arch/arm-raspi/boot/elf.c

   1 /*
   2     Copyright © 2013-2019, 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 #if AROS_BIG_ENDIAN
  73                         eh->ident[EI_DATA]        != ELFDATA2MSB ||
  74 #else
  75                         eh->ident[EI_DATA]        != ELFDATA2LSB ||
  76 #endif
  77                         eh->machine               != EM_ARM
  78         )
  79         {
  80                 return 0;
  81         }
  82
  83         return 1;
  84 }
  85
  86 int getElfSize(void *elf_file, uint32_t *size_rw, uint32_t *size_ro)
  87 {
  88         struct elfheader *eh = (struct elfheader *)elf_file;
  89         uint32_t s_ro = 0;
  90         uint32_t s_rw = 0;
  91
  92         DELF(kprintf("[BOOT:ELF] getElfSize(%p)", eh));
  93
  94         if (checkHeader(eh))
  95         {
  96                 struct sheader *sh = (struct sheader *)((intptr_t)elf_file + eh->shoff);
  97                 int i;
  98
  99                 for (i = 0; i < int_shnum; i++)
 100                 {
 101                         /* Does the section require memoy allcation? */
 102                         if (sh[i].flags & SHF_ALLOC)
 103                         {
 104                                 uint32_t size = (sh[i].size + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 105
 106                                 /*
 107                                  * I extend the section size according to the alignment requirement. However, also the already
 108                                  * measured size has to be aligned poperly. It is so, because the loader has to align the load address later on.
 109                                  */
 110                                 if (sh[i].flags & SHF_WRITE)
 111                                 {
 112                                         s_rw = (s_rw + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 113                                         s_rw += size;
 114                                 }
 115                                 else
 116                                 {
 117                                         s_ro = (s_ro + sh[i].addralign - 1) & ~(sh[i].addralign - 1);
 118                                         s_ro += size;
 119                                 }
 120                         }
 121                 }
 122         }
 123         DELF(kprintf(": ro=%p, rw=%p\n", s_ro, s_rw));
 124
 125         if (size_ro)
 126                 *size_ro = s_ro;
 127         if (size_rw)
 128                 *size_rw = s_rw;
 129
 130         return 1;
 131 }
 132
 133 static uintptr_t ptr_ro;
 134 static uintptr_t ptr_rw;
 135 static uintptr_t virtoffset;
 136
 137 void initAllocator(uintptr_t addr_ro, uintptr_t addr_rw, uintptr_t virtoff)
 138 {
 139         ptr_ro = addr_ro;
 140         ptr_rw = addr_rw;
 141         virtoffset = virtoff;
 142 }
 143
 144 struct bss_tracker tracker[MAX_BSS_SECTIONS];
 145 static struct bss_tracker *bss_tracker = &tracker[0];
 146
 147 /*
 148  * read_block function copies the range of memory within ELF file to any specified location.
 149  */
 150 static inline void read_block(void *file, long offset, void *dest, long length)
 151 {
 152         memcpy(dest, (void *)((unsigned long)file + offset), length);
 153 }
 154
 155 /*
 156  * Get the memory for chunk and load it
 157  */
 158 static int load_hunk(void *file, struct sheader *sh)
 159 {
 160         void *ptr = (void *)0;
 161
 162         /* empty chunk? Who cares :) */
 163         if (!sh->size)
 164                 return 1;
 165
 166         /* Allocate a chunk with write access */
 167         if (sh->flags & SHF_WRITE)
 168         {
 169                 ptr_rw = (((unsigned long)ptr_rw
 170                                 + (unsigned long)sh->addralign - 1)
 171                                 & ~((unsigned long)sh->addralign - 1));
 172                 ptr = (APTR)ptr_rw;
 173                 ptr_rw = ptr_rw + sh->size;
 174         }
 175         else
 176         {
 177                 /* Read-Only mode? Get the memory from the kernel space, align it accorting to the demand */
 178                 ptr_ro = (((unsigned long)ptr_ro
 179                                 + (unsigned long)sh->addralign - 1)
 180                                 & ~((unsigned long)sh->addralign - 1));
 181                 ptr = (APTR)ptr_ro;
 182                 ptr_ro = ptr_ro + sh->size;
 183         }
 184
 185         sh->addr = ptr;
 186
 187         /* copy block of memory from ELF file if it exists */
 188         if (sh->type != SHT_NOBITS)
 189         {
 190                 read_block(file, sh->offset, (void *)((unsigned long)sh->addr),
 191                                 sh->size);
 192         }
 193         else
 194         {
 195                 bzero(ptr, sh->size);
 196                 bss_tracker->addr =
 197                                 (void *)((unsigned long)ptr + virtoffset);
 198                 bss_tracker->length = sh->size;
 199                 bss_tracker++;
 200                 /*
 201                  * empty the subsequent tracker in case it's the last one. We did that in case a buggy firmare
 202                  * forgot to clear our .bss section
 203                  */
 204                 bss_tracker->addr = (void*)0;
 205                 bss_tracker->length = 0;
 206         }
 207
 208         return 1;
 209 }
 210
 211 /* Perform relocations of given section */
 212 static int relocate(struct elfheader *eh, struct sheader *sh, long shrel_idx,
 213                 uint32_t virt)
 214 {
 215         struct sheader *shrel = &sh[shrel_idx];
 216         struct sheader *shsymtab = &sh[shrel->link];
 217         struct sheader *toreloc = &sh[shrel->info];
 218         int is_exec = (eh->type == ET_EXEC);
 219
 220         struct symbol *symtab =
 221                         (struct symbol *)((unsigned long)shsymtab->addr);
 222         struct relo *rel = (struct relo *)((unsigned long)shrel->addr);
 223         char *section = (char *)((unsigned long)toreloc->addr);
 224
 225         unsigned int numrel = (unsigned long)shrel->size
 226                         / (unsigned long)shrel->entsize;
 227         unsigned int i;
 228
 229         uint32_t virtoffset;
 230
 231         struct symbol *SysBase_sym = (void *)0;
 232
 233         for (i = 0; i < numrel; i++, rel++)
 234         {
 235                 struct symbol *sym = &symtab[ELF32_R_SYM(rel->info)];
 236                 uint32_t *p = (uint32_t *) & section[rel->offset];
 237                 uint32_t s;
 238                 virtoffset = virt;
 239
 240                 /*
 241                  * R_ARM_V4BX are actually special marks for the linker.
