arch/armeb-raspi/boot/elf.c

   1 /*
   2     Copyright � 2013, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: elf.c
   6     Lang: english
   7  */
   8
   9 #include "elf.h"
  10 #include "boot.h"
  11
  12 #include <dos/elf.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15
  16 #define DELF(x) /* x */
  17
  18 uint32_t        int_shnum;
  19 uint32_t        int_shstrndx;
  20
  21 int checkHeader(struct elfheader *eh)
  22 {
  23         if (eh->ident[0] != 0x7f || eh->ident[1] != 'E'  ||
  24                         eh->ident[2] != 'L'  || eh->ident[3] != 'F')
  25         {
  26                 return 0;
  27         }
  28
  29         int_shnum = eh->shnum;
  30         int_shstrndx = eh->shstrndx;
  31
  32         /* the ELF header only uses 16 bits to store the count of section headers,
  33          * so it can't handle more than 65535 headers. if the count is 0, and an
  34          * offset is defined, then the real count can be found in the first
  35          * section header (which always exists).
  36          *
  37          * similarly, if the string table index is SHN_XINDEX, then the actual
  38          * index is found in the first section header also.
  39          *
  40          * see the System V ABI 2001-04-24 draft for more details.
  41          */
  42         if (int_shnum == 0 || int_shstrndx == SHN_XINDEX)
  43         {
  44                 if (eh->shoff == 0)
  45                 {
  46                         return 0;
  47                 }
  48
  49                 /* Get section header. I hope it's there, in memory already. */
  50                 struct sheader *sh = (struct sheader *)((intptr_t)eh + eh->shoff);
  51
  52                 /* wider section header count is in the size field */
  53                 if (int_shnum == 0)
  54                         int_shnum = sh->size;
  55
  56                 /* wider string table index is in the link field */
  57                 if (int_shstrndx == SHN_XINDEX)
  58                         int_shstrndx = sh->link;
  59
  60                 /* sanity, if they're still invalid then this isn't elf */
  61                 if (int_shnum == 0 || int_shstrndx == SHN_XINDEX)
  62                 {
  63                         return 0;
  64                 }
  65         }
  66
  67         if
  68         (
  69                         eh->ident[EI_CLASS]   != ELFCLASS32  ||
  70                         eh->ident[EI_VERSION] != EV_CURRENT  ||
  71                         eh->type              != ET_REL      ||
  72                         eh->ident[EI_DATA]        != ELFDATA2MSB ||
  73                         eh->machine               != EM_ARM
  74         )
  75         {
  76                 return 0;
  77         }
  78
  79         return 1;
  80 }
  81
  82 int getElfSize(void *elf_file, uint32_t *size_rw, uint32_t *size_ro)
  83 {
  84         struct elfheader *eh = (struct elfheader *)elf_file;
  85         uint32_t s_ro = 0;
  86         uint32_t s_rw = 0;
  87
  88         DELF(kprintf("[BOOT:ELF] getElfSize(%p)", eh));
  89
  90         if (checkHeader(eh))
  91         {
  92                 struct sheader *sh = (struct sheader *)((intptr_t)elf_file + eh->shoff);
  93                 int i;
  94
  95                 for (i = 0; i < int_shnum; i++)
  96                 {
  97                         /* Does the section require memoy allcation? */
  98                         if (sh[i].flags & SHF_ALLOC)
  99                         {
 100                                 uint32_t size = (sh[i].size + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 101
 102                                 /*
 103                                  * I extend the section size according to the alignment requirement. However, also the already
 104                                  * measured size has to be aligned poperly. It is so, because the loader has to align the load address later on.
 105                                  */
 106                                 if (sh[i].flags & SHF_WRITE)
 107                                 {
 108                                         s_rw = (s_rw + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 109                                         s_rw += size;
 110                                 }
 111                                 else
 112                                 {
 113                                         s_ro = (s_ro + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 114                                         s_ro += size;
 115                                 }
 116                         }
 117                 }
 118         }
 119         DELF(kprintf(": ro=%p, rw=%p\n", s_ro, s_rw));
 120
 121         if (size_ro)
 122                 *size_ro = s_ro;
 123         if (size_rw)
 124                 *size_rw = s_rw;
 125
 126         return 1;
 127 }
 128
 129 static uintptr_t ptr_ro;
 130 static uintptr_t ptr_rw;
 131 static uintptr_t virtoffset;
 132
 133 void initAllocator(uintptr_t addr_ro, uintptr_t addr_rw, uintptr_t virtoff)
 134 {
 135         ptr_ro = addr_ro;
 136         ptr_rw = addr_rw;
 137         virtoffset = virtoff;
 138 }
 139
 140 struct bss_tracker tracker[MAX_BSS_SECTIONS];
 141 static struct bss_tracker *bss_tracker = &tracker[0];
 142
 143 /*
 144  * read_block function copies the range of memory within ELF file to any specified location.
