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mdreloc.c revision 1.2 
      1 #include <sys/types.h>
      2 #include <sys/mman.h>
      3 #include <err.h>
      4 #include <errno.h>
      5 #include <fcntl.h>
      6 #include <stdarg.h>
      7 #include <stdio.h>
      8 #include <stdlib.h>
      9 #include <string.h>
     10 #include <unistd.h>
     11 #include <elf.h>
     12 
     13 #include "debug.h"
     14 #include "rtld.h"
     15 
     16 extern Elf64_Addr _GLOBAL_OFFSET_TABLE_[];
     17 
     18 int
     19 _rtld_relocate_nonplt_object(Obj_Entry *obj, const Elf_Rela *rela, bool dodebug)
     20 {
     21 	Elf64_Addr *where64;
     22 	Elf32_Addr *where32;
     23 	const Elf_Sym *def;
     24 	const Obj_Entry *defobj;
     25 	Elf64_Addr tmp64;
     26 	Elf32_Addr tmp32;
     27 
     28 	where64 = (Elf64_Addr *)(obj->relocbase + rela->r_offset);
     29 	where32 = (Elf32_Addr *)where64;
     30 
     31 	switch (ELF_R_TYPE(rela->r_info)) {
     32 
     33 	case R_TYPE(NONE):
     34 		break;
     35 
     36 	case R_TYPE(32):	/* word32 S + A, truncate */
     37 	case R_TYPE(32S):	/* word32 S + A, signed truncate */
     38 	case R_TYPE(GOT32):	/* word32 G + A (XXX can we see these?) */
     39 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
     40 		    &defobj, false);
     41 		if (def == NULL)
     42 			return -1;
     43 		tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + def->st_value +
     44 		    rela->r_addend);
     45 
     46 		if (*where32 != tmp32)
     47 			*where32 = tmp32;
     48 		rdbg(dodebug, ("32/32S %s in %s --> %p in %s",
     49 		    defobj->strtab + def->st_name, obj->path,
     50 		    (void *)(unsigned long)*where32, defobj->path));
     51 		break;
     52 	case R_TYPE(64):	/* word64 S + A */
     53 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
     54 		    &defobj, false);
     55 		if (def == NULL)
     56 			return -1;
     57 
     58 		tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value +
     59 		    rela->r_addend);
     60 
     61 		if (*where64 != tmp64)
     62 			*where64 = tmp64;
     63 		rdbg(dodebug, ("64 %s in %s --> %p in %s",
     64 		    defobj->strtab + def->st_name, obj->path,
     65 		    (void *)*where64, defobj->path));
     66 		break;
     67 	case R_TYPE(PC32):	/* word32 S + A - P */
     68 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
     69 		    &defobj, false);
     70 		if (def == NULL)
     71 			return -1;
     72 		tmp32 = (Elf32_Addr)(u_long)(defobj->relocbase + def->st_value +
     73 		    rela->r_addend - (Elf64_Addr)where64);
     74 		if (*where32 != tmp32)
     75 			*where32 = tmp32;
     76 		rdbg(dodebug, ("PC32 %s in %s --> %p in %s",
     77 		    defobj->strtab + def->st_name, obj->path,
     78 		    (void *)(unsigned long)*where32, defobj->path));
     79 		break;
     80 	case R_TYPE(GLOB_DAT):	/* word64 S */
     81 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
     82 		    &defobj, false);
     83 		if (def == NULL)
     84 			return -1;
     85 
     86 		tmp64 = (Elf64_Addr)(defobj->relocbase + def->st_value);
     87 
     88 		if (*where64 != tmp64)
     89 			*where64 = tmp64;
     90 		rdbg(dodebug, ("64 %s in %s --> %p in %s",
     91 		    defobj->strtab + def->st_name, obj->path,
     92 		    (void *)*where64, defobj->path));
     93 		break;
     94 	case R_TYPE(RELATIVE):  /* word64 B + A */
     95 		tmp64 = (Elf64_Addr)(obj->relocbase + rela->r_addend);
     96 		if (*where64 != tmp64)
     97 			*where64 = tmp64;
     98 		rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path,
     99 		    (void *)*where64));
    100                 break;
    101 
    102 	case R_TYPE(COPY):
    103 		rdbg(dodebug, ("COPY"));
    104 		break;
    105 
    106 	default:
    107 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
    108 		    &defobj, true);
    109 		rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, "
    110 		    "addend = %p, contents = %p, symbol = %s",
    111 		    (u_long)ELF_R_SYM(rela->r_info),
    112 		    (u_long)ELF_R_TYPE(rela->r_info),
    113 		    (void *)rela->r_offset, (void *)rela->r_addend,
    114 		    (void *)*where64,
    115 		    def ? defobj->strtab + def->st_name : "??"));
    116 		_rtld_error("%s: Unsupported relocation type %ld "
    117 		    "in non-PLT relocations\n",
    118 		    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
    119 		return -1;
    120 	}
    121 	return 0;
    122 }
    123 
    124 
    125 
    126 int
    127 _rtld_relocate_plt_object(Obj_Entry *obj, const Elf_Rela *rela, caddr_t *addrp,
    128 			  bool bind_now, bool dodebug)
    129 {
    130 	Elf32_Addr *where = (Elf32_Addr *)(obj->relocbase + rela->r_offset);
    131 	Elf32_Addr new_value;
    132 
    133 	/* Fully resolve procedure addresses now */
    134 
    135 	if (bind_now || obj->pltgot == NULL) {
    136 		const Elf_Sym  *def;
    137 		const Obj_Entry *defobj;
    138 
    139 		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT));
    140 
    141 		def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj,
    142 		    &defobj, true);
    143 		if (def == NULL)
    144 			return -1;
    145 
    146 		new_value = (Elf32_Addr)(u_long)
    147 		    (defobj->relocbase + def->st_value + rela->r_addend);
    148 		rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p",
    149 		    (int)bind_now,
    150 		    defobj->strtab + def->st_name,
    151 		    (void *)(u_long)*where, (void *)(u_long)new_value));
    152 	} else {
    153 		if (!obj->mainprog) {
    154 			/* Just relocate the GOT slots pointing into the PLT */
    155 			new_value = *where + (Elf32_Addr)(u_long)
    156 			    obj->relocbase;
    157 			rdbg(dodebug, ("fixup !main in %s --> %p", obj->path,
    158 			    (void *)(unsigned long)*where));
    159 		} else {
    160 			return 0;
    161 		}
    162 	}
    163 	/*
    164          * Since this page is probably copy-on-write, let's not write
    165          * it unless we really really have to.
    166          */
    167 	if (*where != new_value)
    168 		*where = new_value;
    169 	if (addrp != NULL)
    170 		*addrp = *(caddr_t *)(obj->relocbase + rela->r_offset) -
    171 		    rela->r_addend;
    172 	return 0;
    173 }
    174