1 /* Recover relocatibility for addresses computed from debug information. 2 Copyright (C) 2005, 2006, 2007, 2008 Red Hat, Inc. 3 This file is part of Red Hat elfutils. 4 5 Red Hat elfutils is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by the 7 Free Software Foundation; version 2 of the License. 8 9 Red Hat elfutils is distributed in the hope that it will be useful, but 10 WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 General Public License for more details. 13 14 You should have received a copy of the GNU General Public License along 15 with Red Hat elfutils; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. 17 18 In addition, as a special exception, Red Hat, Inc. gives You the 19 additional right to link the code of Red Hat elfutils with code licensed 20 under any Open Source Initiative certified open source license 21 (http://www.opensource.org/licenses/index.php) which requires the 22 distribution of source code with any binary distribution and to 23 distribute linked combinations of the two. Non-GPL Code permitted under 24 this exception must only link to the code of Red Hat elfutils through 25 those well defined interfaces identified in the file named EXCEPTION 26 found in the source code files (the "Approved Interfaces"). The files 27 of Non-GPL Code may instantiate templates or use macros or inline 28 functions from the Approved Interfaces without causing the resulting 29 work to be covered by the GNU General Public License. Only Red Hat, 30 Inc. may make changes or additions to the list of Approved Interfaces. 31 Red Hat's grant of this exception is conditioned upon your not adding 32 any new exceptions. If you wish to add a new Approved Interface or 33 exception, please contact Red Hat. You must obey the GNU General Public 34 License in all respects for all of the Red Hat elfutils code and other 35 code used in conjunction with Red Hat elfutils except the Non-GPL Code 36 covered by this exception. If you modify this file, you may extend this 37 exception to your version of the file, but you are not obligated to do 38 so. If you do not wish to provide this exception without modification, 39 you must delete this exception statement from your version and license 40 this file solely under the GPL without exception. 41 42 Red Hat elfutils is an included package of the Open Invention Network. 43 An included package of the Open Invention Network is a package for which 44 Open Invention Network licensees cross-license their patents. No patent 45 license is granted, either expressly or impliedly, by designation as an 46 included package. Should you wish to participate in the Open Invention 47 Network licensing program, please visit www.openinventionnetwork.com 48 <http://www.openinventionnetwork.com>. */ 49 50 #include "libdwflP.h" 51 #include <fcntl.h> 52 #include <unistd.h> 53 54 /* Since dwfl_report_elf lays out the sections already, this will only be 55 called when the section headers of the debuginfo file are being 56 consulted instead, or for the section placed at 0. With binutils 57 strip-to-debug, the symbol table is in the debuginfo file and relocation 58 looks there. */ 59 int 60 dwfl_offline_section_address (Dwfl_Module *mod, 61 void **userdata __attribute__ ((unused)), 62 const char *modname __attribute__ ((unused)), 63 Dwarf_Addr base __attribute__ ((unused)), 64 const char *secname __attribute__ ((unused)), 65 Elf32_Word shndx, 66 const GElf_Shdr *shdr __attribute__ ((unused)), 67 Dwarf_Addr *addr) 68 { 69 assert (mod->e_type == ET_REL); 70 assert (shdr->sh_addr == 0); 71 assert (shdr->sh_flags & SHF_ALLOC); 72 73 if (mod->debug.elf == NULL) 74 /* We are only here because sh_addr is zero even though layout is complete. 