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9#include <assert.h>
10#include <elf.h>
11#include <errno.h>
12#include <fcntl.h>
13#include <limits.h>
14#include <stdio.h>
15#include <stdlib.h>
16#include <sys/mman.h>
17#include <sys/stat.h>
18#include <unistd.h>
19
20#include <asm/relocs.h>
21
22#define hdr_field(pfx, idx, field) ({ \
23 uint64_t _val; \
24 unsigned int _size; \
25 \
26 if (is_64) { \
27 _val = pfx##hdr64[idx].field; \
28 _size = sizeof(pfx##hdr64[0].field); \
29 } else { \
30 _val = pfx##hdr32[idx].field; \
31 _size = sizeof(pfx##hdr32[0].field); \
32 } \
33 \
34 switch (_size) { \
35 case 1: \
36 break; \
37 case 2: \
38 _val = is_be ? be16toh(_val) : le16toh(_val); \
39 break; \
40 case 4: \
41 _val = is_be ? be32toh(_val) : le32toh(_val); \
42 break; \
43 case 8: \
44 _val = is_be ? be64toh(_val) : le64toh(_val); \
45 break; \
46 } \
47 \
48 _val; \
49})
50
51#define set_hdr_field(pfx, idx, field, val) ({ \
52 uint64_t _val; \
53 unsigned int _size; \
54 \
55 if (is_64) \
56 _size = sizeof(pfx##hdr64[0].field); \
57 else \
58 _size = sizeof(pfx##hdr32[0].field); \
59 \
60 switch (_size) { \
61 case 1: \
62 _val = val; \
63 break; \
64 case 2: \
65 _val = is_be ? htobe16(val) : htole16(val); \
66 break; \
67 case 4: \
68 _val = is_be ? htobe32(val) : htole32(val); \
69 break; \
70 case 8: \
71 _val = is_be ? htobe64(val) : htole64(val); \
72 break; \
73 default: \
74 \
75 _val = 0; \
76 assert(0); \
77 break; \
78 } \
79 \
80 if (is_64) \
81 pfx##hdr64[idx].field = _val; \
82 else \
83 pfx##hdr32[idx].field = _val; \
84})
85
86#define ehdr_field(field) \
87 hdr_field(e, 0, field)
88#define phdr_field(idx, field) \
89 hdr_field(p, idx, field)
90#define shdr_field(idx, field) \
91 hdr_field(s, idx, field)
92
93#define set_phdr_field(idx, field, val) \
94 set_hdr_field(p, idx, field, val)
95#define set_shdr_field(idx, field, val) \
96 set_hdr_field(s, idx, field, val)
97
98#define shstr(idx) (&shstrtab[idx])
99
100bool is_64, is_be;
101uint64_t text_base;
102
103struct mips_reloc {
104 uint8_t type;
105 uint64_t offset;
106} *relocs;
107size_t relocs_sz, relocs_idx;
108
109static int add_reloc(unsigned int type, uint64_t off)
110{
111 struct mips_reloc *new;
112 size_t new_sz;
113
114 switch (type) {
115 case R_MIPS_NONE:
116 case R_MIPS_LO16:
117 case R_MIPS_PC16:
118 case R_MIPS_HIGHER:
119 case R_MIPS_HIGHEST:
120 case R_MIPS_PC21_S2:
121 case R_MIPS_PC26_S2:
122
123 return 0;
124
125 default:
126 break;
127 }
128
129 if (relocs_idx == relocs_sz) {
130 new_sz = relocs_sz ? relocs_sz * 2 : 128;
131 new = realloc(relocs, new_sz * sizeof(*relocs));
132 if (!new) {
133 fprintf(stderr, "Out of memory\n");
134 return -ENOMEM;
135 }
136
137 relocs = new;
138 relocs_sz = new_sz;
139 }
140
141 relocs[relocs_idx++] = (struct mips_reloc){
142 .type = type,
143 .offset = off,
144 };
145
146 return 0;
147}
148
149static int parse_mips32_rel(const void *_rel)
150{
151 const Elf32_Rel *rel = _rel;
152 uint32_t off, type;
153
154 off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset);
155 off -= text_base;
156
157 type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info);
158 type = ELF32_R_TYPE(type);
159
160 return add_reloc(type, off);
