arch/common/boot/grub2/loader/i386/linux.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2006,2007,2008  Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <grub/loader.h>
  20 #include <grub/machine/machine.h>
  21 #include <grub/machine/memory.h>
  22 #include <grub/machine/loader.h>
  23 #include <grub/file.h>
  24 #include <grub/disk.h>
  25 #include <grub/err.h>
  26 #include <grub/misc.h>
  27 #include <grub/types.h>
  28 #include <grub/rescue.h>
  29 #include <grub/dl.h>
  30 #include <grub/mm.h>
  31 #include <grub/term.h>
  32 #include <grub/cpu/linux.h>
  33
  34 #define GRUB_LINUX_CL_OFFSET            0x1000
  35 #define GRUB_LINUX_CL_END_OFFSET        0x2000
  36
  37 static grub_dl_t my_mod;
  38
  39 static grub_size_t linux_mem_size;
  40 static int loaded;
  41 static void *real_mode_mem;
  42 static void *prot_mode_mem;
  43 static void *initrd_mem;
  44 static grub_uint32_t real_mode_pages;
  45 static grub_uint32_t prot_mode_pages;
  46 static grub_uint32_t initrd_pages;
  47
  48 static grub_uint8_t gdt[] __attribute__ ((aligned(16))) =
  49   {
  50     /* NULL.  */
  51     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  52     /* Reserved.  */
  53     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  54     /* Code segment.  */
  55     0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9A, 0xCF, 0x00,
  56     /* Data segment.  */
  57     0xFF, 0xFF, 0x00, 0x00, 0x00, 0x92, 0xCF, 0x00
  58   };
  59
  60 struct gdt_descriptor
  61 {
  62   grub_uint16_t limit;
  63   void *base;
  64 } __attribute__ ((packed));
  65
  66 static struct gdt_descriptor gdt_desc =
  67   {
  68     sizeof (gdt) - 1,
  69     gdt
  70   };
  71
  72 struct idt_descriptor
  73 {
  74   grub_uint16_t limit;
  75   void *base;
  76 } __attribute__ ((packed));
  77
  78 static struct idt_descriptor idt_desc =
  79   {
  80     0,
  81     0
  82   };
  83
  84 static inline grub_size_t
  85 page_align (grub_size_t size)
  86 {
  87   return (size + (1 << 12) - 1) & (~((1 << 12) - 1));
  88 }
  89
  90 /* Find the optimal number of pages for the memory map. */
  91 static grub_size_t
  92 find_mmap_size (void)
  93 {
  94   grub_size_t count = 0, mmap_size;
  95
  96   auto int NESTED_FUNC_ATTR hook (grub_uint64_t, grub_uint64_t, grub_uint32_t);
  97   int NESTED_FUNC_ATTR hook (grub_uint64_t addr __attribute__ ((unused)),
  98                              grub_uint64_t size __attribute__ ((unused)),
  99                              grub_uint32_t type __attribute__ ((unused)))
 100     {
 101       count++;
 102       return 0;
 103     }
 104
 105   grub_machine_mmap_iterate (hook);
 106
 107   mmap_size = count * sizeof (struct grub_e820_mmap);
 108
 109   /* Increase the size a bit for safety, because GRUB allocates more on
 110      later.  */
 111   mmap_size += (1 << 12);
 112
 113   return page_align (mmap_size);
 114 }
 115
 116 static void
 117 free_pages (void)
 118 {
 119   real_mode_mem = prot_mode_mem = initrd_mem = 0;
 120 }
 121
 122 /* Allocate pages for the real mode code and the protected mode code
 123    for linux as well as a memory map buffer.  */
 124 static int
 125 allocate_pages (grub_size_t prot_size)
 126 {
 127   grub_size_t real_size, mmap_size;
 128
 129   /* Make sure that each size is aligned to a page boundary.  */
 130   real_size = GRUB_LINUX_CL_END_OFFSET;
 131   prot_size = page_align (prot_size);
 132   mmap_size = find_mmap_size ();
 133
 134   grub_dprintf ("linux", "real_size = %x, prot_size = %x, mmap_size = %x\n",
 135                 (unsigned) real_size, (unsigned) prot_size, (unsigned) mmap_size);
 136
 137   /* Calculate the number of pages; Combine the real mode code with
