xref: /openbmc/u-boot/tools/mips-relocs.c (revision 6f443330)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * MIPS Relocation Data Generator
4  *
5  * Copyright (c) 2017 Imagination Technologies Ltd.
6  */
7 
8 #include <assert.h>
9 #include <elf.h>
10 #include <errno.h>
11 #include <fcntl.h>
12 #include <limits.h>
13 #include <stdbool.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 		/* We should never reach here */		\
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 
100 bool is_64, is_be;
101 uint64_t text_base;
102 
103 struct mips_reloc {
104 	uint8_t type;
105 	uint64_t offset;
106 } *relocs;
107 size_t relocs_sz, relocs_idx;
108 
add_reloc(unsigned int type,uint64_t off)109 static 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 		/* Skip these relocs */
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 
parse_mips32_rel(const void * _rel)149 static 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 
parse_mips64_rela(const void * _rel)163 static 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 
output_uint(uint8_t ** buf,uint64_t val)176 static 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 
compare_relocs(const void * a,const void * b)188 static 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 
main(int argc,char * argv[])195 int 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;
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_Shdr *shdr32;
206 	Elf64_Shdr *shdr64;
207 	struct stat st;
208 	int err, fd;
209 	void *elf;
210 	bool skip;
211 
212 	fd = open(argv[1], O_RDWR);
213 	if (fd == -1) {
214 		fprintf(stderr, "Unable to open input file %s\n", argv[1]);
215 		err = errno;
216 		goto out_ret;
217 	}
218 
219 	err = fstat(fd, &st);
220 	if (err) {
221 		fprintf(stderr, "Unable to fstat() input file\n");
222 		goto out_close_fd;
223 	}
224 
225 	elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
226 	if (elf == MAP_FAILED) {
227 		fprintf(stderr, "Unable to mmap() input file\n");
228 		err = errno;
229 		goto out_close_fd;
230 	}
231 
232 	ehdr32 = elf;
233 	ehdr64 = elf;
234 
235 	if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
236 		fprintf(stderr, "Input file is not an ELF\n");
237 		err = -EINVAL;
238 		goto out_free_relocs;
239 	}
240 
241 	if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
242 		fprintf(stderr, "Unrecognised ELF version\n");
243 		err = -EINVAL;
244 		goto out_free_relocs;
245 	}
246 
247 	switch (ehdr32->e_ident[EI_CLASS]) {
248 	case ELFCLASS32:
249 		is_64 = false;
250 		break;
251 	case ELFCLASS64:
252 		is_64 = true;
253 		break;
254 	default:
255 		fprintf(stderr, "Unrecognised ELF class\n");
256 		err = -EINVAL;
257 		goto out_free_relocs;
258 	}
259 
260 	switch (ehdr32->e_ident[EI_DATA]) {
261 	case ELFDATA2LSB:
262 		is_be = false;
263 		break;
264 	case ELFDATA2MSB:
265 		is_be = true;
266 		break;
267 	default:
268 		fprintf(stderr, "Unrecognised ELF data encoding\n");
269 		err = -EINVAL;
270 		goto out_free_relocs;
271 	}
272 
273 	if (ehdr_field(e_type) != ET_EXEC) {
274 		fprintf(stderr, "Input ELF is not an executable\n");
275 		printf("type 0x%lx\n", ehdr_field(e_type));
276 		err = -EINVAL;
277 		goto out_free_relocs;
278 	}
279 
280 	if (ehdr_field(e_machine) != EM_MIPS) {
281 		fprintf(stderr, "Input ELF does not target MIPS\n");
282 		err = -EINVAL;
283 		goto out_free_relocs;
284 	}
285 
286 	shdr32 = elf + ehdr_field(e_shoff);
287 	shdr64 = elf + ehdr_field(e_shoff);
288 	shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
289 
290 	i_rel_shdr = UINT_MAX;
291 	for (i = 0; i < ehdr_field(e_shnum); i++) {
292 		sh_name = shstr(shdr_field(i, sh_name));
293 
294 		if (!strcmp(sh_name, ".data.reloc")) {
295 			i_rel_shdr = i;
296 			continue;
297 		}
298 
299 		if (!strcmp(sh_name, ".text")) {
300 			text_base = shdr_field(i, sh_addr);
301 			continue;
302 		}
303 	}
304 	if (i_rel_shdr == UINT_MAX) {
305 		fprintf(stderr, "Unable to find .rel section\n");
306 		err = -EINVAL;
307 		goto out_free_relocs;
308 	}
309 	if (!text_base) {
310 		fprintf(stderr, "Unable to find .text base address\n");
311 		err = -EINVAL;
312 		goto out_free_relocs;
313 	}
314 
315 	rel_pfx = is_64 ? ".rela." : ".rel.";
316 
317 	for (i = 0; i < ehdr_field(e_shnum); i++) {
318 		sh_type = shdr_field(i, sh_type);
319 		if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
320 			continue;
321 
322 		sh_name = shstr(shdr_field(i, sh_name));
323 		if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
324 			if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn"))
325 				fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
326 			continue;
327 		}
328 
329 		/*
330 		 * Skip reloc sections which either don't correspond to another
331 		 * section in the ELF, or whose corresponding section isn't
332 		 * loaded as part of the U-Boot binary (ie. doesn't have the
333 		 * alloc flags set).
