Annotation of src/libexec/ld.elf_so/map_object.c, Revision 1.11
1.11 ! chs 1: /* $NetBSD: map_object.c,v 1.10 1999/11/07 00:21:13 mycroft Exp $ */
1.1 cgd 2:
3: /*
4: * Copyright 1996 John D. Polstra.
5: * Copyright 1996 Matt Thomas <matt@3am-software.com>
6: * All rights reserved.
7: *
8: * Redistribution and use in source and binary forms, with or without
9: * modification, are permitted provided that the following conditions
10: * are met:
11: * 1. Redistributions of source code must retain the above copyright
12: * notice, this list of conditions and the following disclaimer.
13: * 2. Redistributions in binary form must reproduce the above copyright
14: * notice, this list of conditions and the following disclaimer in the
15: * documentation and/or other materials provided with the distribution.
16: * 3. All advertising materials mentioning features or use of this software
17: * must display the following acknowledgement:
18: * This product includes software developed by John Polstra.
19: * 4. The name of the author may not be used to endorse or promote products
20: * derived from this software without specific prior written permission.
21: *
22: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32: */
33:
34: #include <errno.h>
35: #include <stddef.h>
1.10 mycroft 36: #include <stdlib.h>
1.1 cgd 37: #include <string.h>
38: #include <unistd.h>
1.10 mycroft 39: #include <sys/stat.h>
1.1 cgd 40: #include <sys/types.h>
41: #include <sys/mman.h>
42:
43: #include "rtld.h"
1.7 hannken 44:
1.4 christos 45: static int protflags __P((int)); /* Elf flags -> mmap protection */
1.1 cgd 46:
47: /*
48: * Map a shared object into memory. The argument is a file descriptor,
49: * which must be open on the object and positioned at its beginning.
50: *
51: * The return value is a pointer to a newly-allocated Obj_Entry structure
52: * for the shared object. Returns NULL on failure.
53: */
54: Obj_Entry *
1.10 mycroft 55: _rtld_map_object(path, fd, sb)
1.4 christos 56: const char *path;
57: int fd;
1.10 mycroft 58: const struct stat *sb;
1.1 cgd 59: {
1.4 christos 60: Obj_Entry *obj;
61: union {
62: Elf_Ehdr hdr;
63: char buf[PAGESIZE];
64: } u;
65: int nbytes;
66: Elf_Phdr *phdr;
67: Elf_Phdr *phlimit;
68: Elf_Phdr *segs[2];
69: int nsegs;
70: Elf_Phdr *phdyn;
71: Elf_Phdr *phphdr;
1.10 mycroft 72: Elf_Phdr *phinterp;
1.4 christos 73: caddr_t mapbase;
74: size_t mapsize;
75: Elf_Off base_offset;
76: Elf_Addr base_vaddr;
77: Elf_Addr base_vlimit;
1.5 thorpej 78: Elf_Addr text_vlimit;
1.4 christos 79: caddr_t base_addr;
80: Elf_Off data_offset;
81: Elf_Addr data_vaddr;
82: Elf_Addr data_vlimit;
83: caddr_t data_addr;
1.5 thorpej 84: caddr_t gap_addr;
85: size_t gap_size;
1.1 cgd 86: #ifdef RTLD_LOADER
1.4 christos 87: Elf_Addr clear_vaddr;
88: caddr_t clear_addr;
89: size_t nclear;
1.1 cgd 90: #endif
91:
1.4 christos 92: if ((nbytes = read(fd, u.buf, PAGESIZE)) == -1) {
93: _rtld_error("%s: read error: %s", path, xstrerror(errno));
94: return NULL;
95: }
96: /* Make sure the file is valid */
97: if (nbytes < sizeof(Elf_Ehdr) ||
1.8 kleink 98: memcmp(ELFMAG, u.hdr.e_ident, SELFMAG) != 0 ||
99: u.hdr.e_ident[EI_CLASS] != ELFCLASS) {
1.4 christos 100: _rtld_error("%s: unrecognized file format", path);
101: return NULL;
102: }
103: /* Elf_e_ident includes class */
1.8 kleink 104: if (u.hdr.e_ident[EI_VERSION] != EV_CURRENT ||
105: u.hdr.e_version != EV_CURRENT ||
106: u.hdr.e_ident[EI_DATA] != ELFDEFNNAME(MACHDEP_ENDIANNESS)) {
1.4 christos 107: _rtld_error("%s: Unsupported file version", path);
108: return NULL;
109: }
1.8 kleink 110: if (u.hdr.e_type != ET_EXEC && u.hdr.e_type != ET_DYN) {
1.4 christos 111: _rtld_error("%s: Unsupported file type", path);
112: return NULL;
113: }
114: switch (u.hdr.e_machine) {
115: ELFDEFNNAME(MACHDEP_ID_CASES)
116: default:
117: _rtld_error("%s: Unsupported machine", path);
118: return NULL;
119: }
120:
121: /*
122: * We rely on the program header being in the first page. This is
123: * not strictly required by the ABI specification, but it seems to
124: * always true in practice. And, it simplifies things considerably.
