Linux Audio

Check our new training course

Loading...
v5.4
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * elf.c - ELF access library
  4 *
  5 * Adapted from kpatch (https://github.com/dynup/kpatch):
  6 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
  7 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
  8 */
  9
 10#include <sys/types.h>
 11#include <sys/stat.h>
 12#include <fcntl.h>
 13#include <stdio.h>
 14#include <stdlib.h>
 15#include <string.h>
 16#include <unistd.h>
 17#include <errno.h>
 
 18
 19#include "elf.h"
 20#include "warn.h"
 21
 22#define MAX_NAME_LEN 128
 23
 24struct section *find_section_by_name(struct elf *elf, const char *name)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 25{
 26	struct section *sec;
 27
 28	list_for_each_entry(sec, &elf->sections, list)
 29		if (!strcmp(sec->name, name))
 30			return sec;
 31
 32	return NULL;
 33}
 34
 35static struct section *find_section_by_index(struct elf *elf,
 36					     unsigned int idx)
 37{
 38	struct section *sec;
 39
 40	list_for_each_entry(sec, &elf->sections, list)
 41		if (sec->idx == idx)
 42			return sec;
 43
 44	return NULL;
 45}
 46
 47static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
 48{
 49	struct section *sec;
 50	struct symbol *sym;
 51
 52	list_for_each_entry(sec, &elf->sections, list)
 53		hash_for_each_possible(sec->symbol_hash, sym, hash, idx)
 54			if (sym->idx == idx)
 55				return sym;
 56
 57	return NULL;
 58}
 59
 60struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
 61{
 62	struct symbol *sym;
 63
 64	list_for_each_entry(sym, &sec->symbol_list, list)
 65		if (sym->type != STT_SECTION &&
 66		    sym->offset == offset)
 67			return sym;
 
 
 68
 69	return NULL;
 70}
 71
 72struct symbol *find_symbol_by_name(struct elf *elf, const char *name)
 73{
 74	struct section *sec;
 75	struct symbol *sym;
 76
 77	list_for_each_entry(sec, &elf->sections, list)
 78		list_for_each_entry(sym, &sec->symbol_list, list)
 79			if (!strcmp(sym->name, name))
 80				return sym;
 
 
 81
 82	return NULL;
 83}
 84
 85struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
 86{
 87	struct symbol *sym;
 88
 89	list_for_each_entry(sym, &sec->symbol_list, list)
 90		if (sym->type != STT_SECTION &&
 91		    offset >= sym->offset && offset < sym->offset + sym->len)
 92			return sym;
 
 
 93
 94	return NULL;
 95}
 96
 97struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,
 98				     unsigned int len)
 99{
100	struct rela *rela;
101	unsigned long o;
102
103	if (!sec->rela)
104		return NULL;
105
106	for (o = offset; o < offset + len; o++)
107		hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
108			if (rela->offset == o)
109				return rela;
110
111	return NULL;
112}
113
114struct rela *find_rela_by_dest(struct section *sec, unsigned long offset)
115{
116	return find_rela_by_dest_range(sec, offset, 1);
 
 
 
 
 
 
117}
118
119struct symbol *find_containing_func(struct section *sec, unsigned long offset)
 
120{
121	struct symbol *func;
 
122
123	list_for_each_entry(func, &sec->symbol_list, list)
124		if (func->type == STT_FUNC && offset >= func->offset &&
125		    offset < func->offset + func->len)
126			return func;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
127
128	return NULL;
129}
130
 
 
 
 
 
131static int read_sections(struct elf *elf)
132{
133	Elf_Scn *s = NULL;
134	struct section *sec;
135	size_t shstrndx, sections_nr;
136	int i;
137
138	if (elf_getshdrnum(elf->elf, &sections_nr)) {
139		WARN_ELF("elf_getshdrnum");
140		return -1;
141	}
142
143	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
144		WARN_ELF("elf_getshdrstrndx");
145		return -1;
146	}
147
148	for (i = 0; i < sections_nr; i++) {
149		sec = malloc(sizeof(*sec));
150		if (!sec) {
151			perror("malloc");
152			return -1;
153		}
154		memset(sec, 0, sizeof(*sec));
155
156		INIT_LIST_HEAD(&sec->symbol_list);
157		INIT_LIST_HEAD(&sec->rela_list);
158		hash_init(sec->rela_hash);
159		hash_init(sec->symbol_hash);
160
161		list_add_tail(&sec->list, &elf->sections);
162
163		s = elf_getscn(elf->elf, i);
164		if (!s) {
165			WARN_ELF("elf_getscn");
166			return -1;
167		}
168
169		sec->idx = elf_ndxscn(s);
170
171		if (!gelf_getshdr(s, &sec->sh)) {
172			WARN_ELF("gelf_getshdr");
173			return -1;
174		}
175
176		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
177		if (!sec->name) {
178			WARN_ELF("elf_strptr");
179			return -1;
180		}
181
182		if (sec->sh.sh_size != 0) {
183			sec->data = elf_getdata(s, NULL);
184			if (!sec->data) {
185				WARN_ELF("elf_getdata");
186				return -1;
187			}
188			if (sec->data->d_off != 0 ||
189			    sec->data->d_size != sec->sh.sh_size) {
190				WARN("unexpected data attributes for %s",
191				     sec->name);
192				return -1;
193			}
194		}
195		sec->len = sec->sh.sh_size;
 
 
 
 
196	}
197
 
 
 
198	/* sanity check, one more call to elf_nextscn() should return NULL */
199	if (elf_nextscn(elf->elf, s)) {
200		WARN("section entry mismatch");
201		return -1;
202	}
203
204	return 0;
205}
206
207static int read_symbols(struct elf *elf)
208{
209	struct section *symtab, *sec;
210	struct symbol *sym, *pfunc, *alias;
211	struct list_head *entry, *tmp;
 
212	int symbols_nr, i;
213	char *coldstr;
 
 
214
215	symtab = find_section_by_name(elf, ".symtab");
216	if (!symtab) {
217		WARN("missing symbol table");
218		return -1;
219	}
220
 
 
 