 145  */
 146 static inline void read_block(void *file, long offset, void *dest, long length)
 147 {
 148         memcpy(dest, (void *)((unsigned long)file + offset), length);
 149 }
 150
 151 /*
 152  * Get the memory for chunk and load it
 153  */
 154 static int load_hunk(void *file, struct sheader *sh)
 155 {
 156         void *ptr = (void *)0;
 157
 158         /* empty chunk? Who cares :) */
 159         if (!sh->size)
 160                 return 1;
 161
 162         /* Allocate a chunk with write access */
 163         if (sh->flags & SHF_WRITE)
 164         {
 165                 ptr_rw = (((unsigned long)ptr_rw
 166                                 + (unsigned long)sh->addralign - 1)
 167                                 & ~((unsigned long)sh->addralign - 1));
 168                 ptr = (APTR)ptr_rw;
 169                 ptr_rw = ptr_rw + sh->size;
 170         }
 171         else
 172         {
 173                 /* Read-Only mode? Get the memory from the kernel space, align it accorting to the demand */
 174                 ptr_ro = (((unsigned long)ptr_ro
 175                                 + (unsigned long)sh->addralign - 1)
 176                                 & ~((unsigned long)sh->addralign - 1));
 177                 ptr = (APTR)ptr_ro;
 178                 ptr_ro = ptr_ro + sh->size;
 179         }
 180
 181         sh->addr = ptr;
 182
 183         /* copy block of memory from ELF file if it exists */
 184         if (sh->type != SHT_NOBITS)
 185         {
 186                 read_block(file, sh->offset, (void *)((unsigned long)sh->addr),
 187                                 sh->size);
 188         }
 189         else
 190         {
 191                 bzero(ptr, sh->size);
 192                 bss_tracker->addr =
 193                                 (void *)((unsigned long)ptr + virtoffset);
 194                 bss_tracker->length = sh->size;
 195                 bss_tracker++;
 196                 /*
 197                  * empty the subsequent tracker in case it's the last one. We did that in case a buggy firmare
 198                  * forgot to clear our .bss section
 199                  */
 200                 bss_tracker->addr = (void*)0;
 201                 bss_tracker->length = 0;
 202         }
 203
 204         return 1;
 205 }
 206
 207 /* Perform relocations of given section */
 208 static int relocate(struct elfheader *eh, struct sheader *sh, long shrel_idx,
 209                 uint32_t virt)
 210 {
 211         struct sheader *shrel = &sh[shrel_idx];
 212         struct sheader *shsymtab = &sh[shrel->link];
 213         struct sheader *toreloc = &sh[shrel->info];
 214
 215         struct symbol *symtab =
 216                         (struct symbol *)((unsigned long)shsymtab->addr);
 217         struct relo *rel = (struct relo *)((unsigned long)shrel->addr);
 218         char *section = (char *)((unsigned long)toreloc->addr);
 219
 220         unsigned int numrel = (unsigned long)shrel->size
 221                         / (unsigned long)shrel->entsize;
 222         unsigned int i;
 223
 224         uint32_t virtoffset;
 225
 226         struct symbol *SysBase_sym = (void *)0;
 227
 228         for (i = 0; i < numrel; i++, rel++)
 229         {
 230                 struct symbol *sym = &symtab[ELF32_R_SYM(rel->info)];
 231                 uint32_t *p = (uint32_t *) & section[rel->offset];
 232                 uint32_t s;
 233                 virtoffset = virt;
 234
 235                 /*
 236                  * R_ARM_V4BX are actually special marks for the linker.
 237                  * They even never have a target (shindex == SHN_UNDEF),
 238                  * so we simply ignore them before doing any checks.
 239                  */
 240                 if (ELF_R_TYPE(rel->info) == R_ARM_V4BX)
 241                         continue;
 242
 243                 switch (sym->shindex)
 244                 {
 245                 case SHN_UNDEF:
 246                         kprintf
 247                         ("[BOOT:ELF] Undefined symbol '%s' in section '%s'\n",
 248                                         (char *)((uint32_t) sh[shsymtab->link].addr) +
 249                                         sym->name,
 250                                         (char *)((uint32_t) sh[eh->shstrndx].addr) +
 251                                         toreloc->name);
 252                         return 0;
 253
 254                 case SHN_COMMON:
 255                         kprintf
 256                         ("[BOOT:ELF] COMMON symbol '%s' in section '%s'\n",
 257                                         (char *)((uint32_t) sh[shsymtab->link].addr) +
 258                                         sym->name,
 259                                         (char *)((uint32_t) sh[eh->shstrndx].addr) +
 260                                         toreloc->name);
 261
 262                         return 0;
 263
 264                 case SHN_ABS:
 265                         if (SysBase_sym == (void *)0) {
 266                                 if (strncmp
 267                                                 ((char *)((uint32_t) sh[shsymtab->link].
