2 * AcessOS 1 - Dynamic Loader
12 # define DEBUGS(v...) SysDebug(v)
19 //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"};
20 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"};
24 Uint32 ElfHashString(const char *name);
28 \fn int ElfRelocate(void *Base, char **envp, char *Filename)
29 \brief Relocates a loaded ELF Executable
31 void *ElfRelocate(void *Base, char **envp, char *Filename)
33 Elf32_Ehdr *hdr = Base;
41 Elf32_Rel *rel = NULL;
42 Elf32_Rela *rela = NULL;
43 Uint32 *pltgot = NULL;
45 int relSz=0, relEntSz=8;
46 int relaSz=0, relaEntSz=8;
47 int pltSz=0, pltType=0;
48 Elf32_Dyn *dynamicTab = NULL; // Dynamic Table Pointer
49 char *dynstrtab = NULL; // .dynamic String Table
52 DEBUGS("ElfRelocate: (Base=0x%x)", Base);
57 // Parse Program Header to get Dynamic Table
58 phtab = Base + hdr->phoff;
59 iSegmentCount = hdr->phentcount;
60 for(i=0;i<iSegmentCount;i++)
62 // Determine linked base address
63 if(phtab[i].Type == PT_LOAD && iRealBase > phtab[i].VAddr)
64 iRealBase = phtab[i].VAddr;
66 // Find Dynamic Section
67 if(phtab[i].Type == PT_DYNAMIC) {
69 DEBUGS(" WARNING - elf_relocate: Multiple PT_DYNAMIC segments");
72 dynamicTab = (void *) (intptr_t) phtab[i].VAddr;
73 j = i; // Save Dynamic Table ID
77 // Page Align real base
79 DEBUGS(" elf_relocate: True Base = 0x%x, Compiled Base = 0x%x", Base, iRealBase);
82 iBaseDiff = (intptr_t)Base - iRealBase;
84 // hdr->entrypoint += iBaseDiff; // Adjust Entrypoint
86 // Check if a PT_DYNAMIC segement was found
88 SysDebug(" elf_relocate: No PT_DYNAMIC segment in image %p, returning", Base);
89 return (void *)hdr->entrypoint + iBaseDiff;
92 // Adjust Dynamic Table
93 dynamicTab = (void *)( (intptr_t)dynamicTab + iBaseDiff );
95 // === Get Symbol table and String Table ===
96 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
98 switch(dynamicTab[j].d_tag)
100 // --- Symbol Table ---
102 DEBUGS(" elf_relocate: DYNAMIC Symbol Table 0x%x (0x%x)",
103 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
104 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
105 dynsymtab = (void*)(dynamicTab[j].d_val);
106 // hdr->misc.SymTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
108 // --- String Table ---
110 DEBUGS(" elf_relocate: DYNAMIC String Table 0x%x (0x%x)",
111 dynamicTab[j].d_val, dynamicTab[j].d_val + iBaseDiff);
112 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
113 dynstrtab = (void*)(dynamicTab[j].d_val);
117 if(iBaseDiff != 0) dynamicTab[j].d_val += iBaseDiff;
118 iSymCount = ((Uint*)(dynamicTab[j].d_val))[1];
119 // hdr->misc.HashTable = dynamicTab[j].d_val; // Saved in unused bytes of ident
124 if(dynsymtab == NULL) {
125 SysDebug("ld-acess.so - WARNING: No Dynamic Symbol table in %p, returning", hdr);
126 return (void *) hdr->entrypoint + iBaseDiff;
130 // Alter Symbols to true base
131 for(i=0;i<iSymCount;i++)
133 dynsymtab[i].value += iBaseDiff;
134 dynsymtab[i].nameOfs += (intptr_t)dynstrtab;
135 //DEBUGS("elf_relocate: Sym '%s' = 0x%x (relocated)", dynsymtab[i].name, dynsymtab[i].value);
139 // === Add to loaded list (can be imported now) ===
140 AddLoaded( Filename, Base );
142 // === Parse Relocation Data ===
143 DEBUGS(" elf_relocate: dynamicTab = 0x%x", dynamicTab);
144 for( j = 0; dynamicTab[j].d_tag != DT_NULL; j++)
146 switch(dynamicTab[j].d_tag)