 
221	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
222
223	for (i = 0; i < symbols_nr; i++) {
224		sym = malloc(sizeof(*sym));
225		if (!sym) {
226			perror("malloc");
227			return -1;
228		}
229		memset(sym, 0, sizeof(*sym));
230		alias = sym;
231
232		sym->idx = i;
233
234		if (!gelf_getsym(symtab->data, i, &sym->sym)) {
235			WARN_ELF("gelf_getsym");
 
236			goto err;
237		}
238
239		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
240				       sym->sym.st_name);
241		if (!sym->name) {
242			WARN_ELF("elf_strptr");
243			goto err;
244		}
245
246		sym->type = GELF_ST_TYPE(sym->sym.st_info);
247		sym->bind = GELF_ST_BIND(sym->sym.st_info);
248
249		if (sym->sym.st_shndx > SHN_UNDEF &&
250		    sym->sym.st_shndx < SHN_LORESERVE) {
251			sym->sec = find_section_by_index(elf,
252							 sym->sym.st_shndx);
 
 
 
253			if (!sym->sec) {
254				WARN("couldn't find section for symbol %s",
255				     sym->name);
256				goto err;
257			}
258			if (sym->type == STT_SECTION) {
259				sym->name = sym->sec->name;
260				sym->sec->sym = sym;
261			}
262		} else
263			sym->sec = find_section_by_index(elf, 0);
264
265		sym->offset = sym->sym.st_value;
266		sym->len = sym->sym.st_size;
267
268		/* sorted insert into a per-section list */
269		entry = &sym->sec->symbol_list;
270		list_for_each_prev(tmp, &sym->sec->symbol_list) {
271			struct symbol *s;
272
273			s = list_entry(tmp, struct symbol, list);
274
275			if (sym->offset > s->offset) {
276				entry = tmp;
277				break;
278			}
279
280			if (sym->offset == s->offset) {
281				if (sym->len && sym->len == s->len && alias == sym)
282					alias = s;
283
284				if (sym->len >= s->len) {
285					entry = tmp;
286					break;
287				}
288			}
289		}
290		sym->alias = alias;
291		list_add(&sym->list, entry);
292		hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
 
293	}
294
 
 
 
295	/* Create parent/child links for any cold subfunctions */
296	list_for_each_entry(sec, &elf->sections, list) {
297		list_for_each_entry(sym, &sec->symbol_list, list) {
298			char pname[MAX_NAME_LEN + 1];
299			size_t pnamelen;
300			if (sym->type != STT_FUNC)
301				continue;
302			sym->pfunc = sym->cfunc = sym;
 
 
 
 
 
 
303			coldstr = strstr(sym->name, ".cold");
304			if (!coldstr)
305				continue;
306
307			pnamelen = coldstr - sym->name;
308			if (pnamelen > MAX_NAME_LEN) {
309				WARN("%s(): parent function name exceeds maximum length of %d characters",
310				     sym->name, MAX_NAME_LEN);
311				return -1;
312			}
313
314			strncpy(pname, sym->name, pnamelen);
315			pname[pnamelen] = '\0';
316			pfunc = find_symbol_by_name(elf, pname);
317
318			if (!pfunc) {
319				WARN("%s(): can't find parent function",
320				     sym->name);
321				return -1;
322			}
323
324			sym->pfunc = pfunc;
325			pfunc->cfunc = sym;
326
327			/*
328			 * Unfortunately, -fnoreorder-functions puts the child
329			 * inside the parent.  Remove the overlap so we can
330			 * have sane assumptions.
331			 *
332			 * Note that pfunc->len now no longer matches
333			 * pfunc->sym.st_size.
334			 */
335			if (sym->sec == pfunc->sec &&
336			    sym->offset >= pfunc->offset &&
337			    sym->offset + sym->len == pfunc->offset + pfunc->len) {
338				pfunc->len -= sym->len;
339			}
340		}
341	}
342
343	return 0;
344
345err:
346	free(sym);
347	return -1;
348}
349
350static int read_relas(struct elf *elf)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
351{
352	struct section *sec;
353	struct rela *rela;
354	int i;
355	unsigned int symndx;
 
356
357	list_for_each_entry(sec, &elf->sections, list) {
358		if (sec->sh.sh_type != SHT_RELA)
 
359			continue;
360
361		sec->base = find_section_by_name(elf, sec->name + 5);
362		if (!sec->base) {
363			WARN("can't find base section for rela section %s",
364			     sec->name);
365			return -1;
366		}
367
368		sec->base->rela = sec;
369
 
370		for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
371			rela = malloc(sizeof(*rela));
372			if (!rela) {
373				perror("malloc");
374				return -1;
375			}
376			memset(rela, 0, sizeof(*rela));
377
378			if (!gelf_getrela(sec->data, i, &rela->rela)) {
379				WARN_ELF("gelf_getrela");
380				return -1;
 
 
 
 
 
 
381			}
382
383			rela->type = GELF_R_TYPE(rela->rela.r_info);
384			rela->addend = rela->rela.r_addend;
385			rela->offset = rela->rela.r_offset;
386			symndx = GELF_R_SYM(rela->rela.r_info);
387			rela->sym = find_symbol_by_index(elf, symndx);
388			rela->sec = sec;
389			if (!rela->sym) {
390				WARN("can't find rela entry symbol %d for %s",
391				     symndx, sec->name);
392				return -1;
393			}
394
395			list_add_tail(&rela->list, &sec->rela_list);
396			hash_add(sec->rela_hash, &rela->hash, rela->offset);
397
398		}
 
 
 
 
 
 
 
399	}
400
401	return 0;
402}
403
404struct elf *elf_read(const char *name, int flags)
405{
406	struct elf *elf;
407	Elf_Cmd cmd;
408
409	elf_version(EV_CURRENT);
410
411	elf = malloc(sizeof(*elf));
412	if (!elf) {
413		perror("malloc");
414		return NULL;
415	}
416	memset(elf, 0, sizeof(*elf));
417
418	INIT_LIST_HEAD(&elf->sections);
419
 
 
 
 
 
