2 * AcessOS 1 - Dynamic Loader
13 # define DEBUGS(v...) SysDebug("ld-acess - " v)
19 # define SUPPORT_ELF64
24 //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"};
25 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"};
29 void *ElfRelocate(void *Base, char **envp, const char *Filename);
30 int ElfGetSymbol(void *Base, const char *Name, void **Ret);
31 void *Elf32Relocate(void *Base, char **envp, const char *Filename);
32 int Elf32GetSymbol(void *Base, const char *Name, void **Ret);
34 void *Elf64Relocate(void *Base, char **envp, const char *Filename);
35 int Elf64GetSymbol(void *Base, const char *Name, void **Ret);
37 Uint32 ElfHashString(const char *name);
41 * \fn int ElfRelocate(void *Base, char **envp, const char *Filename)
42 * \brief Relocates a loaded ELF Executable
44 void *ElfRelocate(void *Base, char **envp, const char *Filename)
46 Elf32_Ehdr *hdr = Base;
48 switch(hdr->e_ident[4])
51 return Elf32Relocate(Base, envp, Filename);
54 return Elf64Relocate(Base, envp, Filename);
57 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);
63 * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)
65 int ElfGetSymbol(void *Base, const char *Name, void **ret)
67 Elf32_Ehdr *hdr = Base;
69 switch(hdr->e_ident[4])
72 return Elf32GetSymbol(Base, Name, ret);
75 return Elf64GetSymbol(Base, Name, ret);
78 SysDebug("ld-acess - ElfRelocate: Unknown file class %i", hdr->e_ident[4]);
83 void *Elf32Relocate(void *Base, char **envp, const char *Filename)
85 Elf32_Ehdr *hdr = Base;
89 intptr_t iRealBase = -1;
93 Elf32_Rel *rel = NULL;
94 Elf32_Rela *rela = NULL;
95 Uint32 *pltgot = NULL;
97 int relSz=0, relEntSz=8;
98 int relaSz=0, relaEntSz=8;
99 int pltSz=0, pltType=0;
100 Elf32_Dyn *dynamicTab = NULL; // Dynamic Table Pointer
101 char *dynstrtab = NULL; // .dynamic String Table
102 Elf32_Sym *dynsymtab;
103 void (*do_relocate)(uint32_t t_info, uint32_t *ptr, Elf32_Addr addend, int Type, const char *Sym);
105 DEBUGS("ElfRelocate: (Base=0x%x)", Base);
107 // Check magic header
110 // Parse Program Header to get Dynamic Table
111 phtab = Base + hdr->phoff;
112 iSegmentCount = hdr->phentcount;
113 for(i=0;i<iSegmentCount;i++)
115 // Determine linked base address
116 if(phtab[i].Type == PT_LOAD && iRealBase > phtab[i].VAddr)
117 iRealBase = phtab[i].VAddr;
119 // Find Dynamic Section
120 if(phtab[i].Type == PT_DYNAMIC) {
122 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");
125 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;
126 j = i; // Save Dynamic Table ID
130 // Page Align real base
132 DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);
134 // Adjust "Real" Base
135 iBaseDiff = (intptr_t)Base - iRealBase;
137 // hdr->entrypoint += iBaseDiff; // Adjust Entrypoint
139 // Check if a PT_DYNAMIC segement was found
141 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);
142 return (void *)(intptr_t)(hdr->entrypoint + iBaseDiff);
145 // Adjust Dynamic Table
146 dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );
148 // === Get Symbol table and String Table ===
149 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
151 switch(dynamicTab[j].d_tag)
153 // --- Symbol Table ---
155 DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",
156 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
157 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