 242                  * They even never have a target (shindex == SHN_UNDEF),
 243                  * so we simply ignore them before doing any checks.
 244                  */
 245                 if (ELF_R_TYPE(rel->info) == R_ARM_V4BX)
 246                         continue;
 247
 248                 switch (sym->shindex)
 249                 {
 250                 case SHN_UNDEF:
 251                         kprintf
 252                         ("[BOOT:ELF] Undefined symbol '%s' in section '%s'\n",
 253                                         (char *)((uint32_t) sh[shsymtab->link].addr) +
 254                                         sym->name,
 255                                         (char *)((uint32_t) sh[eh->shstrndx].addr) +
 256                                         toreloc->name);
 257                         return 0;
 258
 259                 case SHN_COMMON:
 260                         kprintf
 261                         ("[BOOT:ELF] COMMON symbol '%s' in section '%s'\n",
 262                                         (char *)((uint32_t) sh[shsymtab->link].addr) +
 263                                         sym->name,
 264                                         (char *)((uint32_t) sh[eh->shstrndx].addr) +
 265                                         toreloc->name);
 266
 267                         return 0;
 268
 269                 case SHN_ABS:
 270                         if (SysBase_sym == (void *)0) {
 271                                 if (strncmp
 272                                                 ((char *)((uint32_t) sh[shsymtab->link].
 273                                                                 addr) + sym->name, "SysBase",
 274                                                                 8) == 0) {
 275                                         SysBase_sym = sym;
 276                                         goto SysBase_yes;
 277                                 } else
 278                                         goto SysBase_no;
 279                         } else if (SysBase_sym == sym) {
 280                                 SysBase_yes:                    s = (uint32_t) 4UL;
 281                                 virtoffset = 0;
 282                         } else
 283                                 SysBase_no:                     s = sym->value;
 284                         break;
 285                 default:
 286                         s = (uint32_t) sh[sym->shindex].addr + sym->value - deltas[sym->shindex];
 287                 }
 288                 switch (ELF32_R_TYPE(rel->info)) {
 289                 case R_ARM_CALL:
 290                 case R_ARM_JUMP24:
 291                 case R_ARM_PC24:
 292                 {
 293                         if (is_exec)
 294                         {
 295                                 /*
 296                                         Real executables are already properly relocated. Here, adjustment is
 297                                         necessary *only* if the jump is across sections and *only* if offset
 298                                         between both sections differs from the one in executable.
 299
 300                                         if shrel->info == sym->shindex don't do anything!