 
420	elf->fd = open(name, flags);
421	if (elf->fd == -1) {
422		fprintf(stderr, "objtool: Can't open '%s': %s\n",
423			name, strerror(errno));
424		goto err;
425	}
426
427	if ((flags & O_ACCMODE) == O_RDONLY)
428		cmd = ELF_C_READ_MMAP;
429	else if ((flags & O_ACCMODE) == O_RDWR)
430		cmd = ELF_C_RDWR;
431	else /* O_WRONLY */
432		cmd = ELF_C_WRITE;
433
434	elf->elf = elf_begin(elf->fd, cmd, NULL);
435	if (!elf->elf) {
436		WARN_ELF("elf_begin");
437		goto err;
438	}
439
440	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
441		WARN_ELF("gelf_getehdr");
442		goto err;
443	}
444
445	if (read_sections(elf))
446		goto err;
447
448	if (read_symbols(elf))
449		goto err;
450
451	if (read_relas(elf))
452		goto err;
453
454	return elf;
455
456err:
457	elf_close(elf);
458	return NULL;
459}
460
461struct section *elf_create_section(struct elf *elf, const char *name,
462				   size_t entsize, int nr)
463{
464	struct section *sec, *shstrtab;
465	size_t size = entsize * nr;
466	Elf_Scn *s;
467	Elf_Data *data;
468
469	sec = malloc(sizeof(*sec));
470	if (!sec) {
471		perror("malloc");
472		return NULL;
473	}
474	memset(sec, 0, sizeof(*sec));
475
476	INIT_LIST_HEAD(&sec->symbol_list);
477	INIT_LIST_HEAD(&sec->rela_list);
478	hash_init(sec->rela_hash);
479	hash_init(sec->symbol_hash);
480
481	list_add_tail(&sec->list, &elf->sections);
482
483	s = elf_newscn(elf->elf);
484	if (!s) {
485		WARN_ELF("elf_newscn");
486		return NULL;
487	}
488
489	sec->name = strdup(name);
490	if (!sec->name) {
491		perror("strdup");
492		return NULL;
493	}
494
495	sec->idx = elf_ndxscn(s);
496	sec->len = size;
497	sec->changed = true;
498
499	sec->data = elf_newdata(s);
500	if (!sec->data) {
501		WARN_ELF("elf_newdata");
502		return NULL;
503	}
504
505	sec->data->d_size = size;
506	sec->data->d_align = 1;
507
508	if (size) {
509		sec->data->d_buf = malloc(size);
510		if (!sec->data->d_buf) {
511			perror("malloc");
512			return NULL;
513		}
514		memset(sec->data->d_buf, 0, size);
515	}
516
517	if (!gelf_getshdr(s, &sec->sh)) {
518		WARN_ELF("gelf_getshdr");
519		return NULL;
520	}
521
522	sec->sh.sh_size = size;
523	sec->sh.sh_entsize = entsize;
524	sec->sh.sh_type = SHT_PROGBITS;
525	sec->sh.sh_addralign = 1;
526	sec->sh.sh_flags = SHF_ALLOC;
527
528
529	/* Add section name to .shstrtab (or .strtab for Clang) */
530	shstrtab = find_section_by_name(elf, ".shstrtab");
531	if (!shstrtab)
532		shstrtab = find_section_by_name(elf, ".strtab");
533	if (!shstrtab) {
534		WARN("can't find .shstrtab or .strtab section");
535		return NULL;
536	}
537
538	s = elf_getscn(elf->elf, shstrtab->idx);
539	if (!s) {
540		WARN_ELF("elf_getscn");
541		return NULL;
542	}
543
544	data = elf_newdata(s);
545	if (!data) {
546		WARN_ELF("elf_newdata");
547		return NULL;
548	}
549
550	data->d_buf = sec->name;
551	data->d_size = strlen(name) + 1;
552	data->d_align = 1;
553
554	sec->sh.sh_name = shstrtab->len;
555
556	shstrtab->len += strlen(name) + 1;
557	shstrtab->changed = true;
558
 
 
 
 
 
 
559	return sec;
560}
561
562struct section *elf_create_rela_section(struct elf *elf, struct section *base)
563{
564	char *relaname;
565	struct section *sec;
566
567	relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
568	if (!relaname) {
569		perror("malloc");
570		return NULL;
571	}
572	strcpy(relaname, ".rela");
573	strcat(relaname, base->name);
574
575	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
576	free(relaname);
577	if (!sec)
578		return NULL;
579
580	base->rela = sec;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
581	sec->base = base;
582
583	sec->sh.sh_type = SHT_RELA;
584	sec->sh.sh_addralign = 8;
585	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
586	sec->sh.sh_info = base->idx;
587	sec->sh.sh_flags = SHF_INFO_LINK;
588
589	return sec;
590}
591
592int elf_rebuild_rela_section(struct section *sec)
 
 
593{
594	struct rela *rela;
595	int nr, idx = 0, size;
596	GElf_Rela *relas;
 
 
 
597
598	nr = 0;
599	list_for_each_entry(rela, &sec->rela_list, list)
600		nr++;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
601
602	size = nr * sizeof(*relas);
603	relas = malloc(size);
604	if (!relas) {
 
 
 
 
 
 
 
605		perror("malloc");
606		return -1;
607	}
608
609	sec->data->d_buf = relas;
610	sec->data->d_size = size;
611
612	sec->sh.sh_size = size;
613
614	idx = 0;
615	list_for_each_entry(rela, &sec->rela_list, list) {
616		relas[idx].r_offset = rela->offset;
617		relas[idx].r_addend = rela->addend;
618		relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
619		idx++;
620	}
621
622	return 0;
623}
624
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
625int elf_write(struct elf *elf)
626{
627	struct section *sec;
628	Elf_Scn *s;
629
630	/* Update section headers for changed sections: */
631	list_for_each_entry(sec, &elf->sections, list) {
632		if (sec->changed) {
633			s = elf_getscn(elf->elf, sec->idx);
634			if (!s) {
635				WARN_ELF("elf_getscn");
636				return -1;
637			}
638			if (!gelf_update_shdr(s, &sec->sh)) {
639				WARN_ELF("gelf_update_shdr");
640				return -1;
641			}
 
 
642		}
643	}
644
645	/* Make sure the new section header entries get updated properly. */
646	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
647
648	/* Write all changes to the file. */
649	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
650		WARN_ELF("elf_update");
651		return -1;
652	}
653
 