125: */
126: assert(u.hdr.e_phentsize == sizeof(Elf_Phdr));
127: assert(u.hdr.e_phoff + u.hdr.e_phnum * sizeof(Elf_Phdr) <= PAGESIZE);
128: assert(u.hdr.e_phoff + u.hdr.e_phnum * sizeof(Elf_Phdr) <= nbytes);
129:
130: /*
131: * Scan the program header entries, and save key information.
132: *
133: * We rely on there being exactly two load segments, text and data,
134: * in that order.
135: */
136: phdr = (Elf_Phdr *) (u.buf + u.hdr.e_phoff);
137: phlimit = phdr + u.hdr.e_phnum;
138: nsegs = 0;
1.10 mycroft 139: phdyn = phphdr = phinterp = NULL;
1.4 christos 140: while (phdr < phlimit) {
141: switch (phdr->p_type) {
1.10 mycroft 142: case PT_INTERP:
143: phinterp = phdr;
144: break;
1.1 cgd 145:
1.8 kleink 146: case PT_LOAD:
1.2 jonathan 147: #ifdef __mips__
1.4 christos 148: /* NetBSD/pmax 1.1 elf toolchain peculiarity */
149: if (nsegs >= 2) {
150: _rtld_error("%s: too many sections\n", path);
151: return NULL;
152: }
1.2 jonathan 153: #endif
1.4 christos 154: assert(nsegs < 2);
155: segs[nsegs] = phdr;
156: ++nsegs;
157: break;
158:
1.8 kleink 159: case PT_PHDR:
1.4 christos 160: phphdr = phdr;
161: break;
162:
1.8 kleink 163: case PT_DYNAMIC:
1.4 christos 164: phdyn = phdr;
165: break;
166: }
1.1 cgd 167:
1.4 christos 168: ++phdr;
169: }
170: if (phdyn == NULL) {
171: _rtld_error("%s: not dynamically-linked", path);
172: return NULL;
173: }
174: assert(nsegs == 2);
1.1 cgd 175: #ifdef __i386__
1.4 christos 176: assert(segs[0]->p_align <= PAGESIZE);
177: assert(segs[1]->p_align <= PAGESIZE);
1.1 cgd 178: #endif
179:
1.4 christos 180: /*
1.11 ! chs 181: * Map the entire address space of the object as a file
1.5 thorpej 182: * region to stake out our contiguous region and establish a
1.11 ! chs 183: * base for relocation. We use a file mapping so that
! 184: * the kernel will give us whatever alignment is appropriate
! 185: * for the platform we're running on.
1.5 thorpej 186: *
1.11 ! chs 187: * We map it using the text protection, map the data segment
! 188: * into the right place, then map an anon segment for the bss
! 189: * and unmap the gaps left by padding to alignment.
1.5 thorpej 190: */
1.11 ! chs 191:
1.4 christos 192: base_offset = round_down(segs[0]->p_offset);
193: base_vaddr = round_down(segs[0]->p_vaddr);
194: base_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_memsz);
1.11 ! chs 195: text_vlimit = round_up(segs[0]->p_vaddr + segs[0]->p_memsz);
1.4 christos 196: mapsize = base_vlimit - base_vaddr;
1.11 ! chs 197:
1.1 cgd 198: #ifdef RTLD_LOADER
1.8 kleink 199: base_addr = u.hdr.e_type == ET_EXEC ? (caddr_t) base_vaddr : NULL;
1.1 cgd 200: #else
1.4 christos 201: base_addr = NULL;
1.1 cgd 202: #endif
203:
1.11 ! chs 204: mapbase = mmap(base_addr, mapsize, protflags(segs[0]->p_flags),
! 205: MAP_FILE | MAP_PRIVATE, fd, base_offset);
1.5 thorpej 206: if (mapbase == MAP_FAILED) {
1.4 christos 207: _rtld_error("mmap of entire address space failed: %s",
208: xstrerror(errno));
209: return NULL;
210: }
1.11 ! chs 211:
1.5 thorpej 212: base_addr = mapbase;
213:
1.4 christos 214: /* Overlay the data segment onto the proper region. */
215: data_offset = round_down(segs[1]->p_offset);
216: data_vaddr = round_down(segs[1]->p_vaddr);
217: data_vlimit = round_up(segs[1]->p_vaddr + segs[1]->p_filesz);
218: data_addr = mapbase + (data_vaddr - base_vaddr);
219: if (mmap(data_addr, data_vlimit - data_vaddr,
1.11 ! chs 220: protflags(segs[1]->p_flags),
! 221: MAP_FILE | MAP_PRIVATE | MAP_FIXED, fd, data_offset)
! 222: == MAP_FAILED) {
