efiemu/loadcore.c

   1 /* Load runtime image of EFIemu. Functions specific to 32/64-bit mode */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2009  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/err.h>
  21 #include <grub/mm.h>
  22 #include <grub/misc.h>
  23 #include <grub/efiemu/efiemu.h>
  24 #include <grub/cpu/efiemu.h>
  25 #include <grub/machine/efiemu.h>
  26 #include <grub/elf.h>
  27
  28 /* ELF symbols and their values */
  29 static struct grub_efiemu_elf_sym *grub_efiemu_elfsyms = 0;
  30 static int grub_efiemu_nelfsyms = 0;
  31
  32 /* Return the address of a section whose index is N.  */
  33 static grub_err_t
  34 grub_efiemu_get_section_addr (grub_efiemu_segment_t segs, unsigned n,
  35                               int *handle, grub_off_t *off)
  36 {
  37   grub_efiemu_segment_t seg;
  38
  39   for (seg = segs; seg; seg = seg->next)
  40     if (seg->section == n)
  41       {
  42         *handle = seg->handle;
  43         *off = seg->off;
  44         return GRUB_ERR_NONE;
  45       }
  46
  47   return grub_error (GRUB_ERR_BAD_OS, "section %d not found", n);
  48 }
  49
  50 grub_err_t
  51 SUFFIX (grub_efiemu_loadcore_unload) (void)
  52 {
  53   grub_free (grub_efiemu_elfsyms);
  54   grub_efiemu_elfsyms = 0;
  55   return GRUB_ERR_NONE;
  56 }
  57
  58 /* Check if EHDR is a valid ELF header.  */
  59 int
  60 SUFFIX (grub_efiemu_check_header) (void *ehdr, grub_size_t size)
  61 {
  62   Elf_Ehdr *e = ehdr;
  63
  64   /* Check the header size.  */
  65   if (size < sizeof (Elf_Ehdr))
  66     return 0;
  67
  68   /* Check the magic numbers.  */
  69   if (!SUFFIX (grub_arch_efiemu_check_header) (ehdr)
  70       || e->e_ident[EI_MAG0] != ELFMAG0
  71       || e->e_ident[EI_MAG1] != ELFMAG1
  72       || e->e_ident[EI_MAG2] != ELFMAG2
  73       || e->e_ident[EI_MAG3] != ELFMAG3
  74       || e->e_ident[EI_VERSION] != EV_CURRENT
  75       || e->e_version != EV_CURRENT)
  76     return 0;
  77
  78   return 1;
  79 }
  80
  81 /* Load all segments from memory specified by E.  */
  82 static grub_err_t
  83 grub_efiemu_load_segments (grub_efiemu_segment_t segs, const Elf_Ehdr *e)
  84 {
  85   Elf_Shdr *s;
  86   grub_efiemu_segment_t cur;
  87
  88   grub_dprintf ("efiemu", "loading segments\n");
  89
  90   for (cur=segs; cur; cur = cur->next)
  91     {
  92       s = (Elf_Shdr *)cur->srcptr;
  93
  94       if ((s->sh_flags & SHF_ALLOC) && s->sh_size)
  95         {
  96           void *addr;
  97
  98           addr = (grub_uint8_t *) grub_efiemu_mm_obtain_request (cur->handle)
  99             + cur->off;
 100
 101           switch (s->sh_type)
 102             {
 103             case SHT_PROGBITS:
 104               grub_memcpy (addr, (char *) e + s->sh_offset, s->sh_size);
 105               break;
 106             case SHT_NOBITS:
 107               grub_memset (addr, 0, s->sh_size);
 108               break;
 109             }
 110         }
 111     }
 112
 113   return GRUB_ERR_NONE;
 114 }
 115
 116 /* Get a string at offset OFFSET from strtab */
 117 static char *
 118 grub_efiemu_get_string (unsigned offset, const Elf_Ehdr *e)
 119 {
 120   unsigned i;
 121   Elf_Shdr *s;
 122
 123   for (i = 0, s = (Elf_Shdr *)((char *) e + e->e_shoff);
 124        i < e->e_shnum;
 125        i++, s = (Elf_Shdr *)((char *) s + e->e_shentsize))
 126     if (s->sh_type == SHT_STRTAB && offset < s->sh_size)
 127       return (char *) e + s->sh_offset + offset;
 128   return 0;
 129 }
 130
 131 /* Request memory for segments and fill segments info */
 132 static grub_err_t
 133 grub_efiemu_init_segments (grub_efiemu_segment_t *segs, const Elf_Ehdr *e)
 134 {
 135   unsigned i;
 136   Elf_Shdr *s;
 137
 138   for (i = 0, s = (Elf_Shdr *)((char *) e + e->e_shoff);
 139        i < e->e_shnum;
 140        i++, s = (Elf_Shdr *)((char *) s + e->e_shentsize))
 141     {
 142       if (s->sh_flags & SHF_ALLOC)
 143         {
