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mdreloc.c revision 1.10 
      1 #include <sys/types.h>
      2 #include <sys/stat.h>
      3 
      4 #include "debug.h"
      5 #include "rtld.h"
      6 
      7 void
      8 _rtld_setup_pltgot(const Obj_Entry *obj)
      9 {
     10 	obj->pltgot[1] = (Elf_Addr) obj;
     11 	obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
     12 }
     13 
     14 int
     15 _rtld_relocate_nonplt_objects(obj, self, dodebug)
     16 	const Obj_Entry *obj;
     17 	bool self;
     18 	bool dodebug;
     19 {
     20 	const Elf_Rel *rel;
     21 #define COMBRELOC
     22 #ifdef COMBRELOC
     23 	unsigned long lastsym = -1;
     24 #endif
     25 	Elf_Addr target;
     26 
     27 	for (rel = obj->rel; rel < obj->rellim; rel++) {
     28 		Elf_Addr        *where;
     29 		const Elf_Sym   *def;
     30 		const Obj_Entry *defobj;
     31 		Elf_Addr         tmp;
     32 		unsigned long	 symnum;
     33 
     34 		where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
     35 		symnum = ELF_R_SYM(rel->r_info);
     36 
     37 		switch (ELF_R_TYPE(rel->r_info)) {
     38 		case R_TYPE(NONE):
     39 			break;
     40 
     41 #if 1 /* XXX should not occur */
     42 		case R_TYPE(PC32):
     43 #ifdef COMBRELOC
     44 			if (symnum != lastsym) {
     45 #endif
     46 				def = _rtld_find_symdef(symnum, obj, &defobj,
     47 				    false);
     48 				if (def == NULL)
     49 					return -1;
     50 				target = (Elf_Addr)(defobj->relocbase +
     51 				    def->st_value);
     52 #ifdef COMBRELOC
     53 				lastsym = symnum;
     54 			}
     55 #endif
     56 
     57 			*where += target - (Elf_Addr)where;
     58 			rdbg(dodebug, ("PC32 %s in %s --> %p in %s",
     59 			    obj->strtab + obj->symtab[symnum].st_name,
     60 			    obj->path, (void *)*where, defobj->path));
     61 			break;
     62 
     63 		case R_TYPE(GOT32):
     64 #endif
     65 		case R_TYPE(32):
     66 		case R_TYPE(GLOB_DAT):
     67 #ifdef COMBRELOC
     68 			if (symnum != lastsym) {
     69 #endif
     70 				def = _rtld_find_symdef(symnum, obj, &defobj,
     71 				    false);
     72 				if (def == NULL)
     73 					return -1;
     74 				target = (Elf_Addr)(defobj->relocbase +
     75 				    def->st_value);
     76 #ifdef COMBRELOC
     77 				lastsym = symnum;
     78 			}
     79 #endif
     80 
     81 			tmp = target + *where;
     82 			if (*where != tmp)
     83 				*where = tmp;
     84 			rdbg(dodebug, ("32/GLOB_DAT %s in %s --> %p in %s",
     85 			    obj->strtab + obj->symtab[symnum].st_name,
     86 			    obj->path, (void *)*where, defobj->path));
     87 			break;
     88 
     89 		case R_TYPE(RELATIVE):
     90 		    {
     91 			extern Elf_Addr	_GLOBAL_OFFSET_TABLE_[];
     92 			extern Elf_Addr	_GOT_END_[];
     93 
     94 			/* This is the ...iffy hueristic. */
     95 			if (!self ||
     96 			    (caddr_t)where < (caddr_t)_GLOBAL_OFFSET_TABLE_ ||
     97 			    (caddr_t)where >= (caddr_t)_GOT_END_) {
     98 				*where += (Elf_Addr)obj->relocbase;
     99 				rdbg(dodebug, ("RELATIVE in %s --> %p",
    100 				    obj->path, (void *)*where));
    101 			} else
    102 				rdbg(dodebug, ("RELATIVE in %s stays at %p",
    103 				    obj->path, (void *)*where));
    104 			break;
    105 		    }
    106 
    107 		case R_TYPE(COPY):
    108 			/*
    109 			 * These are deferred until all other relocations have
    110 			 * been done.  All we do here is make sure that the
    111 			 * COPY relocation is not in a shared library.  They
    112 			 * are allowed only in executable files.
    113 			 */
    114 			if (obj->isdynamic) {
    115 				_rtld_error(
    116 			"%s: Unexpected R_COPY relocation in shared library",
    117 				    obj->path);
    118 				return -1;
    119 			}
    120 			rdbg(dodebug, ("COPY (avoid in main)"));
    121 			break;
    122 
    123 		default:
    124 			rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, "
    125 			    "contents = %p, symbol = %s",
    126 			    symnum, (u_long)ELF_R_TYPE(rel->r_info),
    127 			    (void *)rel->r_offset, (void *)*where,
    128 			    obj->strtab + obj->symtab[symnum].st_name));
    129 			_rtld_error("%s: Unsupported relocation type %ld "
    130 			    "in non-PLT relocations\n",
    131 			    obj->path, (u_long) ELF_R_TYPE(rel->r_info));
    132 			return -1;
    133 		}
    134 	}
    135 	return 0;
    136 }
    137 
    138 int
    139 _rtld_relocate_plt_lazy(obj, dodebug)
    140 	const Obj_Entry *obj;
    141 	bool dodebug;
    142 {
    143 	const Elf_Rel *rel;
    144 
    145 	if (!obj->isdynamic)
    146 		return 0;
    147 
    148 	for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
    149 		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
    150 
    151 		assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT));
    152 
    153 		/* Just relocate the GOT slots pointing into the PLT */
    154 		*where += (Elf_Addr)obj->relocbase;
    155 		rdbg(dodebug, ("fixup !main in %s --> %p", obj->path,
    156 		    (void *)*where));
    157 	}
    158 
    159 	return 0;
    160 }
    161 
    162 int
    163 _rtld_relocate_plt_object(obj, rela, addrp, dodebug)
    164 	const Obj_Entry *obj;
    165 	const Elf_Rela *rela;
    166 	caddr_t *addrp;
    167 	bool dodebug;
    168 {
    169 	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
    170 	Elf_Addr new_value;
    171 	const Elf_Sym  *def;
    172 	const Obj_Entry *defobj;
    173 
    174 	assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
    175 
    176 	def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
    177 	if (def == NULL)
    178 		return -1;
    179 
    180 	new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
    181 	rdbg(dodebug, ("bind now/fixup in %s --> old=%p new=%p",
    182 	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
    183 	if (*where != new_value)
    184 		*where = new_value;
    185 
    186 	*addrp = (caddr_t)new_value;
    187 	return 0;
    188 }
    189