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1 | /* |
2 | * MIPS Relocation Data Generator | |
3 | * | |
4 | * Copyright (c) 2017 Imagination Technologies Ltd. | |
5 | * | |
6 | * SPDX-License-Identifier: GPL-2.0+ | |
7 | */ | |
8 | ||
9 | #include <elf.h> | |
10 | #include <errno.h> | |
11 | #include <fcntl.h> | |
12 | #include <limits.h> | |
13 | #include <stdio.h> | |
14 | #include <stdlib.h> | |
15 | #include <sys/mman.h> | |
16 | #include <sys/stat.h> | |
17 | #include <unistd.h> | |
18 | ||
19 | #include <asm/relocs.h> | |
20 | ||
21 | #define hdr_field(pfx, idx, field) ({ \ | |
22 | uint64_t _val; \ | |
23 | unsigned int _size; \ | |
24 | \ | |
25 | if (is_64) { \ | |
26 | _val = pfx##hdr64[idx].field; \ | |
27 | _size = sizeof(pfx##hdr64[0].field); \ | |
28 | } else { \ | |
29 | _val = pfx##hdr32[idx].field; \ | |
30 | _size = sizeof(pfx##hdr32[0].field); \ | |
31 | } \ | |
32 | \ | |
33 | switch (_size) { \ | |
34 | case 1: \ | |
35 | break; \ | |
36 | case 2: \ | |
37 | _val = is_be ? be16toh(_val) : le16toh(_val); \ | |
38 | break; \ | |
39 | case 4: \ | |
40 | _val = is_be ? be32toh(_val) : le32toh(_val); \ | |
41 | break; \ | |
42 | case 8: \ | |
43 | _val = is_be ? be64toh(_val) : le64toh(_val); \ | |
44 | break; \ | |
45 | } \ | |
46 | \ | |
47 | _val; \ | |
48 | }) | |
49 | ||
50 | #define set_hdr_field(pfx, idx, field, val) ({ \ | |
51 | uint64_t _val; \ | |
52 | unsigned int _size; \ | |
53 | \ | |
54 | if (is_64) \ | |
55 | _size = sizeof(pfx##hdr64[0].field); \ | |
56 | else \ | |
57 | _size = sizeof(pfx##hdr32[0].field); \ | |
58 | \ | |
59 | switch (_size) { \ | |
60 | case 1: \ | |
61 | _val = val; \ | |
62 | break; \ | |
63 | case 2: \ | |
64 | _val = is_be ? htobe16(val) : htole16(val); \ | |
65 | break; \ | |
66 | case 4: \ | |
67 | _val = is_be ? htobe32(val) : htole32(val); \ | |
68 | break; \ | |
69 | case 8: \ | |
70 | _val = is_be ? htobe64(val) : htole64(val); \ | |
71 | break; \ | |
72 | } \ | |
73 | \ | |
74 | if (is_64) \ | |
75 | pfx##hdr64[idx].field = _val; \ | |
76 | else \ | |
77 | pfx##hdr32[idx].field = _val; \ | |
78 | }) | |
79 | ||
80 | #define ehdr_field(field) \ | |
81 | hdr_field(e, 0, field) | |
82 | #define phdr_field(idx, field) \ | |
83 | hdr_field(p, idx, field) | |
84 | #define shdr_field(idx, field) \ | |
85 | hdr_field(s, idx, field) | |
86 | ||
87 | #define set_phdr_field(idx, field, val) \ | |
88 | set_hdr_field(p, idx, field, val) | |
89 | #define set_shdr_field(idx, field, val) \ | |
90 | set_hdr_field(s, idx, field, val) | |
91 | ||
92 | #define shstr(idx) (&shstrtab[idx]) | |
93 | ||
94 | bool is_64, is_be; | |
95 | uint64_t text_base; | |
96 | ||
97 | struct mips_reloc { | |
98 | uint8_t type; | |
99 | uint64_t offset; | |
100 | } *relocs; | |
101 | size_t relocs_sz, relocs_idx; | |
102 | ||
103 | static int add_reloc(unsigned int type, uint64_t off) | |
104 | { | |
105 | struct mips_reloc *new; | |
106 | size_t new_sz; | |
107 | ||
108 | switch (type) { | |
109 | case R_MIPS_NONE: | |
110 | case R_MIPS_LO16: | |
111 | case R_MIPS_PC16: | |
112 | case R_MIPS_HIGHER: | |
113 | case R_MIPS_HIGHEST: | |
114 | case R_MIPS_PC21_S2: | |
115 | case R_MIPS_PC26_S2: | |
116 | /* Skip these relocs */ | |