 138      the memory map buffer for simplicity.  */
 139   real_mode_pages = ((real_size + mmap_size) >> 12);
 140   prot_mode_pages = (prot_size >> 12);
 141
 142   /* Initialize the memory pointers with NULL for convenience.  */
 143   real_mode_mem = 0;
 144   prot_mode_mem = 0;
 145
 146   /* i386-pc port adds lower memory to heap, which collides with
 147      `real_mode_mem' allocation below.  */
 148 #ifdef GRUB_MACHINE_PCBIOS
 149 #error
 150 #endif
 151
 152   auto int NESTED_FUNC_ATTR hook (grub_uint64_t, grub_uint64_t, grub_uint32_t);
 153   int NESTED_FUNC_ATTR hook (grub_uint64_t addr, grub_uint64_t size, grub_uint32_t type)
 154     {
 155       /* We must put real mode code in the traditional space.  */
 156
 157       if (type == GRUB_MACHINE_MEMORY_AVAILABLE
 158           && addr <= 0x90000)
 159         {
 160           if (addr < 0x10000)
 161             {
 162               size += addr - 0x10000;
 163               addr = 0x10000;
 164             }
 165
 166           if (addr + size > 0x90000)
 167             size = 0x90000 - addr;
 168
 169           if (real_size + mmap_size > size)
 170             return 0;
 171
 172           real_mode_mem = (addr + size) - (real_size + mmap_size);
 173           return 1;
 174         }
 175
 176       return 0;
 177     }
 178   grub_machine_mmap_iterate (hook);
 179   if (! real_mode_mem)
 180     {
 181       grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate real mode pages");
 182       goto fail;
 183     }
 184
 185   prot_mode_mem = (void *) 0x100000;
 186
 187   grub_dprintf ("linux", "real_mode_mem = %lx, real_mode_pages = %x, "
 188                 "prot_mode_mem = %lx, prot_mode_pages = %x\n",
 189                 (unsigned long) real_mode_mem, (unsigned) real_mode_pages,
 190                 (unsigned long) prot_mode_mem, (unsigned) prot_mode_pages);
 191
 192   return 1;
 193
 194  fail:
 195   free_pages ();
 196   return 0;
 197 }
 198
 199 static void
 200 grub_e820_add_region (struct grub_e820_mmap *e820_map, int *e820_num,
 201                       grub_uint64_t start, grub_uint64_t size,
 202                       grub_uint32_t type)
 203 {
 204   int n = *e820_num;
 205
 206   if (n >= GRUB_E820_MAX_ENTRY)
 207     grub_fatal ("Too many e820 memory map entries");
 208
 209   if ((n > 0) && (e820_map[n - 1].addr + e820_map[n - 1].size == start) &&
 210       (e820_map[n - 1].type == type))
 211       e820_map[n - 1].size += size;
 212   else
 213     {
 214       e820_map[n].addr = start;
 215       e820_map[n].size = size;
 216       e820_map[n].type = type;
 217       (*e820_num)++;
 218     }
 219 }
 220
 221 #ifdef __x86_64__
 222 struct
 223 {
 224   grub_uint32_t kernel_entry;
 225   grub_uint32_t kernel_cs;
 226 } jumpvector;
 227 #endif
 228
 229 static grub_err_t
 230 grub_linux32_boot (void)
 231 {
 232   struct linux_kernel_params *params;
 233   int e820_num;
 234
 235   params = real_mode_mem;
 236
 237   grub_dprintf ("linux", "code32_start = %x, idt_desc = %lx, gdt_desc = %lx\n",
 238                 (unsigned) params->code32_start,
 239                 (unsigned long) &(idt_desc.limit),
 240                 (unsigned long) &(gdt_desc.limit));
 241   grub_dprintf ("linux", "idt = %x:%lx, gdt = %x:%lx\n",
 242                 (unsigned) idt_desc.limit, (unsigned long) idt_desc.base,
 243                 (unsigned) gdt_desc.limit, (unsigned long) gdt_desc.base);
 244
 245   auto int NESTED_FUNC_ATTR hook (grub_uint64_t, grub_uint64_t, grub_uint32_t);
 246   int NESTED_FUNC_ATTR hook (grub_uint64_t addr, grub_uint64_t size, grub_uint32_t type)
 247     {
 248       switch (type)
 249         {
 250         case GRUB_MACHINE_MEMORY_AVAILABLE:
