source: mainline/uspace/srv/loader/elf_load.c@ 08c9f7d5

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 08c9f7d5 was 08c9f7d5, checked in by Jiri Svoboda <jirik.svoboda@…>, 16 years ago

Suppress warnings in loader.
  • Property mode set to 100644
File size: 11.5 KB
Line 
1/*
2 * Copyright (c) 2006 Sergey Bondari
3 * Copyright (c) 2006 Jakub Jermar
4 * Copyright (c) 2008 Jiri Svoboda
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * - Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * - 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 * - The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31/** @addtogroup generic
32 * @{
33 */
34
35/**
36 * @file
37 * @brief Userspace ELF loader.
38 *
39 * This module allows loading ELF binaries (both executables and
40 * shared objects) from VFS. The current implementation allocates
41 * anonymous memory, fills it with segment data and then adjusts
42 * the memory areas' flags to the final value. In the future,
43 * the segments will be mapped directly from the file.
44 */
45
46#include <stdio.h>
47#include <sys/types.h>
48#include <align.h>
49#include <assert.h>
50#include <as.h>
51#include <unistd.h>
52#include <fcntl.h>
53#include <smc.h>
54#include <loader/pcb.h>
55
56#include "elf.h"
57#include "elf_load.h"
58#include "arch.h"
59
60#define DPRINTF(...)
61
62static char *error_codes[] = {
63 "no error",
64 "invalid image",
65 "address space error",
66 "incompatible image",
67 "unsupported image type",
68 "irrecoverable error"
69};
70
71static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
72static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
73static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
74static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
75
76/** Read until the buffer is read in its entirety. */
77static int my_read(int fd, void *buf, size_t len)
78{
79 int cnt = 0;
80 do {
81 buf += cnt;
82 len -= cnt;
83 cnt = read(fd, buf, len);
84 } while ((cnt > 0) && ((len - cnt) > 0));
85
86 return cnt;
87}
88
89/** Load ELF binary from a file.
90 *
91 * Load an ELF binary from the specified file. If the file is
92 * an executable program, it is loaded unbiased. If it is a shared
93 * object, it is loaded with the bias @a so_bias. Some information
94 * extracted from the binary is stored in a elf_info_t structure
95 * pointed to by @a info.
96 *
97 * @param file_name Path to the ELF file.
98 * @param so_bias Bias to use if the file is a shared object.
99 * @param info Pointer to a structure for storing information
100 * extracted from the binary.
101 *
102 * @return EOK on success or negative error code.
103 */
104int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info)
105{
106 elf_ld_t elf;
107
108 int fd;
109 int rc;
110
111 fd = open(file_name, O_RDONLY);
112 if (fd < 0) {
113 DPRINTF("failed opening file\n");
114 return -1;
115 }
116
117 elf.fd = fd;
118 elf.info = info;
119
120 rc = elf_load(&elf, so_bias);
121
122 close(fd);
123
124 return rc;
125}
126
127/** Run an ELF executable.
128 *
129 * Transfers control to the entry point of an ELF executable loaded
130 * earlier with elf_load_file(). This function does not return.
131 *
132 * @param info Info structure filled earlier by elf_load_file()
133 */
134void elf_run(elf_info_t *info, pcb_t *pcb)
135{
136 program_run(info->entry, pcb);
137
138 /* not reached */
139}
140
141/** Create the program control block (PCB).
142 *
143 * Fills the program control block @a pcb with information from
144 * @a info.
145 *
146 * @param info Program info structure
147 * @return EOK on success or negative error code
148 */
149void elf_create_pcb(elf_info_t *info, pcb_t *pcb)
150{
151 pcb->entry = info->entry;
152 pcb->dynamic = info->dynamic;
153}
154
155
156/** Load an ELF binary.
157 *
158 * The @a elf structure contains the loader state, including
159 * an open file, from which the binary will be loaded,
160 * a pointer to the @c info structure etc.
161 *
162 * @param elf Pointer to loader state buffer.
163 * @param so_bias Bias to use if the file is a shared object.
164 * @return EE_OK on success or EE_xx error code.