117 | return 0; | |
118 | ||
119 | default: | |
120 | break; | |
121 | } | |
122 | ||
123 | if (relocs_idx == relocs_sz) { | |
124 | new_sz = relocs_sz ? relocs_sz * 2 : 128; | |
125 | new = realloc(relocs, new_sz * sizeof(*relocs)); | |
126 | if (!new) { | |
127 | fprintf(stderr, "Out of memory\n"); | |
128 | return -ENOMEM; | |
129 | } | |
130 | ||
131 | relocs = new; | |
132 | relocs_sz = new_sz; | |
133 | } | |
134 | ||
135 | relocs[relocs_idx++] = (struct mips_reloc){ | |
136 | .type = type, | |
137 | .offset = off, | |
138 | }; | |
139 | ||
140 | return 0; | |
141 | } | |
142 | ||
143 | static int parse_mips32_rel(const void *_rel) | |
144 | { | |
145 | const Elf32_Rel *rel = _rel; | |
146 | uint32_t off, type; | |
147 | ||
148 | off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset); | |
149 | off -= text_base; | |
150 | ||
151 | type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info); | |
152 | type = ELF32_R_TYPE(type); | |
153 | ||
154 | return add_reloc(type, off); | |
155 | } | |
156 | ||
157 | static int parse_mips64_rela(const void *_rel) | |
158 | { | |
159 | const Elf64_Rela *rel = _rel; | |
160 | uint64_t off, type; | |
161 | ||
162 | off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset); | |
163 | off -= text_base; | |
164 | ||
165 | type = rel->r_info >> (64 - 8); | |
166 | ||
167 | return add_reloc(type, off); | |
168 | } | |
169 | ||
170 | static void output_uint(uint8_t **buf, uint64_t val) | |
171 | { | |
172 | uint64_t tmp; | |
173 | ||
174 | do { | |
175 | tmp = val & 0x7f; | |
176 | val >>= 7; | |
177 | tmp |= !!val << 7; | |
178 | *(*buf)++ = tmp; | |
179 | } while (val); | |
180 | } | |
181 | ||
182 | static int compare_relocs(const void *a, const void *b) | |
183 | { | |
184 | const struct mips_reloc *ra = a, *rb = b; | |
185 | ||
186 | return ra->offset - rb->offset; | |
187 | } | |
188 | ||
189 | int main(int argc, char *argv[]) | |
190 | { | |
191 | unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries; | |
192 | size_t rel_size, rel_actual_size, load_sz; | |
193 | const char *shstrtab, *sh_name, *rel_pfx; | |
194 | int (*parse_fn)(const void *rel); | |
195 | uint8_t *buf_start, *buf; | |
196 | const Elf32_Ehdr *ehdr32; | |
197 | const Elf64_Ehdr *ehdr64; | |
198 | uintptr_t sh_offset; | |
199 | Elf32_Phdr *phdr32; | |
200 | Elf64_Phdr *phdr64; | |
201 | Elf32_Shdr *shdr32; | |
202 | Elf64_Shdr *shdr64; | |
203 | struct stat st; | |
204 | int err, fd; | |
205 | void *elf; | |
206 | bool skip; | |
207 | ||
208 | fd = open(argv[1], O_RDWR); | |
209 | if (fd == -1) { | |
210 | fprintf(stderr, "Unable to open input file %s\n", argv[1]); | |
211 | err = errno; | |
212 | goto out_ret; | |
213 | } | |
214 | ||
215 | err = fstat(fd, &st); | |
216 | if (err) { | |
217 | fprintf(stderr, "Unable to fstat() input file\n"); | |
218 | goto out_close_fd; | |
219 | } | |
220 | ||
221 | elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); | |
222 | if (elf == MAP_FAILED) { | |
223 | fprintf(stderr, "Unable to mmap() input file\n"); | |
224 | err = errno; | |
225 | goto out_close_fd; | |
226 | } | |
227 | ||
228 | ehdr32 = elf; | |
229 | ehdr64 = elf; | |
230 | ||
231 | if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) { | |
