2 * AcessOS 1 - Dynamic Loader
13 # define DEBUGS(v...) SysDebug("ld-acess - " v)
20 //static const char *csaDT_NAMES[] = {"DT_NULL", "DT_NEEDED", "DT_PLTRELSZ", "DT_PLTGOT", "DT_HASH", "DT_STRTAB", "DT_SYMTAB", "DT_RELA", "DT_RELASZ", "DT_RELAENT", "DT_STRSZ", "DT_SYMENT", "DT_INIT", "DT_FINI", "DT_SONAME", "DT_RPATH", "DT_SYMBOLIC", "DT_REL", "DT_RELSZ", "DT_RELENT", "DT_PLTREL", "DT_DEBUG", "DT_TEXTREL", "DT_JMPREL"};
21 static const char *csaR_NAMES[] = {"R_386_NONE", "R_386_32", "R_386_PC32", "R_386_GOT32", "R_386_PLT32", "R_386_COPY", "R_386_GLOB_DAT", "R_386_JMP_SLOT", "R_386_RELATIVE", "R_386_GOTOFF", "R_386_GOTPC", "R_386_LAST"};
25 void *ElfRelocate(void *Base, char **envp, const char *Filename);
26 void *Elf32Relocate(void *Base, char **envp, const char *Filename);
27 void *Elf64Relocate(void *Base, char **envp, const char *Filename);
28 Uint32 ElfHashString(const char *name);
32 * \fn int ElfRelocate(void *Base, char **envp, const char *Filename)
33 * \brief Relocates a loaded ELF Executable
35 void *ElfRelocate(void *Base, char **envp, const char *Filename)
37 Elf32_Ehdr *hdr = Base;
39 switch(hdr->e_ident[4])
42 return Elf32Relocate(Base, envp, Filename);
44 return Elf64Relocate(Base, envp, Filename);
46 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);
51 void *Elf64Relocate(void *Base, char **envp, const char *Filename)
54 Elf64_Ehdr *hdr = Base;
57 Elf64_Addr compiledBase = -1, baseDiff;
58 Elf64_Sym *symtab = NULL;
60 Elf64_Word *hashtab = NULL;
61 Elf64_Rel *rel = NULL;
63 Elf64_Rela *rela = NULL;
66 int plt_size = 0, plt_type = 0;
68 DEBUGS("Elf64Relocate: e_ident = '%.16s'", hdr->e_ident);
69 DEBUGS("Elf64Relocate: e_phoff = %i, e_phnum = %i",
70 hdr->e_phoff, hdr->e_phnum);
72 // Scan for the dynamic table (and find the compiled base)
73 phtab = Base + hdr->e_phoff;
74 for( i = 0; i < hdr->e_phnum; i ++ )
76 if(phtab[i].p_type == PT_DYNAMIC)
77 dyntab = (void *)phtab[i].p_vaddr;
78 if(phtab[i].p_type == PT_LOAD && compiledBase > phtab[i].p_vaddr)
79 compiledBase = phtab[i].p_vaddr;
82 baseDiff = (Elf64_Addr)Base - compiledBase;
84 DEBUGS("baseDiff = %p", baseDiff);
87 SysDebug(" Elf64Relocate: No PT_DYNAMIC segment in image %p, returning", Base);
88 return (void *)(hdr->e_entry + baseDiff);
91 dyntab = (void *)((Elf64_Addr)dyntab + baseDiff);
93 // Parse the dynamic table (first pass)
94 // - Search for String, Symbol and Hash tables
95 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
97 switch(dyntab[i].d_tag)
100 dyntab[i].d_un.d_ptr += baseDiff;
101 symtab = (void *)dyntab[i].d_un.d_ptr;
104 dyntab[i].d_un.d_ptr += baseDiff;
105 strtab = (void *)dyntab[i].d_un.d_ptr;
108 dyntab[i].d_un.d_ptr += baseDiff;
109 hashtab = (void *)dyntab[i].d_un.d_ptr;
114 if( !symtab || !strtab || !hashtab ) {
115 SysDebug("ld-acess - Elf64Relocate: Missing Symbol, string or hash table");
119 // Ready for symbol use
120 AddLoaded( Filename, Base );
122 // Second pass on dynamic table
123 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
125 switch(dyntab[i].d_tag)
127 case DT_SONAME: break;
130 char *libPath = strtab + dyntab[i].d_un.d_val;
131 if(LoadLibrary(libPath, NULL, envp) == 0) {
132 SysDebug("ld-acess - Elf64Relocate: Unable to load '%s'", libPath);
137 // Relocation entries
139 dyntab[i].d_un.d_ptr += baseDiff;
140 rel = (void *)dyntab[i].d_un.d_ptr;
143 rel_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rel);
146 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rel) ) {
147 SysDebug("ld-acess - Elf64Relocate: DT_RELENT(%i) != sizeof(Elf64_Rel)(%i)",
148 dyntab[i].d_un.d_val, sizeof(Elf64_Rel));
153 dyntab[i].d_un.d_ptr += baseDiff;
154 rela = (void *)dyntab[i].d_un.d_ptr;