148 // --- Shared Library Name ---
150 DEBUGS(" elf_relocate: .so Name '%s'", dynstrtab+dynamicTab[j].d_val);
152 // --- Needed Library ---
154 libPath = dynstrtab + dynamicTab[j].d_val;
155 DEBUGS(" Required Library '%s'", libPath);
156 if(LoadLibrary(libPath, NULL, envp) == 0) {
158 DEBUGS(" elf_relocate: Unable to load '%s'", libPath);
160 SysDebug("Unable to load required library '%s'", libPath);
166 case DT_PLTGOT: pltgot = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
167 case DT_JMPREL: plt = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
168 case DT_PLTREL: pltType = dynamicTab[j].d_val; break;
169 case DT_PLTRELSZ: pltSz = dynamicTab[j].d_val; break;
171 // --- Relocation ---
172 case DT_REL: rel = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
173 case DT_RELSZ: relSz = dynamicTab[j].d_val; break;
174 case DT_RELENT: relEntSz = dynamicTab[j].d_val; break;
175 case DT_RELA: rela = (void*)(iBaseDiff + dynamicTab[j].d_val); break;
176 case DT_RELASZ: relaSz = dynamicTab[j].d_val; break;
177 case DT_RELAENT: relaEntSz = dynamicTab[j].d_val; break;
179 // --- Symbol Table ---
181 // --- Hash Table ---
183 // --- String Table ---
189 if(dynamicTab[j].d_tag > DT_JMPREL) continue;
190 //DEBUGS(" elf_relocate: %i-%i = %s,0x%x",
191 // i,j, csaDT_NAMES[dynamicTab[j].d_tag],dynamicTab[j].d_val);
196 DEBUGS(" elf_relocate: Beginning Relocation");
198 void elf_doRelocate(Uint r_info, Uint32 *ptr, Uint32 addend, Elf32_Sym *symtab)
200 int type = ELF32_R_TYPE(r_info);
201 int sym = ELF32_R_SYM(r_info);
203 const char *symname = dynstrtab + symtab[sym].nameOfs;
206 // Standard 32 Bit Relocation (S+A)
208 val = (intptr_t) GetSymbol( symname );
209 DEBUGS(" elf_doRelocate: R_386_32 *0x%x += 0x%x('%s')",
214 // 32 Bit Relocation wrt. Offset (S+A-P)
216 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
217 val = (intptr_t) GetSymbol( symname );
218 DEBUGS(" elf_doRelocate: R_386_PC32 *0x%x = 0x%x + 0x%x - 0x%x",
219 ptr, *ptr, val, (Uint)ptr );
220 *ptr = val + addend - (intptr_t)ptr;
221 //*ptr = val + addend - ((Uint)ptr - iBaseDiff);
224 // Absolute Value of a symbol (S)
227 DEBUGS(" elf_doRelocate: #%i: '%s'", sym, symname);
228 val = (intptr_t) GetSymbol( symname );
229 DEBUGS(" elf_doRelocate: %s *0x%x = 0x%x", csaR_NAMES[type], ptr, val);
233 // Base Address (B+A)
235 DEBUGS(" elf_doRelocate: R_386_RELATIVE *0x%x = 0x%x + 0x%x", ptr, iBaseDiff, addend);
236 *ptr = iBaseDiff + addend;
240 DEBUGS(" elf_doRelocate: Rel 0x%x: 0x%x,%s", ptr, sym, csaR_NAMES[type]);
245 // Parse Relocation Entries
249 DEBUGS(" elf_relocate: rel=0x%x, relSz=0x%x, relEntSz=0x%x", rel, relSz, relEntSz);
250 j = relSz / relEntSz;
251 for( i = 0; i < j; i++ )
253 //DEBUGS(" Rel %i: 0x%x+0x%x", i, iBaseDiff, rel[i].r_offset);
254 ptr = (void*)(iBaseDiff + rel[i].r_offset);
255 elf_doRelocate(rel[i].r_info, ptr, *ptr, dynsymtab);
258 // Parse Relocation Entries
262 DEBUGS(" elf_relocate: rela=0x%x, relaSz=0x%x, relaEntSz=0x%x", rela, relaSz, relaEntSz);
263 j = relaSz / relaEntSz;
264 for( i = 0; i < j; i++ )
266 ptr = (void*)(iBaseDiff + rela[i].r_offset);
267 elf_doRelocate(rel[i].r_info, ptr, rela[i].r_addend, dynsymtab);
271 // === Process PLT (Procedure Linkage Table) ===
275 DEBUGS(" elf_relocate: Relocate PLT, plt=0x%x", plt);
