2 * Copyright 1996-1998 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/param.h>
40 static int protflags(int); /* Elf flags -> mmap protection */
43 * Map a shared object into memory. The "fd" argument is a file descriptor,
44 * which must be open on the object and positioned at its beginning.
45 * The "path" argument is a pathname that is used only for error messages.
47 * The return value is a pointer to a newly-allocated Obj_Entry structure
48 * for the shared object. Returns NULL on failure.
51 map_object(int fd, const char *path, const struct stat *sb)
83 if ((nbytes = read(fd, u.buf, PAGE_SIZE)) == -1) {
84 _rtld_error("%s: read error: %s", path, strerror(errno));
88 /* Make sure the file is valid */
89 if (nbytes < sizeof(Elf_Ehdr)
90 || u.hdr.e_ident[EI_MAG0] != ELFMAG0
91 || u.hdr.e_ident[EI_MAG1] != ELFMAG1
92 || u.hdr.e_ident[EI_MAG2] != ELFMAG2
93 || u.hdr.e_ident[EI_MAG3] != ELFMAG3) {
94 _rtld_error("%s: invalid file format", path);
97 if (u.hdr.e_ident[EI_CLASS] != ELF_TARG_CLASS
98 || u.hdr.e_ident[EI_DATA] != ELF_TARG_DATA) {
99 _rtld_error("%s: unsupported file layout", path);
102 if (u.hdr.e_ident[EI_VERSION] != EV_CURRENT
103 || u.hdr.e_version != EV_CURRENT) {
104 _rtld_error("%s: unsupported file version", path);
107 if (u.hdr.e_type != ET_EXEC && u.hdr.e_type != ET_DYN) {
108 _rtld_error("%s: unsupported file type", path);
111 if (u.hdr.e_machine != ELF_TARG_MACH) {
112 _rtld_error("%s: unsupported machine", path);
117 * We rely on the program header being in the first page. This is
118 * not strictly required by the ABI specification, but it seems to
119 * always true in practice. And, it simplifies things considerably.
121 if (u.hdr.e_phentsize != sizeof(Elf_Phdr)) {
123 "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
126 if (u.hdr.e_phoff + u.hdr.e_phnum*sizeof(Elf_Phdr) > nbytes) {
127 _rtld_error("%s: program header too large", path);
132 * Scan the program header entries, and save key information.
134 * We rely on there being exactly two load segments, text and data,
137 phdr = (Elf_Phdr *) (u.buf + u.hdr.e_phoff);
138 phlimit = phdr + u.hdr.e_phnum;
140 phdyn = phphdr = phinterp = NULL;
141 while (phdr < phlimit) {
142 switch (phdr->p_type) {
150 _rtld_error("%s: too many PT_LOAD segments", path);
169 _rtld_error("%s: object is not dynamically-linked", path);
174 _rtld_error("%s: too few PT_LOAD segments", path);
177 if (segs[0]->p_align < PAGE_SIZE || segs[1]->p_align < PAGE_SIZE) {
178 _rtld_error("%s: PT_LOAD segments not page-aligned", path);
183 * Map the entire address space of the object, to stake out our
184 * contiguous region, and to establish the base address for relocation.
186 base_offset = trunc_page(segs[0]->p_offset);
187 base_vaddr = trunc_page(segs[0]->p_vaddr);
188 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
189 mapsize = base_vlimit - base_vaddr;
190 base_addr = u.hdr.e_type == ET_EXEC ? (caddr_t) base_vaddr : NULL;
192 mapbase = mmap(base_addr, mapsize, protflags(segs[0]->p_flags),
193 MAP_PRIVATE, fd, base_offset);
194 if (mapbase == (caddr_t) -1) {
195 _rtld_error("%s: mmap of entire address space failed: %s",
196 path, strerror(errno));
199 if (base_addr != NULL && mapbase != base_addr) {
200 _rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
201 path, base_addr, mapbase);
202 munmap(mapbase, mapsize);
206 /* Overlay the data segment onto the proper region. */
207 data_offset = trunc_page(segs[1]->p_offset);
208 data_vaddr = trunc_page(segs[1]->p_vaddr);
209 data_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_filesz);
210 data_addr = mapbase + (data_vaddr - base_vaddr);
211 if (mmap(data_addr, data_vlimit - data_vaddr, protflags(segs[1]->p_flags),
212 MAP_PRIVATE|MAP_FIXED, fd, data_offset) == (caddr_t) -1) {
213 _rtld_error("%s: mmap of data failed: %s", path, strerror(errno));
217 /* Clear any BSS in the last page of the data segment. */
218 clear_vaddr = segs[1]->p_vaddr + segs[1]->p_filesz;
219 clear_addr = mapbase + (clear_vaddr - base_vaddr);
220 if ((nclear = data_vlimit - clear_vaddr) > 0)
221 memset(clear_addr, 0, nclear);
223 /* Overlay the BSS segment onto the proper region. */
224 bss_vaddr = data_vlimit;
225 bss_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz);
226 bss_addr = mapbase + (bss_vaddr - base_vaddr);
227 if (bss_vlimit > bss_vaddr) { /* There is something to do */
228 if (mmap(bss_addr, bss_vlimit - bss_vaddr, protflags(segs[1]->p_flags),
229 MAP_PRIVATE|MAP_FIXED|MAP_ANON, -1, 0) == (caddr_t) -1) {
230 _rtld_error("%s: mmap of bss failed: %s", path, strerror(errno));
237 obj->dev = sb->st_dev;
238 obj->ino = sb->st_ino;
240 obj->mapbase = mapbase;
241 obj->mapsize = mapsize;
242 obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
244 obj->vaddrbase = base_vaddr;
245 obj->relocbase = mapbase - base_vaddr;
246 obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
247 if (u.hdr.e_entry != 0)
248 obj->entry = (caddr_t) (obj->relocbase + u.hdr.e_entry);
249 if (phphdr != NULL) {
250 obj->phdr = (const Elf_Phdr *) (obj->relocbase + phphdr->p_vaddr);
251 obj->phsize = phphdr->p_memsz;
253 if (phinterp != NULL)
254 obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
260 obj_free(Obj_Entry *obj)
265 while (obj->needed != NULL) {
266 Needed_Entry *needed = obj->needed;
267 obj->needed = needed->next;
270 while (!STAILQ_EMPTY(&obj->dldags)) {
271 elm = STAILQ_FIRST(&obj->dldags);
272 STAILQ_REMOVE_HEAD(&obj->dldags, link);
275 while (!STAILQ_EMPTY(&obj->dagmembers)) {
276 elm = STAILQ_FIRST(&obj->dagmembers);
277 STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
288 obj = CNEW(Obj_Entry);
289 STAILQ_INIT(&obj->dldags);
290 STAILQ_INIT(&obj->dagmembers);
295 * Given a set of ELF protection flags, return the corresponding protection
299 protflags(int elfflags)