158 dynsymtab = (void*)(dynamicTab[j].d_val);
160 // --- String Table ---
162 DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",
163 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
164 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
165 dynstrtab = (void*)(dynamicTab[j].d_val);
169 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
170 iSymCount = ((Elf32_Word*)(dynamicTab[j].d_val))[1];
175 if(dynsymtab == NULL) {
176 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);
177 return (void *) hdr->entrypoint + iBaseDiff;
180 // === Add to loaded list (can be imported now) ===
181 AddLoaded( Filename, Base );
183 // === Parse Relocation Data ===
184 DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);
185 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
187 switch(dynamicTab[j].d_tag)
189 // --- Shared Library Name ---
191 DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);
193 // --- Needed Library ---
195 libPath = dynstrtab + dynamicTab[j].d_val;
196 DEBUGS(" Required Library '%s'", libPath);
197 if(LoadLibrary(libPath, NULL, envp) == 0) {
199 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);
201 SysDebug("Unable to load required library '%s'", libPath);
205 DEBUGS(" Lib loaded");
208 case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
209 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
210 case DT_PLTREL: pltType = dynamicTab[j].d_val; break;
211 case DT_PLTRELSZ: pltSz = dynamicTab[j].d_val; break;
213 // --- Relocation ---
214 case DT_REL: rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
215 case DT_RELSZ: relSz = dynamicTab[j].d_val; break;
216 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;
217 case DT_RELA: rela = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
218 case DT_RELASZ: relaSz = dynamicTab[j].d_val; break;
219 case DT_RELAENT: relaEntSz = dynamicTab[j].d_val; break;
221 // --- Symbol Table ---
223 // --- Hash Table ---
225 // --- String Table ---
231 if(dynamicTab[j].d_tag > DT_JMPREL) continue;
232 //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",
233 // i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);
238 DEBUGS(" elf_relocate: Beginning Relocation");
240 void elf_doRelocate_386(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, const char *Sym)
245 // Standard 32 Bit Relocation (S+A)
247 val = (intptr_t) GetSymbol( Sym );
248 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += 0x%x('%s')",
253 // 32 Bit Relocation wrt. Offset (S+A-P)
255 DEBUGS(" elf_doRelocate: '%s'", Sym);
256 val = (intptr_t) GetSymbol( Sym );
257 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%x - 0x%x",
258 ptr, *ptr, val, (intptr_t)ptr );
259 *ptr = val + addend - (intptr_t)ptr;
260 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);
263 // Absolute Value of a symbol (S)
266 DEBUGS(" elf_doRelocate: '%s'", Sym);
267 val = (intptr_t) GetSymbol( Sym );
268 DEBUGS(" elf_doRelocate: %s *0x%x = 0x%x", csaR_NAMES[type], ptr, val);
272 // Base Address (B+A)
274 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);
275 *ptr = iBaseDiff + addend;
279 SysDebug("elf_doRelocate_386: Unknown relocation %i", type);
284 void elf_doRelocate_arm(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend, int type, const char *Sym)
291 case R_ARM_JUMP_SLOT:
292 val = (intptr_t)GetSymbol(Sym);