1.4 christos 223: _rtld_error("mmap of data failed: %s", xstrerror(errno));
1.11 ! chs 224: munmap(mapbase, mapsize);
! 225: return NULL;
! 226: }
! 227:
! 228: /* Overlay the bss segment onto the proper region. */
! 229: if (mmap(mapbase + data_vlimit - base_vaddr, base_vlimit - data_vlimit,
! 230: protflags(segs[1]->p_flags),
! 231: MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0)
! 232: == MAP_FAILED) {
! 233: _rtld_error("mmap of bss failed: %s", xstrerror(errno));
! 234: munmap(mapbase, mapsize);
1.4 christos 235: return NULL;
236: }
1.5 thorpej 237:
238: /* Unmap the gap between the text and data. */
239: gap_addr = base_addr + round_up(text_vlimit - base_vaddr);
240: gap_size = data_addr - gap_addr;
241: if (gap_size != 0 && munmap(gap_addr, gap_size) == -1) {
242: _rtld_error("munmap of text -> data gap failed: %s",
243: xstrerror(errno));
1.11 ! chs 244: munmap(mapbase, mapsize);
1.5 thorpej 245: return NULL;
246: }
247:
1.1 cgd 248: #ifdef RTLD_LOADER
1.4 christos 249: /* Clear any BSS in the last page of the data segment. */
250: clear_vaddr = segs[1]->p_vaddr + segs[1]->p_filesz;
251: clear_addr = mapbase + (clear_vaddr - base_vaddr);
252: if ((nclear = data_vlimit - clear_vaddr) > 0)
253: memset(clear_addr, 0, nclear);
254:
1.5 thorpej 255: /* Non-file portion of BSS mapped above. */
1.1 cgd 256: #endif
257:
1.10 mycroft 258: obj = _rtld_obj_new();
259: if (sb != NULL) {
260: obj->dev = sb->st_dev;
261: obj->ino = sb->st_ino;
262: }
1.4 christos 263: obj->mapbase = mapbase;
264: obj->mapsize = mapsize;
265: obj->textsize = round_up(segs[0]->p_vaddr + segs[0]->p_memsz) -
266: base_vaddr;
267: obj->vaddrbase = base_vaddr;
268: obj->relocbase = mapbase - base_vaddr;
269: obj->dynamic = (Elf_Dyn *)(obj->relocbase + phdyn->p_vaddr);
270: if (u.hdr.e_entry != 0)
271: obj->entry = (caddr_t)(obj->relocbase + u.hdr.e_entry);
272: if (phphdr != NULL) {
273: obj->phdr = (const Elf_Phdr *)
274: (obj->relocbase + phphdr->p_vaddr);
275: obj->phsize = phphdr->p_memsz;
276: }
1.10 mycroft 277: if (phinterp != NULL)
278: obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
279:
280: return obj;
281: }
282:
283: void
284: _rtld_obj_free(obj)
285: Obj_Entry *obj;
286: {
287: Objlist_Entry *elm;
288:
289: free(obj->path);
290: while (obj->needed != NULL) {
291: Needed_Entry *needed = obj->needed;
292: obj->needed = needed->next;
293: free(needed);
294: }
295: while (SIMPLEQ_FIRST(&obj->dldags) != NULL) {
296: elm = SIMPLEQ_FIRST(&obj->dldags);
297: SIMPLEQ_REMOVE_HEAD(&obj->dldags, elm, link);
298: free(elm);
299: }
300: while (SIMPLEQ_FIRST(&obj->dagmembers) != NULL) {
301: elm = SIMPLEQ_FIRST(&obj->dagmembers);
302: SIMPLEQ_REMOVE_HEAD(&obj->dagmembers, elm, link);
303: free(elm);
304: }
305: free(obj);
306: }
307:
308: Obj_Entry *
309: _rtld_obj_new(void)
310: {
311: Obj_Entry *obj;
312:
313: obj = CNEW(Obj_Entry);
314: SIMPLEQ_INIT(&obj->dldags);
315: SIMPLEQ_INIT(&obj->dagmembers);
1.4 christos 316: return obj;
1.1 cgd 317: }
318:
319: /*
320: * Given a set of ELF protection flags, return the corresponding protection
321: * flags for MMAP.
322: */
323: static int
1.4 christos 324: protflags(elfflags)
325: int elfflags;
1.1 cgd 326: {
1.4 christos 327: int prot = 0;
1.8 kleink 328: if (elfflags & PF_R)
1.4 christos 329: prot |= PROT_READ;
1.1 cgd 330: #ifdef RTLD_LOADER
1.8 kleink 331: if (elfflags & PF_W)
1.4 christos 332: prot |= PROT_WRITE;
1.1 cgd 333: #endif
1.8 kleink 334: if (elfflags & PF_X)
1.4 christos 335: prot |= PROT_EXEC;
336: return prot;
1.1 cgd 337: }
CVSweb <webmaster@jp.NetBSD.org>