 301                                 */
 302                                 if (shrel->info != sym->shindex)
 303                                 {
 304                                         intptr_t expected_delta = deltas[sym->shindex] - deltas[shrel->info];
 305                                         intptr_t actual_delta = sh[sym->shindex].addr - sh[shrel->info].addr;
 306
 307                                         /* On ARM the 24 bit offset is shifted by 2 to the right */
 308                                         intptr_t offset = (AROS_LE2LONG(*p) & 0x00ffffff) << 2;
 309                                         /* If highest bit set, make offset negative */
 310                                         if (offset & 0x02000000)
 311                                                 offset -= 0x04000000;
 312
 313                                         /* Adjust offset */
 314                                         offset += actual_delta - expected_delta;
 315
 316                                         /* Store back */
 317                                         offset >>= 2;
 318                                         *p &= AROS_LONG2LE(0xff000000);
 319                                         *p |= AROS_LONG2LE(offset & 0x00ffffff);
 320                                 }
 321                         }
 322                         else
 323                         {
 324                                 /* On ARM the 24 bit offset is shifted by 2 to the right */
 325                                 signed long offset = (AROS_LE2LONG(*p) & 0x00ffffff) << 2;
 326                                 /* If highest bit set, make offset negative */
 327                                 if (offset & 0x02000000)
 328                                         offset -= 0x04000000;
 329
 330                                 offset += s - (ULONG)p;
 331
 332                                 offset >>= 2;
 333                                 *p &= AROS_LONG2LE(0xff000000);
 334                                 *p |= AROS_LONG2LE(offset & 0x00ffffff);
 335                                 }
 336                         }
 337                 break;
 338
 339
 340                 case R_ARM_MOVW_ABS_NC:
 341                 case R_ARM_MOVT_ABS:
 342                 {
 343                         intptr_t offset = AROS_LE2LONG(*p);
 344                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 345                         //offset = (offset ^ 0x8000) - 0x8000;
 346
 347                         /* If MOVT relocation shift the offset 16 bits left */
 348                         if (ELF_R_TYPE(rel->info) == R_ARM_MOVT_ABS)
 349                                 offset <<= 16;
 350
 351 kprintf("movw/movt: offset=%08x, s=%08x, sym->value=%08x, section_orig_addr=%08x, section_addr=%08x\n", offset, s, sym->value,
 352         deltas[sym->shindex], sh[sym->shindex].addr + virtoffset);
 353
 354                         if (is_exec)
 355                         {
 356                                 /* Fix address by difference between actual address and expected address */
 357                                 offset += (intptr_t)sh[sym->shindex].addr - (intptr_t)deltas[sym->shindex] + (intptr_t)virtoffset;
 358                         }
 359                         else
 360                         {
 361                                 offset += (intptr_t)(s + virtoffset);
 362                         }
 363
 364                         /* If MOVT shift the offset back */
 365                         if (ELF_R_TYPE(rel->info) == R_ARM_MOVT_ABS)
 366                                 offset >>= 16;
 367
 368                         *p &= AROS_LONG2LE(0xfff0f000);
 369                         *p |= AROS_LONG2LE(((offset & 0xf000) << 4) | (offset & 0x0fff));
 370                 }
 371                 break;
 372
 373                 case R_ARM_ABS32: /* PC relative 32 bit signed */
 374                         if (is_exec)
 375                         {
 376                                 *p += (uintptr_t)sh[sym->shindex].addr - (uintptr_t)deltas[sym->shindex] + (uintptr_t)virtoffset;
 377                         }
 378                         else
 379                         {
 380                                 *p += s + virtoffset;
 381                         }
 382                 break;
 383
 384                 case R_ARM_NONE: /* No reloc */
 385                         break;
 386
 387                 default:
 388                         kprintf("[BOOT:ELF] Unknown relocation %d in ELF file\n",
 389                                         ELF32_R_TYPE(rel->info));
 390                         return 0;
 391                 }
 392         }
 393         return 1;
 394
 395 }
 396
 397 int loadElf(void *elf_file)
 398 {
 399         struct elfheader *eh = (struct elfheader *)elf_file;
 400         //uint32_t s_ro = 0;
 401         //uint32_t s_rw = 0;
 402
 403         DELF(kprintf("[BOOT] loadElf(%p)\n", eh));
 404
 405         if (checkHeader(eh))
 406         {
 407                 struct sheader *sh = (struct sheader *)((intptr_t)elf_file + eh->shoff);
 408                 int i;
 409
 410                 for (i = 0; i < int_shnum; i++)
 411                 {
 412                         /* Load the symbol and string tables */
 413                         if (sh[i].type == SHT_SYMTAB || sh[i].type == SHT_STRTAB)
 414                         {
 415                                 sh[i].addr = (APTR)((unsigned long)elf_file + sh[i].offset);
 416                         }
 417                         /* Does the section require memoy allcation? */
 418                         else if (sh[i].flags & SHF_ALLOC)
 419                         {
 420                                 /* Yup, it does. Load the hunk */
 421                                 if (!load_hunk(elf_file, &sh[i]))
 422                                 {
 423                                         return 0;
 424                                 }
 425                                 else
 426                                 {
 427                                         if (sh[i].size)
 428                                         {
 429                                                 DELF(kprintf("[BOOT:ELF] %s section loaded at %p (Virtual addr: %p)\n",
 430                                                                 sh[i].flags & SHF_WRITE ? "RW":"RO",
 431                                                                                 sh[i].addr,
 432                                                                                 sh[i].addr + virtoffset));
 433                                         }
 434                                 }
 435                         }
 436                 }
 437
 438                 /* For every loaded section perform the relocations */
 439                 for (i = 0; i < int_shnum; i++)
 440                 {
 441                         if (sh[i].type == SHT_REL && sh[sh[i].info].addr)
 442                         {
 443                                 sh[i].addr = (APTR)((uint32_t) elf_file + sh[i].offset);
 444                                 if (!sh[i].addr || !relocate(eh, sh, i, virtoffset))
 445                                 {
 446                                         return 0;
 447                                 }
 448                         }
 449                 }
 450         }
 451     return 1;
 452 }