[linux-2.6-block.git] / tools / objtool / elf.c

/*
 * elf.c - ELF access library
 *
 * Adapted from kpatch (https://github.com/dynup/kpatch):
 * Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include "elf.h"
#include "warn.h"

struct section *find_section_by_name(struct elf *elf, const char *name)
{
	struct section *sec;

	list_for_each_entry(sec, &elf->sections, list)
		if (!strcmp(sec->name, name))
			return sec;

	return NULL;
}

static struct section *find_section_by_index(struct elf *elf,
					     unsigned int idx)
{
	struct section *sec;

	list_for_each_entry(sec, &elf->sections, list)
		if (sec->idx == idx)
			return sec;

	return NULL;
}

static struct symbol *find_symbol_by_index(struct elf *elf, unsigned int idx)
{
	struct section *sec;
	struct symbol *sym;

	list_for_each_entry(sec, &elf->sections, list)
		hash_for_each_possible(sec->symbol_hash, sym, hash, idx)
			if (sym->idx == idx)
				return sym;

	return NULL;
}

struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
{
	struct symbol *sym;

	list_for_each_entry(sym, &sec->symbol_list, list)
		if (sym->type != STT_SECTION &&
		    sym->offset == offset)
			return sym;

	return NULL;
}

struct symbol *find_symbol_by_name(struct elf *elf, const char *name)
{
	struct section *sec;
	struct symbol *sym;

	list_for_each_entry(sec, &elf->sections, list)
		list_for_each_entry(sym, &sec->symbol_list, list)
			if (!strcmp(sym->name, name))
				return sym;

	return NULL;
}

struct symbol *find_symbol_containing(struct section *sec, unsigned long offset)
{
	struct symbol *sym;

	list_for_each_entry(sym, &sec->symbol_list, list)
		if (sym->type != STT_SECTION &&
		    offset >= sym->offset && offset < sym->offset + sym->len)
			return sym;

	return NULL;
}

struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset,
				     unsigned int len)
{
	struct rela *rela;
	unsigned long o;

	if (!sec->rela)
		return NULL;

	for (o = offset; o < offset + len; o++)
		hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
			if (rela->offset == o)
				return rela;

	return NULL;
}

struct rela *find_rela_by_dest(struct section *sec, unsigned long offset)
{
	return find_rela_by_dest_range(sec, offset, 1);
}

struct symbol *find_containing_func(struct section *sec, unsigned long offset)
{
	struct symbol *func;

	list_for_each_entry(func, &sec->symbol_list, list)
		if (func->type == STT_FUNC && offset >= func->offset &&
		    offset < func->offset + func->len)
			return func;

	return NULL;
}

static int read_sections(struct elf *elf)
{
	Elf_Scn *s = NULL;
	struct section *sec;
	size_t shstrndx, sections_nr;
	int i;

	if (elf_getshdrnum(elf->elf, &sections_nr)) {
		WARN_ELF("elf_getshdrnum");
		return -1;
	}

	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
		WARN_ELF("elf_getshdrstrndx");
		return -1;
	}

	for (i = 0; i < sections_nr; i++) {
		sec = malloc(sizeof(*sec));
		if (!sec) {
			perror("malloc");
			return -1;
		}
		memset(sec, 0, sizeof(*sec));

		INIT_LIST_HEAD(&sec->symbol_list);
		INIT_LIST_HEAD(&sec->rela_list);
		hash_init(sec->rela_hash);
		hash_init(sec->symbol_hash);

		list_add_tail(&sec->list, &elf->sections);

		s = elf_getscn(elf->elf, i);
		if (!s) {
			WARN_ELF("elf_getscn");
			return -1;
		}

		sec->idx = elf_ndxscn(s);

		if (!gelf_getshdr(s, &sec->sh)) {
			WARN_ELF("gelf_getshdr");
			return -1;
		}

		sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
		if (!sec->name) {
			WARN_ELF("elf_strptr");
			return -1;
		}

		if (sec->sh.sh_size != 0) {
			sec->data = elf_getdata(s, NULL);
			if (!sec->data) {
				WARN_ELF("elf_getdata");
				return -1;
			}
			if (sec->data->d_off != 0 ||
			    sec->data->d_size != sec->sh.sh_size) {
				WARN("unexpected data attributes for %s",
				     sec->name);
				return -1;
			}
		}
		sec->len = sec->sh.sh_size;
	}

	/* sanity check, one more call to elf_nextscn() should return NULL */
	if (elf_nextscn(elf->elf, s)) {
		WARN("section entry mismatch");
		return -1;
	}

	return 0;
}

static int read_symbols(struct elf *elf)
{
	struct section *symtab, *sec;
	struct symbol *sym, *pfunc;
	struct list_head *entry, *tmp;
	int symbols_nr, i;
	char *coldstr;

	symtab = find_section_by_name(elf, ".symtab");
	if (!symtab) {
		WARN("missing symbol table");
		return -1;
	}

