FIS directory itself.  The FIS directory size is
             * one erase block; if the buf[i].size field is
             * swab32(erasesize) then we know we are looking at
             * a byte swapped FIS directory - swap all the entries!
             * (NOTE: this is 'size' not 'data_length'; size is
             * the full size of the entry.)
             */

            /* RedBoot can combine the FIS directory and
               config partitions into a single eraseblock;
               we assume wrong-endian if either the swapped
               'size' matches the eraseblock size precisely,
               or if the swapped size actually fits in an
               eraseblock while the unswapped size doesn't. */
            if (swab32(buf[i].size) == master->erasesize ||
                (buf[i].size > master->erasesize
                 && swab32(buf[i].size) < master->erasesize)) {
                int j;
                /* Update numslots based on actual FIS directory size */
                numslots = swab32(buf[i].size) / sizeof (struct fis_image_desc);
                for (j = 0; j < numslots; ++j) {

                    /* A single 0xff denotes a deleted entry.
                     * Two of them in a row is the end of the table.
                     */
                    if (buf[j].name[0] == 0xff) {
                        if (buf[j].name[1] == 0xff) {
                            break;
                        } else {
                            continue;
                        }
                    }

                    /* The unsigned long fields were written with the
                     * wrong byte sex, name and pad have no byte sex.
                     */
                    swab32s(&buf[j].flash_base);
                    swab32s(&buf[j].mem_base);
                    swab32s(&buf[j].size);
                    swab32s(&buf[j].entry_point);
                    swab32s(&buf[j].data_length);
                    swab32s(&buf[j].desc_cksum);
                    swab32s(&buf[j].file_cksum);
                }
            } else if (buf[i].size < master->erasesize) {
                /* Update numslots based on actual FIS directory size */
                numslots = buf[i].size / sizeof(struct fis_image_desc);
            }
            break;
        }
    }
    if (i == numslots) {
        /* Didn't find it */
        printk(KERN_NOTICE "No RedBoot partition table detected in %s\n",
               master->name);
        ret = 0;
        goto out;
    }

    for (i = 0; i < numslots; i++) {
        struct fis_list *new_fl, **prev;

        if (buf[i].name[0] == 0xff) {
            if (buf[i].name[1] == 0xff) {
                break;
            } else {
                continue;
            }
        }
        if (!redboot_checksum(&buf[i]))
            break;

        new_fl = kmalloc(sizeof(struct fis_list), GFP_KERNEL);
        namelen += strlen(buf[i].name)+1;
        if (!new_fl) {
            ret = -ENOMEM;
            goto out;
        }
        new_fl->img = &buf[i];
        if (data && data->origin)
            buf[i].flash_base -= data->origin;
        else
            buf[i].flash_base &= master->size-1;

        /* I'm sure the JFFS2 code has done me permanent damage.
         * I now think the following is _normal_
         */
        prev = &fl;
        while(*prev && (*prev)->img->flash_base < new_fl->img->flash_base)
            prev = &(*prev)->next;
        new_fl->next = *prev;
        *prev = new_fl;

        nrparts++;
    }
#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
    if (fl->img->flash_base) {
        nrparts++;
        nulllen = sizeof(nullstring);
    }

    for (tmp_fl = fl; tmp_fl->next; tmp_fl = tmp_fl->next) {
        if (tmp_fl->img->flash_base + tmp_fl->img->size + master->erasesize <= tmp_fl->next->img->flash_base) {
            nrparts++;
            nulllen = sizeof(nullstring);
        }
    }
#endif
    parts = kzalloc(sizeof(*parts)*nrparts + nulllen + namelen, GFP_KERNEL);

    if (!parts) {
        ret = -ENOMEM;
        goto out;
    }

    nullname = (char *)&parts[nrparts];
#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
    if (nulllen > 0) {
        strcpy(nullname, nullstring);
    }
#endif
    names = nullname + nulllen;

    i=0;

#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
    if (fl->img->flash_base) {
           parts[0].name = nullname;
           parts[0].size = fl->img->flash_base;
           parts[0].offset = 0;
        i++;
    }
#endif
    for ( ; i<nrparts; i++) {
        parts[i].size = fl->img->size;
        parts[i].offset = fl->img->flash_base;
        parts[i].name = names;

        strcpy(names, fl->img->name);
#ifdef CONFIG_MTD_REDBOOT_PARTS_READONLY
        if (!memcmp(names, "RedBoot", 8) ||
                !memcmp(names, "RedBoot config", 15) ||
                !memcmp(names, "FIS directory", 14)) {
            parts[i].mask_flags = MTD_WRITEABLE;
        }
#endif
        names += strlen(names)+1;

#ifdef CONFIG_MTD_REDBOOT_PARTS_UNALLOCATED
        if(fl->next && fl->img->flash_base + fl->img->size + master->erasesize <= fl->next->img->flash_base) {
            i++;
            parts[i].offset = parts[i-1].size + parts[i-1].offset;
            parts[i].size = fl->next->img->flash_base - parts[i].offset;
            parts[i].name = nullname;
        }
#endif
        tmp_fl = fl;
        fl = fl->next;
        kfree(tmp_fl);
    }
    ret = nrparts;
    *pparts = parts;
 out:
    while (fl) {
        struct fis_list *old = fl;
        fl = fl->next;
        kfree(old);
    }
    vfree(buf);
    return ret;
}

static struct mtd_part_parser redboot_parser = {
    .owner = THIS_MODULE,
    .parse_fn = parse_redboot_partitions,
    .name = "RedBoot",
};

/* mtd parsers will request the module by parser name */
MODULE_ALIAS("RedBoot");

static int __init redboot_parser_init(void)
{
    return register_mtd_parser(&redboot_parser);
}

static void __exit redboot_parser_exit(void)
{
    deregister_mtd_parser(&redboot_parser);
}

module_init(redboot_parser_init);
module_exit(redboot_parser_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <[email protected]>");
MODULE_DESCRIPTION("Parsing code for RedBoot Flash Image System (FIS) tables");