1 /* Report a module to libdwfl based on ELF program headers. 2 Copyright (C) 2005-2010 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 55 /* We start every ET_REL module at a moderately aligned boundary. 56 This keeps the low addresses easy to read compared to a layout 57 starting at 0 (as when using -e). It also makes it unlikely 58 that a middle section will have a larger alignment and require 59 rejiggering (see below). */ 60 #define REL_MIN_ALIGN ((GElf_Xword) 0x100) 61 62 Dwfl_Module * 63 internal_function 64 __libdwfl_report_elf (Dwfl *dwfl, const char *name, const char *file_name, 65 int fd, Elf *elf, GElf_Addr base, bool sanity) 66 { 67 GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem); 68 if (ehdr == NULL) 69 { 70 elf_error: 71 __libdwfl_seterrno (DWFL_E_LIBELF); 72 return NULL; 73 } 74 75 GElf_Addr vaddr = 0; 76 GElf_Addr address_sync = 0; 77 GElf_Addr start = 0, end = 0, bias = 0; 78 switch (ehdr->e_type) 79 { 80 case ET_REL: 81 /* For a relocatable object, we do an arbitrary section layout. 82 By updating the section header in place, we leave the layout 83 information to be found by relocation. */ 84 85 start = end = base = (base + REL_MIN_ALIGN - 1) & -REL_MIN_ALIGN; 86 87 bool first = true; 88 Elf_Scn *scn = NULL; 89 while ((scn = elf_nextscn (elf, scn)) != NULL) 90 { 91 GElf_Shdr shdr_mem; 92 GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); 93 if (unlikely (shdr == NULL)) 94 goto elf_error; 95 96 if (shdr->sh_flags & SHF_ALLOC) 97 { 98 const GElf_Xword align = shdr->sh_addralign ?: 1; 99 const GElf_Addr next = (end + align - 1) & -align; 100 if (shdr->sh_addr == 0 101 /* Once we've started doing layout we have to do it all, 102 unless we just layed out the first section at 0 when 103 it already was at 0. */ 104 || (bias == 0 && end > start && end != next)) 105 { 106 shdr->sh_addr = next; 107 if (end == base) 108 /* This is the first section assigned a location. 109 Use its aligned address as the module's base. */ 110 start = base = shdr->sh_addr; 111 else if (unlikely (base & (align - 1))) 112 { 113 /* If BASE has less than the maximum alignment of 114 any section, we eat more than the optimal amount 115 of padding and so make the module's apparent 116 size come out larger than it would when placed 117 at zero. So reset the layout with a better base. */ 118 119 start = end = base = (base + align - 1) & -align; 120 Elf_Scn *prev_scn = NULL; 121 do 122 { 123 prev_scn = elf_nextscn (elf, prev_scn); 124 GElf_Shdr prev_shdr_mem; 125 GElf_Shdr *prev_shdr = gelf_getshdr (prev_scn, 126 &prev_shdr_mem); 127 if (unlikely (prev_shdr == NULL)) 128 goto elf_error; 129 if (prev_shdr->sh_flags & SHF_ALLOC) 130 { 131 const GElf_Xword prev_align 132 = prev_shdr->sh_addralign ?: 1; 133 134 prev_shdr->sh_addr 135 = (end + prev_align - 1) & -prev_align; 136 end = prev_shdr->sh_addr + prev_shdr->sh_size; 137 138 if (unlikely (! gelf_update_shdr (prev_scn, 139 prev_shdr))) 140 goto elf_error; 141 } 142 } 143 while (prev_scn != scn); 144 continue; 145 } 146 147 end = shdr->sh_addr + shdr->sh_size; 148 if (likely (shdr->sh_addr != 0) 149 && unlikely (! gelf_update_shdr (scn, shdr))) 150 goto elf_error; 151 } 152 else 153 { 154 /* The address is already assigned. Just track it. */ 155 if (first || end < shdr->sh_addr + shdr->sh_size) 156 end = shdr->sh_addr + shdr->sh_size; 157 if (first || bias > shdr->sh_addr) 158 /* This is the lowest address in the