src/arch/i386/image/bzimage.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 /**
  22  * @file
  23  *
  24  * Linux bzImage image format
  25  *
  26  */
  27
  28 #include <stdint.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <errno.h>
  32 #include <assert.h>
  33 #include <realmode.h>
  34 #include <bzimage.h>
  35 #include <gpxe/uaccess.h>
  36 #include <gpxe/image.h>
  37 #include <gpxe/segment.h>
  38 #include <gpxe/init.h>
  39 #include <gpxe/cpio.h>
  40 #include <gpxe/features.h>
  41
  42 FEATURE ( FEATURE_IMAGE, "bzImage", DHCP_EB_FEATURE_BZIMAGE, 1 );
  43
  44 struct image_type bzimage_image_type __image_type ( PROBE_NORMAL );
  45
  46 /**
  47  * bzImage context
  48  */
  49 struct bzimage_context {
  50         /** Boot protocol version */
  51         unsigned int version;
  52         /** Real-mode kernel portion load segment address */
  53         unsigned int rm_kernel_seg;
  54         /** Real-mode kernel portion load address */
  55         userptr_t rm_kernel;
  56         /** Real-mode kernel portion file size */
  57         size_t rm_filesz;
  58         /** Real-mode heap top (offset from rm_kernel) */
  59         size_t rm_heap;
  60         /** Command line (offset from rm_kernel) */
  61         size_t rm_cmdline;
  62         /** Command line maximum length */
  63         size_t cmdline_size;
  64         /** Real-mode kernel portion total memory size */
  65         size_t rm_memsz;
  66         /** Non-real-mode kernel portion load address */
  67         userptr_t pm_kernel;
  68         /** Non-real-mode kernel portion file and memory size */
  69         size_t pm_sz;
  70         /** Video mode */
  71         unsigned int vid_mode;
  72         /** Memory limit */
  73         uint64_t mem_limit;
  74         /** Initrd address */
  75         physaddr_t ramdisk_image;
  76         /** Initrd size */
  77         physaddr_t ramdisk_size;
  78
  79         /** Command line magic block */
  80         struct bzimage_cmdline cmdline_magic;
  81         /** bzImage header */
  82         struct bzimage_header bzhdr;
  83 };
  84
  85 /**
  86  * Parse bzImage header
  87  *
  88  * @v image             bzImage file
  89  * @v bzimg             bzImage context
  90  * @v src               bzImage to parse
  91  * @ret rc              Return status code
  92  */
  93 static int bzimage_parse_header ( struct image *image,
  94                                   struct bzimage_context *bzimg,
  95                                   userptr_t src ) {
  96         unsigned int syssize;
  97         int is_bzimage;
  98
  99         /* Sanity check */
 100         if ( image->len < ( BZI_HDR_OFFSET + sizeof ( bzimg->bzhdr ) ) ) {
 101                 DBGC ( image, "bzImage %p too short for kernel header\n",
 102                        image );
 103                 return -ENOEXEC;
 104         }
 105
 106         /* Read in header structures */
 107         memset ( bzimg, 0, sizeof ( *bzimg ) );
 108         copy_from_user ( &bzimg->cmdline_magic, src, BZI_CMDLINE_OFFSET,
 109                          sizeof ( bzimg->cmdline_magic ) );
 110         copy_from_user ( &bzimg->bzhdr, src, BZI_HDR_OFFSET,
 111                          sizeof ( bzimg->bzhdr ) );
 112
 113         /* Calculate size of real-mode portion */
 114         bzimg->rm_filesz =
 115                 ( ( bzimg->bzhdr.setup_sects ? bzimg->bzhdr.setup_sects : 4 ) + 1 ) << 9;
 116         if ( bzimg->rm_filesz > image->len ) {
 117                 DBGC ( image, "bzImage %p too short for %zd byte of setup\n",
 118                        image, bzimg->rm_filesz );
 119                 return -ENOEXEC;
 120         }
 121         bzimg->rm_memsz = BZI_ASSUMED_RM_SIZE;
 122
 123         /* Calculate size of protected-mode portion */
 124         bzimg->pm_sz = ( image->len - bzimg->rm_filesz );
 125         syssize = ( ( bzimg->pm_sz + 15 ) / 16 );
 126
 127         /* Check for signatures and determine version */
 128         if ( bzimg->bzhdr.boot_flag != BZI_BOOT_FLAG ) {
 129                 DBGC ( image, "bzImage %p missing 55AA signature\n", image );
 130                 return -ENOEXEC;
 131         }
 132         if ( bzimg->bzhdr.header == BZI_SIGNATURE ) {
 133                 /* 2.00+ */
 134                 bzimg->version = bzimg->bzhdr.version;
 135         } else {
 136                 /* Pre-2.00.  Check that the syssize field is correct,
 137                  * as a guard against accepting arbitrary binary data,
 138                  * since the 55AA check is pretty lax.  Note that the
 139                  * syssize field is unreliable for protocols between
 140                  * 2.00 and 2.03 inclusive, so we should not always
 141                  * check this field.