 
654	return 0;
655}
656
657void elf_close(struct elf *elf)
658{
659	struct section *sec, *tmpsec;
660	struct symbol *sym, *tmpsym;
661	struct rela *rela, *tmprela;
662
663	if (elf->elf)
664		elf_end(elf->elf);
665
666	if (elf->fd > 0)
667		close(elf->fd);
668
669	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
670		list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
671			list_del(&sym->list);
672			hash_del(&sym->hash);
673			free(sym);
674		}
675		list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
676			list_del(&rela->list);
677			hash_del(&rela->hash);
678			free(rela);
679		}
680		list_del(&sec->list);
681		free(sec);
682	}
683
684	free(elf);
685}
v5.9
   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * elf.c - ELF access library
   4 *
   5 * Adapted from kpatch (https://github.com/dynup/kpatch):
   6 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
   7 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
   8 */
   9
  10#include <sys/types.h>
  11#include <sys/stat.h>
  12#include <fcntl.h>
  13#include <stdio.h>
  14#include <stdlib.h>
  15#include <string.h>
  16#include <unistd.h>
  17#include <errno.h>
  18#include "builtin.h"
  19
  20#include "elf.h"
  21#include "warn.h"
  22
  23#define MAX_NAME_LEN 128
  24
  25static inline u32 str_hash(const char *str)
  26{
  27	return jhash(str, strlen(str), 0);
  28}
  29
  30static inline int elf_hash_bits(void)
  31{
  32	return vmlinux ? ELF_HASH_BITS : 16;
  33}
  34
  35#define elf_hash_add(hashtable, node, key) \
  36	hlist_add_head(node, &hashtable[hash_min(key, elf_hash_bits())])
  37
  38static void elf_hash_init(struct hlist_head *table)
  39{
  40	__hash_init(table, 1U << elf_hash_bits());
  41}
  42
  43#define elf_hash_for_each_possible(name, obj, member, key)			\
  44	hlist_for_each_entry(obj, &name[hash_min(key, elf_hash_bits())], member)
  45
  46static void rb_add(struct rb_root *tree, struct rb_node *node,
  47		   int (*cmp)(struct rb_node *, const struct rb_node *))
  48{
  49	struct rb_node **link = &tree->rb_node;
  50	struct rb_node *parent = NULL;
  51
  52	while (*link) {
  53		parent = *link;
  54		if (cmp(node, parent) < 0)
  55			link = &parent->rb_left;
  56		else
  57			link = &parent->rb_right;
  58	}
  59
  60	rb_link_node(node, parent, link);
  61	rb_insert_color(node, tree);
  62}
  63
  64static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key,
  65			       int (*cmp)(const void *key, const struct rb_node *))
  66{
  67	struct rb_node *node = tree->rb_node;
  68	struct rb_node *match = NULL;
  69
  70	while (node) {
  71		int c = cmp(key, node);
  72		if (c <= 0) {
  73			if (!c)
  74				match = node;
  75			node = node->rb_left;
  76		} else if (c > 0) {
  77			node = node->rb_right;
  78		}
  79	}
  80
  81	return match;
  82}
  83
  84static struct rb_node *rb_next_match(struct rb_node *node, const void *key,
  85				    int (*cmp)(const void *key, const struct rb_node *))
  86{
  87	node = rb_next(node);
  88	if (node && cmp(key, node))
  89		node = NULL;
  90	return node;
  91}
  92
  93#define rb_for_each(tree, node, key, cmp) \
  94	for ((node) = rb_find_first((tree), (key), (cmp)); \
  95	     (node); (node) = rb_next_match((node), (key), (cmp)))
  96
  97static int symbol_to_offset(struct rb_node *a, const struct rb_node *b)
  98{
  99	struct symbol *sa = rb_entry(a, struct symbol, node);
 100	struct symbol *sb = rb_entry(b, struct symbol, node);
 101
 102	if (sa->offset < sb->offset)
 103		return -1;
 104	if (sa->offset > sb->offset)
 105		return 1;
 106
 107	if (sa->len < sb->len)
 108		return -1;
 109	if (sa->len > sb->len)
 110		return 1;
 111
 112	sa->alias = sb;
 113
 114	return 0;
 115}
 116
 117static int symbol_by_offset(const void *key, const struct rb_node *node)
 118{
 119	const struct symbol *s = rb_entry(node, struct symbol, node);
 120	const unsigned long *o = key;
 121
 122	if (*o < s->offset)
 123		return -1;
 124	if (*o >= s->offset + s->len)
 125		return 1;
 126
 127	return 0;
 128}
 129
 130struct section *find_section_by_name(const struct elf *elf, const char *name)
 131{
 132	struct section *sec;
 133
 134	elf_hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
 135		if (!strcmp(sec->name, name))
 136			return sec;
 137
 138	return NULL;
 139}
 140
 141static struct section *find_section_by_index(struct elf *elf,
 142					     unsigned int idx)
 143{
 144	struct section *sec;
 145
 146	elf_hash_for_each_possible(elf->section_hash, sec, hash, idx)
 147		if (sec->idx == idx)
 148			return sec;
 149
 150	return NULL;
 151}
 152
 153static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
 154{
 
 155	struct symbol *sym;
 156
 157	elf_hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
 158		if (sym->idx == idx)
 159			return sym;
 
 160
 161	return NULL;
 162}
 163
 164struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
 165{
 166	struct rb_node *node;
 167
 168	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 169		struct symbol *s = rb_entry(node, struct symbol, node);
 170
 171		if (s->offset == offset && s->type != STT_SECTION)
 172			return s;
 173	}
 174
 175	return NULL;
 176}
 177
 178struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
 179{
 180	struct rb_node *node;
 
 181
 182	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 183		struct symbol *s = rb_entry(node, struct symbol, node);
 184
 185		if (s->offset == offset && s->type == STT_FUNC)
 186			return s;
 187	}
 188
 189	return NULL;
 190}
 191
 192struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
 193{
 194	struct rb_node *node;
 195
 196	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 197		struct symbol *s = rb_entry(node, struct symbol, node);
 198
 199		if (s->type != STT_SECTION)
 200			return s;
 201	}
 202
 203	return NULL;
 204}
 205
 206struct symbol *find_func_containing(struct section *sec, unsigned long offset)
 