276 if(pltType == DT_REL)
278 Elf32_Rel *pltRel = plt;
279 j = pltSz / sizeof(Elf32_Rel);
280 DEBUGS(" elf_relocate: PLT Reloc Type = Rel, %i entries", j);
283 ptr = (void*)(iBaseDiff + pltRel[i].r_offset);
284 elf_doRelocate(pltRel[i].r_info, ptr, *ptr, dynsymtab);
289 Elf32_Rela *pltRela = plt;
290 j = pltSz / sizeof(Elf32_Rela);
291 DEBUGS(" elf_relocate: PLT Reloc Type = Rela, %i entries", j);
294 ptr = (void*)(iRealBase + pltRela[i].r_offset);
295 elf_doRelocate(pltRela[i].r_info, ptr, pltRela[i].r_addend, dynsymtab);
300 DEBUGS("ElfRelocate: RETURN 0x%x", hdr->entrypoint + iBaseDiff);
301 return (void*)hdr->entrypoint + iBaseDiff;
306 * \fn int ElfGetSymbol(Uint Base, const char *name, void **ret)
308 int ElfGetSymbol(void *Base, const char *Name, void **ret)
310 Elf32_Ehdr *hdr = Base;
318 const char *dynstrtab;
319 uintptr_t iBaseDiff = -1;
321 //DEBUGS("ElfGetSymbol: (Base=0x%x, Name='%s')", Base, Name);
323 pBuckets = (void *) (intptr_t) hdr->misc.HashTable;
324 symtab = (void *) (intptr_t) hdr->misc.SymTable;
325 dynstrtab = (void *) (intptr_t) hdr->misc.StrTab;
332 // Catch the current executable
336 Elf32_Dyn *dynTab = NULL;
340 phtab = (void*)( Base + hdr->phoff );
341 for( i = 0; i < hdr->phentcount; i ++ )
343 if(phtab[i].Type == PT_LOAD && iBaseDiff > phtab[i].VAddr)
344 iBaseDiff = phtab[i].VAddr;
345 if( phtab[i].Type == PT_DYNAMIC ) {
346 dynTab = (void*)phtab[i].VAddr;
350 SysDebug("ERROR - Unable to find DYNAMIC segment in %p");
353 iBaseDiff = (intptr_t)Base - iBaseDiff; // Make iBaseDiff actually the diff
354 dynTab = (void*)( (intptr_t)dynTab + iBaseDiff );
356 for( j = 0; dynTab[j].d_tag != DT_NULL; j++)
358 switch(dynTab[j].d_tag)
360 // --- Symbol Table ---
362 symtab = (void*)(intptr_t) dynTab[j].d_val; // Rebased in Relocate
365 dynstrtab = (void*)(intptr_t) dynTab[j].d_val;
369 pBuckets = (void*)(intptr_t) dynTab[j].d_val;
375 hdr->misc.HashTable = pBucktets;
376 hdr->misc.SymTable = symtab;
377 hdr->misc.StrTab = dynstrtab;
381 nbuckets = pBuckets[0];
382 iSymCount = pBuckets[1];
383 pBuckets = &pBuckets[2];
384 pChains = &pBuckets[ nbuckets ];
387 iNameHash = ElfHashString(Name);
388 iNameHash %= nbuckets;
389 //DEBUGS(" ElfGetSymbol: iNameHash = 0x%x", iNameHash);
392 i = pBuckets[ iNameHash ];
393 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[i].name);
394 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[i].nameOfs, Name) == 0) {
395 *ret = (void*) (intptr_t) symtab[ i ].value + iBaseDiff;
399 //DEBUGS(" ElfGetSymbol: Hash of first = 0x%x", ElfHashString( symtab[i].name ) % nbuckets);
400 while(pChains[i] != STN_UNDEF)
402 //DEBUGS(" pChains[%i] = %i", i, pChains[i]);
404 //DEBUGS(" ElfGetSymbol: strcmp(Name, \"%s\")", symtab[ i ].name);
405 if(symtab[i].shndx != SHN_UNDEF && strcmp(dynstrtab + symtab[ i ].nameOfs, Name) == 0) {
406 //DEBUGS("ElfGetSymbol: RETURN 1, '%s' = 0x%x", symtab[ i ].name, symtab[ i ].value);
407 *ret = (void*)(intptr_t)symtab[ i ].value + iBaseDiff;
412 //DEBUGS("ElfGetSymbol: RETURN 0, Symbol '%s' not found", Name);
416 Uint32 ElfHashString(const char *name)
421 h = (h << 4) + *(Uint8*)name++;
422 if( (g = h & 0xf0000000) )
430 unsigned long elf_hash(const unsigned char *name)
432 unsigned long h = 0, g;
435 h = (h << 4) + *name++;
436 if (g = h & 0xf0000000)