 268                                                                 addr) + sym->name, "SysBase",
 269                                                                 8) == 0) {
 270                                         SysBase_sym = sym;
 271                                         goto SysBase_yes;
 272                                 } else
 273                                         goto SysBase_no;
 274                         } else if (SysBase_sym == sym) {
 275                                 SysBase_yes:                    s = (uint32_t) 4UL;
 276                                 virtoffset = 0;
 277                         } else
 278                                 SysBase_no:                     s = sym->value;
 279                         break;
 280                 default:
 281                         s = (uint32_t) sh[sym->shindex].addr + sym->value;
 282                 }
 283                 switch (ELF32_R_TYPE(rel->info)) {
 284
 285                 //              case R_386_32: /* 32bit direct/absolute */
 286                 //                      *p += s + virtoffset;
 287                 //                      break;
 288
 289                 case R_ARM_CALL:
 290                 case R_ARM_JUMP24:
 291                 case R_ARM_PC24:
 292                 {
 293                         /* On ARM the 24 bit offset is shifted by 2 to the right */
 294                         signed long offset = (AROS_LE2LONG(*p) & 0x00ffffff) << 2;
 295                         /* If highest bit set, make offset negative */
 296                         if (offset & 0x02000000)
 297                                 offset -= 0x04000000;
 298
 299                         offset += s - (ULONG)p;
 300
 301                         offset >>= 2;
 302                         *p &= AROS_LONG2LE(0xff000000);
 303                         *p |= AROS_LONG2LE(offset & 0x00ffffff);
 304                 }
 305                 break;
 306
 307
 308                 case R_ARM_MOVW_ABS_NC:
 309                 case R_ARM_MOVT_ABS:
 310                 {
 311                         signed long offset = AROS_LE2LONG(*p);
 312                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 313                         offset = (offset ^ 0x8000) - 0x8000;
 314
 315                         offset += s + virtoffset;
 316
 317                         if (ELF_R_TYPE(rel->info) == R_ARM_MOVT_ABS)
 318                                 offset >>= 16;
 319
 320                         *p &= AROS_LONG2LE(0xfff0f000);
 321                         *p |= AROS_LONG2LE(((offset & 0xf000) << 4) | (offset & 0x0fff));
 322                 }
 323                 break;
 324
 325                 case R_ARM_ABS32: /* PC relative 32 bit signed */
 326                 *p += s + virtoffset;
 327                 break;
 328
 329                 case R_ARM_NONE: /* No reloc */
 330                         break;
 331
 332                 default:
 333                         kprintf("[BOOT:ELF] Unknown relocation %d in ELF file\n",
 334                                         ELF32_R_TYPE(rel->info));
 335                         return 0;
 336                 }
 337         }
 338         return 1;
 339
 340 }
 341
 342 int loadElf(void *elf_file)
 343 {
 344         struct elfheader *eh = (struct elfheader *)elf_file;
 345         //uint32_t s_ro = 0;
 346         //uint32_t s_rw = 0;
 347
 348         DELF(kprintf("[BOOT] loadElf(%p)\n", eh));
 349
 350         if (checkHeader(eh))
 351         {
 352                 struct sheader *sh = (struct sheader *)((intptr_t)elf_file + eh->shoff);
 353                 int i;
 354
 355                 for (i = 0; i < int_shnum; i++)
 356                 {
 357                         /* Load the symbol and string tables */
 358                         if (sh[i].type == SHT_SYMTAB || sh[i].type == SHT_STRTAB)
 359                         {
 360                                 sh[i].addr = (APTR)((unsigned long)elf_file + sh[i].offset);
 361                         }
 362                         /* Does the section require memoy allcation? */
 363                         else if (sh[i].flags & SHF_ALLOC)
 364                         {
 365                                 /* Yup, it does. Load the hunk */
 366                                 if (!load_hunk(elf_file, &sh[i]))
 367                                 {
 368                                         return 0;
 369                                 }
 370                                 else
 371                                 {
 372                                         if (sh[i].size)
 373                                         {
 374                                                 DELF(kprintf("[BOOT:ELF] %s section loaded at %p (Virtual addr: %p)\n",
 375                                                                 sh[i].flags & SHF_WRITE ? "RW":"RO",
 376                                                                                 sh[i].addr,
 377                                                                                 sh[i].addr + virtoffset));
 378                                         }
 379                                 }
 380                         }
 381                 }
 382
 383                 /* For every loaded section perform the relocations */
 384                 for (i = 0; i < int_shnum; i++)
 385                 {
 386                         if (sh[i].type == SHT_REL && sh[sh[i].info].addr)
 387                         {
 388                                 sh[i].addr = (APTR)((uint32_t) elf_file + sh[i].offset);
 389                                 if (!sh[i].addr || !relocate(eh, sh, i, virtoffset))
 390                                 {
 391                                         return 0;
 392                                 }
 393                         }
 394                 }
 395         }
 396     return 1;
 397 }