75 The first section in the first file under -e is placed at 0. */ 76 return 0; 77 78 /* The section numbers might not match between the two files. 79 The best we can rely on is the order of SHF_ALLOC sections. */ 80 81 Elf_Scn *ourscn = elf_getscn (mod->debug.elf, shndx); 82 Elf_Scn *scn = NULL; 83 uint_fast32_t skip_alloc = 0; 84 while ((scn = elf_nextscn (mod->debug.elf, scn)) != ourscn) 85 { 86 assert (scn != NULL); 87 GElf_Shdr shdr_mem; 88 GElf_Shdr *sh = gelf_getshdr (scn, &shdr_mem); 89 if (unlikely (sh == NULL)) 90 return -1; 91 if (sh->sh_flags & SHF_ALLOC) 92 ++skip_alloc; 93 } 94 95 scn = NULL; 96 while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL) 97 { 98 GElf_Shdr shdr_mem; 99 GElf_Shdr *main_shdr = gelf_getshdr (scn, &shdr_mem); 100 if (unlikely (main_shdr == NULL)) 101 return -1; 102 if ((main_shdr->sh_flags & SHF_ALLOC) && skip_alloc-- == 0) 103 { 104 assert (main_shdr->sh_flags == shdr->sh_flags); 105 *addr = main_shdr->sh_addr; 106 return 0; 107 } 108 } 109 110 /* This should never happen. */ 111 return -1; 112 } 113 INTDEF (dwfl_offline_section_address) 114 115 /* Forward declarations. */ 116 static Dwfl_Module *process_elf (Dwfl *dwfl, const char *name, 117 const char *file_name, int fd, Elf *elf); 118 static Dwfl_Module *process_archive (Dwfl *dwfl, const char *name, 119 const char *file_name, int fd, Elf *elf, 120 int (*predicate) (const char *module, 121 const char *file)); 122 123 /* Report one module for an ELF file, or many for an archive. 124 Always consumes ELF and FD. */ 125 static Dwfl_Module * 126 process_file (Dwfl *dwfl, const char *name, const char *file_name, int fd, 127 Elf *elf, int (*predicate) (const char *module, 128 const char *file)) 129 { 130 switch (elf_kind (elf)) 131 { 132 default: 133 case ELF_K_NONE: 134 __libdwfl_seterrno (elf == NULL ? DWFL_E_LIBELF : DWFL_E_BADELF); 135 return NULL; 136 137 case ELF_K_ELF: 138 return process_elf (dwfl, name, file_name, fd, elf); 139 140 case ELF_K_AR: 141 return process_archive (dwfl, name, file_name, fd, elf, predicate); 142 } 143 } 144 145 /* Report the open ELF file as a module. Always consumes ELF and FD. */ 146 static Dwfl_Module * 147 process_elf (Dwfl *dwfl, const char *name, const char *file_name, int fd, 148 Elf *elf) 149 { 150 Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name, fd, elf, 151 dwfl->offline_next_address); 152 if (mod != NULL) 153 { 154 /* If this is an ET_EXEC file with fixed addresses, the address range 155 it consumed may or may not intersect with the arbitrary range we 156 will use for relocatable modules. Make sure we always use a free 157 range for the offline allocations. If this module did use 158 offline_next_address, it may have rounded it up for the module's 159 alignment requirements. */ 160 if ((dwfl->offline_next_address >= mod->low_addr 161 || mod->low_addr - dwfl->offline_next_address < OFFLINE_REDZONE) 162 && dwfl->offline_next_address < mod->high_addr + OFFLINE_REDZONE) 163 dwfl->offline_next_address = mod->high_addr + OFFLINE_REDZONE; 164 165 /* Don't keep the file descriptor around. */ 166 if (mod->main.fd != -1 && elf_cntl (mod->main.elf, ELF_C_FDREAD) == 0) 167 { 168 close (mod->main.fd); 169 mod->main.fd = -1; 170 } 171 } 172 173 return mod; 174 } 175 176 /* Always consumes MEMBER. Returns elf_next result on success. 