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3222 svoboda 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
static char *error_codes[] = {
61
    "no error",
62
    "invalid image",
63
    "address space error",
64
    "incompatible image",
65
    "unsupported image type",
66
    "irrecoverable error"
67
};
68
 
69
static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
70
static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry);
71
static int section_header(elf_ld_t *elf, elf_section_header_t *entry);
72
static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry);
73
 
3315 jermar 74
/** Read until the buffer is read in its entirety. */
75
static int my_read(int fd, char *buf, size_t len)
76
{
77
    int cnt = 0;
78
    do {
79
        buf += cnt;
80
        len -= cnt;
81
        cnt = read(fd, buf, len);
82
    } while ((cnt > 0) && ((len - cnt) > 0));
83
 
84
    return cnt;
85
}
86
 
3222 svoboda 87
/** Load ELF binary from a file.
88
 *
89
 * Load an ELF binary from the specified file. If the file is
90
 * an executable program, it is loaded unbiased. If it is a shared
91
 * object, it is loaded with the bias @a so_bias. Some information
92
 * extracted from the binary is stored in a elf_info_t structure
93
 * pointed to by @a info.
94
 *
95
 * @param file_name Path to the ELF file.
96
 * @param so_bias   Bias to use if the file is a shared object.
97
 * @param info      Pointer to a structure for storing information
98
 *          extracted from the binary.
99
 *
100
 * @return EOK on success or negative error code.
101
 */
102
int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info)
103
{
104
    elf_ld_t elf;
105
 
106
    int fd;
107
    int rc;
108
 
109
//  printf("open and read '%s'...\n", file_name);
110
 
111
    fd = open(file_name, O_RDONLY);
112
    if (fd < 0) {
113
        printf("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
 */
134
void 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
 */
149
void 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
 */
166
static 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
 
3315 jermar 172
    rc = my_read(elf->fd, header, sizeof(elf_header_t));
3222 svoboda 173
    if (rc < 0) {
174
        printf("read error\n");
175
        return EE_INVALID;
176
    }
177
 
178
    elf->header = header;
179
 
180
//  printf("ELF-load:");
181
    /* Identify ELF */
182
    if (header->e_ident[EI_MAG0] != ELFMAG0 ||
183
        header->e_ident[EI_MAG1] != ELFMAG1 ||
184
        header->e_ident[EI_MAG2] != ELFMAG2 ||
185
        header->e_ident[EI_MAG3] != ELFMAG3) {
186
        printf("invalid header\n");
187
        return EE_INVALID;
188
    }
189
 
190
    /* Identify ELF compatibility */
191
    if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
192
        header->e_machine != ELF_MACHINE ||
193
        header->e_ident[EI_VERSION] != EV_CURRENT ||
194
        header->e_version != EV_CURRENT ||
195
        header->e_ident[EI_CLASS] != ELF_CLASS) {
196
        printf("incompatible data/version/class\n");
197
        return EE_INCOMPATIBLE;
198
    }
199
 
200
    if (header->e_phentsize != sizeof(elf_segment_header_t)) {
201
        printf("e_phentsize:%d != %d\n", header->e_phentsize,
202
            sizeof(elf_segment_header_t));
203
        return EE_INCOMPATIBLE;
204
    }
205
 
206
    if (header->e_shentsize != sizeof(elf_section_header_t)) {
207
        printf("e_shentsize:%d != %d\n", header->e_shentsize,
208
            sizeof(elf_section_header_t));
209
        return EE_INCOMPATIBLE;
210
    }
211
 
212
    /* Check if the object type is supported. */
213
    if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
214
        printf("Object type %d is not supported\n", header->e_type);
215
        return EE_UNSUPPORTED;
216
    }
217
 
218
    /* Shared objects can be loaded with a bias */
219
//  printf("Object type: %d\n", header->e_type);
220
    if (header->e_type == ET_DYN)
221
        elf->bias = so_bias;
222
    else
223
        elf->bias = 0;
224
 
225
//  printf("Bias set to 0x%x\n", elf->bias);
226
    elf->info->interp = NULL;
227
    elf->info->dynamic = NULL;
228
 
229
//  printf("parse segments\n");
230
 
231
    /* Walk through all segment headers and process them. */
232
    for (i = 0; i < header->e_phnum; i++) {
233
        elf_segment_header_t segment_hdr;
234
 
235
        /* Seek to start of segment header */
236
        lseek(elf->fd, header->e_phoff
237
                + i * sizeof(elf_segment_header_t), SEEK_SET);
238
 
3315 jermar 239
        rc = my_read(elf->fd, &segment_hdr,
240
            sizeof(elf_segment_header_t));
3223 svoboda 241
        if (rc < 0) {
242
            printf("read error\n");
243
            return EE_INVALID;
244
        }
3222 svoboda 245
 
246
        rc = segment_header(elf, &segment_hdr);
247
        if (rc != EE_OK)
248
            return rc;
249
    }
250
 
251
//  printf("parse sections\n");
252
 
253
    /* Inspect all section headers and proccess them. */
254
    for (i = 0; i < header->e_shnum; i++) {
255
        elf_section_header_t section_hdr;
256
 
257
        /* Seek to start of section header */
258
        lseek(elf->fd, header->e_shoff
259
            + i * sizeof(elf_section_header_t), SEEK_SET);
260
 
3315 jermar 261
        rc = my_read(elf->fd, &section_hdr,
262
            sizeof(elf_section_header_t));
3223 svoboda 263
        if (rc < 0) {
264
            printf("read error\n");
265
            return EE_INVALID;
266
        }
3222 svoboda 267
 