 142                  */
 143                 bzimg->version = 0x0100;
 144                 if ( bzimg->bzhdr.syssize != syssize ) {
 145                         DBGC ( image, "bzImage %p bad syssize %x (expected "
 146                                "%x)\n", image, bzimg->bzhdr.syssize, syssize );
 147                         return -ENOEXEC;
 148                 }
 149         }
 150
 151         /* Determine image type */
 152         is_bzimage = ( ( bzimg->version >= 0x0200 ) ?
 153                        ( bzimg->bzhdr.loadflags & BZI_LOAD_HIGH ) : 0 );
 154
 155         /* Calculate load address of real-mode portion */
 156         bzimg->rm_kernel_seg = ( is_bzimage ? 0x1000 : 0x9000 );
 157         bzimg->rm_kernel = real_to_user ( bzimg->rm_kernel_seg, 0 );
 158
 159         /* Allow space for the stack and heap */
 160         bzimg->rm_memsz += BZI_STACK_SIZE;
 161         bzimg->rm_heap = bzimg->rm_memsz;
 162
 163         /* Allow space for the command line */
 164         bzimg->rm_cmdline = bzimg->rm_memsz;
 165         bzimg->rm_memsz += BZI_CMDLINE_SIZE;
 166
 167         /* Calculate load address of protected-mode portion */
 168         bzimg->pm_kernel = phys_to_user ( is_bzimage ? BZI_LOAD_HIGH_ADDR
 169                                         : BZI_LOAD_LOW_ADDR );
 170
 171         /* Extract video mode */
 172         bzimg->vid_mode = bzimg->bzhdr.vid_mode;
 173
 174         /* Extract memory limit */
 175         bzimg->mem_limit = ( ( bzimg->version >= 0x0203 ) ?
 176                              bzimg->bzhdr.initrd_addr_max : BZI_INITRD_MAX );
 177
 178         /* Extract command line size */
 179         bzimg->cmdline_size = ( ( bzimg->version >= 0x0206 ) ?
 180                                 bzimg->bzhdr.cmdline_size : BZI_CMDLINE_SIZE );
 181
 182         DBGC ( image, "bzImage %p version %04x RM %#lx+%#zx PM %#lx+%#zx "
 183                "cmdlen %zd\n", image, bzimg->version,
 184                user_to_phys ( bzimg->rm_kernel, 0 ), bzimg->rm_filesz,
 185                user_to_phys ( bzimg->pm_kernel, 0 ), bzimg->pm_sz,
 186                bzimg->cmdline_size );
 187
 188         return 0;
 189 }
 190
 191 /**
 192  * Update bzImage header in loaded kernel
 193  *
 194  * @v image             bzImage file
 195  * @v bzimg             bzImage context
 196  * @v dst               bzImage to update
 197  */
 198 static void bzimage_update_header ( struct image *image,
 199                                     struct bzimage_context *bzimg,
 200                                     userptr_t dst ) {
 201
 202         /* Set loader type */
 203         if ( bzimg->version >= 0x0200 )
 204                 bzimg->bzhdr.type_of_loader = BZI_LOADER_TYPE_GPXE;
 205
 206         /* Set heap end pointer */
 207         if ( bzimg->version >= 0x0201 ) {
 208                 bzimg->bzhdr.heap_end_ptr = ( bzimg->rm_heap - 0x200 );
 209                 bzimg->bzhdr.loadflags |= BZI_CAN_USE_HEAP;
 210         }
 211
 212         /* Set command line */
 213         if ( bzimg->version >= 0x0202 ) {
 214                 bzimg->bzhdr.cmd_line_ptr = user_to_phys ( bzimg->rm_kernel,
 215                                                            bzimg->rm_cmdline );
 216         } else {
 217                 bzimg->cmdline_magic.magic = BZI_CMDLINE_MAGIC;
 218                 bzimg->cmdline_magic.offset = bzimg->rm_cmdline;
 219                 bzimg->bzhdr.setup_move_size = bzimg->rm_memsz;
 220         }
 221
 222         /* Set video mode */
 223         bzimg->bzhdr.vid_mode = bzimg->vid_mode;
 224
 225         /* Set initrd address */
 226         if ( bzimg->version >= 0x0200 ) {
 227                 bzimg->bzhdr.ramdisk_image = bzimg->ramdisk_image;
 228                 bzimg->bzhdr.ramdisk_size = bzimg->ramdisk_size;
 229         }
 230
 231         /* Write out header structures */
 232         copy_to_user ( dst, BZI_CMDLINE_OFFSET, &bzimg->cmdline_magic,
 233                        sizeof ( bzimg->cmdline_magic ) );
 234         copy_to_user ( dst, BZI_HDR_OFFSET, &bzimg->bzhdr,
 235                        sizeof ( bzimg->bzhdr ) );
 236
 237         DBGC ( image, "bzImage %p vidmode %d\n", image, bzimg->vid_mode );
 238 }
 239
 240 /**
 241  * Parse kernel command line for bootloader parameters
 242  *
 243  * @v image             bzImage file
 244  * @v bzimg             bzImage context