	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;

	for (i = 0; i < symbols_nr; i++) {
		sym = malloc(sizeof(*sym));
		if (!sym) {
			perror("malloc");
			return -1;
		}
		memset(sym, 0, sizeof(*sym));

		sym->idx = i;

		if (!gelf_getsym(symtab->data, i, &sym->sym)) {
			WARN_ELF("gelf_getsym");
			goto err;
		}

		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
				       sym->sym.st_name);
		if (!sym->name) {
			WARN_ELF("elf_strptr");
			goto err;
		}

		sym->type = GELF_ST_TYPE(sym->sym.st_info);
		sym->bind = GELF_ST_BIND(sym->sym.st_info);

		if (sym->sym.st_shndx > SHN_UNDEF &&
		    sym->sym.st_shndx < SHN_LORESERVE) {
			sym->sec = find_section_by_index(elf,
							 sym->sym.st_shndx);
			if (!sym->sec) {
				WARN("couldn't find section for symbol %s",
				     sym->name);
				goto err;
			}
			if (sym->type == STT_SECTION) {
				sym->name = sym->sec->name;
				sym->sec->sym = sym;
			}
		} else
			sym->sec = find_section_by_index(elf, 0);

		sym->offset = sym->sym.st_value;
		sym->len = sym->sym.st_size;

		/* sorted insert into a per-section list */
		entry = &sym->sec->symbol_list;
		list_for_each_prev(tmp, &sym->sec->symbol_list) {
			struct symbol *s;

			s = list_entry(tmp, struct symbol, list);

			if (sym->offset > s->offset) {
				entry = tmp;
				break;
			}

			if (sym->offset == s->offset && sym->len >= s->len) {
				entry = tmp;
				break;
			}
		}
		list_add(&sym->list, entry);
		hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
	}

	/* Create parent/child links for any cold subfunctions */
	list_for_each_entry(sec, &elf->sections, list) {
		list_for_each_entry(sym, &sec->symbol_list, list) {
			if (sym->type != STT_FUNC)
				continue;
			sym->pfunc = sym->cfunc = sym;
			coldstr = strstr(sym->name, ".cold.");
			if (!coldstr)
				continue;

			coldstr[0] = '\0';
			pfunc = find_symbol_by_name(elf, sym->name);
			coldstr[0] = '.';

			if (!pfunc) {
				WARN("%s(): can't find parent function",
				     sym->name);
				goto err;
			}

			sym->pfunc = pfunc;
			pfunc->cfunc = sym;

			/*
			 * Unfortunately, -fnoreorder-functions puts the child
			 * inside the parent.  Remove the overlap so we can
			 * have sane assumptions.
			 *
			 * Note that pfunc->len now no longer matches
			 * pfunc->sym.st_size.
			 */
			if (sym->sec == pfunc->sec &&
			    sym->offset >= pfunc->offset &&
			    sym->offset + sym->len == pfunc->offset + pfunc->len) {
				pfunc->len -= sym->len;
			}
		}
	}

	return 0;

err:
	free(sym);
	return -1;
}

static int read_relas(struct elf *elf)
{
	struct section *sec;
	struct rela *rela;
	int i;
	unsigned int symndx;

	list_for_each_entry(sec, &elf->sections, list) {
		if (sec->sh.sh_type != SHT_RELA)
			continue;

		sec->base = find_section_by_name(elf, sec->name + 5);
		if (!sec->base) {
			WARN("can't find base section for rela section %s",
			     sec->name);
			return -1;
		}

		sec->base->rela = sec;

		for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
			rela = malloc(sizeof(*rela));
			if (!rela) {
				perror("malloc");
				return -1;
			}
			memset(rela, 0, sizeof(*rela));

			if (!gelf_getrela(sec->data, i, &rela->rela)) {
				WARN_ELF("gelf_getrela");
				return -1;
			}

			rela->type = GELF_R_TYPE(rela->rela.r_info);
			rela->addend = rela->rela.r_addend;
			rela->offset = rela->rela.r_offset;
			symndx = GELF_R_SYM(rela->rela.r_info);
			rela->sym = find_symbol_by_index(elf, symndx);
			if (!rela->sym) {
				WARN("can't find rela entry symbol %d for %s",
				     symndx, sec->name);
				return -1;
			}

			list_add_tail(&rela->list, &sec->rela_list);
			hash_add(sec->rela_hash, &rela->hash, rela->offset);