296 SysDebug("elf_doRelocate_arm: Unknown Relocation, %i", type);
301 void _doRelocate(uint32_t r_info, uint32_t *ptr, Elf32_Addr addend)
303 int type = ELF32_R_TYPE(r_info);
304 int sym = ELF32_R_SYM(r_info);
305 const char *symname = dynstrtab + dynsymtab[sym].nameOfs;
306 do_relocate(r_info, ptr, addend, type, symname);
312 do_relocate = elf_doRelocate_386;
315 do_relocate = elf_doRelocate_arm;
318 SysDebug("Elf32Relocate: Unknown machine type %i", hdr->machine);
322 // Parse Relocation Entries
326 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);
327 j = relSz / relEntSz;
328 for( i = 0; i < j; i++ )
330 //DEBUGS(" Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);
331 ptr = (void*)(iBaseDiff + rel[i].r_offset);
332 _doRelocate(rel[i].r_info, ptr, *ptr);
335 // Parse Relocation Entries
339 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);
340 j = relaSz / relaEntSz;
341 for( i = 0; i < j; i++ )
343 ptr = (void*)(iBaseDiff + rela[i].r_offset);
344 _doRelocate(rel[i].r_info, ptr, rela[i].r_addend);
348 // === Process PLT (Procedure Linkage Table) ===
352 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);
353 if(pltType == DT_REL)
355 Elf32_Rel *pltRel = plt;
356 j = pltSz / sizeof(Elf32_Rel);
357 DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", j);
360 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);
361 _doRelocate(pltRel[i].r_info, ptr, *ptr);
366 Elf32_Rela *pltRela = plt;
367 j = pltSz / sizeof(Elf32_Rela);
368 DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", j);
371 ptr = (void*)(iRealBase + pltRela[i].r_offset);
372 _doRelocate(pltRela[i].r_info, ptr, pltRela[i].r_addend);
377 DEBUGS("ElfRelocate: RETURN 0x%x", hdr->entrypoint + iBaseDiff);
378 return (void*)hdr->entrypoint + iBaseDiff;
381 int Elf32GetSymbol(void *Base, const char *Name, void **ret)
383 Elf32_Ehdr *hdr = Base;
391 const char *dynstrtab;
392 uintptr_t iBaseDiff = -1;
394 Elf32_Dyn *dynTab = NULL;
397 phtab = (void*)( Base + hdr->phoff );
398 for( i = 0; i < hdr->phentcount; i ++ )
400 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)
401 iBaseDiff = phtab[i].VAddr;
402 if( phtab[i].Type == PT_DYNAMIC ) {
403 dynTab = (void*)(intptr_t)phtab[i].VAddr;
407 SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);
410 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
411 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
412 for( i = 0; dynTab[i].d_tag != DT_NULL; i++)
414 switch(dynTab[i].d_tag)
416 // --- Symbol Table ---
418 symtab = (void*)(intptr_t) dynTab[i].d_val; // Rebased in Relocate
421 dynstrtab = (void*)(intptr_t) dynTab[i].d_val;
425 pBuckets = (void*)(intptr_t) dynTab[i].d_val;
430 nbuckets = pBuckets[0];
431 iSymCount = pBuckets[1];
432 pBuckets = &pBuckets[2];
433 pChains = &pBuckets[ nbuckets ];
436 iNameHash = ElfHashString(Name);
437 iNameHash %= nbuckets;
440 i = pBuckets[ iNameHash ];
441 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].nameOfs, Name) == 0) {
442 *ret = (void*) (intptr_t) symtab[ i ].value + iBaseDiff;
446 while(pChains[i] != STN_UNDEF)
449 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[ i ].nameOfs, Name) == 0) {
450 *ret = (void*)(intptr_t)symtab[ i ].value + iBaseDiff;
459 void *Elf64Relocate(void *Base, char **envp, const char *Filename)
462 Elf64_Ehdr *hdr = Base;
465 Elf64_Addr compiledBase = -1, baseDiff;