 251           grub_e820_add_region (params->e820_map, &e820_num,
 252                                 addr, size, GRUB_E820_RAM);
 253           break;
 254
 255         default:
 256           grub_e820_add_region (params->e820_map, &e820_num,
 257                                 addr, size, GRUB_E820_RESERVED);
 258         }
 259       return 0;
 260     }
 261
 262   e820_num = 0;
 263   grub_machine_mmap_iterate (hook);
 264   params->mmap_size = e820_num;
 265
 266   /* Hardware interrupts are not safe any longer.  */
 267   asm volatile ("cli" : : );
 268
 269   /* Load the IDT and the GDT for the bootstrap.  */
 270   asm volatile ("lidt %0" : : "m" (idt_desc));
 271   asm volatile ("lgdt %0" : : "m" (gdt_desc));
 272
 273 #ifdef __x86_64__
 274
 275   jumpvector.kernel_entry = (grub_uint64_t) grub_linux_real_boot;
 276   jumpvector.kernel_cs = 0x10;
 277
 278   asm volatile ( "mov %0, %%rbx" : : "m" (params->code32_start));
 279   asm volatile ( "mov %0, %%rsi" : : "m" (real_mode_mem));
 280
 281   asm volatile ( "ljmp *%0" : : "m" (jumpvector));
 282
 283 #else
 284
 285   /* Pass parameters.  */
 286   asm volatile ("movl %0, %%ecx" : : "m" (params->code32_start));
 287   asm volatile ("movl %0, %%esi" : : "m" (real_mode_mem));
 288
 289   asm volatile ("xorl %%ebx, %%ebx" : : );
 290
 291   /* Enter Linux.  */
 292   asm volatile ("jmp *%%ecx" : : );
 293
 294 #endif
 295
 296   /* Never reach here.  */
 297   return GRUB_ERR_NONE;
 298 }
 299
 300 static grub_err_t
 301 grub_linux_unload (void)
 302 {
 303   free_pages ();
 304   grub_dl_unref (my_mod);
 305   loaded = 0;
 306   return GRUB_ERR_NONE;
 307 }
 308
 309 void
 310 grub_rescue_cmd_linux (int argc, char *argv[])
 311 {
 312   grub_file_t file = 0;
 313   struct linux_kernel_header lh;
 314   struct linux_kernel_params *params;
 315   grub_uint8_t setup_sects;
 316   grub_size_t real_size, prot_size;
 317   grub_ssize_t len;
 318   int i;
 319   char *dest;
 320   int video_type;
 321
 322   grub_dl_ref (my_mod);
 323
 324   if (argc == 0)
 325     {
 326       grub_error (GRUB_ERR_BAD_ARGUMENT, "no kernel specified");
 327       goto fail;
 328     }
 329
 330   file = grub_file_open (argv[0]);
 331   if (! file)
 332     goto fail;
 333
 334   if (grub_file_read (file, (char *) &lh, sizeof (lh)) != sizeof (lh))
 335     {
 336       grub_error (GRUB_ERR_READ_ERROR, "cannot read the linux header");
 337       goto fail;
 338     }
 339
 340   if (lh.boot_flag != grub_cpu_to_le16 (0xaa55))
 341     {
 342       grub_error (GRUB_ERR_BAD_OS, "invalid magic number");
 343       goto fail;
 344     }
 345
 346   if (lh.setup_sects > GRUB_LINUX_MAX_SETUP_SECTS)
 347     {
 348       grub_error (GRUB_ERR_BAD_OS, "too many setup sectors");
 349       goto fail;
 350     }
 351
 352   /* FIXME: Is 2.02 recent enough for 32-bit boot?  */
 353   if (lh.header != grub_cpu_to_le32 (GRUB_LINUX_MAGIC_SIGNATURE)
 354       || grub_le_to_cpu16 (lh.version) < 0x0203)
 355     {
 356       grub_error (GRUB_ERR_BAD_OS, "too old version");
 357       goto fail;
 358     }
 359
 360   /* zImage doesn't support 32-bit boot.  */
 361   if (! (lh.loadflags & GRUB_LINUX_FLAG_BIG_KERNEL))
 362     {
 363       grub_error (GRUB_ERR_BAD_OS, "zImage is not supported");
 364       goto fail;
 365     }
 366
 367   setup_sects = lh.setup_sects;
 368
 369   /* If SETUP_SECTS is not set, set it to the default (4).  */
 370   if (! setup_sects)
 371     setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;
 372
 373   real_size = setup_sects << GRUB_DISK_SECTOR_BITS;
 374   prot_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;
 375
 376   if (! allocate_pages (prot_size))
 377     goto fail;