 207{
 208	struct rb_node *node;
 
 209
 210	rb_for_each(&sec->symbol_tree, node, &offset, symbol_by_offset) {
 211		struct symbol *s = rb_entry(node, struct symbol, node);
 212
 213		if (s->type == STT_FUNC)
 214			return s;
 215	}
 
 216
 217	return NULL;
 218}
 219
 220struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
 221{
 222	struct symbol *sym;
 223
 224	elf_hash_for_each_possible(elf->symbol_name_hash, sym, name_hash, str_hash(name))
 225		if (!strcmp(sym->name, name))
 226			return sym;
 227
 228	return NULL;
 229}
 230
 231struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
 232				     unsigned long offset, unsigned int len)
 233{
 234	struct reloc *reloc, *r = NULL;
 235	unsigned long o;
 236
 237	if (!sec->reloc)
 238		return NULL;
 239
 240	sec = sec->reloc;
 241
 242	for_offset_range(o, offset, offset + len) {
 243		elf_hash_for_each_possible(elf->reloc_hash, reloc, hash,
 244				       sec_offset_hash(sec, o)) {
 245			if (reloc->sec != sec)
 246				continue;
 247
 248			if (reloc->offset >= offset && reloc->offset < offset + len) {
 249				if (!r || reloc->offset < r->offset)
 250					r = reloc;
 251			}
 252		}
 253		if (r)
 254			return r;
 255	}
 256
 257	return NULL;
 258}
 259
 260struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset)
 261{
 262	return find_reloc_by_dest_range(elf, sec, offset, 1);
 263}
 264
 265static int read_sections(struct elf *elf)
 266{
 267	Elf_Scn *s = NULL;
 268	struct section *sec;
 269	size_t shstrndx, sections_nr;
 270	int i;
 271
 272	if (elf_getshdrnum(elf->elf, &sections_nr)) {
 273		WARN_ELF("elf_getshdrnum");
 274		return -1;
 275	}
 276
 277	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
 278		WARN_ELF("elf_getshdrstrndx");
 279		return -1;
 280	}
 281
 282	for (i = 0; i < sections_nr; i++) {
 283		sec = malloc(sizeof(*sec));
 284		if (!sec) {
 285			perror("malloc");
 286			return -1;
 287		}
 288		memset(sec, 0, sizeof(*sec));
 289
 290		INIT_LIST_HEAD(&sec->symbol_list);
 291		INIT_LIST_HEAD(&sec->reloc_list);
 
 
 
