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2928 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
3101 svoboda 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.
2928 svoboda 44
 */
45
 
46
#include <stdio.h>
47
#include <sys/types.h>
48
#include <align.h>
49
#include <assert.h>
50
#include <as.h>
2962 svoboda 51
#include <unistd.h>
52
#include <fcntl.h>
3210 svoboda 53
#include <smc.h>
3160 svoboda 54
#include <loader/pcb.h>
2962 svoboda 55
 
2928 svoboda 56
#include "elf.h"
2962 svoboda 57
#include "elf_load.h"
3131 svoboda 58
#include "arch.h"
2928 svoboda 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
 
2972 svoboda 69
static unsigned int elf_load(elf_ld_t *elf, size_t so_bias);
2964 svoboda 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);
2928 svoboda 73
 
3403 svoboda 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
 
3101 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
 */
3552 svoboda 102
int elf_load_file(char *file_name, size_t so_bias, eld_flags_t flags,
103
    elf_info_t *info)
2964 svoboda 104
{
105
    elf_ld_t elf;
2928 svoboda 106
 
2962 svoboda 107
    int fd;
108
    int rc;
109
 
3155 svoboda 110
//  printf("open and read '%s'...\n", file_name);
2962 svoboda 111
 
3101 svoboda 112
    fd = open(file_name, O_RDONLY);
2962 svoboda 113
    if (fd < 0) {
3400 svoboda 114
        printf("failed opening file (error %d)\n", fd);
2962 svoboda 115
        return -1;
116
    }
117
 
2964 svoboda 118
    elf.fd = fd;
119
    elf.info = info;
3552 svoboda 120
    elf.flags = flags;
2964 svoboda 121
 
2972 svoboda 122
    rc = elf_load(&elf, so_bias);
2962 svoboda 123
 
124
    close(fd);
125
 
126
    return rc;
127
}
128
 
3101 svoboda 129
/** Create the program control block (PCB).
130
 *
3170 svoboda 131
 * Fills the program control block @a pcb with information from
132
 * @a info.
3101 svoboda 133
 *
134
 * @param info  Program info structure
135
 * @return EOK on success or negative error code
136
 */
3170 svoboda 137
void elf_create_pcb(elf_info_t *info, pcb_t *pcb)
2962 svoboda 138
{
2964 svoboda 139
    pcb->entry = info->entry;
2965 svoboda 140
    pcb->dynamic = info->dynamic;
3686 svoboda 141
    pcb->rtld_runtime = NULL;
2962 svoboda 142
}
143
 
144
 
3101 svoboda 145
/** Load an ELF binary.
2928 svoboda 146
 *
3101 svoboda 147
 * The @a elf structure contains the loader state, including
148
 * an open file, from which the binary will be loaded,
149
 * a pointer to the @c info structure etc.
150
 *
151
 * @param elf       Pointer to loader state buffer.
152
 * @param so_bias   Bias to use if the file is a shared object.
153
 * @return EE_OK on success or EE_xx error code.
2928 svoboda 154
 */
2972 svoboda 155
static unsigned int elf_load(elf_ld_t *elf, size_t so_bias)
2928 svoboda 156
{
2964 svoboda 157
    elf_header_t header_buf;
158
    elf_header_t *header = &header_buf;
2928 svoboda 159
    int i, rc;
160
 
3403 svoboda 161
    rc = my_read(elf->fd, header, sizeof(elf_header_t));
2928 svoboda 162
    if (rc < 0) {
163
        printf("read error\n");
164
        return EE_INVALID;
165
    }
166
 
2964 svoboda 167
    elf->header = header;
168
 
3155 svoboda 169
//  printf("ELF-load:");
2928 svoboda 170
    /* Identify ELF */
171
    if (header->e_ident[EI_MAG0] != ELFMAG0 ||
172
        header->e_ident[EI_MAG1] != ELFMAG1 ||
173
        header->e_ident[EI_MAG2] != ELFMAG2 ||
174
        header->e_ident[EI_MAG3] != ELFMAG3) {
175
        printf("invalid header\n");
176
        return EE_INVALID;
177
    }
178
 
