root/drivers/mtd/parsers/afs.c

DEFINITIONS

1. word_sum
2. word_sum_v2
3. afs_is_v1
4. afs_is_v2
5. afs_parse_v1_partition
6. afs_parse_v2_partition
7. parse_afs_partitions

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*======================================================================
   3 
   4     drivers/mtd/afs.c: ARM Flash Layout/Partitioning
   5 
   6     Copyright © 2000 ARM Limited
   7     Copyright (C) 2019 Linus Walleij
   8 
   9 
  10    This is access code for flashes using ARM's flash partitioning
  11    standards.
  12 
  13 ======================================================================*/
  14 
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/slab.h>
  19 #include <linux/string.h>
  20 #include <linux/init.h>
  21 
  22 #include <linux/mtd/mtd.h>
  23 #include <linux/mtd/map.h>
  24 #include <linux/mtd/partitions.h>
  25 
  26 #define AFSV1_FOOTER_MAGIC 0xA0FFFF9F
  27 #define AFSV2_FOOTER_MAGIC1 0x464C5348 /* "FLSH" */
  28 #define AFSV2_FOOTER_MAGIC2 0x464F4F54 /* "FOOT" */
  29 
  30 struct footer_v1 {
  31         u32 image_info_base;    /* Address of first word of ImageFooter  */
  32         u32 image_start;        /* Start of area reserved by this footer */
  33         u32 signature;          /* 'Magic' number proves it's a footer   */
  34         u32 type;               /* Area type: ARM Image, SIB, customer   */
  35         u32 checksum;           /* Just this structure                   */
  36 };
  37 
  38 struct image_info_v1 {
  39         u32 bootFlags;          /* Boot flags, compression etc.          */
  40         u32 imageNumber;        /* Unique number, selects for boot etc.  */
  41         u32 loadAddress;        /* Address program should be loaded to   */
  42         u32 length;             /* Actual size of image                  */
  43         u32 address;            /* Image is executed from here           */
  44         char name[16];          /* Null terminated                       */
  45         u32 headerBase;         /* Flash Address of any stripped header  */
  46         u32 header_length;      /* Length of header in memory            */
  47         u32 headerType;         /* AIF, RLF, s-record etc.               */
  48         u32 checksum;           /* Image checksum (inc. this struct)     */
  49 };
  50 
  51 static u32 word_sum(void *words, int num)
  52 {
  53         u32 *p = words;
  54         u32 sum = 0;
  55 
  56         while (num--)
  57                 sum += *p++;
  58 
  59         return sum;
  60 }
  61 
  62 static u32 word_sum_v2(u32 *p, u32 num)
  63 {
  64         u32 sum = 0;
  65         int i;
  66 
  67         for (i = 0; i < num; i++) {
  68                 u32 val;
  69 
  70                 val = p[i];
  71                 if (val > ~sum)
  72                         sum++;
  73                 sum += val;
  74         }
  75         return ~sum;
  76 }
  77 
  78 static bool afs_is_v1(struct mtd_info *mtd, u_int off)
  79 {
  80         /* The magic is 12 bytes from the end of the erase block */
  81         u_int ptr = off + mtd->erasesize - 12;
  82         u32 magic;
  83         size_t sz;
  84         int ret;
  85 
  86         ret = mtd_read(mtd, ptr, 4, &sz, (u_char *)&magic);
  87         if (ret < 0) {
  88                 printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
  89                        ptr, ret);
  90                 return false;
  91         }
  92         if (ret >= 0 && sz != 4)
  93                 return false;
  94 
  95         return (magic == AFSV1_FOOTER_MAGIC);
  96 }
  97 
  98 static bool afs_is_v2(struct mtd_info *mtd, u_int off)
  99 {
 100         /* The magic is the 8 last bytes of the erase block */
 101         u_int ptr = off + mtd->erasesize - 8;
 102         u32 foot[2];
 103         size_t sz;
 104         int ret;
 105 
 106         ret = mtd_read(mtd, ptr, 8, &sz, (u_char *)foot);
 107         if (ret < 0) {
 108                 printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
 109                        ptr, ret);
 110                 return false;
 111         }
 112         if (ret >= 0 && sz != 8)
 113                 return false;
 114 
 115         return (foot[0] == AFSV2_FOOTER_MAGIC1 &&
 116                 foot[1] == AFSV2_FOOTER_MAGIC2);
 117 }
 118 
 119 static int afs_parse_v1_partition(struct mtd_info *mtd,
 120                                   u_int off, struct mtd_partition *part)
 121 {
 122         struct footer_v1 fs;
 123         struct image_info_v1 iis;
 124         u_int mask;
 125         /*
 126          * Static checks cannot see that we bail out if we have an error
 127          * reading the footer.
