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: hdr = {");
69 DEBUGS("Elf64Relocate: e_ident = '%.16s'", hdr->e_ident);
70 DEBUGS("Elf64Relocate: e_type = 0x%x", hdr->e_type);
71 DEBUGS("Elf64Relocate: e_machine = 0x%x", hdr->e_machine);
72 DEBUGS("Elf64Relocate: e_version = 0x%x", hdr->e_version);
73 DEBUGS("Elf64Relocate: e_entry = %p", hdr->e_entry);
74 DEBUGS("Elf64Relocate: e_phoff = 0x%llx", hdr->e_phoff);
75 DEBUGS("Elf64Relocate: e_shoff = 0x%llx", hdr->e_shoff);
76 DEBUGS("Elf64Relocate: e_flags = 0x%x", hdr->e_flags);
77 DEBUGS("Elf64Relocate: e_ehsize = 0x%x", hdr->e_ehsize);
78 DEBUGS("Elf64Relocate: e_phentsize = 0x%x", hdr->e_phentsize);
79 DEBUGS("Elf64Relocate: e_phnum = %i", hdr->e_phnum);
81 // Scan for the dynamic table (and find the compiled base)
82 phtab = Base + hdr->e_phoff;
83 for( i = 0; i < hdr->e_phnum; i ++ )
85 if(phtab[i].p_type == PT_DYNAMIC)
86 dyntab = (void *)(intptr_t)phtab[i].p_vaddr;
87 if(phtab[i].p_type == PT_LOAD && compiledBase > phtab[i].p_vaddr)
88 compiledBase = phtab[i].p_vaddr;
91 baseDiff = (Elf64_Addr)Base - compiledBase;
93 DEBUGS("baseDiff = %p", baseDiff);
96 SysDebug(" Elf64Relocate: No PT_DYNAMIC segment in image %p, returning", Base);
97 return (void *)(hdr->e_entry + baseDiff);
100 dyntab = (void *)((Elf64_Addr)dyntab + baseDiff);
102 // Parse the dynamic table (first pass)
103 // - Search for String, Symbol and Hash tables
104 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
106 switch(dyntab[i].d_tag)
109 dyntab[i].d_un.d_ptr += baseDiff;
110 symtab = (void *)dyntab[i].d_un.d_ptr;
113 dyntab[i].d_un.d_ptr += baseDiff;
114 strtab = (void *)dyntab[i].d_un.d_ptr;
117 dyntab[i].d_un.d_ptr += baseDiff;
118 hashtab = (void *)dyntab[i].d_un.d_ptr;
123 if( !symtab || !strtab || !hashtab ) {
124 SysDebug("ld-acess - Elf64Relocate: Missing Symbol, string or hash table");
128 // Ready for symbol use
129 AddLoaded( Filename, Base );
131 // Second pass on dynamic table
132 for(i = 0; dyntab[i].d_tag != DT_NULL; i ++)
134 DEBUGS("dyntab[%i].d_tag = %i", i, dyntab[i].d_tag);
135 switch(dyntab[i].d_tag)
137 case DT_SONAME: break;
140 char *libPath = strtab + dyntab[i].d_un.d_val;
141 DEBUGS("Elf64Relocate: libPath = '%s'", libPath);
142 if(LoadLibrary(libPath, NULL, envp) == 0) {
143 SysDebug("ld-acess - Elf64Relocate: Unable to load '%s'", libPath);
148 // Relocation entries
150 dyntab[i].d_un.d_ptr += baseDiff;
151 rel = (void *)dyntab[i].d_un.d_ptr;
154 rel_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rel);
157 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rel) ) {
158 SysDebug("ld-acess - Elf64Relocate: DT_RELENT(%i) != sizeof(Elf64_Rel)(%i)",
159 dyntab[i].d_un.d_val, sizeof(Elf64_Rel));
164 dyntab[i].d_un.d_ptr += baseDiff;
165 rela = (void *)dyntab[i].d_un.d_ptr;
168 rela_count = dyntab[i].d_un.d_val / sizeof(Elf64_Rela);
171 if( dyntab[i].d_un.d_val != sizeof(Elf64_Rela) ) {
172 SysDebug("ld-acess - Elf64Relocate: DT_RELAENT(%i) != sizeof(Elf64_Rela)(%i)",
173 dyntab[i].d_un.d_val, sizeof(Elf64_Rela));
178 dyntab[i].d_un.d_ptr += baseDiff;
179 pltrel = (void *)dyntab[i].d_un.d_ptr;
182 plt_type = dyntab[i].d_un.d_val;
185 plt_size = dyntab[i].d_un.d_val;
190 // Relocation function
191 void _Elf64DoReloc(Elf64_Xword r_info, void *ptr, Elf64_Sxword addend)
193 int sym = ELF64_R_SYM(r_info);
194 int type = ELF64_R_TYPE(r_info);
195 const char *symname = strtab + symtab[sym].st_name;
201 *(uint64_t*)ptr = (uint64_t)GetSymbol(symname) + addend;
204 SysDebug("ld-acess - _Elf64DoReloc: Unknown relocation type %i", type);