		}
	}

	return 0;
}

struct elf *elf_open(const char *name, int flags)
{
	struct elf *elf;
	Elf_Cmd cmd;

	elf_version(EV_CURRENT);

	elf = malloc(sizeof(*elf));
	if (!elf) {
		perror("malloc");
		return NULL;
	}
	memset(elf, 0, sizeof(*elf));

	INIT_LIST_HEAD(&elf->sections);

	elf->fd = open(name, flags);
	if (elf->fd == -1) {
		fprintf(stderr, "objtool: Can't open '%s': %s\n",
			name, strerror(errno));
		goto err;
	}

	if ((flags & O_ACCMODE) == O_RDONLY)
		cmd = ELF_C_READ_MMAP;
	else if ((flags & O_ACCMODE) == O_RDWR)
		cmd = ELF_C_RDWR;
	else /* O_WRONLY */
		cmd = ELF_C_WRITE;

	elf->elf = elf_begin(elf->fd, cmd, NULL);
	if (!elf->elf) {
		WARN_ELF("elf_begin");
		goto err;
	}

	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
		WARN_ELF("gelf_getehdr");
		goto err;
	}

	if (read_sections(elf))
		goto err;

	if (read_symbols(elf))
		goto err;

	if (read_relas(elf))
		goto err;

	return elf;

err:
	elf_close(elf);
	return NULL;
}

struct section *elf_create_section(struct elf *elf, const char *name,
				   size_t entsize, int nr)
{
	struct section *sec, *shstrtab;
	size_t size = entsize * nr;
	struct Elf_Scn *s;
	Elf_Data *data;

	sec = malloc(sizeof(*sec));
	if (!sec) {
		perror("malloc");
		return NULL;
	}
	memset(sec, 0, sizeof(*sec));

	INIT_LIST_HEAD(&sec->symbol_list);
	INIT_LIST_HEAD(&sec->rela_list);
	hash_init(sec->rela_hash);
	hash_init(sec->symbol_hash);

	list_add_tail(&sec->list, &elf->sections);

	s = elf_newscn(elf->elf);
	if (!s) {
		WARN_ELF("elf_newscn");
		return NULL;
	}

	sec->name = strdup(name);
	if (!sec->name) {
		perror("strdup");
		return NULL;
	}

	sec->idx = elf_ndxscn(s);
	sec->len = size;
	sec->changed = true;

	sec->data = elf_newdata(s);
	if (!sec->data) {
		WARN_ELF("elf_newdata");
		return NULL;
	}

	sec->data->d_size = size;
	sec->data->d_align = 1;

	if (size) {
		sec->data->d_buf = malloc(size);
		if (!sec->data->d_buf) {
			perror("malloc");
			return NULL;
		}
		memset(sec->data->d_buf, 0, size);
	}

	if (!gelf_getshdr(s, &sec->sh)) {
		WARN_ELF("gelf_getshdr");
		return NULL;
	}

	sec->sh.sh_size = size;
	sec->sh.sh_entsize = entsize;
	sec->sh.sh_type = SHT_PROGBITS;
	sec->sh.sh_addralign = 1;
	sec->sh.sh_flags = SHF_ALLOC;


	/* Add section name to .shstrtab (or .strtab for Clang) */
	shstrtab = find_section_by_name(elf, ".shstrtab");
	if (!shstrtab)
		shstrtab = find_section_by_name(elf, ".strtab");
	if (!shstrtab) {
		WARN("can't find .shstrtab or .strtab section");
		return NULL;
	}

	s = elf_getscn(elf->elf, shstrtab->idx);
	if (!s) {
		WARN_ELF("elf_getscn");
		return NULL;
	}

	data = elf_newdata(s);
	if (!data) {
		WARN_ELF("elf_newdata");
		return NULL;
	}

	data->d_buf = sec->name;
	data->d_size = strlen(name) + 1;
	data->d_align = 1;

	sec->sh.sh_name = shstrtab->len;

	shstrtab->len += strlen(name) + 1;
	shstrtab->changed = true;

	return sec;
}

struct section *elf_create_rela_section(struct elf *elf, struct section *base)
{
	char *relaname;
	struct section *sec;

	relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
	if (!relaname) {
		perror("malloc");
		return NULL;
	}
	strcpy(relaname, ".rela");
	strcat(relaname, base->name);