 144           grub_efiemu_segment_t seg;
 145           seg = (grub_efiemu_segment_t) grub_malloc (sizeof (*seg));
 146           if (! seg)
 147             return grub_errno;
 148
 149           if (s->sh_size)
 150             {
 151               seg->handle
 152                 = grub_efiemu_request_memalign
 153                 (s->sh_addralign, s->sh_size,
 154                  s->sh_flags & SHF_EXECINSTR ? GRUB_EFI_RUNTIME_SERVICES_CODE
 155                  : GRUB_EFI_RUNTIME_SERVICES_DATA);
 156               if (seg->handle < 0)
 157                 return grub_errno;
 158               seg->off = 0;
 159             }
 160
 161           /*
 162              .text-physical doesn't need to be relocated when switching to
 163              virtual mode
 164            */
 165           if (!grub_strcmp (grub_efiemu_get_string (s->sh_name, e),
 166                             ".text-physical"))
 167             seg->ptv_rel_needed = 0;
 168           else
 169             seg->ptv_rel_needed = 1;
 170           seg->size = s->sh_size;
 171           seg->section = i;
 172           seg->next = *segs;
 173           seg->srcptr = s;
 174           *segs = seg;
 175         }
 176     }
 177
 178   return GRUB_ERR_NONE;
 179 }
 180
 181 /* Count symbols and relocators and allocate/request memory for them */
 182 static grub_err_t
 183 grub_efiemu_count_symbols (const Elf_Ehdr *e)
 184 {
 185   unsigned i;
 186   Elf_Shdr *s;
 187   int num = 0;
 188
 189   /* Symbols */
 190   for (i = 0, s = (Elf_Shdr *) ((char *) e + e->e_shoff);
 191        i < e->e_shnum;
 192        i++, s = (Elf_Shdr *) ((char *) s + e->e_shentsize))
 193     if (s->sh_type == SHT_SYMTAB)
 194       break;
 195
 196   if (i == e->e_shnum)
 197     return grub_error (GRUB_ERR_BAD_OS, "no symbol table");
 198
 199   grub_efiemu_nelfsyms = (unsigned) s->sh_size / (unsigned) s->sh_entsize;
 200   grub_efiemu_elfsyms = (struct grub_efiemu_elf_sym *)
 201     grub_malloc (sizeof (struct grub_efiemu_elf_sym) * grub_efiemu_nelfsyms);
 202
 203   /* Relocators */
 204   for (i = 0, s = (Elf_Shdr *) ((char *) e + e->e_shoff);
 205        i < e->e_shnum;
 206        i++, s = (Elf_Shdr *) ((char *) s + e->e_shentsize))
 207     if (s->sh_type == SHT_REL || s->sh_type == SHT_RELA)
 208       num += ((unsigned) s->sh_size) / ((unsigned) s->sh_entsize);
 209
 210   grub_efiemu_request_symbols (num);
 211
 212   return GRUB_ERR_NONE;
 213 }
 214
 215 /* Fill grub_efiemu_elfsyms with symbol values */
 216 static grub_err_t
 217 grub_efiemu_resolve_symbols (grub_efiemu_segment_t segs, Elf_Ehdr *e)
 218 {
 219   unsigned i;
 220   Elf_Shdr *s;
 221   Elf_Sym *sym;
 222   const char *str;
 223   Elf_Word size, entsize;
 224
 225   grub_dprintf ("efiemu", "resolving symbols\n");
 226
 227   for (i = 0, s = (Elf_Shdr *) ((char *) e + e->e_shoff);
 228        i < e->e_shnum;
 229        i++, s = (Elf_Shdr *) ((char *) s + e->e_shentsize))
 230     if (s->sh_type == SHT_SYMTAB)
 231       break;
 232
 233   if (i == e->e_shnum)
 234     return grub_error (GRUB_ERR_BAD_OS, "no symbol table");
 235
 236   sym = (Elf_Sym *) ((char *) e + s->sh_offset);
 237   size = s->sh_size;
 238   entsize = s->sh_entsize;
 239
 240   s = (Elf_Shdr *) ((char *) e + e->e_shoff + e->e_shentsize * s->sh_link);
 241   str = (char *) e + s->sh_offset;
 242
 243   for (i = 0;
 244        i < size / entsize;
 245        i++, sym = (Elf_Sym *) ((char *) sym + entsize))
 246     {
 247       unsigned char type = ELF_ST_TYPE (sym->st_info);
 248       unsigned char bind = ELF_ST_BIND (sym->st_info);
 249       int handle;
 250       grub_off_t off;
 251       grub_err_t err;
 252       const char *name = str + sym->st_name;
 253       grub_efiemu_elfsyms[i].section = sym->st_shndx;
 254       switch (type)
 255         {
 256         case STT_NOTYPE:
 257           /* Resolve a global symbol.  */
 258           if (sym->st_name != 0 && sym->st_shndx == 0)