165 */
166static unsigned int elf_load(elf_ld_t *elf, size_t so_bias)
167{
168 elf_header_t header_buf;
169 elf_header_t *header = &header_buf;
170 int i, rc;
171
172 rc = my_read(elf->fd, header, sizeof(elf_header_t));
173 if (rc < 0) {
174 DPRINTF("Read error.\n");
175 return EE_INVALID;
176 }
177
178 elf->header = header;
179
180 /* Identify ELF */
181 if (header->e_ident[EI_MAG0] != ELFMAG0 ||
182 header->e_ident[EI_MAG1] != ELFMAG1 ||
183 header->e_ident[EI_MAG2] != ELFMAG2 ||
184 header->e_ident[EI_MAG3] != ELFMAG3) {
185 DPRINTF("Invalid header.\n");
186 return EE_INVALID;
187 }
188
189 /* Identify ELF compatibility */
190 if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
191 header->e_machine != ELF_MACHINE ||
192 header->e_ident[EI_VERSION] != EV_CURRENT ||
193 header->e_version != EV_CURRENT ||
194 header->e_ident[EI_CLASS] != ELF_CLASS) {
195 DPRINTF("Incompatible data/version/class.\n");
196 return EE_INCOMPATIBLE;
197 }
198
199 if (header->e_phentsize != sizeof(elf_segment_header_t)) {
200 DPRINTF("e_phentsize:%d != %d\n", header->e_phentsize,
201 sizeof(elf_segment_header_t));
202 return EE_INCOMPATIBLE;
203 }
204
205 if (header->e_shentsize != sizeof(elf_section_header_t)) {
206 DPRINTF("e_shentsize:%d != %d\n", header->e_shentsize,
207 sizeof(elf_section_header_t));
208 return EE_INCOMPATIBLE;
209 }
210
211 /* Check if the object type is supported. */
212 if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
213 DPRINTF("Object type %d is not supported\n", header->e_type);
214 return EE_UNSUPPORTED;
215 }
216
217 /* Shared objects can be loaded with a bias */
218 if (header->e_type == ET_DYN)
219 elf->bias = so_bias;
220 else
221 elf->bias = 0;
222
223 elf->info->interp = NULL;
224 elf->info->dynamic = NULL;
225
226 /* Walk through all segment headers and process them. */
227 for (i = 0; i < header->e_phnum; i++) {
228 elf_segment_header_t segment_hdr;
229
230 /* Seek to start of segment header */
231 lseek(elf->fd, header->e_phoff
232 + i * sizeof(elf_segment_header_t), SEEK_SET);
233
234 rc = my_read(elf->fd, &segment_hdr,
235 sizeof(elf_segment_header_t));
236 if (rc < 0) {
237 DPRINTF("Read error.\n");
238 return EE_INVALID;
239 }
240
241 rc = segment_header(elf, &segment_hdr);
242 if (rc != EE_OK)
243 return rc;
244 }
245
246 DPRINTF("Parse sections.\n");
247
248 /* Inspect all section headers and proccess them. */
249 for (i = 0; i < header->e_shnum; i++) {
250 elf_section_header_t section_hdr;
251
252 /* Seek to start of section header */
253 lseek(elf->fd, header->e_shoff
254 + i * sizeof(elf_section_header_t), SEEK_SET);
255
256 rc = my_read(elf->fd, &section_hdr,
257 sizeof(elf_section_header_t));
258 if (rc < 0) {
259 DPRINTF("Read error.\n");
260 return EE_INVALID;
261 }
262
263 rc = section_header(elf, &section_hdr);
264 if (rc != EE_OK)
265 return rc;
266 }
267
268 elf->info->entry =
269 (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
270
271 DPRINTF("Done.\n");
272
273 return EE_OK;
274}
275
276/** Print error message according to error code.
277 *
278 * @param rc Return code returned by elf_load().
279 *
280 * @return NULL terminated description of error.
281 */
282char *elf_error(unsigned int rc)
283{
284 assert(rc < sizeof(error_codes) / sizeof(char *));
285
286 return error_codes[rc];
287}
288
289/** Process segment header.
290 *
291 * @param entry Segment header.
292 *
293 * @return EE_OK on success, error code otherwise.
294 */
295static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
296{
297 switch (entry->p_type) {
298 case PT_NULL:
299 case PT_PHDR:
300 break;
301 case PT_LOAD:
302 return load_segment(elf, entry);
303 break;
304 case PT_INTERP:
305 /* Assume silently interp == "/rtld.so" */
306 elf->info->interp = "/rtld.so";
307 break;
308 case PT_DYNAMIC:
309 case PT_SHLIB:
310 case PT_NOTE:
311 case PT_LOPROC:
312 case PT_HIPROC:
313 default:
314 DPRINTF("Segment p_type %d unknown.\n", entry->p_type);
315 return EE_UNSUPPORTED;
316 break;
317 }
318 return EE_OK;
319}
320
321/** Load segment described by program header entry.