	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
	free(relaname);
	if (!sec)
		return NULL;

	base->rela = sec;
	sec->base = base;

	sec->sh.sh_type = SHT_RELA;
	sec->sh.sh_addralign = 8;
	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
	sec->sh.sh_info = base->idx;
	sec->sh.sh_flags = SHF_INFO_LINK;

	return sec;
}

int elf_rebuild_rela_section(struct section *sec)
{
	struct rela *rela;
	int nr, idx = 0, size;
	GElf_Rela *relas;

	nr = 0;
	list_for_each_entry(rela, &sec->rela_list, list)
		nr++;

	size = nr * sizeof(*relas);
	relas = malloc(size);
	if (!relas) {
		perror("malloc");
		return -1;
	}

	sec->data->d_buf = relas;
	sec->data->d_size = size;

	sec->sh.sh_size = size;

	idx = 0;
	list_for_each_entry(rela, &sec->rela_list, list) {
		relas[idx].r_offset = rela->offset;
		relas[idx].r_addend = rela->addend;
		relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
		idx++;
	}

	return 0;
}

int elf_write(struct elf *elf)
{
	struct section *sec;
	Elf_Scn *s;

	/* Update section headers for changed sections: */
	list_for_each_entry(sec, &elf->sections, list) {
		if (sec->changed) {
			s = elf_getscn(elf->elf, sec->idx);
			if (!s) {
				WARN_ELF("elf_getscn");
				return -1;
			}
			if (!gelf_update_shdr(s, &sec->sh)) {
				WARN_ELF("gelf_update_shdr");
				return -1;
			}
		}
	}

	/* Make sure the new section header entries get updated properly. */
	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);

	/* Write all changes to the file. */
	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
		WARN_ELF("elf_update");
		return -1;
	}

	return 0;
}

void elf_close(struct elf *elf)
{
	struct section *sec, *tmpsec;
	struct symbol *sym, *tmpsym;
	struct rela *rela, *tmprela;

	if (elf->elf)
		elf_end(elf->elf);

	if (elf->fd > 0)
		close(elf->fd);

	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
		list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
			list_del(&sym->list);
			hash_del(&sym->hash);
			free(sym);
		}
		list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
			list_del(&rela->list);
			hash_del(&rela->hash);
			free(rela);
		}
		list_del(&sec->list);
		free(sec);
	}