161}
162
163static int parse_mips64_rela(const void *_rel)
164{
165 const Elf64_Rela *rel = _rel;
166 uint64_t off, type;
167
168 off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset);
169 off -= text_base;
170
171 type = rel->r_info >> (64 - 8);
172
173 return add_reloc(type, off);
174}
175
176static void output_uint(uint8_t **buf, uint64_t val)
177{
178 uint64_t tmp;
179
180 do {
181 tmp = val & 0x7f;
182 val >>= 7;
183 tmp |= !!val << 7;
184 *(*buf)++ = tmp;
185 } while (val);
186}
187
188static int compare_relocs(const void *a, const void *b)
189{
190 const struct mips_reloc *ra = a, *rb = b;
191
192 return ra->offset - rb->offset;
193}
194
195int main(int argc, char *argv[])
196{
197 unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries;
198 size_t rel_size, rel_actual_size, load_sz;
199 const char *shstrtab, *sh_name, *rel_pfx;
200 int (*parse_fn)(const void *rel);
201 uint8_t *buf_start, *buf;
202 const Elf32_Ehdr *ehdr32;
203 const Elf64_Ehdr *ehdr64;
204 uintptr_t sh_offset;
205 Elf32_Phdr *phdr32;
206 Elf64_Phdr *phdr64;
207 Elf32_Shdr *shdr32;
208 Elf64_Shdr *shdr64;
209 struct stat st;
210 int err, fd;
211 void *elf;
212 bool skip;
213
214 fd = open(argv[1], O_RDWR);
215 if (fd == -1) {
216 fprintf(stderr, "Unable to open input file %s\n", argv[1]);
217 err = errno;
218 goto out_ret;
219 }
220
221 err = fstat(fd, &st);
222 if (err) {
223 fprintf(stderr, "Unable to fstat() input file\n");
224 goto out_close_fd;
225 }
226
227 elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
228 if (elf == MAP_FAILED) {
229 fprintf(stderr, "Unable to mmap() input file\n");
230 err = errno;
231 goto out_close_fd;
232 }
233
234 ehdr32 = elf;
235 ehdr64 = elf;
236
237 if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
238 fprintf(stderr, "Input file is not an ELF\n");
239 err = -EINVAL;
240 goto out_free_relocs;
241 }
242
243 if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
244 fprintf(stderr, "Unrecognised ELF version\n");
245 err = -EINVAL;
246 goto out_free_relocs;
247 }
248
249 switch (ehdr32->e_ident[EI_CLASS]) {
250 case ELFCLASS32:
251 is_64 = false;
252 break;
253 case ELFCLASS64:
254 is_64 = true;
255 break;
256 default:
257 fprintf(stderr, "Unrecognised ELF class\n");
258 err = -EINVAL;
259 goto out_free_relocs;
260 }
261
262 switch (ehdr32->e_ident[EI_DATA]) {
263 case ELFDATA2LSB:
264 is_be = false;
265 break;
266 case ELFDATA2MSB:
267 is_be = true;
268 break;
269 default:
270 fprintf(stderr, "Unrecognised ELF data encoding\n");
271 err = -EINVAL;
272 goto out_free_relocs;
273 }
274
275 if (ehdr_field(e_type) != ET_EXEC) {
276 fprintf(stderr, "Input ELF is not an executable\n");
277 printf("type 0x%lx\n", ehdr_field(e_type));
278 err = -EINVAL;
279 goto out_free_relocs;
280 }
281
282 if (ehdr_field(e_machine) != EM_MIPS) {
283 fprintf(stderr, "Input ELF does not target MIPS\n");
284 err = -EINVAL;
285 goto out_free_relocs;
286 }
287
288 phdr32 = elf + ehdr_field(e_phoff);
289 phdr64 = elf + ehdr_field(e_phoff);
290 shdr32 = elf + ehdr_field(e_shoff);
291 shdr64 = elf + ehdr_field(e_shoff);
292 shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
293
294 i_rel_shdr = UINT_MAX;
