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
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		/* 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
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;
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			fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
325			continue;
326		}
327		if (!strcmp(sh_name, ".rel") || !strcmp(sh_name, ".rel.dyn"))
328			continue;
329
330		/*
331		 * Skip reloc sections which either don't correspond to another
332		 * section in the ELF, or whose corresponding section isn't
333		 * loaded as part of the U-Boot binary (ie. doesn't have the
334		 * alloc flags set).
335		 */
336		skip = true;
337		for (j = 0; j < ehdr_field(e_shnum); j++) {
338			if (strcmp(&sh_name[strlen(rel_pfx)], shstr(shdr_field(j, sh_name))))
339				continue;
340
341			skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
342			break;
343		}
344		if (skip)
345			continue;
346
347		sh_offset = shdr_field(i, sh_offset);
348		sh_entsize = shdr_field(i, sh_entsize);
349		sh_entries = shdr_field(i, sh_size) / sh_entsize;
350
351		if (sh_type == SHT_REL) {
352			if (is_64) {
353				fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
354				err = -EINVAL;
355				goto out_free_relocs;
356			} else {
357				parse_fn = parse_mips32_rel;
358			}
359		} else {
360			if (is_64) {
361				parse_fn = parse_mips64_rela;
362			} else {
363				fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
364				err = -EINVAL;
365				goto out_free_relocs;
366			}
367		}
368
369		for (j = 0; j < sh_entries; j++) {
370			err = parse_fn(elf + sh_offset + (j * sh_entsize));
371			if (err)
372				goto out_free_relocs;
373		}
374	}
375
376	/* Sort relocs in ascending order of offset */
377	qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
378
379	/* Make reloc offsets relative to their predecessor */
380	for (i = relocs_idx - 1; i > 0; i--)
381		relocs[i].offset -= relocs[i - 1].offset;
382
383	/* Write the relocations to the .rel section */
384	buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
385	for (i = 0; i < relocs_idx; i++) {
386		output_uint(&buf, relocs[i].type);
387		output_uint(&buf, relocs[i].offset >> 2);
388	}
389
390	/* Write a terminating R_MIPS_NONE (0) */
391	output_uint(&buf, R_MIPS_NONE);
392
393	/* Ensure the relocs didn't overflow the .rel section */
394	rel_size = shdr_field(i_rel_shdr, sh_size);
395	rel_actual_size = buf - buf_start;
396	if (rel_actual_size > rel_size) {
397		fprintf(stderr, "Relocations overflow available space of 0x%lx (required 0x%lx)!\n",
398			rel_size, rel_actual_size);
399		fprintf(stderr, "Please adjust CONFIG_MIPS_RELOCATION_TABLE_SIZE to at least 0x%lx\n",
400			(rel_actual_size + 0x100) & ~0xFF);
401		err = -ENOMEM;
402		goto out_free_relocs;
403	}
404
405	/* Make sure data is written back to the file */
406	err = msync(elf, st.st_size, MS_SYNC);
407	if (err) {
408		fprintf(stderr, "Failed to msync: %d\n", errno);
409		goto out_free_relocs;
410	}
411
412out_free_relocs:
413	free(relocs);
414	munmap(elf, st.st_size);
415out_close_fd:
416	close(fd);
417out_ret:
418	return err;
419}
420