 245  * @v cmdline           Kernel command line
 246  * @ret rc              Return status code
 247  */
 248 static int bzimage_parse_cmdline ( struct image *image,
 249                                    struct bzimage_context *bzimg,
 250                                    const char *cmdline ) {
 251         char *vga;
 252         char *mem;
 253
 254         /* Look for "vga=" */
 255         if ( ( vga = strstr ( cmdline, "vga=" ) ) ) {
 256                 vga += 4;
 257                 if ( strcmp ( vga, "normal" ) == 0 ) {
 258                         bzimg->vid_mode = BZI_VID_MODE_NORMAL;
 259                 } else if ( strcmp ( vga, "ext" ) == 0 ) {
 260                         bzimg->vid_mode = BZI_VID_MODE_EXT;
 261                 } else if ( strcmp ( vga, "ask" ) == 0 ) {
 262                         bzimg->vid_mode = BZI_VID_MODE_ASK;
 263                 } else {
 264                         bzimg->vid_mode = strtoul ( vga, &vga, 0 );
 265                         if ( *vga && ( *vga != ' ' ) ) {
 266                                 DBGC ( image, "bzImage %p strange \"vga=\""
 267                                        "terminator '%c'\n", image, *vga );
 268                         }
 269                 }
 270         }
 271
 272         /* Look for "mem=" */
 273         if ( ( mem = strstr ( cmdline, "mem=" ) ) ) {
 274                 mem += 4;
 275                 bzimg->mem_limit = strtoul ( mem, &mem, 0 );
 276                 switch ( *mem ) {
 277                 case 'G':
 278                 case 'g':
 279                         bzimg->mem_limit <<= 10;
 280                 case 'M':
 281                 case 'm':
 282                         bzimg->mem_limit <<= 10;
 283                 case 'K':
 284                 case 'k':
 285                         bzimg->mem_limit <<= 10;
 286                         break;
 287                 case '\0':
 288                 case ' ':
 289                         break;
 290                 default:
 291                         DBGC ( image, "bzImage %p strange \"mem=\" "
 292                                "terminator '%c'\n", image, *mem );
 293                         break;
 294                 }
 295                 bzimg->mem_limit -= 1;
 296         }
 297
 298         return 0;
 299 }
 300
 301 /**
 302  * Set command line
 303  *
 304  * @v image             bzImage image
 305  * @v bzimg             bzImage context
 306  * @v cmdline           Kernel command line
 307  * @ret rc              Return status code
 308  */
 309 static int bzimage_set_cmdline ( struct image *image,
 310                                  struct bzimage_context *bzimg,
 311                                  const char *cmdline ) {
 312         size_t cmdline_len;
 313
 314         /* Copy command line down to real-mode portion */
 315         cmdline_len = ( strlen ( cmdline ) + 1 );
 316         if ( cmdline_len > bzimg->cmdline_size )
 317                 cmdline_len = bzimg->cmdline_size;
 318         copy_to_user ( bzimg->rm_kernel, bzimg->rm_cmdline,
 319                        cmdline, cmdline_len );
 320         DBGC ( image, "bzImage %p command line \"%s\"\n", image, cmdline );
 321
 322         return 0;
 323 }
 324
 325 /**
 326  * Load initrd
 327  *
 328  * @v image             bzImage image
 329  * @v initrd            initrd image
 330  * @v address           Address at which to load, or UNULL
 331  * @ret len             Length of loaded image, rounded up to 4 bytes
 332  */
 333 static size_t bzimage_load_initrd ( struct image *image,
 334                                     struct image *initrd,
 335                                     userptr_t address ) {
 336         char *filename = initrd->cmdline;
 337         struct cpio_header cpio;
 338         size_t offset = 0;
 339
 340         /* Do not include kernel image itself as an initrd */
 341         if ( initrd == image )
 342                 return 0;
 343
 344         /* Create cpio header before non-prebuilt images */
 345         if ( filename && filename[0] ) {
 346                 size_t name_len = ( strlen ( filename ) + 1 );
 347
 348                 DBGC ( image, "bzImage %p inserting initrd %p as %s\n",
 349                        image, initrd, filename );
 350                 memset ( &cpio, '0', sizeof ( cpio ) );
 351                 memcpy ( cpio.c_magic, CPIO_MAGIC, sizeof ( cpio.c_magic ) );