 128          */
 129         u_int uninitialized_var(iis_ptr);
 130         u_int uninitialized_var(img_ptr);
 131         u_int ptr;
 132         size_t sz;
 133         int ret;
 134         int i;
 135 
 136         /*
 137          * This is the address mask; we use this to mask off out of
 138          * range address bits.
 139          */
 140         mask = mtd->size - 1;
 141 
 142         ptr = off + mtd->erasesize - sizeof(fs);
 143         ret = mtd_read(mtd, ptr, sizeof(fs), &sz, (u_char *)&fs);
 144         if (ret >= 0 && sz != sizeof(fs))
 145                 ret = -EINVAL;
 146         if (ret < 0) {
 147                 printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
 148                        ptr, ret);
 149                 return ret;
 150         }
 151         /*
 152          * Check the checksum.
 153          */
 154         if (word_sum(&fs, sizeof(fs) / sizeof(u32)) != 0xffffffff)
 155                 return -EINVAL;
 156 
 157         /*
 158          * Hide the SIB (System Information Block)
 159          */
 160         if (fs.type == 2)
 161                 return 0;
 162 
 163         iis_ptr = fs.image_info_base & mask;
 164         img_ptr = fs.image_start & mask;
 165 
 166         /*
 167          * Check the image info base.  This can not
 168          * be located after the footer structure.
 169          */
 170         if (iis_ptr >= ptr)
 171                 return 0;
 172 
 173         /*
 174          * Check the start of this image.  The image
 175          * data can not be located after this block.
 176          */
 177         if (img_ptr > off)
 178                 return 0;
 179 
 180         /* Read the image info block */
 181         memset(&iis, 0, sizeof(iis));
 182         ret = mtd_read(mtd, iis_ptr, sizeof(iis), &sz, (u_char *)&iis);
 183         if (ret < 0) {
 184                 printk(KERN_ERR "AFS: mtd read failed at 0x%x: %d\n",
 185                        iis_ptr, ret);
 186                 return -EINVAL;
 187         }
 188 
 189         if (sz != sizeof(iis))
 190                 return -EINVAL;
 191 
 192         /*
 193          * Validate the name - it must be NUL terminated.
 194          */
 195         for (i = 0; i < sizeof(iis.name); i++)
 196                 if (iis.name[i] == '\0')
 197                         break;
 198         if (i > sizeof(iis.name))
 199                 return -EINVAL;
 200 
 201         part->name = kstrdup(iis.name, GFP_KERNEL);
 202         if (!part->name)
 203                 return -ENOMEM;
 204 
 205         part->size = (iis.length + mtd->erasesize - 1) & ~(mtd->erasesize - 1);
 206         part->offset = img_ptr;
 207         part->mask_flags = 0;
 208 
 209         printk("  mtd: at 0x%08x, %5lluKiB, %8u, %s\n",
 210                img_ptr, part->size / 1024,
 211                iis.imageNumber, part->name);
 212 
 213         return 0;
 214 }
 215 
 216 static int afs_parse_v2_partition(struct mtd_info *mtd,
 217                                   u_int off, struct mtd_partition *part)
 218 {
 219         u_int ptr;
 220         u32 footer[12];
 221         u32 imginfo[36];
 222         char *name;
 223         u32 version;
 224         u32 entrypoint;
 225         u32 attributes;
 226         u32 region_count;
 227         u32 block_start;
 228         u32 block_end;
 229         u32 crc;
 230         size_t sz;
 231         int ret;
 232         int i;
 233         int pad = 0;
 234 
 235         pr_debug("Parsing v2 partition @%08x-%08x\n",
 236                  off, off + mtd->erasesize);
 237 
 238         /* First read the footer */
 239         ptr = off + mtd->erasesize - sizeof(footer);
 240         ret = mtd_read(mtd, ptr, sizeof(footer), &sz, (u_char *)footer);
 241         if ((ret < 0) || (ret >= 0 && sz != sizeof(footer))) {
 242                 pr_err("AFS: mtd read failed at 0x%x: %d\n",
 243                        ptr, ret);
 244                 return -EIO;
 245         }
 246         name = (char *) &footer[0];
 247         version = footer[9];
 248         ptr = off + mtd->erasesize - sizeof(footer) - footer[8];
 249 
 250         pr_debug("found image \"%s\", version %08x, info @%08x\n",
 251                  name, version, ptr);
 252 
 253         /* Then read the image information */
 254         ret = mtd_read(mtd, ptr, sizeof(imginfo), &sz, (u_char *)imginfo);
 255         if ((ret < 0) || (ret >= 0 && sz != sizeof(imginfo))) {
 256                 pr_err("AFS: mtd read failed at 0x%x: %d\n",
 257                        ptr, ret);
 258                 return -EIO;
 259         }
 260 
 261         /* 32bit platforms have 4 bytes padding */
 262         crc = word_sum_v2(&imginfo[1], 34);
 263         if (!crc) {
 264                 pr_debug("Padding 1 word (4 bytes)\n");
 265                 pad = 1;
 266         } else {
 267                 /* 64bit platforms have 8 bytes padding */