 259             {
 260               if ((err = grub_efiemu_resolve_symbol (name, &handle, &off)))
 261                 return err;
 262               grub_efiemu_elfsyms[i].handle = handle;
 263               grub_efiemu_elfsyms[i].off = off;
 264             }
 265           else
 266             sym->st_value = 0;
 267           break;
 268
 269         case STT_OBJECT:
 270           if ((err = grub_efiemu_get_section_addr
 271                (segs, sym->st_shndx, &handle, &off)))
 272             return err;
 273
 274           off += sym->st_value;
 275           if (bind != STB_LOCAL)
 276             if ((err = grub_efiemu_register_symbol (name, handle, off)))
 277               return err;
 278           grub_efiemu_elfsyms[i].handle = handle;
 279           grub_efiemu_elfsyms[i].off = off;
 280           break;
 281
 282         case STT_FUNC:
 283           if ((err = grub_efiemu_get_section_addr
 284                (segs, sym->st_shndx, &handle, &off)))
 285             return err;
 286
 287           off += sym->st_value;
 288           if (bind != STB_LOCAL)
 289             if ((err = grub_efiemu_register_symbol (name, handle, off)))
 290               return err;
 291           grub_efiemu_elfsyms[i].handle = handle;
 292           grub_efiemu_elfsyms[i].off = off;
 293           break;
 294
 295         case STT_SECTION:
 296           if ((err = grub_efiemu_get_section_addr
 297                (segs, sym->st_shndx, &handle, &off)))
 298             {
 299               grub_efiemu_elfsyms[i].handle = 0;
 300               grub_efiemu_elfsyms[i].off = 0;
 301               grub_errno = GRUB_ERR_NONE;
 302               break;
 303             }
 304
 305           grub_efiemu_elfsyms[i].handle = handle;
 306           grub_efiemu_elfsyms[i].off = off;
 307           break;
 308
 309         case STT_FILE:
 310           grub_efiemu_elfsyms[i].handle = 0;
 311           grub_efiemu_elfsyms[i].off = 0;
 312           break;
 313
 314         default:
 315           return grub_error (GRUB_ERR_BAD_MODULE,
 316                              "unknown symbol type `%d'", (int) type);
 317         }
 318     }
 319
 320   return GRUB_ERR_NONE;
 321 }
 322
 323 /* Load runtime to the memory and request memory for definitive location*/
 324 grub_err_t
 325 SUFFIX (grub_efiemu_loadcore_init) (void *core, grub_size_t core_size,
 326                                     grub_efiemu_segment_t *segments)
 327 {
 328   Elf_Ehdr *e = (Elf_Ehdr *) core;
 329   grub_err_t err;
 330
 331   if (e->e_type != ET_REL)
 332     return grub_error (GRUB_ERR_BAD_MODULE, "invalid ELF file type");
 333
 334   /* Make sure that every section is within the core.  */
 335   if ((grub_size_t) core_size < e->e_shoff + e->e_shentsize * e->e_shnum)
 336     return grub_error (GRUB_ERR_BAD_OS, "ELF sections outside core");
 337
 338   if ((err = grub_efiemu_init_segments (segments, core)))
 339     return err;
 340   if ((err = grub_efiemu_count_symbols (core)))
 341     return err;
 342
 343   grub_efiemu_request_symbols (1);
 344   return GRUB_ERR_NONE;
 345 }
 346
 347 /* Load runtime definitively */
 348 grub_err_t
 349 SUFFIX (grub_efiemu_loadcore_load) (void *core,
 350                                     grub_size_t core_size
 351                                     __attribute__ ((unused)),
 352                                     grub_efiemu_segment_t segments)
 353 {
 354   grub_err_t err;
 355   err = grub_efiemu_load_segments (segments, core);
 356   if (err)
 357     return err;
 358
 359   err = grub_efiemu_resolve_symbols (segments, core);
 360   if (err)
 361     return err;
 362
 363   err = SUFFIX (grub_arch_efiemu_relocate_symbols) (segments,
 364                                                     grub_efiemu_elfsyms,
 365                                                     core);
 366   if (err)
 367     return err;
 368
 369   return GRUB_ERR_NONE;
 370 }