 
 292
 293		s = elf_getscn(elf->elf, i);
 294		if (!s) {
 295			WARN_ELF("elf_getscn");
 296			return -1;
 297		}
 298
 299		sec->idx = elf_ndxscn(s);
 300
 301		if (!gelf_getshdr(s, &sec->sh)) {
 302			WARN_ELF("gelf_getshdr");
 303			return -1;
 304		}
 305
 306		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
 307		if (!sec->name) {
 308			WARN_ELF("elf_strptr");
 309			return -1;
 310		}
 311
 312		if (sec->sh.sh_size != 0) {
 313			sec->data = elf_getdata(s, NULL);
 314			if (!sec->data) {
 315				WARN_ELF("elf_getdata");
 316				return -1;
 317			}
 318			if (sec->data->d_off != 0 ||
 319			    sec->data->d_size != sec->sh.sh_size) {
 320				WARN("unexpected data attributes for %s",
 321				     sec->name);
 322				return -1;
 323			}
 324		}
 325		sec->len = sec->sh.sh_size;
 326
 327		list_add_tail(&sec->list, &elf->sections);
 328		elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
 329		elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 330	}
 331
 332	if (stats)
 333		printf("nr_sections: %lu\n", (unsigned long)sections_nr);
 334
 335	/* sanity check, one more call to elf_nextscn() should return NULL */
 336	if (elf_nextscn(elf->elf, s)) {
 337		WARN("section entry mismatch");
 338		return -1;
 339	}
 340
 341	return 0;
 342}
 343
 344static int read_symbols(struct elf *elf)
 345{
 346	struct section *symtab, *symtab_shndx, *sec;
 347	struct symbol *sym, *pfunc;
 348	struct list_head *entry;
 349	struct rb_node *pnode;
 350	int symbols_nr, i;
 351	char *coldstr;
 352	Elf_Data *shndx_data = NULL;
 353	Elf32_Word shndx;
 354
 355	symtab = find_section_by_name(elf, ".symtab");
 356	if (!symtab) {
 357		WARN("missing symbol table");
 358		return -1;
 359	}
 360
 361	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
 362	if (symtab_shndx)
 363		shndx_data = symtab_shndx->data;
 364
 365	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
 366
 367	for (i = 0; i < symbols_nr; i++) {
 368		sym = malloc(sizeof(*sym));
 369		if (!sym) {
 370			perror("malloc");
 371			return -1;
 372		}
 373		memset(sym, 0, sizeof(*sym));
 374		sym->alias = sym;
 375
 376		sym->idx = i;
 377
 378		if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
 379				      &shndx)) {
 380			WARN_ELF("gelf_getsymshndx");
 381			goto err;
 382		}
 383
 384		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
 385				       sym->sym.st_name);
 386		if (!sym->name) {
 387			WARN_ELF("elf_strptr");
 388			goto err;
 389		}
 390
 391		sym->type = GELF_ST_TYPE(sym->sym.st_info);
 392		sym->bind = GELF_ST_BIND(sym->sym.st_info);
 393
 394		if ((sym->sym.st_shndx > SHN_UNDEF &&
 395		     sym->sym.st_shndx < SHN_LORESERVE) ||
 396		    (shndx_data && sym->sym.st_shndx == SHN_XINDEX)) {
 397			if (sym->sym.st_shndx != SHN_XINDEX)
 398				shndx = sym->sym.st_shndx;
 399
 400			sym->sec = find_section_by_index(elf, shndx);
 401			if (!sym->sec) {
 402				WARN("couldn't find section for symbol %s",
 403				     sym->name);
 404				goto err;
 405			}
 406			if (sym->type == STT_SECTION) {
 407				sym->name = sym->sec->name;
 408				sym->sec->sym = sym;
 409			}
 410		} else
 411			sym->sec = find_section_by_index(elf, 0);
 412
 413		sym->offset = sym->sym.st_value;
 414		sym->len = sym->sym.st_size;
 415
 416		rb_add(&sym->sec->symbol_tree, &sym->node, symbol_to_offset);
 417		pnode = rb_prev(&sym->node);
 418		if (pnode)
 419			entry = &rb_entry(pnode, struct symbol, node)->list;
 420		else
 421			entry = &sym->sec->symbol_list;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 422		list_add(&sym->list, entry);
 423		elf_hash_add(elf->symbol_hash, &sym->hash, sym->idx);
 424		elf_hash_add(elf->symbol_name_hash, &sym->name_hash, str_hash(sym->name));
 425	}
 426
 427	if (stats)
 428		printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
 429
 430	/* Create parent/child links for any cold subfunctions */
 431	list_for_each_entry(sec, &elf->sections, list) {
 432		list_for_each_entry(sym, &sec->symbol_list, list) {
 433			char pname[MAX_NAME_LEN + 1];
 434			size_t pnamelen;
 435			if (sym->type != STT_FUNC)
 436				continue;
 437
 438			if (sym->pfunc == NULL)
 439				sym->pfunc = sym;
 440
 441			if (sym->cfunc == NULL)
 442				sym->cfunc = sym;
 443
 444			coldstr = strstr(sym->name, ".cold");
 445			if (!coldstr)
 446				continue;
 447
 448			pnamelen = coldstr - sym->name;
 449			if (pnamelen > MAX_NAME_LEN) {
 450				WARN("%s(): parent function name exceeds maximum length of %d characters",
 451				     sym->name, MAX_NAME_LEN);
 452				return -1;
 453			}
 454
 455			strncpy(pname, sym->name, pnamelen);
 456			pname[pnamelen] = '\0';
 457			pfunc = find_symbol_by_name(elf, pname);
 458
 459			if (!pfunc) {
 460				WARN("%s(): can't find parent function",
 461				     sym->name);
 462				return -1;
 463			}
 464
 465			sym->pfunc = pfunc;
 466			pfunc->cfunc = sym;
 467
 468			/*
 469			 * Unfortunately, -fnoreorder-functions puts the child
 470			 * inside the parent.  Remove the overlap so we can
 471			 * have sane assumptions.
 472			 *
 473			 * Note that pfunc->len now no longer matches
 474			 * pfunc->sym.st_size.
 475			 */
 476			if (sym->sec == pfunc->sec &&
 477			    sym->offset >= pfunc->offset &&
 478			    sym->offset + sym->len == pfunc->offset + pfunc->len) {
 479				pfunc->len -= sym->len;
 480			}
 481		}
 482	}
 483
 484	return 0;
 485
 486err:
 487	free(sym);
 488	return -1;
 489}
 490
 491void elf_add_reloc(struct elf *elf, struct reloc *reloc)
 492{
 493	struct section *sec = reloc->sec;
 494
 495	list_add_tail(&reloc->list, &sec->reloc_list);
 496	elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
 497}
 498
 499static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
 500{
 501	if (!gelf_getrel(sec->data, i, &reloc->rel)) {
 502		WARN_ELF("gelf_getrel");
 503		return -1;
 504	}
 505	reloc->type = GELF_R_TYPE(reloc->rel.r_info);
 506	reloc->addend = 0;
 507	reloc->offset = reloc->rel.r_offset;
 508	*symndx = GELF_R_SYM(reloc->rel.r_info);
 509	return 0;
 510}
 511
 512static int read_rela_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
 513{
 514	if (!gelf_getrela(sec->data, i, &reloc->rela)) {
 515		WARN_ELF("gelf_getrela");
 516		return -1;
 517	}
 518	reloc->type = GELF_R_TYPE(reloc->rela.r_info);
 519	reloc->addend = reloc->rela.r_addend;
 520	reloc->offset = reloc->rela.r_offset;
 521	*symndx = GELF_R_SYM(reloc->rela.r_info);
 522	return 0;
 523}
 524
 525static int read_relocs(struct elf *elf)
 526{
 527	struct section *sec;
 528	struct reloc *reloc;
 529	int i;
 530	unsigned int symndx;
 531	unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
 532
 533	list_for_each_entry(sec, &elf->sections, list) {
 534		if ((sec->sh.sh_type != SHT_RELA) &&
 535		    (sec->sh.sh_type != SHT_REL))
 536			continue;
 537
 538		sec->base = find_section_by_index(elf, sec->sh.sh_info);
 539		if (!sec->base) {
 540			WARN("can't find base section for reloc section %s",
 541			     sec->name);
 542			return -1;
 543		}
 544
 545		sec->base->reloc = sec;
 546
 547		nr_reloc = 0;
 548		for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
 549			reloc = malloc(sizeof(*reloc));
 550			if (!reloc) {
 551				perror("malloc");
 552				return -1;
 553			}
 554			memset(reloc, 0, sizeof(*reloc));
 555			switch (sec->sh.sh_type) {
 556			case SHT_REL:
 557				if (read_rel_reloc(sec, i, reloc, &symndx))
 558					return -1;
 559				break;
 560			case SHT_RELA:
 561				if (read_rela_reloc(sec, i, reloc, &symndx))
 562					return -1;
 563				break;
 564			default: return -1;
 565			}
 566
 567			reloc->sec = sec;
 568			reloc->idx = i;
 569			reloc->sym = find_symbol_by_index(elf, symndx);
 570			if (!reloc->sym) {
 571				WARN("can't find reloc entry symbol %d for %s",
 
 
 
 572				     symndx, sec->name);
 573				return -1;
 574			}
 575
 576			elf_add_reloc(elf, reloc);
 577			nr_reloc++;
 