179
    /* Identify ELF compatibility */
180
    if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING ||
181
        header->e_machine != ELF_MACHINE ||
182
        header->e_ident[EI_VERSION] != EV_CURRENT ||
183
        header->e_version != EV_CURRENT ||
184
        header->e_ident[EI_CLASS] != ELF_CLASS) {
185
        printf("incompatible data/version/class\n");
186
        return EE_INCOMPATIBLE;
187
    }
188
 
2992 svoboda 189
    if (header->e_phentsize != sizeof(elf_segment_header_t)) {
190
        printf("e_phentsize:%d != %d\n", header->e_phentsize,
191
            sizeof(elf_segment_header_t));
2928 svoboda 192
        return EE_INCOMPATIBLE;
2992 svoboda 193
    }
2928 svoboda 194
 
2992 svoboda 195
    if (header->e_shentsize != sizeof(elf_section_header_t)) {
196
        printf("e_shentsize:%d != %d\n", header->e_shentsize,
197
            sizeof(elf_section_header_t));
2928 svoboda 198
        return EE_INCOMPATIBLE;
2992 svoboda 199
    }
2928 svoboda 200
 
201
    /* Check if the object type is supported. */
202
    if (header->e_type != ET_EXEC && header->e_type != ET_DYN) {
203
        printf("Object type %d is not supported\n", header->e_type);
204
        return EE_UNSUPPORTED;
205
    }
206
 
2972 svoboda 207
    /* Shared objects can be loaded with a bias */
3155 svoboda 208
//  printf("Object type: %d\n", header->e_type);
2964 svoboda 209
    if (header->e_type == ET_DYN)
2972 svoboda 210
        elf->bias = so_bias;
2964 svoboda 211
    else
212
        elf->bias = 0;
213
 
3155 svoboda 214
//  printf("Bias set to 0x%x\n", elf->bias);
3004 svoboda 215
    elf->info->interp = NULL;
216
    elf->info->dynamic = NULL;
2971 svoboda 217
 
3155 svoboda 218
//  printf("parse segments\n");
2928 svoboda 219
 
220
    /* Walk through all segment headers and process them. */
221
    for (i = 0; i < header->e_phnum; i++) {
2964 svoboda 222
        elf_segment_header_t segment_hdr;
2928 svoboda 223
 
2961 svoboda 224
        /* Seek to start of segment header */
2964 svoboda 225
        lseek(elf->fd, header->e_phoff
226
                + i * sizeof(elf_segment_header_t), SEEK_SET);
2928 svoboda 227
 
3403 svoboda 228
        rc = my_read(elf->fd, &segment_hdr,
229
            sizeof(elf_segment_header_t));
230
        if (rc < 0) {
231
            printf("read error\n");
232
            return EE_INVALID;
233
        }
2964 svoboda 234
 
235
        rc = segment_header(elf, &segment_hdr);
2928 svoboda 236
        if (rc != EE_OK)
237
            return rc;
238
    }
239
 
3155 svoboda 240
//  printf("parse sections\n");
2928 svoboda 241
 
242
    /* Inspect all section headers and proccess them. */
243
    for (i = 0; i < header->e_shnum; i++) {
2964 svoboda 244
        elf_section_header_t section_hdr;
2928 svoboda 245
 
2961 svoboda 246
        /* Seek to start of section header */
2964 svoboda 247
        lseek(elf->fd, header->e_shoff
248
            + i * sizeof(elf_section_header_t), SEEK_SET);
2961 svoboda 249
 
3403 svoboda 250
        rc = my_read(elf->fd, &section_hdr,
251
            sizeof(elf_section_header_t));
252
        if (rc < 0) {
253
            printf("read error\n");
254
            return EE_INVALID;
255
        }
2964 svoboda 256
 
257
        rc = section_header(elf, &section_hdr);
2928 svoboda 258
        if (rc != EE_OK)
2961 svoboda 259
            return rc;
2928 svoboda 260
    }
261
 