	free(elf);
}
Commit	Line	Data
442f04c3 JP	1	/*
	2	* elf.c - ELF access library
	3	*
	4	* Adapted from kpatch (https://github.com/dynup/kpatch):
	5	* Copyright (C) 2013-2015 Josh Poimboeuf <jpoimboe@redhat.com>
	6	* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License
	10	* as published by the Free Software Foundation; either version 2
	11	* of the License, or (at your option) any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with this program; if not, see <http://www.gnu.org/licenses/>.
	20	*/
	21
	22	#include <sys/types.h>
	23	#include <sys/stat.h>
	24	#include <fcntl.h>
	25	#include <stdio.h>
	26	#include <stdlib.h>
	27	#include <string.h>
	28	#include <unistd.h>
385d11b1	29	#include <errno.h>
442f04c3 JP	30
	31	#include "elf.h"
	32	#include "warn.h"
	33
	34	struct section find_section_by_name(struct elf elf, const char *name)
	35	{
	36	struct section *sec;
	37
	38	list_for_each_entry(sec, &elf->sections, list)
	39	if (!strcmp(sec->name, name))
	40	return sec;
	41
	42	return NULL;
	43	}
	44
	45	static struct section find_section_by_index(struct elf elf,
	46	unsigned int idx)
	47	{
	48	struct section *sec;
	49
	50	list_for_each_entry(sec, &elf->sections, list)
	51	if (sec->idx == idx)
	52	return sec;
	53
	54	return NULL;
	55	}
	56
	57	static struct symbol find_symbol_by_index(struct elf elf, unsigned int idx)
	58	{
	59	struct section *sec;
	60	struct symbol *sym;
	61
	62	list_for_each_entry(sec, &elf->sections, list)
042ba73f	63	hash_for_each_possible(sec->symbol_hash, sym, hash, idx)
442f04c3 JP	64	if (sym->idx == idx)
	65	return sym;
	66
	67	return NULL;
	68	}
	69
	70	struct symbol find_symbol_by_offset(struct section sec, unsigned long offset)
	71	{
	72	struct symbol *sym;
	73
a196e171	74	list_for_each_entry(sym, &sec->symbol_list, list)
442f04c3 JP	75	if (sym->type != STT_SECTION &&
	76	sym->offset == offset)
	77	return sym;
	78
	79	return NULL;
	80	}
	81
13810435 JP	82	struct symbol find_symbol_by_name(struct elf elf, const char *name)
	83	{
	84	struct section *sec;
	85	struct symbol *sym;
	86
	87	list_for_each_entry(sec, &elf->sections, list)
	88	list_for_each_entry(sym, &sec->symbol_list, list)
	89	if (!strcmp(sym->name, name))
	90	return sym;
	91
	92	return NULL;
	93	}
	94
5c51f4ae JP	95	struct symbol find_symbol_containing(struct section sec, unsigned long offset)
	96	{
	97	struct symbol *sym;
	98
	99	list_for_each_entry(sym, &sec->symbol_list, list)
	100	if (sym->type != STT_SECTION &&
	101	offset >= sym->offset && offset < sym->offset + sym->len)
	102	return sym;
	103
	104	return NULL;
	105	}
	106
442f04c3 JP	107	struct rela find_rela_by_dest_range(struct section sec, unsigned long offset,
	108	unsigned int len)
	109	{
	110	struct rela *rela;
042ba73f	111	unsigned long o;
442f04c3 JP	112
	113	if (!sec->rela)
	114	return NULL;
	115
042ba73f JP	116	for (o = offset; o < offset + len; o++)
	117	hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
	118	if (rela->offset == o)
	119	return rela;
442f04c3 JP	120
	121	return NULL;
	122	}
	123
	124	struct rela find_rela_by_dest(struct section sec, unsigned long offset)
	125	{
	126	return find_rela_by_dest_range(sec, offset, 1);
	127	}
	128
	129	struct symbol find_containing_func(struct section sec, unsigned long offset)
	130	{
	131	struct symbol *func;
	132
a196e171	133	list_for_each_entry(func, &sec->symbol_list, list)
442f04c3 JP	134	if (func->type == STT_FUNC && offset >= func->offset &&
	135	offset < func->offset + func->len)
	136	return func;
	137
	138	return NULL;
	139	}
	140
	141	static int read_sections(struct elf *elf)
	142	{
	143	Elf_Scn *s = NULL;
	144	struct section *sec;
	145	size_t shstrndx, sections_nr;
	146	int i;
	147
	148	if (elf_getshdrnum(elf->elf, &sections_nr)) {
baa41469	149	WARN_ELF("elf_getshdrnum");
442f04c3 JP	150	return -1;
	151	}
	152
	153	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
baa41469	154	WARN_ELF("elf_getshdrstrndx");
442f04c3 JP	155	return -1;
	156	}
	157
	158	for (i = 0; i < sections_nr; i++) {
	159	sec = malloc(sizeof(*sec));
	160	if (!sec) {
	161	perror("malloc");
	162	return -1;
	163	}
	164	memset(sec, 0, sizeof(*sec));
	165
a196e171 JP	166	INIT_LIST_HEAD(&sec->symbol_list);