232 | fprintf(stderr, "Input file is not an ELF\n"); | |
233 | err = -EINVAL; | |
234 | goto out_free_relocs; | |
235 | } | |
236 | ||
237 | if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) { | |
238 | fprintf(stderr, "Unrecognised ELF version\n"); | |
239 | err = -EINVAL; | |
240 | goto out_free_relocs; | |
241 | } | |
242 | ||
243 | switch (ehdr32->e_ident[EI_CLASS]) { | |
244 | case ELFCLASS32: | |
245 | is_64 = false; | |
246 | break; | |
247 | case ELFCLASS64: | |
248 | is_64 = true; | |
249 | break; | |
250 | default: | |
251 | fprintf(stderr, "Unrecognised ELF class\n"); | |
252 | err = -EINVAL; | |
253 | goto out_free_relocs; | |
254 | } | |
255 | ||
256 | switch (ehdr32->e_ident[EI_DATA]) { | |
257 | case ELFDATA2LSB: | |
258 | is_be = false; | |
259 | break; | |
260 | case ELFDATA2MSB: | |
261 | is_be = true; | |
262 | break; | |
263 | default: | |
264 | fprintf(stderr, "Unrecognised ELF data encoding\n"); | |
265 | err = -EINVAL; | |
266 | goto out_free_relocs; | |
267 | } | |
268 | ||
269 | if (ehdr_field(e_type) != ET_EXEC) { | |
270 | fprintf(stderr, "Input ELF is not an executable\n"); | |
271 | printf("type 0x%lx\n", ehdr_field(e_type)); | |
272 | err = -EINVAL; | |
273 | goto out_free_relocs; | |
274 | } | |
275 | ||
276 | if (ehdr_field(e_machine) != EM_MIPS) { | |
277 | fprintf(stderr, "Input ELF does not target MIPS\n"); | |
278 | err = -EINVAL; | |
279 | goto out_free_relocs; | |
280 | } | |
281 | ||
282 | phdr32 = elf + ehdr_field(e_phoff); | |
283 | phdr64 = elf + ehdr_field(e_phoff); | |
284 | shdr32 = elf + ehdr_field(e_shoff); | |
285 | shdr64 = elf + ehdr_field(e_shoff); | |
286 | shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset); | |
287 | ||
288 | i_rel_shdr = UINT_MAX; | |
289 | for (i = 0; i < ehdr_field(e_shnum); i++) { | |
290 | sh_name = shstr(shdr_field(i, sh_name)); | |
291 | ||
292 | if (!strcmp(sh_name, ".rel")) { | |
293 | i_rel_shdr = i; | |
294 | continue; | |
295 | } | |
296 | ||
297 | if (!strcmp(sh_name, ".text")) { | |
298 | text_base = shdr_field(i, sh_addr); | |
299 | continue; | |
300 | } | |
301 | } | |
302 | if (i_rel_shdr == UINT_MAX) { | |
303 | fprintf(stderr, "Unable to find .rel section\n"); | |
304 | err = -EINVAL; | |
305 | goto out_free_relocs; | |
306 | } | |
307 | if (!text_base) { | |
308 | fprintf(stderr, "Unable to find .text base address\n"); | |
309 | err = -EINVAL; | |
310 | goto out_free_relocs; | |
311 | } | |
312 | ||
313 | rel_pfx = is_64 ? ".rela." : ".rel."; | |
314 | ||
315 | for (i = 0; i < ehdr_field(e_shnum); i++) { | |
316 | sh_type = shdr_field(i, sh_type); | |
317 | if ((sh_type != SHT_REL) && (sh_type != SHT_RELA)) | |
318 | continue; | |
319 | ||
320 | sh_name = shstr(shdr_field(i, sh_name)); | |
321 | if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) { | |
322 | if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn")) | |
323 | fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name); | |
324 | continue; | |
325 | } | |
326 | ||
327 | /* | |
328 | * Skip reloc sections which either don't correspond to another | |
329 | * section in the ELF, or whose corresponding section isn't | |
