1 /* Do relocations for ELF dynamic linking. 2 Copyright (C) 1995-2021 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 /* This file may be included twice, to define both 20 `elf_dynamic_do_rel' and `elf_dynamic_do_rela'. */ 21 22 #ifdef DO_RELA 23 # define elf_dynamic_do_Rel elf_dynamic_do_Rela 24 # define Rel Rela 25 # define elf_machine_rel elf_machine_rela 26 # define elf_machine_rel_relative elf_machine_rela_relative 27 #endif 28 29 #ifndef DO_ELF_MACHINE_REL_RELATIVE 30 # define DO_ELF_MACHINE_REL_RELATIVE(map, l_addr, relative) \ 31 elf_machine_rel_relative (l_addr, relative, \ 32 (void *) (l_addr + relative->r_offset)) 33 #endif 34 35 /* Perform the relocations in MAP on the running program image as specified 36 by RELTAG, SZTAG. If LAZY is nonzero, this is the first pass on PLT 37 relocations; they should be set up to call _dl_runtime_resolve, rather 38 than fully resolved now. */ 39 40 static inline void __attribute__ ((always_inline)) 41 elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[], 42 ElfW(Addr) reladdr, ElfW(Addr) relsize, 43 __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative, 44 int lazy, int skip_ifunc) 45 { 46 const ElfW(Rel) *r = (const void *) reladdr; 47 const ElfW(Rel) *end = (const void *) (reladdr + relsize); 48 ElfW(Addr) l_addr = map->l_addr; 49 # if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP 50 const ElfW(Rel) *r2 = NULL; 51 const ElfW(Rel) *end2 = NULL; 52 # endif 53 54 #if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP 55 /* We never bind lazily during ld.so bootstrap. Unfortunately gcc is 56 not clever enough to see through all the function calls to realize 57 that. */ 58 if (lazy) 59 { 60 /* Doing lazy PLT relocations; they need very little info. */ 61 for (; r < end; ++r) 62 # ifdef ELF_MACHINE_IRELATIVE 63 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE) 64 { 65 if (r2 == NULL) 66 r2 = r; 67 end2 = r; 68 } 69 else 70 # endif 71 elf_machine_lazy_rel (map, scope, l_addr, r, skip_ifunc); 72 73 # ifdef ELF_MACHINE_IRELATIVE 74 if (r2 != NULL) 75 for (; r2 <= end2; ++r2) 76 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE) 77 elf_machine_lazy_rel (map, scope, l_addr, r2, skip_ifunc); 78 # endif 79 } 80 else 81 #endif 82 { 83 const ElfW(Sym) *const symtab = 84 (const void *) D_PTR (map, l_info[DT_SYMTAB]); 85 const ElfW(Rel) *relative = r; 86 r += nrelative; 87 88 #ifndef RTLD_BOOTSTRAP 89 /* This is defined in rtld.c, but nowhere in the static libc.a; make 90 the reference weak so static programs can still link. This 91 declaration cannot be done when compiling rtld.c (i.e. #ifdef 92 RTLD_BOOTSTRAP) because rtld.c contains the common defn for 93 _dl_rtld_map, which is incompatible with a weak decl in the same 94 file. */ 95 # ifndef SHARED 96 weak_extern (GL(dl_rtld_map)); 97 # endif 98 if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */ 99 # if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE 100 /* Rela platforms get the offset from r_addend and this must 101 be copied in the relocation address. Therefore we can skip 102 the relative relocations only if this is for rel 103 relocations or rela relocations if they are computed as 104 memory_loc += l_addr... */ 105 if (l_addr != 0) 106 # else 107 /* ...or we know the object has been prelinked. */ 108 if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)]) 109 # endif 110 #endif 111 for (; relative < r; ++relative) 112 DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative); 113 114 #ifdef RTLD_BOOTSTRAP 115 /* The dynamic linker always uses versioning. */ 116 assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL); 117 #else 118 if (map->l_info[VERSYMIDX (DT_VERSYM)]) 119 #endif 120 { 121 const ElfW(Half) *const version = 122 (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]); 123 124 for (; r < end; ++r) 125 { 126 #if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP 127 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE) 128 { 129 if (r2 == NULL) 130 r2 = r; 131 end2 = r; 132 continue; 133 } 134 #endif 135 136 ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff; 137 elf_machine_rel (map, scope, r, &symtab[ELFW(R_SYM) (r->r_info)], 138 &map->l_versions[ndx], 139 (void *) (l_addr + r->r_offset), skip_ifunc); 140 } 141 142 #if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP 143 if (r2 != NULL) 144 for (; r2 <= end2; ++r2) 145 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE) 146 { 147 ElfW(Half) ndx 148 = version[ELFW(R_SYM) (r2->r_info)] & 0x7fff; 149 elf_machine_rel (map, scope, r2, 150 &symtab[ELFW(R_SYM) (r2->r_info)], 151 &map->l_versions[ndx], 152 (void *) (l_addr + r2->r_offset), 153 skip_ifunc); 154 } 155 #endif 156 } 157 #ifndef RTLD_BOOTSTRAP 158 else 159 { 160 for (; r < end; ++r) 161 # ifdef ELF_MACHINE_IRELATIVE 162 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE) 163 { 164 if (r2 == NULL) 165 r2 = r; 166 end2 = r; 167 } 168 else 169 # endif 170 elf_machine_rel (map, scope, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL, 171 (void *) (l_addr + r->r_offset), skip_ifunc); 172 173 # ifdef ELF_MACHINE_IRELATIVE 174 if (r2 != NULL) 175 for (; r2 <= end2; ++r2) 176 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE) 177 elf_machine_rel (map, scope, r2, &symtab[ELFW(R_SYM) (r2->r_info)], 178 NULL, (void *) (l_addr + r2->r_offset), 179 skip_ifunc); 180 # endif 181 } 182 #endif 183 } 184 } 185 186 #undef elf_dynamic_do_Rel 187 #undef Rel 188 #undef elf_machine_rel 189 #undef elf_machine_rel_relative 190 #undef DO_ELF_MACHINE_REL_RELATIVE 191 #undef DO_RELA 192