211 DEBUGS("rel_count = %i", rel_count);
212 for( i = 0; i < rel_count; i ++ )
214 uint64_t *ptr = (void *)( rel[i].r_offset + baseDiff );
215 _Elf64DoReloc( rel[i].r_info, ptr, *ptr);
221 DEBUGS("rela_count = %i", rela_count);
222 for( i = 0; i < rela_count; i ++ )
224 _Elf64DoReloc( rela[i].r_info, (void *)( rela[i].r_offset + baseDiff ), rela[i].r_addend );
228 if( pltrel && plt_type )
230 if( plt_type == DT_REL ) {
231 Elf64_Rel *plt = pltrel;
232 int count = plt_size / sizeof(Elf64_Rel);
233 DEBUGS("plt rel count = %i", count);
234 for( i = 0; i < count; i ++ )
236 uint64_t *ptr = (void *)( plt[i].r_offset + baseDiff );
237 _Elf64DoReloc( plt[i].r_info, ptr, *ptr);
241 Elf64_Rela *plt = pltrel;
242 int count = plt_size / sizeof(Elf64_Rela);
243 DEBUGS("plt rela count = %i", count);
244 for( i = 0; i < count; i ++ )
246 _Elf64DoReloc( plt[i].r_info, (void *)(plt[i].r_offset + baseDiff), plt[i].r_addend);
251 DEBUGS("Elf64Relocate: Relocations done, return %p", (void *)(hdr->e_entry + baseDiff));
252 return (void *)(hdr->e_entry + baseDiff);
255 void *Elf32Relocate(void *Base, char **envp, const char *Filename)
257 Elf32_Ehdr *hdr = Base;
259 int i, j; // Counters
265 Elf32_Rel *rel = NULL;
266 Elf32_Rela *rela = NULL;
267 Uint32 *pltgot = NULL;
269 int relSz=0, relEntSz=8;
270 int relaSz=0, relaEntSz=8;
271 int pltSz=0, pltType=0;
272 Elf32_Dyn *dynamicTab = NULL; // Dynamic Table Pointer
273 char *dynstrtab = NULL; // .dynamic String Table
274 Elf32_Sym *dynsymtab;
276 DEBUGS("ElfRelocate: (Base=0x%x)", Base);
278 // Check magic header
281 // Parse Program Header to get Dynamic Table
282 phtab = Base + hdr->phoff;
283 iSegmentCount = hdr->phentcount;
284 for(i=0;i<iSegmentCount;i++)
286 // Determine linked base address
287 if(phtab[i].Type == PT_LOAD && iRealBase > phtab[i].VAddr)
288 iRealBase = phtab[i].VAddr;
290 // Find Dynamic Section
291 if(phtab[i].Type == PT_DYNAMIC) {
293 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");
296 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;
297 j = i; // Save Dynamic Table ID
301 // Page Align real base
303 DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);
305 // Adjust "Real" Base
306 iBaseDiff = (intptr_t)Base - iRealBase;
308 // hdr->entrypoint += iBaseDiff; // Adjust Entrypoint
310 // Check if a PT_DYNAMIC segement was found
312 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);
313 return (void *)hdr->entrypoint + iBaseDiff;
316 // Adjust Dynamic Table
317 dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );
319 // === Get Symbol table and String Table ===
320 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
322 switch(dynamicTab[j].d_tag)
324 // --- Symbol Table ---
326 DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",
327 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
328 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
329 dynsymtab = (void*)(dynamicTab[j].d_val);
330 // hdr->misc.SymTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
332 // --- String Table ---
334 DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",
335 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
336 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
337 dynstrtab = (void*)(dynamicTab[j].d_val);
341 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
342 iSymCount = ((Uint*)(dynamicTab[j].d_val))[1];
343 // hdr->misc.HashTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
348 if(dynsymtab == NULL) {
349 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);