268
        rc = section_header(elf, &section_hdr);
269
        if (rc != EE_OK)
270
            return rc;
271
    }
272
 
273
    elf->info->entry =
274
        (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
275
 
276
//  printf("done\n");
277
 
278
    return EE_OK;
279
}
280
 
281
/** Print error message according to error code.
282
 *
283
 * @param rc Return code returned by elf_load().
284
 *
285
 * @return NULL terminated description of error.
286
 */
287
char *elf_error(unsigned int rc)
288
{
289
    assert(rc < sizeof(error_codes) / sizeof(char *));
290
 
291
    return error_codes[rc];
292
}
293
 
294
/** Process segment header.
295
 *
296
 * @param entry Segment header.
297
 *
298
 * @return EE_OK on success, error code otherwise.
299
 */
300
static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
301
{
302
    switch (entry->p_type) {
303
    case PT_NULL:
304
    case PT_PHDR:
305
        break;
306
    case PT_LOAD:
307
        return load_segment(elf, entry);
308
        break;
309
    case PT_INTERP:
310
        /* Assume silently interp == "/rtld.so" */
311
        elf->info->interp = "/rtld.so";
312
        break;
313
    case PT_DYNAMIC:
314
    case PT_SHLIB:
315
    case PT_NOTE:
316
    case PT_LOPROC:
317
    case PT_HIPROC:
318
    default:
319
        printf("segment p_type %d unknown\n", entry->p_type);
320
        return EE_UNSUPPORTED;
321
        break;
322
    }
323
    return EE_OK;
324
}
325
 
326
/** Load segment described by program header entry.
327
 *
328
 * @param elf   Loader state.
329
 * @param entry Program header entry describing segment to be loaded.
330
 *
331
 * @return EE_OK on success, error code otherwise.
332
 */
333
int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
334
{
335
    void *a;
336
    int flags = 0;
337
    uintptr_t bias;
338
    uintptr_t base;
339
    size_t mem_sz;
340
    int rc;
341
 
342
//  printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
343
//      entry->p_memsz);
344
 
345
    bias = elf->bias;
346
 
347
    if (entry->p_align > 1) {
348
        if ((entry->p_offset % entry->p_align) !=
349
            (entry->p_vaddr % entry->p_align)) {
3223 svoboda 350
            printf("align check 1 failed offset%%align=%d, "
351
                "vaddr%%align=%d\n",
352
                entry->p_offset % entry->p_align,
353
                entry->p_vaddr % entry->p_align
3222 svoboda 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
//  printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
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
     */
3315 jermar 379
    a = as_area_create((uint8_t *)base + bias, mem_sz,
380
        AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
3222 svoboda 381
    if (a == (void *)(-1)) {
382
        printf("memory mapping failed\n");
383
        return EE_MEMORY;
384
    }
385
 
386
//  printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
387
//      entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a);
388
 
389
    /*
390
     * Load segment data
391
     */
392
//  printf("seek to %d\n", entry->p_offset);
393
    rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
3223 svoboda 394
    if (rc < 0) {
395
        printf("seek error\n");
396
        return EE_INVALID;
397
    }
3222 svoboda 398
 
399
//  printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
400
/*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
401
    if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
402
 
403
    /* Long reads are not possible yet. Load segment picewise */
404
 
405
    unsigned left, now;
406
    uint8_t *dp;
407
 
408
    left = entry->p_filesz;
409
    dp = (uint8_t *)(entry->p_vaddr + bias);
410
 
411
    while (left > 0) {
412
        now = 16384;
413
        if (now > left) now = left;
414
 
415
//      printf("read %d...", now);
3315 jermar 416
        rc = my_read(elf->fd, dp, now);
3222 svoboda 417
//      printf("->%d\n", rc);
418
 
3223 svoboda 419
        if (rc < 0) {
420
            printf("read error\n");
421
            return EE_INVALID;
422
        }
3222 svoboda 423
 
424
        left -= now;
425
        dp += now;
426
    }
427
 
428
//  printf("set area flags to %d\n", flags);
429
    rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags);
430
    if (rc != 0) {
431
        printf("failed to set memory area flags\n");
432
        return EE_MEMORY;
433
    }
434
 
435
    if (flags & AS_AREA_EXEC) {
436
        /* Enforce SMC coherence for the segment */
437
        if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz))
438
            return EE_MEMORY;
439
    }
440
 
441
    return EE_OK;
442
}
443
 
444
/** Process section header.
445
 *
446
 * @param elf   Loader state.
447
 * @param entry Segment header.
448
 *
449
 * @return EE_OK on success, error code otherwise.
450
 */
451
static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
452
{
453
    switch (entry->sh_type) {
454
    case SHT_PROGBITS:
455
        if (entry->sh_flags & SHF_TLS) {
456
            /* .tdata */
457
        }
458
        break;
459
    case SHT_NOBITS:
460
        if (entry->sh_flags & SHF_TLS) {
461
            /* .tbss */
462
        }
463
        break;
464
    case SHT_DYNAMIC:
465
        /* Record pointer to dynamic section into info structure */
466
        elf->info->dynamic =
467
            (void *)((uint8_t *)entry->sh_addr + elf->bias);
468
        printf("dynamic section found at 0x%x\n",
469
            (uintptr_t)elf->info->dynamic);
470
        break;
471
    default:
472
        break;
473
    }
474
 
475
    return EE_OK;
476
}
477
 
478
/** @}
479
 */