 352                 cpio_set_field ( cpio.c_mode, 0100644 );
 353                 cpio_set_field ( cpio.c_nlink, 1 );
 354                 cpio_set_field ( cpio.c_filesize, initrd->len );
 355                 cpio_set_field ( cpio.c_namesize, name_len );
 356                 if ( address ) {
 357                         copy_to_user ( address, offset, &cpio,
 358                                        sizeof ( cpio ) );
 359                 }
 360                 offset += sizeof ( cpio );
 361                 if ( address ) {
 362                         copy_to_user ( address, offset, filename,
 363                                        name_len );
 364                 }
 365                 offset += name_len;
 366                 offset = ( ( offset + 0x03 ) & ~0x03 );
 367         }
 368
 369         /* Copy in initrd image body */
 370         if ( address )
 371                 memcpy_user ( address, offset, initrd->data, 0, initrd->len );
 372         offset += initrd->len;
 373         if ( address ) {
 374                 DBGC ( image, "bzImage %p has initrd %p at [%lx,%lx)\n",
 375                        image, initrd, user_to_phys ( address, 0 ),
 376                        user_to_phys ( address, offset ) );
 377         }
 378
 379         /* Round up to 4-byte boundary */
 380         offset = ( ( offset + 0x03 ) & ~0x03 );
 381         return offset;
 382 }
 383
 384 /**
 385  * Load initrds, if any
 386  *
 387  * @v image             bzImage image
 388  * @v bzimg             bzImage context
 389  * @ret rc              Return status code
 390  */
 391 static int bzimage_load_initrds ( struct image *image,
 392                                   struct bzimage_context *bzimg ) {
 393         struct image *initrd;
 394         size_t total_len = 0;
 395         physaddr_t address;
 396         int rc;
 397
 398         /* Add up length of all initrd images */
 399         for_each_image ( initrd )
 400                 total_len += bzimage_load_initrd ( image, initrd, UNULL );
 401
 402         /* Give up if no initrd images found */
 403         if ( ! total_len )
 404                 return 0;
 405
 406         /* Find a suitable start address.  Try 1MB boundaries,
 407          * starting from the downloaded kernel image itself and
 408          * working downwards until we hit an available region.
 409          */
 410         for ( address = ( user_to_phys ( image->data, 0 ) & ~0xfffff ) ; ;
 411               address -= 0x100000 ) {
 412                 /* Check that we're not going to overwrite the
 413                  * kernel itself.  This check isn't totally
 414                  * accurate, but errs on the side of caution.
 415                  */
 416                 if ( address <= ( BZI_LOAD_HIGH_ADDR + image->len ) ) {
 417                         DBGC ( image, "bzImage %p could not find a location "
 418                                "for initrd\n", image );
 419                         return -ENOBUFS;
 420                 }
 421                 /* Check that we are within the kernel's range */
 422                 if ( ( address + total_len - 1 ) > bzimg->mem_limit )
 423                         continue;
 424                 /* Prepare and verify segment */
 425                 if ( ( rc = prep_segment ( phys_to_user ( address ), 0,
 426                                            total_len ) ) != 0 )
 427                         continue;
 428                 /* Use this address */
 429                 break;
 430         }
 431
 432         /* Record initrd location */
 433         bzimg->ramdisk_image = address;
 434         bzimg->ramdisk_size = total_len;
 435
 436         /* Construct initrd */
 437         DBGC ( image, "bzImage %p constructing initrd at [%lx,%lx)\n",
 438                image, address, ( address + total_len ) );
 439         for_each_image ( initrd ) {
 440                 address += bzimage_load_initrd ( image, initrd,
 441                                                  phys_to_user ( address ) );
 442         }
 443
 444         return 0;
 445 }
 446
 447 /**
 448  * Execute bzImage image
 449  *
 450  * @v image             bzImage image
 451  * @ret rc              Return status code
 452  */
 453 static int bzimage_exec ( struct image *image ) {
 454         struct bzimage_context bzimg;
 455         const char *cmdline = ( image->cmdline ? image->cmdline : "" );