a196e171 JP	167	INIT_LIST_HEAD(&sec->rela_list);
042ba73f JP	168	hash_init(sec->rela_hash);
042ba73f JP	169	hash_init(sec->symbol_hash);
442f04c3 JP	170
	171	list_add_tail(&sec->list, &elf->sections);
	172
	173	s = elf_getscn(elf->elf, i);
	174	if (!s) {
baa41469	175	WARN_ELF("elf_getscn");
442f04c3 JP	176	return -1;
	177	}
	178
	179	sec->idx = elf_ndxscn(s);
	180
	181	if (!gelf_getshdr(s, &sec->sh)) {
baa41469	182	WARN_ELF("gelf_getshdr");
442f04c3 JP	183	return -1;
	184	}
	185
	186	sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
	187	if (!sec->name) {
baa41469	188	WARN_ELF("elf_strptr");
442f04c3 JP	189	return -1;
	190	}
	191
df968c93 PV	192	if (sec->sh.sh_size != 0) {
	193	sec->data = elf_getdata(s, NULL);
	194	if (!sec->data) {
	195	WARN_ELF("elf_getdata");
	196	return -1;
	197	}
	198	if (sec->data->d_off != 0 \|\|
	199	sec->data->d_size != sec->sh.sh_size) {
	200	WARN("unexpected data attributes for %s",
	201	sec->name);
	202	return -1;
	203	}
442f04c3	204	}
df968c93	205	sec->len = sec->sh.sh_size;
442f04c3 JP	206	}
	207
	208	/* sanity check, one more call to elf_nextscn() should return NULL */
	209	if (elf_nextscn(elf->elf, s)) {
	210	WARN("section entry mismatch");
	211	return -1;
	212	}
	213
	214	return 0;
	215	}
	216
	217	static int read_symbols(struct elf *elf)
	218	{
13810435 JP	219	struct section symtab, sec;
13810435 JP	220	struct symbol sym, pfunc;
442f04c3 JP	221	struct list_head entry, tmp;
442f04c3 JP	222	int symbols_nr, i;
13810435	223	char *coldstr;
442f04c3 JP	224
	225	symtab = find_section_by_name(elf, ".symtab");
	226	if (!symtab) {
	227	WARN("missing symbol table");
	228	return -1;
	229	}
	230
	231	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
	232
	233	for (i = 0; i < symbols_nr; i++) {
	234	sym = malloc(sizeof(*sym));
	235	if (!sym) {
	236	perror("malloc");
	237	return -1;
	238	}
	239	memset(sym, 0, sizeof(*sym));
	240
	241	sym->idx = i;
	242
baa41469 JP	243	if (!gelf_getsym(symtab->data, i, &sym->sym)) {
baa41469 JP	244	WARN_ELF("gelf_getsym");
442f04c3 JP	245	goto err;
	246	}
	247
	248	sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
	249	sym->sym.st_name);
	250	if (!sym->name) {
baa41469	251	WARN_ELF("elf_strptr");
442f04c3 JP	252	goto err;
	253	}
	254
	255	sym->type = GELF_ST_TYPE(sym->sym.st_info);
	256	sym->bind = GELF_ST_BIND(sym->sym.st_info);
	257
	258	if (sym->sym.st_shndx > SHN_UNDEF &&
	259	sym->sym.st_shndx < SHN_LORESERVE) {
	260	sym->sec = find_section_by_index(elf,
	261	sym->sym.st_shndx);
	262	if (!sym->sec) {
	263	WARN("couldn't find section for symbol %s",
	264	sym->name);
	265	goto err;
	266	}
	267	if (sym->type == STT_SECTION) {
	268	sym->name = sym->sec->name;
	269	sym->sec->sym = sym;
	270	}
	271	} else
	272	sym->sec = find_section_by_index(elf, 0);
	273
	274	sym->offset = sym->sym.st_value;
	275	sym->len = sym->sym.st_size;
	276
	277	/* sorted insert into a per-section list */
a196e171 JP	278	entry = &sym->sec->symbol_list;
a196e171 JP	279	list_for_each_prev(tmp, &sym->sec->symbol_list) {
442f04c3 JP	280	struct symbol *s;
	281
	282	s = list_entry(tmp, struct symbol, list);
	283
	284	if (sym->offset > s->offset) {
	285	entry = tmp;
	286	break;
	287	}
	288
	289	if (sym->offset == s->offset && sym->len >= s->len) {
	290	entry = tmp;
	291	break;
	292	}
	293	}
	294	list_add(&sym->list, entry);
042ba73f	295	hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
442f04c3 JP	296	}
442f04c3 JP	297
13810435 JP	298	/* Create parent/child links for any cold subfunctions */
	299	list_for_each_entry(sec, &elf->sections, list) {
	300	list_for_each_entry(sym, &sec->symbol_list, list) {
	301	if (sym->type != STT_FUNC)
	302	continue;
	303	sym->pfunc = sym->cfunc = sym;
	304	coldstr = strstr(sym->name, ".cold.");
08b393d0 JP	305	if (!coldstr)
	306	continue;
	307
	308	coldstr[0] = '\0';
	309	pfunc = find_symbol_by_name(elf, sym->name);
	310	coldstr[0] = '.';
	311
	312	if (!pfunc) {
	313	WARN("%s(): can't find parent function",
	314	sym->name);
	315	goto err;
	316	}
	317
	318	sym->pfunc = pfunc;
	319	pfunc->cfunc = sym;
	320
	321	/*
	322	* Unfortunately, -fnoreorder-functions puts the child
	323	* inside the parent. Remove the overlap so we can
	324	* have sane assumptions.