466 Elf64_Sym *symtab = NULL;
468 Elf64_Word *hashtab = NULL;
469 Elf64_Rel *rel = NULL;
471 Elf64_Rela *rela = NULL;
474 int plt_size = 0, plt_type = 0;
476 DEBUGS("Elf64Relocate: hdr = {");
477 DEBUGS("Elf64Relocate: e_ident = '%.16s'", hdr->e_ident);
478 DEBUGS("Elf64Relocate: e_type = 0x%x", hdr->e_type);
479 DEBUGS("Elf64Relocate: e_machine = 0x%x", hdr->e_machine);
480 DEBUGS("Elf64Relocate: e_version = 0x%x", hdr->e_version);
481 DEBUGS("Elf64Relocate: e_entry = %p", hdr->e_entry);
482 DEBUGS("Elf64Relocate: e_phoff = 0x%llx", hdr->e_phoff);
483 DEBUGS("Elf64Relocate: e_shoff = 0x%llx", hdr->e_shoff);
484 DEBUGS("Elf64Relocate: e_flags = 0x%x", hdr->e_flags);
485 DEBUGS("Elf64Relocate: e_ehsize = 0x%x", hdr->e_ehsize);
486 DEBUGS("Elf64Relocate: e_phentsize = 0x%x", hdr->e_phentsize);
487 DEBUGS("Elf64Relocate: e_phnum = %i", hdr->e_phnum);
489 // Scan for the dynamic table (and find the compiled base)
490 phtab = Base + hdr->e_phoff;
491 for( i = 0; i < hdr->e_phnum; i ++ )
493 if(phtab[i].p_type == PT_DYNAMIC)
494 dyntab = (void *)(intptr_t)phtab[i].p_vaddr;
495 if(phtab[i].p_type == PT_LOAD && compiledBase > phtab[i].p_vaddr)
496 compiledBase = phtab[i].p_vaddr;
499 baseDiff = (Elf64_Addr)Base - compiledBase;
501 DEBUGS("baseDiff = %p", baseDiff);
504 SysDebug(" Elf64Relocate: No PT_DYNAMIC segment in image %p, returning", Base);
505 return (void *)(hdr->e_entry + baseDiff);
508 dyntab = (void *)((Elf64_Addr)dyntab + baseDiff);
510 // Parse the dynamic table (first pass)
511 // - Search for String, Symbol and Hash tables
512 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
514 switch(dyntab[i].d_tag)
517 dyntab[i].d_un.d_ptr += baseDiff;
518 symtab = (void *)dyntab[i].d_un.d_ptr;
521 dyntab[i].d_un.d_ptr += baseDiff;
522 strtab = (void *)dyntab[i].d_un.d_ptr;
525 dyntab[i].d_un.d_ptr += baseDiff;
526 hashtab = (void *)dyntab[i].d_un.d_ptr;
531 if( !symtab || !strtab || !hashtab ) {
532 SysDebug("ld-acess - Elf64Relocate: Missing Symbol, string or hash table");
536 // Ready for symbol use
537 AddLoaded( Filename, Base );
539 // Second pass on dynamic table
540 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
542 DEBUGS("dyntab[%i].d_tag = %i", i, dyntab[i].d_tag);
543 switch(dyntab[i].d_tag)
545 case DT_SONAME: break;
548 char *libPath = strtab + dyntab[i].d_un.d_val;
549 DEBUGS("Elf64Relocate: libPath = '%s'", libPath);
550 if(LoadLibrary(libPath, NULL, envp) == 0) {
551 SysDebug("ld-acess - Elf64Relocate: Unable to load '%s'", libPath);
556 // Relocation entries
558 dyntab[i].d_un.d_ptr += baseDiff;
559 rel = (void *)dyntab[i].d_un.d_ptr;
562 rel_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rel);
565 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rel) ) {
566 SysDebug("ld-acess - Elf64Relocate: DT_RELENT(%i) != sizeof(Elf64_Rel)(%i)",
567 dyntab[i].d_un.d_val, sizeof(Elf64_Rel));
572 dyntab[i].d_un.d_ptr += baseDiff;
573 rela = (void *)dyntab[i].d_un.d_ptr;
576 rela_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rela);
579 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rela) ) {
580 SysDebug("ld-acess - Elf64Relocate: DT_RELAENT(%i) != sizeof(Elf64_Rela)(%i)",
581 dyntab[i].d_un.d_val, sizeof(Elf64_Rela));
586 dyntab[i].d_un.d_ptr += baseDiff;
587 pltrel = (void *)dyntab[i].d_un.d_ptr;
590 plt_type = dyntab[i].d_un.d_val;