350 return (void *) hdr->entrypoint + iBaseDiff;
354 // Alter Symbols to true base
355 for(i=0;i<iSymCount;i++)
357 dynsymtab[i].value += iBaseDiff;
358 dynsymtab[i].nameOfs += (intptr_t)dynstrtab;
359 //DEBUGS("elf_relocate: Sym '%s' = 0x%x (relocated)", dynsymtab[i].name, dynsymtab[i].value);
363 // === Add to loaded list (can be imported now) ===
364 AddLoaded( Filename, Base );
366 // === Parse Relocation Data ===
367 DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);
368 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
370 switch(dynamicTab[j].d_tag)
372 // --- Shared Library Name ---
374 DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);
376 // --- Needed Library ---
378 libPath = dynstrtab + dynamicTab[j].d_val;
379 DEBUGS(" Required Library '%s'", libPath);
380 if(LoadLibrary(libPath, NULL, envp) == 0) {
382 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);
384 SysDebug("Unable to load required library '%s'", libPath);
390 case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
391 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
392 case DT_PLTREL: pltType = dynamicTab[j].d_val; break;
393 case DT_PLTRELSZ: pltSz = dynamicTab[j].d_val; break;
395 // --- Relocation ---
396 case DT_REL: rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
397 case DT_RELSZ: relSz = dynamicTab[j].d_val; break;
398 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;
399 case DT_RELA: rela = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
400 case DT_RELASZ: relaSz = dynamicTab[j].d_val; break;
401 case DT_RELAENT: relaEntSz = dynamicTab[j].d_val; break;
403 // --- Symbol Table ---
405 // --- Hash Table ---
407 // --- String Table ---
413 if(dynamicTab[j].d_tag > DT_JMPREL) continue;
414 //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",
415 // i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);
420 DEBUGS(" elf_relocate: Beginning Relocation");
422 void elf_doRelocate(Uint r_info, Uint32 *ptr, Uint32 addend, Elf32_Sym *symtab)
424 int type = ELF32_R_TYPE(r_info);
425 int sym = ELF32_R_SYM(r_info);
427 const char *symname = dynstrtab + symtab[sym].nameOfs;
430 // Standard 32 Bit Relocation (S+A)
432 val = (intptr_t) GetSymbol( symname );
433 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += 0x%x('%s')",
438 // 32 Bit Relocation wrt. Offset (S+A-P)
440 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
441 val = (intptr_t) GetSymbol( symname );
442 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%x - 0x%x",
443 ptr, *ptr, val, (intptr_t)ptr );
444 *ptr = val + addend - (intptr_t)ptr;
445 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);
448 // Absolute Value of a symbol (S)
451 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
452 val = (intptr_t) GetSymbol( symname );
453 DEBUGS(" elf_doRelocate: %s *0x%x = 0x%x", csaR_NAMES[type], ptr, val);
457 // Base Address (B+A)
459 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);
460 *ptr = iBaseDiff + addend;
464 DEBUGS(" elf_doRelocate: Rel 0x%x: 0x%x,%s", ptr, sym, csaR_NAMES[type]);
469 // Parse Relocation Entries
473 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);
474 j = relSz / relEntSz;
475 for( i = 0; i < j; i++ )
477 //DEBUGS(" Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);
478 ptr = (void*)(iBaseDiff + rel[i].r_offset);
479 elf_doRelocate(rel[i].r_info, ptr, *ptr, dynsymtab);
482 // Parse Relocation Entries
486 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);
487 j = relaSz / relaEntSz;