	325	*
	326	* Note that pfunc->len now no longer matches
	327	* pfunc->sym.st_size.
	328	*/
	329	if (sym->sec == pfunc->sec &&
	330	sym->offset >= pfunc->offset &&
	331	sym->offset + sym->len == pfunc->offset + pfunc->len) {
	332	pfunc->len -= sym->len;
13810435 JP	333	}
	334	}
	335	}
	336
442f04c3 JP	337	return 0;
	338
	339	err:
	340	free(sym);
	341	return -1;
	342	}
	343
	344	static int read_relas(struct elf *elf)
	345	{
	346	struct section *sec;
	347	struct rela *rela;
	348	int i;
	349	unsigned int symndx;
	350
	351	list_for_each_entry(sec, &elf->sections, list) {
	352	if (sec->sh.sh_type != SHT_RELA)
	353	continue;
	354
	355	sec->base = find_section_by_name(elf, sec->name + 5);
	356	if (!sec->base) {
	357	WARN("can't find base section for rela section %s",
	358	sec->name);
	359	return -1;
	360	}
	361
	362	sec->base->rela = sec;
	363
	364	for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
	365	rela = malloc(sizeof(*rela));
	366	if (!rela) {
	367	perror("malloc");
	368	return -1;
	369	}
	370	memset(rela, 0, sizeof(*rela));
	371
baa41469 JP	372	if (!gelf_getrela(sec->data, i, &rela->rela)) {
baa41469 JP	373	WARN_ELF("gelf_getrela");
442f04c3 JP	374	return -1;
	375	}
	376
	377	rela->type = GELF_R_TYPE(rela->rela.r_info);
	378	rela->addend = rela->rela.r_addend;
	379	rela->offset = rela->rela.r_offset;
	380	symndx = GELF_R_SYM(rela->rela.r_info);
	381	rela->sym = find_symbol_by_index(elf, symndx);
	382	if (!rela->sym) {
	383	WARN("can't find rela entry symbol %d for %s",
	384	symndx, sec->name);
	385	return -1;
	386	}
042ba73f JP	387
	388	list_add_tail(&rela->list, &sec->rela_list);
	389	hash_add(sec->rela_hash, &rela->hash, rela->offset);
	390
442f04c3 JP	391	}
	392	}
	393
	394	return 0;
	395	}
	396
627fce14	397	struct elf elf_open(const char name, int flags)
442f04c3 JP	398	{
442f04c3 JP	399	struct elf *elf;
627fce14	400	Elf_Cmd cmd;
442f04c3 JP	401
	402	elf_version(EV_CURRENT);
	403
	404	elf = malloc(sizeof(*elf));
	405	if (!elf) {
	406	perror("malloc");
	407	return NULL;
	408	}
	409	memset(elf, 0, sizeof(*elf));
	410
	411	INIT_LIST_HEAD(&elf->sections);
	412
627fce14	413	elf->fd = open(name, flags);
442f04c3	414	if (elf->fd == -1) {
385d11b1 JP	415	fprintf(stderr, "objtool: Can't open '%s': %s\n",
385d11b1 JP	416	name, strerror(errno));
442f04c3 JP	417	goto err;
	418	}
	419
627fce14 JP	420	if ((flags & O_ACCMODE) == O_RDONLY)
	421	cmd = ELF_C_READ_MMAP;
	422	else if ((flags & O_ACCMODE) == O_RDWR)
	423	cmd = ELF_C_RDWR;
	424	else /* O_WRONLY */
	425	cmd = ELF_C_WRITE;
	426
	427	elf->elf = elf_begin(elf->fd, cmd, NULL);
442f04c3	428	if (!elf->elf) {
baa41469	429	WARN_ELF("elf_begin");
442f04c3 JP	430	goto err;
	431	}
	432
	433	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
baa41469	434	WARN_ELF("gelf_getehdr");
442f04c3 JP	435	goto err;
	436	}
	437
	438	if (read_sections(elf))
	439	goto err;
	440
	441	if (read_symbols(elf))
	442	goto err;
	443
	444	if (read_relas(elf))
	445	goto err;
	446
	447	return elf;
	448
	449	err:
	450	elf_close(elf);
	451	return NULL;
	452	}
	453
627fce14 JP	454	struct section elf_create_section(struct elf elf, const char *name,
	455	size_t entsize, int nr)
	456	{
	457	struct section sec, shstrtab;
	458	size_t size = entsize * nr;
	459	struct Elf_Scn *s;
	460	Elf_Data *data;
	461
	462	sec = malloc(sizeof(*sec));
	463	if (!sec) {
	464	perror("malloc");
	465	return NULL;
	466	}
	467	memset(sec, 0, sizeof(*sec));
	468
	469	INIT_LIST_HEAD(&sec->symbol_list);
	470	INIT_LIST_HEAD(&sec->rela_list);
	471	hash_init(sec->rela_hash);
	472	hash_init(sec->symbol_hash);
	473
	474	list_add_tail(&sec->list, &elf->sections);
	475
	476	s = elf_newscn(elf->elf);
	477	if (!s) {
	478	WARN_ELF("elf_newscn");
	479	return NULL;
	480	}
	481
	482	sec->name = strdup(name);
	483	if (!sec->name) {
	484	perror("strdup");
	485	return NULL;
	486	}
	487
	488	sec->idx = elf_ndxscn(s);
	489	sec->len = size;
	490	sec->changed = true;
	491
	492	sec->data = elf_newdata(s);
	493	if (!sec->data) {
	494	WARN_ELF("elf_newdata");
	495	return NULL;
	496	}
	497
	498	sec->data->d_size = size;
	499	sec->data->d_align = 1;
	500
	501	if (size) {
	502	sec->data->d_buf = malloc(size);
	503	if (!sec->data->d_buf) {