 456         int rc;
 457
 458         /* Read and parse header from loaded kernel */
 459         if ( ( rc = bzimage_parse_header ( image, &bzimg,
 460                                            image->priv.user ) ) != 0 )
 461                 return rc;
 462         assert ( bzimg.rm_kernel == image->priv.user );
 463
 464         /* Parse command line for bootloader parameters */
 465         if ( ( rc = bzimage_parse_cmdline ( image, &bzimg, cmdline ) ) != 0)
 466                 return rc;
 467
 468         /* Store command line */
 469         if ( ( rc = bzimage_set_cmdline ( image, &bzimg, cmdline ) ) != 0 )
 470                 return rc;
 471
 472         /* Load any initrds */
 473         if ( ( rc = bzimage_load_initrds ( image, &bzimg ) ) != 0 )
 474                 return rc;
 475
 476         /* Update kernel header */
 477         bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );
 478
 479         /* Prepare for exiting */
 480         shutdown ( SHUTDOWN_BOOT );
 481
 482         DBGC ( image, "bzImage %p jumping to RM kernel at %04x:0000 "
 483                "(stack %04x:%04zx)\n", image, ( bzimg.rm_kernel_seg + 0x20 ),
 484                bzimg.rm_kernel_seg, bzimg.rm_heap );
 485
 486         /* Jump to the kernel */
 487         __asm__ __volatile__ ( REAL_CODE ( "movw %w0, %%ds\n\t"
 488                                            "movw %w0, %%es\n\t"
 489                                            "movw %w0, %%fs\n\t"
 490                                            "movw %w0, %%gs\n\t"
 491                                            "movw %w0, %%ss\n\t"
 492                                            "movw %w1, %%sp\n\t"
 493                                            "pushw %w2\n\t"
 494                                            "pushw $0\n\t"
 495                                            "lret\n\t" )
 496                                : : "r" ( bzimg.rm_kernel_seg ),
 497                                    "r" ( bzimg.rm_heap ),
 498                                    "r" ( bzimg.rm_kernel_seg + 0x20 ) );
 499
 500         /* There is no way for the image to return, since we provide
 501          * no return address.
 502          */
 503         assert ( 0 );
 504
 505         return -ECANCELED; /* -EIMPOSSIBLE */
 506 }
 507
 508 /**
 509  * Load bzImage image into memory
 510  *
 511  * @v image             bzImage file
 512  * @ret rc              Return status code
 513  */
 514 int bzimage_load ( struct image *image ) {
 515         struct bzimage_context bzimg;
 516         int rc;
 517
 518         /* Read and parse header from image */
 519         if ( ( rc = bzimage_parse_header ( image, &bzimg,
 520                                            image->data ) ) != 0 )
 521                 return rc;
 522
 523         /* This is a bzImage image, valid or otherwise */
 524         if ( ! image->type )
 525                 image->type = &bzimage_image_type;
 526
 527         /* Prepare segments */
 528         if ( ( rc = prep_segment ( bzimg.rm_kernel, bzimg.rm_filesz,
 529                                    bzimg.rm_memsz ) ) != 0 ) {
 530                 DBGC ( image, "bzImage %p could not prepare RM segment: %s\n",
 531                        image, strerror ( rc ) );
 532                 return rc;
 533         }
 534         if ( ( rc = prep_segment ( bzimg.pm_kernel, bzimg.pm_sz,
 535                                    bzimg.pm_sz ) ) != 0 ) {
 536                 DBGC ( image, "bzImage %p could not prepare PM segment: %s\n",
 537                        image, strerror ( rc ) );
 538                 return rc;
 539         }
 540
 541         /* Load segments */
 542         memcpy_user ( bzimg.rm_kernel, 0, image->data,
 543                       0, bzimg.rm_filesz );
 544         memcpy_user ( bzimg.pm_kernel, 0, image->data,
 545                       bzimg.rm_filesz, bzimg.pm_sz );
 546
 547         /* Update and write out header */
 548         bzimage_update_header ( image, &bzimg, bzimg.rm_kernel );
 549
 550         /* Record real-mode segment in image private data field */
 551         image->priv.user = bzimg.rm_kernel;
 552
 553         return 0;
 554 }
 555
 556 /** Linux bzImage image type */
 557 struct image_type bzimage_image_type __image_type ( PROBE_NORMAL ) = {
 558         .name = "bzImage",
 559         .load = bzimage_load,
 560         .exec = bzimage_exec,
 561 };