488 for( i = 0; i < j; i++ )
490 ptr = (void*)(iBaseDiff + rela[i].r_offset);
491 elf_doRelocate(rel[i].r_info, ptr, rela[i].r_addend, dynsymtab);
495 // === Process PLT (Procedure Linkage Table) ===
499 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);
500 if(pltType == DT_REL)
502 Elf32_Rel *pltRel = plt;
503 j = pltSz / sizeof(Elf32_Rel);
504 DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", j);
507 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);
508 elf_doRelocate(pltRel[i].r_info, ptr, *ptr, dynsymtab);
513 Elf32_Rela *pltRela = plt;
514 j = pltSz / sizeof(Elf32_Rela);
515 DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", j);
518 ptr = (void*)(iRealBase + pltRela[i].r_offset);
519 elf_doRelocate(pltRela[i].r_info, ptr, pltRela[i].r_addend, dynsymtab);
524 DEBUGS("ElfRelocate: RETURN 0x%x", hdr->entrypoint + iBaseDiff);
525 return (void*)hdr->entrypoint + iBaseDiff;
530 * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)
532 int ElfGetSymbol(void *Base, const char *Name, void **ret)
534 Elf32_Ehdr *hdr = Base;
542 const char *dynstrtab;
543 uintptr_t iBaseDiff = -1;
545 //DEBUGS("ElfGetSymbol: (Base=0x%x, Name='%s')", Base, Name);
547 pBuckets = (void *) (intptr_t) hdr->misc.HashTable;
548 symtab = (void *) (intptr_t) hdr->misc.SymTable;
549 dynstrtab = (void *) (intptr_t) hdr->misc.StrTab;
556 // Catch the current executable
560 Elf32_Dyn *dynTab = NULL;
564 phtab = (void*)( Base + hdr->phoff );
565 for( i = 0; i < hdr->phentcount; i ++ )
567 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)
568 iBaseDiff = phtab[i].VAddr;
569 if( phtab[i].Type == PT_DYNAMIC ) {
570 dynTab = (void*)(intptr_t)phtab[i].VAddr;
574 SysDebug("ERROR - Unable to find DYNAMIC segment in %p");
577 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
578 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
580 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)
582 switch(dynTab[j].d_tag)
584 // --- Symbol Table ---
586 symtab = (void*)(intptr_t) dynTab[j].d_val; // Rebased in Relocate
589 dynstrtab = (void*)(intptr_t) dynTab[j].d_val;
593 pBuckets = (void*)(intptr_t) dynTab[j].d_val;
599 hdr->misc.HashTable = pBucktets;
600 hdr->misc.SymTable = symtab;
601 hdr->misc.StrTab = dynstrtab;
605 nbuckets = pBuckets[0];
606 iSymCount = pBuckets[1];
607 pBuckets = &pBuckets[2];
608 pChains = &pBuckets[ nbuckets ];
611 iNameHash = ElfHashString(Name);
612 iNameHash %= nbuckets;
613 //DEBUGS(" ElfGetSymbol: iNameHash = 0x%x", iNameHash);
616 i = pBuckets[ iNameHash ];
617 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[i].name);
618 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].nameOfs, Name) == 0) {
619 *ret = (void*) (intptr_t) symtab[ i ].value + iBaseDiff;
623 //DEBUGS(" ElfGetSymbol: Hash of first = 0x%x", ElfHashString( symtab[i].name ) % nbuckets);
624 while(pChains[i] != STN_UNDEF)
626 //DEBUGS(" pChains[%i] = %i", i, pChains[i]);
628 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[ i ].name);
629 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[ i ].nameOfs, Name) == 0) {
630 //DEBUGS("ElfGetSymbol: RETURN 1, '%s' = 0x%x", symtab[ i ].name, symtab[ i ].value);
631 *ret = (void*)(intptr_t)symtab[ i ].value + iBaseDiff;
636 //DEBUGS("ElfGetSymbol: RETURN 0, Symbol '%s' not found", Name);
640 Uint32 ElfHashString(const char *name)
645 h = (h << 4) + *(Uint8*)name++;
646 if( (g = h & 0xf0000000) )
654 unsigned long elf_hash(const unsigned char *name)
656 unsigned long h = 0, g;
659 h = (h << 4) + *name++;
660 if (g = h & 0xf0000000)