module. */ 159 bias = shdr->sh_addr; 160 161 if ((shdr->sh_addr - bias + base) & (align - 1)) 162 /* This section winds up misaligned using BASE. 163 Adjust BASE upwards to make it congruent to 164 the lowest section address in the file modulo ALIGN. */ 165 base = (((base + align - 1) & -align) 166 + (bias & (align - 1))); 167 } 168 169 first = false; 170 } 171 } 172 173 if (bias != 0) 174 { 175 /* The section headers had nonzero sh_addr values. The layout 176 was already done. We've just collected the total span. 177 Now just compute the bias from the requested base. */ 178 start = base; 179 end = end - bias + start; 180 bias = start - bias; 181 } 182 break; 183 184 /* Everything else has to have program headers. */ 185 186 case ET_EXEC: 187 case ET_CORE: 188 /* An assigned base address is meaningless for these. */ 189 base = 0; 190 191 case ET_DYN: 192 default:; 193 size_t phnum; 194 if (unlikely (elf_getphdrnum (elf, &phnum) != 0)) 195 goto elf_error; 196 for (size_t i = 0; i < phnum; ++i) 197 { 198 GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem); 199 if (unlikely (ph == NULL)) 200 goto elf_error; 201 if (ph->p_type == PT_LOAD) 202 { 203 vaddr = ph->p_vaddr & -ph->p_align; 204 address_sync = ph->p_vaddr + ph->p_memsz; 205 if ((base & (ph->p_align - 1)) != 0) 206 base = (base + ph->p_align - 1) & -ph->p_align; 207 start = base + (ph->p_vaddr & -ph->p_align); 208 break; 209 } 210 } 211 bias = start - vaddr; 212 213 for (size_t i = phnum; i-- > 0;) 214 { 215 GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem); 216 if (unlikely (ph == NULL)) 217 goto elf_error; 218 if (ph->p_type == PT_LOAD 219 && ph->p_vaddr + ph->p_memsz > 0) 220 { 221 end = base + (ph->p_vaddr + ph->p_memsz); 222 break; 223 } 224 } 225 226 if (end == 0 && sanity) 227 { 228 __libdwfl_seterrno (DWFL_E_NO_PHDR); 229 return NULL; 230 } 231 break; 232 } 233 234 Dwfl_Module *m = INTUSE(dwfl_report_module) (dwfl, name, start, end); 235 if (m != NULL) 236 { 237 if (m->main.name == NULL) 238 { 239 m->main.name = strdup (file_name); 240 m->main.fd = fd; 241 } 242 else if ((fd >= 0 && m->main.fd != fd) 243 || strcmp (m->main.name, file_name)) 244 { 245 overlap: 246 m->gc = true; 247 __libdwfl_seterrno (DWFL_E_OVERLAP); 248 return NULL; 249 } 250 251 /* Preinstall the open ELF handle for the module. */ 252 if (m->main.elf == NULL) 253 { 254 m->main.elf = elf; 255 m->main.vaddr = vaddr; 256 m->main.address_sync = address_sync; 257 m->main_bias = bias; 258 m->e_type = ehdr->e_type; 259 } 260 else 261 { 262 elf_end (elf); 263 if (m->main_bias != bias 264 || m->main.vaddr != vaddr || m->main.address_sync != address_sync) 265 goto overlap; 266 } 267 } 268 return m; 269 } 270 271 Dwfl_Module * 272 dwfl_report_elf (Dwfl *dwfl, const char *name, 273 const char *file_name, int fd, GElf_Addr base) 274 { 275 bool closefd = false; 276 if (fd < 0) 277 { 278 closefd = true; 279 fd = open64 (file_name, O_RDONLY); 280 if (fd < 0) 281 { 282 __libdwfl_seterrno (DWFL_E_ERRNO); 283 return NULL; 284 } 285 } 286 287 Elf *elf; 288 Dwfl_Error error = __libdw_open_file (&fd, &elf, closefd, false); 289 if (error != DWFL_E_NOERROR) 290 { 291 __libdwfl_seterrno (error); 292 return NULL; 293 } 294 295 Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name, 296 fd, elf, base, true); 297 if (mod == NULL) 298 { 299 elf_end (elf); 300 if (closefd) 301 close (fd); 302 } 303 304 return mod; 305 } 306 INTDEF (dwfl_report_elf) 307
