1 /* Report a module to libdwfl based on ELF program headers. 2 Copyright (C) 2005, 2007 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) 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 start = 0, end = 0, bias = 0; 76 switch (ehdr->e_type) 77 { 78 case ET_REL: 79 /* For a relocatable object, we do an arbitrary section layout. 80 By updating the section header in place, we leave the layout 81 information to be found by relocation. */ 82 83 start = end = base = (base + REL_MIN_ALIGN - 1) & -REL_MIN_ALIGN; 84 85 bool first = true; 86 Elf_Scn *scn = NULL; 87 while ((scn = elf_nextscn (elf, scn)) != NULL) 88 { 89 GElf_Shdr shdr_mem; 90 GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); 91 if (unlikely (shdr == NULL)) 92 goto elf_error; 93 94 if (shdr->sh_flags & SHF_ALLOC) 95 { 96 const GElf_Xword align = shdr->sh_addralign ?: 1; 97 const GElf_Addr next = (end + align - 1) & -align; 98 if (shdr->sh_addr == 0 99 /* Once we've started doing layout we have to do it all, 100 unless we just layed out the first section at 0 when 101 it already was at 0. */ 102 || (bias == 0 && end > start && end != next)) 103 { 104 shdr->sh_addr = next; 105 if (end == base) 106 /* This is the first section assigned a location. 107 Use its aligned address as the module's base. */ 108 start = base = shdr->sh_addr; 109 else if (unlikely (base & (align - 1))) 110 { 111 /* If BASE has less than the maximum alignment of 112 any section, we eat more than the optimal amount 113 of padding and so make the module's apparent 114 size come out larger than it would when placed 115 at zero. So reset the layout with a better base. */ 116 117 start = end = base = (base + align - 1) & -align; 118 Elf_Scn *prev_scn = NULL; 119 do 120 { 121 prev_scn = elf_nextscn (elf, prev_scn); 122 GElf_Shdr prev_shdr_mem; 123 GElf_Shdr *prev_shdr = gelf_getshdr (prev_scn, 124 &prev_shdr_mem); 125 if (unlikely (prev_shdr == NULL)) 126 goto elf_error; 127 if (prev_shdr->sh_flags & SHF_ALLOC) 128 { 129 const GElf_Xword prev_align 130 = prev_shdr->sh_addralign ?: 1; 131 132 prev_shdr->sh_addr 133 = (end + prev_align - 1) & -prev_align; 134 end = prev_shdr->sh_addr + prev_shdr->sh_size; 135 136 if (unlikely (! gelf_update_shdr (prev_scn, 137 prev_shdr))) 138 goto elf_error; 139 } 140 } 141 while (prev_scn != scn); 142 continue; 143 } 144 145 end = shdr->sh_addr + shdr->sh_size; 146 if (likely (shdr->sh_addr != 0) 147 && unlikely (! gelf_update_shdr (scn, shdr))) 148 goto elf_error; 149 } 150 else 151 { 152 /* The address is already assigned. Just track it. */ 153 if (first || end < shdr->sh_addr + shdr->sh_size) 154 end = shdr->sh_addr + shdr->sh_size; 155 if (first || bias > shdr->sh_addr) 156 /* This is the lowest address in the module. */ 157 bias = shdr->sh_addr; 158 159 if ((shdr->sh_addr - bias + base) & (align - 1)) 160 /* This section winds up misaligned using BASE. 161 Adjust BASE upwards to make it congruent to 162 the lowest section address in the file modulo ALIGN. */ 163 base = (((base + align - 1) & -align) 164 + (bias & (align - 1))); 165 } 166 167 first = false; 168 } 169 } 170 171 if (bias != 0) 172 { 173 /* The section headers had nonzero sh_addr values. The layout 174 was already done. We've just collected the total span. 175 Now just compute the bias from the requested base. */ 176 start = base; 177 end = end - bias + start; 178 bias = start - bias; 179 } 180 break; 181 182 /* Everything else has to have program headers. */ 183 184 case ET_EXEC: 185 case ET_CORE: 186 /* An assigned base address is meaningless for these. */ 187 base = 0; 188 189 case ET_DYN: 190 default: 191 for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i) 192 { 193 GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem); 194 if (unlikely (ph == NULL)) 195 goto elf_error; 196 if (ph->p_type == PT_LOAD) 197 { 198 if ((base & (ph->p_align - 1)) != 0) 199 base = (base + ph->p_align - 1) & -ph->p_align; 200 start = base + (ph->p_vaddr & -ph->p_align); 201 break; 202 } 203 } 204 bias = base; 205 206 for (uint_fast16_t i = ehdr->e_phnum; i-- > 0;) 207 { 208 GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem); 209 if (unlikely (ph == NULL)) 210 goto elf_error; 211 if (ph->p_type == PT_LOAD) 212 { 213 end = base + (ph->p_vaddr + ph->p_memsz); 214 break; 215 } 216 } 217 218 if (end == 0) 219 { 220 __libdwfl_seterrno (DWFL_E_NO_PHDR); 221 return NULL; 222 } 223 break; 224 } 225 226 Dwfl_Module *m = INTUSE(dwfl_report_module) (dwfl, name, start, end); 227 if (m != NULL) 228 { 229 if (m->main.name == NULL) 230 { 231 m->main.name = strdup (file_name); 232 m->main.fd = fd; 233 } 234 else if ((fd >= 0 && m->main.fd != fd) 235 || strcmp (m->main.name, file_name)) 236 { 237 elf_end (elf); 238 overlap: 239 m->gc = true; 240 __libdwfl_seterrno (DWFL_E_OVERLAP); 241 m = NULL; 242 } 243 244 /* Preinstall the open ELF handle for the module. */ 245 if (m->main.elf == NULL) 246 { 247 m->main.elf = elf; 248 m->main.bias = bias; 249 m->e_type = ehdr->e_type; 250 } 251 else 252 { 253 elf_end (elf); 254 if (m->main.bias != base) 255 goto overlap; 256 } 257 } 258 return m; 259 } 260 261 Dwfl_Module * 262 dwfl_report_elf (Dwfl *dwfl, const char *name, 263 const char *file_name, int fd, GElf_Addr base) 264 { 265 bool closefd = false; 266 if (fd < 0) 267 { 268 closefd = true; 269 fd = open64 (file_name, O_RDONLY); 270 if (fd < 0) 271 { 272 __libdwfl_seterrno (DWFL_E_ERRNO); 273 return NULL; 274 } 275 } 276 277 Elf *elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL); 278 Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name, 279 fd, elf, base); 280 if (mod == NULL) 281 { 282 elf_end (elf); 283 if (closefd) 284 close (fd); 285 } 286 287 return mod; 288 } 289 INTDEF (dwfl_report_elf) 290