 578		}
 579		max_reloc = max(max_reloc, nr_reloc);
 580		tot_reloc += nr_reloc;
 581	}
 582
 583	if (stats) {
 584		printf("max_reloc: %lu\n", max_reloc);
 585		printf("tot_reloc: %lu\n", tot_reloc);
 586	}
 587
 588	return 0;
 589}
 590
 591struct elf *elf_open_read(const char *name, int flags)
 592{
 593	struct elf *elf;
 594	Elf_Cmd cmd;
 595
 596	elf_version(EV_CURRENT);
 597
 598	elf = malloc(sizeof(*elf));
 599	if (!elf) {
 600		perror("malloc");
 601		return NULL;
 602	}
 603	memset(elf, 0, offsetof(struct elf, sections));
 604
 605	INIT_LIST_HEAD(&elf->sections);
 606
 607	elf_hash_init(elf->symbol_hash);
 608	elf_hash_init(elf->symbol_name_hash);
 609	elf_hash_init(elf->section_hash);
 610	elf_hash_init(elf->section_name_hash);
 611	elf_hash_init(elf->reloc_hash);
 612
 613	elf->fd = open(name, flags);
 614	if (elf->fd == -1) {
 615		fprintf(stderr, "objtool: Can't open '%s': %s\n",
 616			name, strerror(errno));
 617		goto err;
 618	}
 619
 620	if ((flags & O_ACCMODE) == O_RDONLY)
 621		cmd = ELF_C_READ_MMAP;
 622	else if ((flags & O_ACCMODE) == O_RDWR)
 623		cmd = ELF_C_RDWR;
 624	else /* O_WRONLY */
 625		cmd = ELF_C_WRITE;
 626
 627	elf->elf = elf_begin(elf->fd, cmd, NULL);
 628	if (!elf->elf) {
 629		WARN_ELF("elf_begin");
 630		goto err;
 631	}
 632
 633	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
 634		WARN_ELF("gelf_getehdr");
 635		goto err;
 636	}
 637
 638	if (read_sections(elf))
 639		goto err;
 640
 641	if (read_symbols(elf))
 642		goto err;
 643
 644	if (read_relocs(elf))
 645		goto err;
 646
 647	return elf;
 648
 649err:
 650	elf_close(elf);
 651	return NULL;
 652}
 653
 654struct section *elf_create_section(struct elf *elf, const char *name,
 655				   size_t entsize, int nr)
 656{
 657	struct section *sec, *shstrtab;
 658	size_t size = entsize * nr;
 659	Elf_Scn *s;
 660	Elf_Data *data;
 661
 662	sec = malloc(sizeof(*sec));
 663	if (!sec) {
 664		perror("malloc");
 665		return NULL;
 666	}
 667	memset(sec, 0, sizeof(*sec));
 668
 669	INIT_LIST_HEAD(&sec->symbol_list);
 670	INIT_LIST_HEAD(&sec->reloc_list);
 
 
 