157 rela_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rela);
160 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rela) ) {
161 SysDebug("ld-acess - Elf64Relocate: DT_RELAENT(%i) != sizeof(Elf64_Rela)(%i)",
162 dyntab[i].d_un.d_val, sizeof(Elf64_Rela));
167 dyntab[i].d_un.d_ptr += baseDiff;
168 pltrel = (void *)dyntab[i].d_un.d_ptr;
171 plt_type = dyntab[i].d_un.d_val;
174 plt_size = dyntab[i].d_un.d_val;
179 // Relocation function
180 void _Elf64DoReloc(Elf64_Xword r_info, void *ptr, Elf64_Sxword addend)
182 int sym = ELF64_R_SYM(r_info);
183 int type = ELF64_R_TYPE(r_info);
184 const char *symname = strtab + symtab[sym].st_name;
190 *(uint64_t*)ptr = (uint64_t)GetSymbol(symname) + addend;
193 SysDebug("ld-acess - _Elf64DoReloc: Unknown relocation type %i", type);
199 for( i = 0; i < rel_count; i ++ )
201 uint64_t *ptr = (void *)( rel[i].r_offset + baseDiff );
202 _Elf64DoReloc( rel[i].r_info, ptr, *ptr);
208 for( i = 0; i < rela_count; i ++ )
210 _Elf64DoReloc( rela[i].r_info, (void *)( rela[i].r_offset + baseDiff ), rela[i].r_addend );
214 if( pltrel && plt_type )
216 if( plt_type == DT_REL ) {
217 Elf64_Rel *plt = pltrel;
218 int count = plt_size / sizeof(Elf64_Rel);
219 for( i = 0; i < count; i ++ )
221 uint64_t *ptr = (void *)( plt[i].r_offset + baseDiff );
222 _Elf64DoReloc( plt[i].r_info, ptr, *ptr);
226 Elf64_Rela *plt = pltrel;
227 int count = plt_size / sizeof(Elf64_Rela);
228 for( i = 0; i < count; i ++ )
230 _Elf64DoReloc( plt[i].r_info, (void *)(plt[i].r_offset + baseDiff), plt[i].r_addend);
235 return (void *)(hdr->e_entry + baseDiff);
238 void *Elf32Relocate(void *Base, char **envp, const char *Filename)
240 Elf32_Ehdr *hdr = Base;
242 int i, j; // Counters
248 Elf32_Rel *rel = NULL;
249 Elf32_Rela *rela = NULL;
250 Uint32 *pltgot = NULL;
252 int relSz=0, relEntSz=8;
253 int relaSz=0, relaEntSz=8;
254 int pltSz=0, pltType=0;
255 Elf32_Dyn *dynamicTab = NULL; // Dynamic Table Pointer
256 char *dynstrtab = NULL; // .dynamic String Table
257 Elf32_Sym *dynsymtab;
259 DEBUGS("ElfRelocate: (Base=0x%x)", Base);
261 // Check magic header
264 // Parse Program Header to get Dynamic Table
265 phtab = Base + hdr->phoff;
266 iSegmentCount = hdr->phentcount;
267 for(i=0;i<iSegmentCount;i++)
269 // Determine linked base address
270 if(phtab[i].Type == PT_LOAD && iRealBase > phtab[i].VAddr)
271 iRealBase = phtab[i].VAddr;
273 // Find Dynamic Section
274 if(phtab[i].Type == PT_DYNAMIC) {
276 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");
279 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;
280 j = i; // Save Dynamic Table ID
284 // Page Align real base
286 DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);
288 // Adjust "Real" Base
289 iBaseDiff = (intptr_t)Base - iRealBase;
291 // hdr->entrypoint += iBaseDiff; // Adjust Entrypoint
293 // Check if a PT_DYNAMIC segement was found
295 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);
296 return (void *)hdr->entrypoint + iBaseDiff;
299 // Adjust Dynamic Table
300 dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );
302 // === Get Symbol table and String Table ===
303 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
305 switch(dynamicTab[j].d_tag)
307 // --- Symbol Table ---
309 DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",
310 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
311 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
312 dynsymtab = (void*)(dynamicTab[j].d_val);
313 // hdr->misc.SymTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
315 // --- String Table ---
317 DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",
318 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