593 plt_size = dyntab[i].d_un.d_val;
598 // Relocation function
599 void _Elf64DoReloc(Elf64_Xword r_info, void *ptr, Elf64_Sxword addend)
601 int sym = ELF64_R_SYM(r_info);
602 int type = ELF64_R_TYPE(r_info);
603 const char *symname = strtab + symtab[sym].st_name;
609 *(uint64_t*)ptr = (uint64_t)GetSymbol(symname) + addend;
613 case R_X86_64_GLOB_DAT:
614 *(uint64_t*)ptr = (uint64_t)GetSymbol(symname);
616 case R_X86_64_JUMP_SLOT:
617 *(uint64_t*)ptr = (uint64_t)GetSymbol(symname);
620 SysDebug("ld-acess - _Elf64DoReloc: Unknown relocation type %i", type);
627 DEBUGS("rel_count = %i", rel_count);
628 for( i = 0; i < rel_count; i ++ )
630 uint64_t *ptr = (void *)( rel[i].r_offset + baseDiff );
631 _Elf64DoReloc( rel[i].r_info, ptr, *ptr);
637 DEBUGS("rela_count = %i", rela_count);
638 for( i = 0; i < rela_count; i ++ )
640 _Elf64DoReloc( rela[i].r_info, (void *)( rela[i].r_offset + baseDiff ), rela[i].r_addend );
644 if( pltrel && plt_type )
646 if( plt_type == DT_REL ) {
647 Elf64_Rel *plt = pltrel;
648 int count = plt_size / sizeof(Elf64_Rel);
649 DEBUGS("plt rel count = %i", count);
650 for( i = 0; i < count; i ++ )
652 uint64_t *ptr = (void *)( plt[i].r_offset + baseDiff );
653 _Elf64DoReloc( plt[i].r_info, ptr, *ptr);
657 Elf64_Rela *plt = pltrel;
658 int count = plt_size / sizeof(Elf64_Rela);
659 DEBUGS("plt rela count = %i", count);
660 for( i = 0; i < count; i ++ )
662 _Elf64DoReloc( plt[i].r_info, (void *)(plt[i].r_offset + baseDiff), plt[i].r_addend);
667 DEBUGS("Elf64Relocate: Relocations done, return %p", (void *)(hdr->e_entry + baseDiff));
668 return (void *)(hdr->e_entry + baseDiff);
671 int Elf64GetSymbol(void *Base, const char *Name, void **Ret)
673 Elf64_Ehdr *hdr = Base;
678 Elf64_Word *pBuckets;
681 const char *dynstrtab;
682 uintptr_t iBaseDiff = -1;
688 // Catch the current executable
692 Elf64_Dyn *dynTab = NULL;
696 phtab = (void*)( Base + hdr->e_phoff );
697 for( i = 0; i < hdr->e_phnum; i ++ )
699 if(phtab[i].p_type == PT_LOAD && iBaseDiff > phtab[i].p_vaddr)
700 iBaseDiff = phtab[i].p_vaddr;
701 if( phtab[i].p_type == PT_DYNAMIC ) {
702 dynTab = (void*)(intptr_t)phtab[i].p_vaddr;
706 SysDebug("ERROR - Unable to find DYNAMIC segment in %p", Base);
709 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
710 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
712 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)
714 switch(dynTab[j].d_tag)
716 // --- Symbol Table ---
718 symtab = (void*)(intptr_t) dynTab[j].d_un.d_val; // Rebased in Relocate
721 dynstrtab = (void*)(intptr_t) dynTab[j].d_un.d_val;
725 pBuckets = (void*)(intptr_t) dynTab[j].d_un.d_val;
731 nbuckets = pBuckets[0];
732 iSymCount = pBuckets[1];
733 pBuckets = &pBuckets[2];
734 pChains = &pBuckets[ nbuckets ];
737 iNameHash = ElfHashString(Name);
738 iNameHash %= nbuckets;
741 i = pBuckets[ iNameHash ];
742 if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {
743 *Ret = (void*) (intptr_t) symtab[i].st_value + iBaseDiff;
744 DEBUGS("%s = %p", Name, *Ret);
748 while(pChains[i] != STN_UNDEF)
751 if(symtab[i].st_shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].st_name, Name) == 0) {
752 *Ret = (void*)(intptr_t)symtab[i].st_value + iBaseDiff;
753 DEBUGS("%s = %p", Name, *Ret);
763 Uint32 ElfHashString(const char *name)
768 h = (h << 4) + *(Uint8*)name++;
769 if( (g = h & 0xf0000000) )