 
 671
 672	s = elf_newscn(elf->elf);
 673	if (!s) {
 674		WARN_ELF("elf_newscn");
 675		return NULL;
 676	}
 677
 678	sec->name = strdup(name);
 679	if (!sec->name) {
 680		perror("strdup");
 681		return NULL;
 682	}
 683
 684	sec->idx = elf_ndxscn(s);
 685	sec->len = size;
 686	sec->changed = true;
 687
 688	sec->data = elf_newdata(s);
 689	if (!sec->data) {
 690		WARN_ELF("elf_newdata");
 691		return NULL;
 692	}
 693
 694	sec->data->d_size = size;
 695	sec->data->d_align = 1;
 696
 697	if (size) {
 698		sec->data->d_buf = malloc(size);
 699		if (!sec->data->d_buf) {
 700			perror("malloc");
 701			return NULL;
 702		}
 703		memset(sec->data->d_buf, 0, size);
 704	}
 705
 706	if (!gelf_getshdr(s, &sec->sh)) {
 707		WARN_ELF("gelf_getshdr");
 708		return NULL;
 709	}
 710
 711	sec->sh.sh_size = size;
 712	sec->sh.sh_entsize = entsize;
 713	sec->sh.sh_type = SHT_PROGBITS;
 714	sec->sh.sh_addralign = 1;
 715	sec->sh.sh_flags = SHF_ALLOC;
 716
 717
 718	/* Add section name to .shstrtab (or .strtab for Clang) */
 719	shstrtab = find_section_by_name(elf, ".shstrtab");
 720	if (!shstrtab)
 721		shstrtab = find_section_by_name(elf, ".strtab");
 722	if (!shstrtab) {
 723		WARN("can't find .shstrtab or .strtab section");
 724		return NULL;
 725	}
 726
 727	s = elf_getscn(elf->elf, shstrtab->idx);
 728	if (!s) {
 729		WARN_ELF("elf_getscn");
 730		return NULL;
 731	}
 732
 733	data = elf_newdata(s);
 734	if (!data) {
 735		WARN_ELF("elf_newdata");
 736		return NULL;
 737	}
 738
 739	data->d_buf = sec->name;
 740	data->d_size = strlen(name) + 1;
 741	data->d_align = 1;
 742
 743	sec->sh.sh_name = shstrtab->len;
 744
 745	shstrtab->len += strlen(name) + 1;
 746	shstrtab->changed = true;
 747
 748	list_add_tail(&sec->list, &elf->sections);
 749	elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
 750	elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
 751
 752	elf->changed = true;
 753
 754	return sec;
 755}
 756
 757static struct section *elf_create_rel_reloc_section(struct elf *elf, struct section *base)
 758{
 759	char *relocname;
 760	struct section *sec;
 761
 762	relocname = malloc(strlen(base->name) + strlen(".rel") + 1);
 763	if (!relocname) {
 764		perror("malloc");
 765		return NULL;
 766	}
 767	strcpy(relocname, ".rel");
 768	strcat(relocname, base->name);
 769
 770	sec = elf_create_section(elf, relocname, sizeof(GElf_Rel), 0);
 771	free(relocname);
 772	if (!sec)
 773		return NULL;
 774
 775	base->reloc = sec;
 776	sec->base = base;
 777
 778	sec->sh.sh_type = SHT_REL;
 779	sec->sh.sh_addralign = 8;
 780	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
 781	sec->sh.sh_info = base->idx;
 782	sec->sh.sh_flags = SHF_INFO_LINK;
 783
 784	return sec;
 785}
 786
 787static struct section *elf_create_rela_reloc_section(struct elf *elf, struct section *base)
 788{
 789	char *relocname;
 790	struct section *sec;
 791
 792	relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
 793	if (!relocname) {
 794		perror("malloc");
 795		return NULL;
 796	}
 797	strcpy(relocname, ".rela");
 798	strcat(relocname, base->name);
 799
 800	sec = elf_create_section(elf, relocname, sizeof(GElf_Rela), 0);
 801	free(relocname);
 802	if (!sec)
 803		return NULL;
 804
 805	base->reloc = sec;
 806	sec->base = base;
 807
 808	sec->sh.sh_type = SHT_RELA;
 809	sec->sh.sh_addralign = 8;
 810	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
 811	sec->sh.sh_info = base->idx;
 812	sec->sh.sh_flags = SHF_INFO_LINK;
 813
 814	return sec;
 815}
 816
 817struct section *elf_create_reloc_section(struct elf *elf,
 818					 struct section *base,
 819					 int reltype)
 820{
 821	switch (reltype) {
 822	case SHT_REL:  return elf_create_rel_reloc_section(elf, base);
 823	case SHT_RELA: return elf_create_rela_reloc_section(elf, base);
 824	default:       return NULL;
 825	}
 826}
 827
 828static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
 829{
 830	struct reloc *reloc;
 831	int idx = 0, size;
 832	GElf_Rel *relocs;
 833
 834	/* Allocate a buffer for relocations */
 835	size = nr * sizeof(*relocs);
 836	relocs = malloc(size);
 837	if (!relocs) {
 838		perror("malloc");
 839		return -1;
 840	}
 841
 842	sec->data->d_buf = relocs;
 843	sec->data->d_size = size;
 844
 845	sec->sh.sh_size = size;
 846
 847	idx = 0;
 848	list_for_each_entry(reloc, &sec->reloc_list, list) {
 849		relocs[idx].r_offset = reloc->offset;
 850		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
 851		idx++;
 852	}
 853
 854	return 0;
 855}
 856
 857static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
 858{
 859	struct reloc *reloc;
 860	int idx = 0, size;
 861	GElf_Rela *relocs;
 862
 863	/* Allocate a buffer for relocations with addends */
 864	size = nr * sizeof(*relocs);
 865	relocs = malloc(size);
 866	if (!relocs) {
 867		perror("malloc");
 868		return -1;
 869	}
 870
 871	sec->data->d_buf = relocs;
 872	sec->data->d_size = size;
 873
 874	sec->sh.sh_size = size;
 875
 876	idx = 0;
 877	list_for_each_entry(reloc, &sec->reloc_list, list) {
 878		relocs[idx].r_offset = reloc->offset;
 879		relocs[idx].r_addend = reloc->addend;
 880		relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
 881		idx++;
 882	}
 883
 884	return 0;
 885}
 886
 887int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
 888{
 889	struct reloc *reloc;
 890	int nr;
 891
 892	sec->changed = true;
 893	elf->changed = true;
 894
 895	nr = 0;
 896	list_for_each_entry(reloc, &sec->reloc_list, list)
 897		nr++;
 898
 899	switch (sec->sh.sh_type) {
 900	case SHT_REL:  return elf_rebuild_rel_reloc_section(sec, nr);
 901	case SHT_RELA: return elf_rebuild_rela_reloc_section(sec, nr);
 902	default:       return -1;
 903	}
 904}
 905
 906int elf_write_insn(struct elf *elf, struct section *sec,
 907		   unsigned long offset, unsigned int len,
 908		   const char *insn)
 909{
 910	Elf_Data *data = sec->data;
 911
 912	if (data->d_type != ELF_T_BYTE || data->d_off) {
 913		WARN("write to unexpected data for section: %s", sec->name);
 914		return -1;
 915	}
 916
 917	memcpy(data->d_buf + offset, insn, len);
 918	elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
 919
 920	elf->changed = true;
 921
 922	return 0;
 923}
 924
 925int elf_write_reloc(struct elf *elf, struct reloc *reloc)
 926{
 927	struct section *sec = reloc->sec;
 928
 929	if (sec->sh.sh_type == SHT_REL) {
 930		reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
 931		reloc->rel.r_offset = reloc->offset;
 932
 933		if (!gelf_update_rel(sec->data, reloc->idx, &reloc->rel)) {
 934			WARN_ELF("gelf_update_rel");
 935			return -1;
 936		}
 937	} else {
 938		reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
 939		reloc->rela.r_addend = reloc->addend;
 940		reloc->rela.r_offset = reloc->offset;
 941
 942		if (!gelf_update_rela(sec->data, reloc->idx, &reloc->rela)) {
 943			WARN_ELF("gelf_update_rela");
 944			return -1;
 945		}
 946	}
 947
 948	elf->changed = true;
 949
 950	return 0;
 951}
 952
 953int elf_write(struct elf *elf)
 954{
 955	struct section *sec;
 956	Elf_Scn *s;
 957
 958	/* Update section headers for changed sections: */
 959	list_for_each_entry(sec, &elf->sections, list) {
 960		if (sec->changed) {
 961			s = elf_getscn(elf->elf, sec->idx);
 962			if (!s) {
 963				WARN_ELF("elf_getscn");
 964				return -1;
 965			}
 966			if (!gelf_update_shdr(s, &sec->sh)) {
 967				WARN_ELF("gelf_update_shdr");
 968				return -1;
 969			}
 970
 971			sec->changed = false;
 972		}
 973	}
 974
 975	/* Make sure the new section header entries get updated properly. */
 976	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
 977
 978	/* Write all changes to the file. */
 979	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
 980		WARN_ELF("elf_update");
 981		return -1;
 982	}
 983
 984	elf->changed = false;
 985
 986	return 0;
 987}
 988
 989void elf_close(struct elf *elf)
 990{
 991	struct section *sec, *tmpsec;
 992	struct symbol *sym, *tmpsym;
 993	struct reloc *reloc, *tmpreloc;
 994
 995	if (elf->elf)
 996		elf_end(elf->elf);
 997
 998	if (elf->fd > 0)
 999		close(elf->fd);
1000
1001	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
1002		list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
1003			list_del(&sym->list);
1004			hash_del(&sym->hash);
1005			free(sym);
1006		}
1007		list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
1008			list_del(&reloc->list);
1009			hash_del(&reloc->hash);
1010			free(reloc);
1011		}
1012		list_del(&sec->list);
1013		free(sec);
1014	}
1015
1016	free(elf);
1017}