 378
 379   params = (struct linux_kernel_params *) real_mode_mem;
 380   grub_memset (params, 0, GRUB_LINUX_CL_END_OFFSET);
 381   grub_memcpy (&params->setup_sects, &lh.setup_sects, sizeof (lh) - 0x1F1);
 382
 383   params->ps_mouse = params->padding10 =  0;
 384
 385   len = 0x400 - sizeof (lh);
 386   if (grub_file_read (file, (char *) real_mode_mem + sizeof (lh), len) != len)
 387     {
 388       grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");
 389       goto fail;
 390     }
 391
 392   params->type_of_loader = (LINUX_LOADER_ID_GRUB << 4);
 393
 394   params->cl_magic = GRUB_LINUX_CL_MAGIC;
 395   params->cl_offset = 0x1000;
 396   params->cmd_line_ptr = (unsigned long) real_mode_mem + 0x1000;
 397   params->ramdisk_image = 0;
 398   params->ramdisk_size = 0;
 399
 400   params->heap_end_ptr = GRUB_LINUX_HEAP_END_OFFSET;
 401   params->loadflags |= GRUB_LINUX_FLAG_CAN_USE_HEAP;
 402
 403   /* These are not needed to be precise, because Linux uses these values
 404      only to raise an error when the decompression code cannot find good
 405      space.  */
 406   params->ext_mem = ((32 * 0x100000) >> 10);
 407   params->alt_mem = ((32 * 0x100000) >> 10);
 408
 409   params->video_cursor_x = grub_getxy () >> 8;
 410   params->video_cursor_y = grub_getxy () & 0xff;
 411   params->video_page = 0; /* ??? */
 412   params->video_mode = 0;
 413   params->video_width = (grub_getwh () >> 8);
 414   params->video_ega_bx = 0;
 415   params->video_height = (grub_getwh () & 0xff);
 416   params->have_vga = 0;
 417   params->font_size = 16; /* XXX */
 418
 419   /* The other parameters are filled when booting.  */
 420
 421   grub_file_seek (file, real_size + GRUB_DISK_SECTOR_SIZE);
 422
 423   grub_printf ("   [Linux-bzImage, setup=0x%x, size=0x%x]\n",
 424                (unsigned) real_size, (unsigned) prot_size);
 425
 426   /* Detect explicitly specified memory size, if any.  */
 427   linux_mem_size = 0;
 428   video_type = 0;
 429   for (i = 1; i < argc; i++)
 430     if (grub_memcmp (argv[i], "mem=", 4) == 0)
 431       {
 432         char *val = argv[i] + 4;
 433
 434         linux_mem_size = grub_strtoul (val, &val, 0);
 435
 436         if (grub_errno)
 437           {
 438             grub_errno = GRUB_ERR_NONE;
 439             linux_mem_size = 0;
 440           }
 441         else
 442           {
 443             int shift = 0;
 444
 445             switch (grub_tolower (val[0]))
 446               {
 447               case 'g':
 448                 shift += 10;
 449               case 'm':
 450                 shift += 10;
 451               case 'k':
 452                 shift += 10;
 453               default:
 454                 break;
 455               }
 456
 457             /* Check an overflow.  */
 458             if (linux_mem_size > (~0UL >> shift))
 459               linux_mem_size = 0;
 460             else
 461               linux_mem_size <<= shift;
 462           }
 463       }
 464
 465   /* Specify the boot file.  */
 466   dest = grub_stpcpy ((char *) real_mode_mem + GRUB_LINUX_CL_OFFSET,
 467                       "BOOT_IMAGE=");
 468   dest = grub_stpcpy (dest, argv[0]);
 469
 470   /* Copy kernel parameters.  */
 471   for (i = 1;
 472        i < argc
 473          && dest + grub_strlen (argv[i]) + 1 < ((char *) real_mode_mem
 474                                                 + GRUB_LINUX_CL_END_OFFSET);
 475        i++)
 476     {
 477       *dest++ = ' ';
 478       dest = grub_stpcpy (dest, argv[i]);
 479     }
 480
 481   len = prot_size;
 482   if (grub_file_read (file, (char *) GRUB_LINUX_BZIMAGE_ADDR, len) != len)
 483     grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");