2964 svoboda 262
    elf->info->entry =
263
        (entry_point_t)((uint8_t *)header->e_entry + elf->bias);
264
 
3155 svoboda 265
//  printf("done\n");
2928 svoboda 266
 
267
    return EE_OK;
268
}
269
 
270
/** Print error message according to error code.
271
 *
272
 * @param rc Return code returned by elf_load().
273
 *
274
 * @return NULL terminated description of error.
275
 */
276
char *elf_error(unsigned int rc)
277
{
278
    assert(rc < sizeof(error_codes) / sizeof(char *));
279
 
280
    return error_codes[rc];
281
}
282
 
283
/** Process segment header.
284
 *
3101 svoboda 285
 * @param entry Segment header.
2928 svoboda 286
 *
287
 * @return EE_OK on success, error code otherwise.
288
 */
2964 svoboda 289
static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry)
2928 svoboda 290
{
291
    switch (entry->p_type) {
292
    case PT_NULL:
293
    case PT_PHDR:
294
        break;
295
    case PT_LOAD:
2964 svoboda 296
        return load_segment(elf, entry);
2928 svoboda 297
        break;
3004 svoboda 298
    case PT_INTERP:
3681 svoboda 299
        /* Assume silently interp == "/app/dload" */
300
        elf->info->interp = "/app/dload";
3004 svoboda 301
        break;
2928 svoboda 302
    case PT_DYNAMIC:
3690 svoboda 303
        /* Record pointer to dynamic section into info structure */
304
        elf->info->dynamic =
305
            (void *)((uint8_t *)entry->p_vaddr + elf->bias);
306
        printf("dynamic section found at 0x%x\n",
307
            (uintptr_t)elf->info->dynamic);
308
        break;
3772 svoboda 309
    case 0x70000000:
310
        /* FIXME: MIPS reginfo */
311
        break;
2928 svoboda 312
    case PT_SHLIB:
313
    case PT_NOTE:
3772 svoboda 314
//  case PT_LOPROC:
315
//  case PT_HIPROC:
2928 svoboda 316
    default:
317
        printf("segment p_type %d unknown\n", entry->p_type);
318
        return EE_UNSUPPORTED;
319
        break;
320
    }
321
    return EE_OK;
322
}
323
 
324
/** Load segment described by program header entry.
325
 *
3101 svoboda 326
 * @param elf   Loader state.
2928 svoboda 327
 * @param entry Program header entry describing segment to be loaded.
328
 *
329
 * @return EE_OK on success, error code otherwise.
330
 */
2964 svoboda 331
int load_segment(elf_ld_t *elf, elf_segment_header_t *entry)
2928 svoboda 332
{
333
    void *a;
334
    int flags = 0;
2932 svoboda 335
    uintptr_t bias;
3010 svoboda 336
    uintptr_t base;
337
    size_t mem_sz;
2928 svoboda 338
    int rc;
339
 
3155 svoboda 340
//  printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr,
341
//      entry->p_memsz);
2928 svoboda 342
 
2964 svoboda 343
    bias = elf->bias;
2928 svoboda 344
 
345
    if (entry->p_align > 1) {
346
        if ((entry->p_offset % entry->p_align) !=
347
            (entry->p_vaddr % entry->p_align)) {
3403 svoboda 348
            printf("align check 1 failed offset%%align=%d, "
349
                "vaddr%%align=%d\n",
350
                entry->p_offset % entry->p_align,
351
                entry->p_vaddr % entry->p_align
2928 svoboda 352
            );
353
            return EE_INVALID;
354
        }
355
    }
356
 
2992 svoboda 357
    /* Final flags that will be set for the memory area */
358
 
2985 svoboda 359
    if (entry->p_flags & PF_X)
2928 svoboda 360
        flags |= AS_AREA_EXEC;
361
    if (entry->p_flags & PF_W)
362
        flags |= AS_AREA_WRITE;
363
    if (entry->p_flags & PF_R)
364
        flags |= AS_AREA_READ;
365
    flags |= AS_AREA_CACHEABLE;
3010 svoboda 366
 