319 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
320 dynstrtab = (void*)(dynamicTab[j].d_val);
324 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
325 iSymCount = ((Uint*)(dynamicTab[j].d_val))[1];
326 // hdr->misc.HashTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
331 if(dynsymtab == NULL) {
332 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);
333 return (void *) hdr->entrypoint + iBaseDiff;
337 // Alter Symbols to true base
338 for(i=0;i<iSymCount;i++)
340 dynsymtab[i].value += iBaseDiff;
341 dynsymtab[i].nameOfs += (intptr_t)dynstrtab;
342 //DEBUGS("elf_relocate: Sym '%s' = 0x%x (relocated)", dynsymtab[i].name, dynsymtab[i].value);
346 // === Add to loaded list (can be imported now) ===
347 AddLoaded( Filename, Base );
349 // === Parse Relocation Data ===
350 DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);
351 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
353 switch(dynamicTab[j].d_tag)
355 // --- Shared Library Name ---
357 DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);
359 // --- Needed Library ---
361 libPath = dynstrtab + dynamicTab[j].d_val;
362 DEBUGS(" Required Library '%s'", libPath);
363 if(LoadLibrary(libPath, NULL, envp) == 0) {
365 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);
367 SysDebug("Unable to load required library '%s'", libPath);
373 case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
374 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
375 case DT_PLTREL: pltType = dynamicTab[j].d_val; break;
376 case DT_PLTRELSZ: pltSz = dynamicTab[j].d_val; break;
378 // --- Relocation ---
379 case DT_REL: rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
380 case DT_RELSZ: relSz = dynamicTab[j].d_val; break;
381 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;
382 case DT_RELA: rela = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
383 case DT_RELASZ: relaSz = dynamicTab[j].d_val; break;
384 case DT_RELAENT: relaEntSz = dynamicTab[j].d_val; break;
386 // --- Symbol Table ---
388 // --- Hash Table ---
390 // --- String Table ---
396 if(dynamicTab[j].d_tag > DT_JMPREL) continue;
397 //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",
398 // i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);
403 DEBUGS(" elf_relocate: Beginning Relocation");
405 void elf_doRelocate(Uint r_info, Uint32 *ptr, Uint32 addend, Elf32_Sym *symtab)
407 int type = ELF32_R_TYPE(r_info);
408 int sym = ELF32_R_SYM(r_info);
410 const char *symname = dynstrtab + symtab[sym].nameOfs;
413 // Standard 32 Bit Relocation (S+A)
415 val = (intptr_t) GetSymbol( symname );
416 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += 0x%x('%s')",
421 // 32 Bit Relocation wrt. Offset (S+A-P)
423 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
424 val = (intptr_t) GetSymbol( symname );
425 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%x - 0x%x",
426 ptr, *ptr, val, (intptr_t)ptr );
427 *ptr = val + addend - (intptr_t)ptr;
428 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);
431 // Absolute Value of a symbol (S)
434 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
435 val = (intptr_t) GetSymbol( symname );
436 DEBUGS(" elf_doRelocate: %s *0x%x = 0x%x", csaR_NAMES[type], ptr, val);
440 // Base Address (B+A)
442 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);
443 *ptr = iBaseDiff + addend;
447 DEBUGS(" elf_doRelocate: Rel 0x%x: 0x%x,%s", ptr, sym, csaR_NAMES[type]);
452 // Parse Relocation Entries
456 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);
457 j = relSz / relEntSz;
458 for( i = 0; i < j; i++ )
460 //DEBUGS(" Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);
461 ptr = (void*)(iBaseDiff + rel[i].r_offset);
