Ben Cheng | 25b3c04 | 2013-11-20 14:45:36 -0800 | [diff] [blame^] | 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) |