 268                 crc = word_sum_v2(&imginfo[2], 34);
 269                 if (!crc) {
 270                         pr_debug("Padding 2 words (8 bytes)\n");
 271                         pad = 2;
 272                 }
 273         }
 274         if (crc) {
 275                 pr_err("AFS: bad checksum on v2 image info: %08x\n", crc);
 276                 return -EINVAL;
 277         }
 278         entrypoint = imginfo[pad];
 279         attributes = imginfo[pad+1];
 280         region_count = imginfo[pad+2];
 281         block_start = imginfo[20];
 282         block_end = imginfo[21];
 283 
 284         pr_debug("image entry=%08x, attr=%08x, regions=%08x, "
 285                  "bs=%08x, be=%08x\n",
 286                  entrypoint, attributes, region_count,
 287                  block_start, block_end);
 288 
 289         for (i = 0; i < region_count; i++) {
 290                 u32 region_load_addr = imginfo[pad + 3 + i*4];
 291                 u32 region_size = imginfo[pad + 4 + i*4];
 292                 u32 region_offset = imginfo[pad + 5 + i*4];
 293                 u32 region_start;
 294                 u32 region_end;
 295 
 296                 pr_debug("  region %d: address: %08x, size: %08x, "
 297                          "offset: %08x\n",
 298                          i,
 299                          region_load_addr,
 300                          region_size,
 301                          region_offset);
 302 
 303                 region_start = off + region_offset;
 304                 region_end = region_start + region_size;
 305                 /* Align partition to end of erase block */
 306                 region_end += (mtd->erasesize - 1);
 307                 region_end &= ~(mtd->erasesize -1);
 308                 pr_debug("   partition start = %08x, partition end = %08x\n",
 309                          region_start, region_end);
 310 
 311                 /* Create one partition per region */
 312                 part->name = kstrdup(name, GFP_KERNEL);
 313                 if (!part->name)
 314                         return -ENOMEM;
 315                 part->offset = region_start;
 316                 part->size = region_end - region_start;
 317                 part->mask_flags = 0;
 318         }
 319 
 320         return 0;
 321 }
 322 
 323 static int parse_afs_partitions(struct mtd_info *mtd,
 324                                 const struct mtd_partition **pparts,
 325                                 struct mtd_part_parser_data *data)
 326 {
 327         struct mtd_partition *parts;
 328         u_int off, sz;
 329         int ret = 0;
 330         int i;
 331 
 332         /* Count the partitions by looping over all erase blocks */
 333         for (i = off = sz = 0; off < mtd->size; off += mtd->erasesize) {
 334                 if (afs_is_v1(mtd, off)) {
 335                         sz += sizeof(struct mtd_partition);
 336                         i += 1;
 337                 }
 338                 if (afs_is_v2(mtd, off)) {
 339                         sz += sizeof(struct mtd_partition);
 340                         i += 1;
 341                 }
 342         }
 343 
 344         if (!i)
 345                 return 0;
 346 
 347         parts = kzalloc(sz, GFP_KERNEL);
 348         if (!parts)
 349                 return -ENOMEM;
 350 
 351         /*
 352          * Identify the partitions
 353          */
 354         for (i = off = 0; off < mtd->size; off += mtd->erasesize) {
 355                 if (afs_is_v1(mtd, off)) {
 356                         ret = afs_parse_v1_partition(mtd, off, &parts[i]);
 357                         if (ret)
 358                                 goto out_free_parts;
 359                         i++;
 360                 }
 361                 if (afs_is_v2(mtd, off)) {
 362                         ret = afs_parse_v2_partition(mtd, off, &parts[i]);
 363                         if (ret)
 364                                 goto out_free_parts;
 365                         i++;
 366                 }
 367         }
 368 
 369         *pparts = parts;
 370         return i;
 371 
 372 out_free_parts:
 373         while (i >= 0) {
 374                 kfree(parts[i].name);
 375                 i--;
 376         }
 377         kfree(parts);
 378         *pparts = NULL;
 379         return ret;
 380 }
 381 
 382 static const struct of_device_id mtd_parser_afs_of_match_table[] = {
 383         { .compatible = "arm,arm-firmware-suite" },
 384         {},
 385 };
 386 MODULE_DEVICE_TABLE(of, mtd_parser_afs_of_match_table);
 387 
 388 static struct mtd_part_parser afs_parser = {
 389         .parse_fn = parse_afs_partitions,
 390         .name = "afs",
 391         .of_match_table = mtd_parser_afs_of_match_table,
 392 };
 393 module_mtd_part_parser(afs_parser);
 394 
 395 MODULE_AUTHOR("ARM Ltd");
 396 MODULE_DESCRIPTION("ARM Firmware Suite partition parser");
 397 MODULE_LICENSE("GPL");