177 For errors returns ELF_C_NULL with *MOD set to null. */ 178 static Elf_Cmd 179 process_archive_member (Dwfl *dwfl, const char *name, const char *file_name, 180 int (*predicate) (const char *module, const char *file), 181 int fd, Elf *member, Dwfl_Module **mod) 182 { 183 const Elf_Arhdr *h = elf_getarhdr (member); 184 if (unlikely (h == NULL)) 185 { 186 __libdwfl_seterrno (DWFL_E_LIBELF); 187 fail: 188 elf_end (member); 189 *mod = NULL; 190 return ELF_C_NULL; 191 } 192 193 if (!strcmp (h->ar_name, "/") || !strcmp (h->ar_name, "//")) 194 { 195 skip:; 196 /* Skip this and go to the next. */ 197 Elf_Cmd result = elf_next (member); 198 elf_end (member); 199 return result; 200 } 201 202 char *member_name; 203 if (unlikely (asprintf (&member_name, "%s(%s)", file_name, h->ar_name) < 0)) 204 { 205 nomem: 206 __libdwfl_seterrno (DWFL_E_NOMEM); 207 elf_end (member); 208 *mod = NULL; 209 return ELF_C_NULL; 210 } 211 212 char *module_name = NULL; 213 if (name == NULL || name[0] == '\0') 214 name = h->ar_name; 215 else if (unlikely (asprintf (&module_name, "%s:%s", name, h->ar_name) < 0)) 216 { 217 free (member_name); 218 goto nomem; 219 } 220 else 221 name = module_name; 222 223 if (predicate != NULL) 224 { 225 /* Let the predicate decide whether to use this one. */ 226 int want = (*predicate) (name, member_name); 227 if (want <= 0) 228 { 229 free (member_name); 230 free (module_name); 231 if (unlikely (want < 0)) 232 { 233 __libdwfl_seterrno (DWFL_E_CB); 234 goto fail; 235 } 236 goto skip; 237 } 238 } 239 240 /* We let __libdwfl_report_elf cache the fd in mod->main.fd, 241 though it's the same fd for all the members. 242 On module teardown we will close it only on the last Elf reference. */ 243 *mod = process_file (dwfl, name, member_name, fd, member, predicate); 244 free (member_name); 245 free (module_name); 246 247 if (*mod == NULL) /* process_file called elf_end. */ 248 return ELF_C_NULL; 249 250 /* Advance the archive-reading offset for the next iteration. */ 251 return elf_next (member); 252 } 253 254 /* Report each member of the archive as its own module. */ 255 static Dwfl_Module * 256 process_archive (Dwfl *dwfl, const char *name, const char *file_name, int fd, 257 Elf *archive, 258 int (*predicate) (const char *module, const char *file)) 259 260 { 261 Dwfl_Module *mod = NULL; 262 Elf *member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive); 263 if (unlikely (member == NULL)) /* Empty archive. */ 264 { 265 __libdwfl_seterrno (DWFL_E_BADELF); 266 return NULL; 267 } 268 269 while (process_archive_member (dwfl, name, file_name, predicate, 270 fd, member, &mod) != ELF_C_NULL) 271 member = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, archive); 272 273 /* We can drop the archive Elf handle even if we're still using members 274 in live modules. When the last module's elf_end on a member returns 275 zero, that module will close FD. If no modules survived the predicate, 276 we are all done with the file right here. */ 277 if (mod != NULL /* If no modules, caller will clean up. */ 278 && elf_end (archive) == 0) 279 close (fd); 280 281 return mod; 282 } 283 284 Dwfl_Module * 285 internal_function 286 __libdwfl_report_offline (Dwfl *dwfl, const char *name, 287 const char *file_name, int fd, bool closefd, 288 int (*predicate) (const char *module, 289 const char *file)) 290 { 291 Elf *elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL); 292 Dwfl_Module *mod = process_file (dwfl, name, file_name, fd, elf, predicate); 293 if (mod == NULL) 294 { 295 elf_end (elf); 296 if (closefd) 297 close (fd); 298 } 299 return mod; 300 } 301 302 Dwfl_Module * 303 dwfl_report_offline (Dwfl *dwfl, const char *name, 304 const char *file_name, int fd) 305 { 306 if (dwfl == NULL) 307 return NULL; 308 309 bool closefd = false; 310 if (fd < 0) 311 { 312 closefd = true; 313 fd = open64 (file_name, O_RDONLY); 314 if (fd < 0) 315 { 316 __libdwfl_seterrno (DWFL_E_ERRNO); 317 return NULL; 318 } 319 } 320 321 return __libdwfl_report_offline (dwfl, name, file_name, fd, closefd, NULL); 322 } 323 INTDEF (dwfl_report_offline) 324