 484
 485   if (grub_errno == GRUB_ERR_NONE)
 486     {
 487       grub_loader_set (grub_linux32_boot, grub_linux_unload, 1);
 488       loaded = 1;
 489     }
 490
 491  fail:
 492
 493   if (file)
 494     grub_file_close (file);
 495
 496   if (grub_errno != GRUB_ERR_NONE)
 497     {
 498       grub_dl_unref (my_mod);
 499       loaded = 0;
 500     }
 501 }
 502
 503 void
 504 grub_rescue_cmd_initrd (int argc, char *argv[])
 505 {
 506   grub_file_t file = 0;
 507   grub_ssize_t size;
 508   grub_addr_t addr_min, addr_max;
 509   grub_addr_t addr;
 510   struct linux_kernel_header *lh;
 511
 512   if (argc == 0)
 513     {
 514       grub_error (GRUB_ERR_BAD_ARGUMENT, "No module specified");
 515       goto fail;
 516     }
 517
 518   if (! loaded)
 519     {
 520       grub_error (GRUB_ERR_BAD_ARGUMENT, "You need to load the kernel first.");
 521       goto fail;
 522     }
 523
 524   file = grub_file_open (argv[0]);
 525   if (! file)
 526     goto fail;
 527
 528   size = grub_file_size (file);
 529   initrd_pages = (page_align (size) >> 12);
 530
 531   lh = (struct linux_kernel_header *) real_mode_mem;
 532
 533   /* Get the highest address available for the initrd.  */
 534   if (grub_le_to_cpu16 (lh->version) >= 0x0203)
 535     {
 536       addr_max = grub_cpu_to_le32 (lh->initrd_addr_max);
 537
 538       /* XXX in reality, Linux specifies a bogus value, so
 539          it is necessary to make sure that ADDR_MAX does not exceed
 540          0x3fffffff.  */
 541       if (addr_max > GRUB_LINUX_INITRD_MAX_ADDRESS)
 542         addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;
 543     }
 544   else
 545     addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;
 546
 547   if (linux_mem_size != 0 && linux_mem_size < addr_max)
 548     addr_max = linux_mem_size;
 549
 550   /* Linux 2.3.xx has a bug in the memory range check, so avoid
 551      the last page.
 552      Linux 2.2.xx has a bug in the memory range check, which is
 553      worse than that of Linux 2.3.xx, so avoid the last 64kb.  */
 554   addr_max -= 0x10000;
 555
 556   /* Usually, the compression ratio is about 50%.  */
 557   addr_min = (grub_addr_t) prot_mode_mem + ((prot_mode_pages * 3) << 12)
 558              + page_align (size);
 559
 560   if (addr_max > grub_os_area_addr + grub_os_area_size)
 561     addr_max = grub_os_area_addr + grub_os_area_size;
 562
 563   /* Put the initrd as high as possible, 4KiB aligned.  */
 564   addr = (addr_max - size) & ~0xFFF;
 565
 566   if (addr < addr_min)
 567     {
 568       grub_error (GRUB_ERR_OUT_OF_RANGE, "The initrd is too big");
 569       goto fail;
 570     }
 571
 572   initrd_mem = (void *) addr;
 573
 574   if (grub_file_read (file, initrd_mem, size) != size)
 575     {
 576       grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");
 577       goto fail;
 578     }
 579
 580   grub_printf ("   [Initrd, addr=0x%x, size=0x%x]\n",
 581                (unsigned) addr, (unsigned) size);
 582
 583   lh->ramdisk_image = addr;
 584   lh->ramdisk_size = size;
 585   lh->root_dev = 0x0100; /* XXX */
 586
 587  fail:
 588   if (file)
 589     grub_file_close (file);
 590 }
 591
 592
 593 GRUB_MOD_INIT(linux)
 594 {
 595   grub_rescue_register_command ("linux",
 596                                 grub_rescue_cmd_linux,
 597                                 "load linux");
 598   grub_rescue_register_command ("initrd",
 599                                 grub_rescue_cmd_initrd,
 600                                 "load initrd");
 601   my_mod = mod;
 602 }
 603
 604 GRUB_MOD_FINI(linux)
 605 {
 606   grub_rescue_unregister_command ("linux");
 607   grub_rescue_unregister_command ("initrd");
 608 }