334 		 */
335 		skip = true;
336 		for (j = 0; j < ehdr_field(e_shnum); j++) {
337 			if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name))))
338 				continue;
339 
340 			skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
341 			break;
342 		}
343 		if (skip)
344 			continue;
345 
346 		sh_offset = shdr_field(i, sh_offset);
347 		sh_entsize = shdr_field(i, sh_entsize);
348 		sh_entries = shdr_field(i, sh_size) / sh_entsize;
349 
350 		if (sh_type == SHT_REL) {
351 			if (is_64) {
352 				fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
353 				err = -EINVAL;
354 				goto out_free_relocs;
355 			} else {
356 				parse_fn = parse_mips32_rel;
357 			}
358 		} else {
359 			if (is_64) {
360 				parse_fn = parse_mips64_rela;
361 			} else {
362 				fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
363 				err = -EINVAL;
364 				goto out_free_relocs;
365 			}
366 		}
367 
368 		for (j = 0; j < sh_entries; j++) {
369 			err = parse_fn(elf + sh_offset + (j * sh_entsize));
370 			if (err)
371 				goto out_free_relocs;
372 		}
373 	}
374 
375 	/* Sort relocs in ascending order of offset */
376 	qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
377 
378 	/* Make reloc offsets relative to their predecessor */
379 	for (i = relocs_idx - 1; i > 0; i--)
380 		relocs[i].offset -= relocs[i - 1].offset;
381 
382 	/* Write the relocations to the .rel section */
383 	buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
384 	for (i = 0; i < relocs_idx; i++) {
385 		output_uint(&buf, relocs[i].type);
386 		output_uint(&buf, relocs[i].offset >> 2);
387 	}
388 
389 	/* Write a terminating R_MIPS_NONE (0) */
390 	output_uint(&buf, R_MIPS_NONE);
391 
392 	/* Ensure the relocs didn't overflow the .rel section */
393 	rel_size = shdr_field(i_rel_shdr, sh_size);
394 	rel_actual_size = buf - buf_start;
395 	if (rel_actual_size > rel_size) {
396 		fprintf(stderr, "Relocations overflow available space of 0x%lx (required 0x%lx)!\n",
397 			rel_size, rel_actual_size);
398 		fprintf(stderr, "Please adjust CONFIG_MIPS_RELOCATION_TABLE_SIZE to at least 0x%lx\n",
399 			(rel_actual_size + 0x100) & ~0xFF);
400 		err = -ENOMEM;
401 		goto out_free_relocs;
402 	}
403 
404 	/* Make sure data is written back to the file */
405 	err = msync(elf, st.st_size, MS_SYNC);
406 	if (err) {
407 		fprintf(stderr, "Failed to msync: %d\n", errno);
408 		goto out_free_relocs;
409 	}
410 
411 out_free_relocs:
412 	free(relocs);
413 	munmap(elf, st.st_size);
414 out_close_fd:
415 	close(fd);
416 out_ret:
417 	return err;
418 }
419