295 for (i = 0; i < ehdr_field(e_shnum); i++) {
296 sh_name = shstr(shdr_field(i, sh_name));
297
298 if (!strcmp(sh_name, ".rel")) {
299 i_rel_shdr = i;
300 continue;
301 }
302
303 if (!strcmp(sh_name, ".text")) {
304 text_base = shdr_field(i, sh_addr);
305 continue;
306 }
307 }
308 if (i_rel_shdr == UINT_MAX) {
309 fprintf(stderr, "Unable to find .rel section\n");
310 err = -EINVAL;
311 goto out_free_relocs;
312 }
313 if (!text_base) {
314 fprintf(stderr, "Unable to find .text base address\n");
315 err = -EINVAL;
316 goto out_free_relocs;
317 }
318
319 rel_pfx = is_64 ? ".rela." : ".rel.";
320
321 for (i = 0; i < ehdr_field(e_shnum); i++) {
322 sh_type = shdr_field(i, sh_type);
323 if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
324 continue;
325
326 sh_name = shstr(shdr_field(i, sh_name));
327 if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
328 if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn"))
329 fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
330 continue;
331 }
332
333
334
335
336
337
338
339 skip = true;
340 for (j = 0; j < ehdr_field(e_shnum); j++) {
341 if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name))))
342 continue;
343
344 skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
345 break;
346 }
347 if (skip)
348 continue;
349
350 sh_offset = shdr_field(i, sh_offset);
351 sh_entsize = shdr_field(i, sh_entsize);
352 sh_entries = shdr_field(i, sh_size) / sh_entsize;
353
354 if (sh_type == SHT_REL) {
355 if (is_64) {
356 fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
357 err = -EINVAL;
358 goto out_free_relocs;
359 } else {
360 parse_fn = parse_mips32_rel;
361 }
362 } else {
363 if (is_64) {
364 parse_fn = parse_mips64_rela;
365 } else {
366 fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
367 err = -EINVAL;
368 goto out_free_relocs;
369 }
370 }
371
372 for (j = 0; j < sh_entries; j++) {
373 err = parse_fn(elf + sh_offset + (j * sh_entsize));
374 if (err)
375 goto out_free_relocs;
376 }
377 }
378
379
380 qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
381
382
383 for (i = relocs_idx - 1; i > 0; i--)
384 relocs[i].offset -= relocs[i - 1].offset;
385
386
387 buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
388 for (i = 0; i < relocs_idx; i++) {
389 output_uint(&buf, relocs[i].type);
390 output_uint(&buf, relocs[i].offset >> 2);
391 }
392
393
394 output_uint(&buf, R_MIPS_NONE);
395
396
397 rel_size = shdr_field(i_rel_shdr, sh_size);
398 rel_actual_size = buf - buf_start;
399 if (rel_actual_size > rel_size) {
400 fprintf(stderr, "Relocs overflowed .rel section\n");
401 return -ENOMEM;
402 }
403
404
405 set_shdr_field(i_rel_shdr, sh_size, rel_actual_size);
406
407
408 for (i = 0; i < ehdr_field(e_phnum); i++) {
409 if (phdr_field(i, p_type) != PT_LOAD)
410 continue;
411
412 load_sz = phdr_field(i, p_filesz);
413 load_sz -= rel_size - rel_actual_size;
414 set_phdr_field(i, p_filesz, load_sz);
415 break;
416 }
417
418
419 err = msync(elf, st.st_size, MS_SYNC);
420 if (err) {
421 fprintf(stderr, "Failed to msync: %d\n", errno);
422 goto out_free_relocs;
423 }
424
425out_free_relocs:
426 free(relocs);
427 munmap(elf, st.st_size);
428out_close_fd:
429 close(fd);
430out_ret:
431 return err;
432}
433