462 elf_doRelocate(rel[i].r_info, ptr, *ptr, dynsymtab);
465 // Parse Relocation Entries
469 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);
470 j = relaSz / relaEntSz;
471 for( i = 0; i < j; i++ )
473 ptr = (void*)(iBaseDiff + rela[i].r_offset);
474 elf_doRelocate(rel[i].r_info, ptr, rela[i].r_addend, dynsymtab);
478 // === Process PLT (Procedure Linkage Table) ===
482 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);
483 if(pltType == DT_REL)
485 Elf32_Rel *pltRel = plt;
486 j = pltSz / sizeof(Elf32_Rel);
487 DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", j);
490 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);
491 elf_doRelocate(pltRel[i].r_info, ptr, *ptr, dynsymtab);
496 Elf32_Rela *pltRela = plt;
497 j = pltSz / sizeof(Elf32_Rela);
498 DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", j);
501 ptr = (void*)(iRealBase + pltRela[i].r_offset);
502 elf_doRelocate(pltRela[i].r_info, ptr, pltRela[i].r_addend, dynsymtab);
507 DEBUGS("ElfRelocate: RETURN 0x%x", hdr->entrypoint + iBaseDiff);
508 return (void*)hdr->entrypoint + iBaseDiff;
513 * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)
515 int ElfGetSymbol(void *Base, const char *Name, void **ret)
517 Elf32_Ehdr *hdr = Base;
525 const char *dynstrtab;
526 uintptr_t iBaseDiff = -1;
528 //DEBUGS("ElfGetSymbol: (Base=0x%x, Name='%s')", Base, Name);
530 pBuckets = (void *) (intptr_t) hdr->misc.HashTable;
531 symtab = (void *) (intptr_t) hdr->misc.SymTable;
532 dynstrtab = (void *) (intptr_t) hdr->misc.StrTab;
539 // Catch the current executable
543 Elf32_Dyn *dynTab = NULL;
547 phtab = (void*)( Base + hdr->phoff );
548 for( i = 0; i < hdr->phentcount; i ++ )
550 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)
551 iBaseDiff = phtab[i].VAddr;
552 if( phtab[i].Type == PT_DYNAMIC ) {
553 dynTab = (void*)(intptr_t)phtab[i].VAddr;
557 SysDebug("ERROR - Unable to find DYNAMIC segment in %p");
560 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
561 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
563 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)
565 switch(dynTab[j].d_tag)
567 // --- Symbol Table ---
569 symtab = (void*)(intptr_t) dynTab[j].d_val; // Rebased in Relocate
572 dynstrtab = (void*)(intptr_t) dynTab[j].d_val;
576 pBuckets = (void*)(intptr_t) dynTab[j].d_val;
582 hdr->misc.HashTable = pBucktets;
583 hdr->misc.SymTable = symtab;
584 hdr->misc.StrTab = dynstrtab;
588 nbuckets = pBuckets[0];
589 iSymCount = pBuckets[1];
590 pBuckets = &pBuckets[2];
591 pChains = &pBuckets[ nbuckets ];
594 iNameHash = ElfHashString(Name);
595 iNameHash %= nbuckets;
596 //DEBUGS(" ElfGetSymbol: iNameHash = 0x%x", iNameHash);
599 i = pBuckets[ iNameHash ];
600 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[i].name);
601 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].nameOfs, Name) == 0) {
602 *ret = (void*) (intptr_t) symtab[ i ].value + iBaseDiff;
606 //DEBUGS(" ElfGetSymbol: Hash of first = 0x%x", ElfHashString( symtab[i].name ) % nbuckets);
607 while(pChains[i] != STN_UNDEF)
609 //DEBUGS(" pChains[%i] = %i", i, pChains[i]);
611 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[ i ].name);
612 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[ i ].nameOfs, Name) == 0) {
613 //DEBUGS("ElfGetSymbol: RETURN 1, '%s' = 0x%x", symtab[ i ].name, symtab[ i ].value);
614 *ret = (void*)(intptr_t)symtab[ i ].value + iBaseDiff;
619 //DEBUGS("ElfGetSymbol: RETURN 0, Symbol '%s' not found", Name);
623 Uint32 ElfHashString(const char *name)
628 h = (h << 4) + *(Uint8*)name++;
629 if( (g = h & 0xf0000000) )
637 unsigned long elf_hash(const unsigned char *name)
639 unsigned long h = 0, g;
642 h = (h << 4) + *name++;
643 if (g = h & 0xf0000000)