330 | * loaded as part of the U-Boot binary (ie. doesn't have the | |
331 | * alloc flags set). | |
332 | */ | |
333 | skip = true; | |
334 | for (j = 0; j < ehdr_field(e_shnum); j++) { | |
335 | if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name)))) | |
336 | continue; | |
337 | ||
338 | skip = !(shdr_field(j, sh_flags) & SHF_ALLOC); | |
339 | break; | |
340 | } | |
341 | if (skip) | |
342 | continue; | |
343 | ||
344 | sh_offset = shdr_field(i, sh_offset); | |
345 | sh_entsize = shdr_field(i, sh_entsize); | |
346 | sh_entries = shdr_field(i, sh_size) / sh_entsize; | |
347 | ||
348 | if (sh_type == SHT_REL) { | |
349 | if (is_64) { | |
350 | fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n"); | |
351 | err = -EINVAL; | |
352 | goto out_free_relocs; | |
353 | } else { | |
354 | parse_fn = parse_mips32_rel; | |
355 | } | |
356 | } else { | |
357 | if (is_64) { | |
358 | parse_fn = parse_mips64_rela; | |
359 | } else { | |
360 | fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n"); | |
361 | err = -EINVAL; | |
362 | goto out_free_relocs; | |
363 | } | |
364 | } | |
365 | ||
366 | for (j = 0; j < sh_entries; j++) { | |
367 | err = parse_fn(elf + sh_offset + (j * sh_entsize)); | |
368 | if (err) | |
369 | goto out_free_relocs; | |
370 | } | |
371 | } | |
372 | ||
373 | /* Sort relocs in ascending order of offset */ | |
374 | qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs); | |
375 | ||
376 | /* Make reloc offsets relative to their predecessor */ | |
377 | for (i = relocs_idx - 1; i > 0; i--) | |
378 | relocs[i].offset -= relocs[i - 1].offset; | |
379 | ||
380 | /* Write the relocations to the .rel section */ | |
381 | buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset); | |
382 | for (i = 0; i < relocs_idx; i++) { | |
383 | output_uint(&buf, relocs[i].type); | |
384 | output_uint(&buf, relocs[i].offset >> 2); | |
385 | } | |
386 | ||
387 | /* Write a terminating R_MIPS_NONE (0) */ | |
388 | output_uint(&buf, R_MIPS_NONE); | |
389 | ||
390 | /* Ensure the relocs didn't overflow the .rel section */ | |
391 | rel_size = shdr_field(i_rel_shdr, sh_size); | |
392 | rel_actual_size = buf - buf_start; | |
393 | if (rel_actual_size > rel_size) { | |
394 | fprintf(stderr, "Relocs overflowed .rel section\n"); | |
395 | return -ENOMEM; | |
396 | } | |
397 | ||
398 | /* Update the .rel section's size */ | |
399 | set_shdr_field(i_rel_shdr, sh_size, rel_actual_size); | |
400 | ||
401 | /* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */ | |
402 | for (i = 0; i < ehdr_field(e_phnum); i++) { | |
403 | if (phdr_field(i, p_type) != PT_LOAD) | |
404 | continue; | |
405 | ||
406 | load_sz = phdr_field(i, p_filesz); | |
407 | load_sz -= rel_size - rel_actual_size; | |
408 | set_phdr_field(i, p_filesz, load_sz); | |
409 | break; | |
410 | } | |
411 | ||
412 | /* Make sure data is written back to the file */ | |
413 | err = msync(elf, st.st_size, MS_SYNC); | |
414 | if (err) { | |
415 | fprintf(stderr, "Failed to msync: %d\n", errno); | |
416 | goto out_free_relocs; | |
417 | } | |
418 | ||
419 | out_free_relocs: | |
420 | free(relocs); | |
421 | munmap(elf, st.st_size); | |
422 | out_close_fd: | |
423 | close(fd); | |
424 | out_ret: | |
425 | return err; | |
426 | } |