367
    base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE);
368
    mem_sz = entry->p_memsz + (entry->p_vaddr - base);
2985 svoboda 369
 
3155 svoboda 370
//  printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias,
371
//  entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE));
2928 svoboda 372
 
2985 svoboda 373
    /*
374
     * For the course of loading, the area needs to be readable
375
     * and writeable.
376
     */
3403 svoboda 377
    a = as_area_create((uint8_t *)base + bias, mem_sz,
378
        AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
2928 svoboda 379
    if (a == (void *)(-1)) {
3772 svoboda 380
        printf("memory mapping failed (0x%x, %d)\n",
381
            base+bias, mem_sz);
2928 svoboda 382
        return EE_MEMORY;
383
    }
384
 
3155 svoboda 385
//  printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n",
386
//      entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a);
2928 svoboda 387
 
388
    /*
389
     * Load segment data
390
     */
3155 svoboda 391
//  printf("seek to %d\n", entry->p_offset);
2964 svoboda 392
    rc = lseek(elf->fd, entry->p_offset, SEEK_SET);
3403 svoboda 393
    if (rc < 0) {
394
        printf("seek error\n");
395
        return EE_INVALID;
396
    }
2928 svoboda 397
 
3155 svoboda 398
//  printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias);
2949 svoboda 399
/*  rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz);
400
    if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/
3101 svoboda 401
 
402
    /* Long reads are not possible yet. Load segment picewise */
403
 
2949 svoboda 404
    unsigned left, now;
405
    uint8_t *dp;
2928 svoboda 406
 
2949 svoboda 407
    left = entry->p_filesz;
408
    dp = (uint8_t *)(entry->p_vaddr + bias);
409
 
410
    while (left > 0) {
2977 svoboda 411
        now = 16384;
3101 svoboda 412
        if (now > left) now = left;
413
 
3155 svoboda 414
//      printf("read %d...", now);
3403 svoboda 415
        rc = my_read(elf->fd, dp, now);
3155 svoboda 416
//      printf("->%d\n", rc);
3101 svoboda 417
 
3403 svoboda 418
        if (rc < 0) {
419
            printf("read error\n");
420
            return EE_INVALID;
421
        }
3101 svoboda 422
 
2949 svoboda 423
        left -= now;
424
        dp += now;
425
    }
426
 
3552 svoboda 427
    /*
428
     * The caller wants to modify the segments first. He will then
429
     * need to set the right access mode and ensure SMC coherence.
430
     */
431
    if ((elf->flags & ELDF_RW) != 0) return EE_OK;
432
 
3562 svoboda 433
//  printf("set area flags to %d\n", flags);
2985 svoboda 434
    rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags);
435
    if (rc != 0) {
436
        printf("failed to set memory area flags\n");
437
        return EE_MEMORY;
438
    }
439
 
3210 svoboda 440
    if (flags & AS_AREA_EXEC) {
441
        /* Enforce SMC coherence for the segment */
442
        if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz))
443
            return EE_MEMORY;
444
    }
445
 
2928 svoboda 446
    return EE_OK;
447
}
448
 
449
/** Process section header.
450
 *
3101 svoboda 451
 * @param elf   Loader state.
2928 svoboda 452
 * @param entry Segment header.
453
 *
454
 * @return EE_OK on success, error code otherwise.
455
 */
2964 svoboda 456
static int section_header(elf_ld_t *elf, elf_section_header_t *entry)
2928 svoboda 457
{
458
    switch (entry->sh_type) {
459
    case SHT_PROGBITS:
460
        if (entry->sh_flags & SHF_TLS) {
461
            /* .tdata */
462
        }
463
        break;
464
    case SHT_NOBITS:
465
        if (entry->sh_flags & SHF_TLS) {
466
            /* .tbss */
467
        }
468
        break;
2961 svoboda 469
    case SHT_DYNAMIC:
470
        break;
2928 svoboda 471
    default:
472
        break;
473
    }
474
 
475
    return EE_OK;
476
}
477
 
478
/** @}
479
 */