322 *
323 * @param elf Loader state.
324 * @param entry Program header entry describing segment to be loaded.
325 *
326 * @return EE_OK on success, error code otherwise.
327 */
328int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
329{
330 void *a;
331 int flags = 0;
332 uintptr_t bias;
333 uintptr_t base;
334 void *seg_ptr;
335 uintptr_t seg_addr;
336 size_t mem_sz;
337 int rc;
338
339 bias = elf->bias;
340
341 seg_addr = entry->p_vaddr + bias;
342 seg_ptr = (void *) seg_addr;
343
344 DPRINTF("Load segment at addr 0x%x, size 0x%x\n", seg_addr,
345 entry->p_memsz);
346
347 if (entry->p_align > 1) {
348 if ((entry->p_offset % entry->p_align) !=
349 (seg_addr % entry->p_align)) {
350 DPRINTF("Align check 1 failed offset%%align=%d, "
351 "vaddr%%align=%d\n",
352 entry->p_offset % entry->p_align,
353 seg_addr % entry->p_align
354 );
355 return EE_INVALID;
356 }
357 }
358
359 /* Final flags that will be set for the memory area */
360
361 if (entry->p_flags & PF_X)
362 flags |= AS_AREA_EXEC;
363 if (entry->p_flags & PF_W)
364 flags |= AS_AREA_WRITE;
365 if (entry->p_flags & PF_R)
366 flags |= AS_AREA_READ;
367 flags |= AS_AREA_CACHEABLE;
368
369 base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
370 mem_sz = entry->p_memsz + (entry->p_vaddr - base);
371
372 DPRINTF("Map to seg_addr=0x%x-0x%x.\n", seg_addr,
373 entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
374
375 /*
376 * For the course of loading, the area needs to be readable
377 * and writeable.
378 */
379 a = as_area_create((uint8_t *)base + bias, mem_sz,
380 AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
381 if (a == (void *)(-1)) {
382 DPRINTF("Memory mapping failed.\n");
383 return EE_MEMORY;
384 }
385
386 DPRINTF("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
387 base + bias, mem_sz, flags, (uintptr_t)a);
388
389 /*
390 * Load segment data
391 */
392 rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
393 if (rc < 0) {
394 printf("seek error\n");
395 return EE_INVALID;
396 }
397
398/* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
399 if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
400
401 /* Long reads are not possible yet. Load segment piecewise. */
402
403 unsigned left, now;
404 uint8_t *dp;
405
406 left = entry->p_filesz;
407 dp = seg_ptr;
408
409 while (left > 0) {
410 now = 16384;
411 if (now > left) now = left;
412
413 rc = my_read(elf->fd, dp, now);
414
415 if (rc < 0) {
416 DPRINTF("Read error.\n");
417 return EE_INVALID;
418 }
419
420 left -= now;
421 dp += now;
422 }
423
424 rc = as_area_change_flags(seg_ptr, flags);
425 if (rc != 0) {
426 DPRINTF("Failed to set memory area flags.\n");
427 return EE_MEMORY;
428 }
429
430 if (flags & AS_AREA_EXEC) {
431 /* Enforce SMC coherence for the segment */
432 if (smc_coherence(seg_ptr, entry->p_filesz))
433 return EE_MEMORY;
434 }
435
436 return EE_OK;
437}
438
439/** Process section header.
440 *
441 * @param elf Loader state.
442 * @param entry Segment header.
443 *
444 * @return EE_OK on success, error code otherwise.
445 */
446static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
447{
448 switch (entry->sh_type) {
449 case SHT_PROGBITS:
450 if (entry->sh_flags & SHF_TLS) {
451 /* .tdata */
452 }
453 break;
454 case SHT_NOBITS:
455 if (entry->sh_flags & SHF_TLS) {
456 /* .tbss */
457 }
458 break;
459 case SHT_DYNAMIC:
460 /* Record pointer to dynamic section into info structure */
461 elf->info->dynamic =
462 (void *)((uint8_t *)entry->sh_addr + elf->bias);
463 DPRINTF("Dynamic section found at 0x%x.\n",
464 (uintptr_t)elf->info->dynamic);
465 break;
466 default:
467 break;
468 }
469
470 return EE_OK;
471}
472
473/** @}
474 */
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