	504	perror("malloc");
	505	return NULL;
	506	}
	507	memset(sec->data->d_buf, 0, size);
	508	}
	509
	510	if (!gelf_getshdr(s, &sec->sh)) {
	511	WARN_ELF("gelf_getshdr");
	512	return NULL;
	513	}
	514
	515	sec->sh.sh_size = size;
	516	sec->sh.sh_entsize = entsize;
	517	sec->sh.sh_type = SHT_PROGBITS;
518	sec->sh.sh_addralign = 1;
519	sec->sh.sh_flags = SHF_ALLOC;
520
521
6d77d3b4	522	/* Add section name to .shstrtab (or .strtab for Clang) */
627fce14	523	shstrtab = find_section_by_name(elf, ".shstrtab");
6d77d3b4 SS	524	if (!shstrtab)
6d77d3b4 SS	525	shstrtab = find_section_by_name(elf, ".strtab");
627fce14	526	if (!shstrtab) {
6d77d3b4	527	WARN("can't find .shstrtab or .strtab section");
627fce14 JP	528	return NULL;
	529	}
	530
	531	s = elf_getscn(elf->elf, shstrtab->idx);
	532	if (!s) {
	533	WARN_ELF("elf_getscn");
	534	return NULL;
	535	}
	536
	537	data = elf_newdata(s);
	538	if (!data) {
	539	WARN_ELF("elf_newdata");
	540	return NULL;
	541	}
	542
	543	data->d_buf = sec->name;
	544	data->d_size = strlen(name) + 1;
	545	data->d_align = 1;
	546
	547	sec->sh.sh_name = shstrtab->len;
	548
	549	shstrtab->len += strlen(name) + 1;
	550	shstrtab->changed = true;
	551
	552	return sec;
	553	}
	554
	555	struct section elf_create_rela_section(struct elf elf, struct section *base)
	556	{
	557	char *relaname;
	558	struct section *sec;
	559
	560	relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
	561	if (!relaname) {
	562	perror("malloc");
	563	return NULL;
	564	}
	565	strcpy(relaname, ".rela");
	566	strcat(relaname, base->name);
	567
	568	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
0998b7a0	569	free(relaname);
627fce14 JP	570	if (!sec)
	571	return NULL;
	572
	573	base->rela = sec;
	574	sec->base = base;
	575
	576	sec->sh.sh_type = SHT_RELA;
	577	sec->sh.sh_addralign = 8;
	578	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
	579	sec->sh.sh_info = base->idx;
	580	sec->sh.sh_flags = SHF_INFO_LINK;
	581
	582	return sec;
	583	}
	584
	585	int elf_rebuild_rela_section(struct section *sec)
	586	{
	587	struct rela *rela;
	588	int nr, idx = 0, size;
	589	GElf_Rela *relas;
	590
	591	nr = 0;
	592	list_for_each_entry(rela, &sec->rela_list, list)
	593	nr++;
	594
	595	size = nr * sizeof(*relas);
	596	relas = malloc(size);
	597	if (!relas) {
	598	perror("malloc");
	599	return -1;
	600	}
	601
	602	sec->data->d_buf = relas;
	603	sec->data->d_size = size;
	604
	605	sec->sh.sh_size = size;
	606
	607	idx = 0;
	608	list_for_each_entry(rela, &sec->rela_list, list) {
	609	relas[idx].r_offset = rela->offset;
	610	relas[idx].r_addend = rela->addend;
	611	relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
	612	idx++;
	613	}
	614
	615	return 0;
	616	}
	617
	618	int elf_write(struct elf *elf)
	619	{
	620	struct section *sec;
	621	Elf_Scn *s;
	622
97dab2ae	623	/* Update section headers for changed sections: */
627fce14 JP	624	list_for_each_entry(sec, &elf->sections, list) {
	625	if (sec->changed) {
	626	s = elf_getscn(elf->elf, sec->idx);
	627	if (!s) {
	628	WARN_ELF("elf_getscn");
	629	return -1;
	630	}
97dab2ae	631	if (!gelf_update_shdr(s, &sec->sh)) {
627fce14 JP	632	WARN_ELF("gelf_update_shdr");
	633	return -1;
	634	}
	635	}
	636	}
	637
97dab2ae JP	638	/* Make sure the new section header entries get updated properly. */
	639	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
	640
	641	/* Write all changes to the file. */
627fce14 JP	642	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
	643	WARN_ELF("elf_update");
	644	return -1;
	645	}
	646
	647	return 0;
	648	}
	649
442f04c3 JP	650	void elf_close(struct elf *elf)
	651	{
	652	struct section sec, tmpsec;
	653	struct symbol sym, tmpsym;
	654	struct rela rela, tmprela;
	655
baa41469 JP	656	if (elf->elf)
	657	elf_end(elf->elf);
	658
	659	if (elf->fd > 0)
	660	close(elf->fd);
	661
442f04c3	662	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
a196e171	663	list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
442f04c3	664	list_del(&sym->list);
042ba73f	665	hash_del(&sym->hash);
442f04c3 JP	666	free(sym);
442f04c3 JP	667	}
a196e171	668	list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
442f04c3	669	list_del(&rela->list);
042ba73f	670	hash_del(&rela->hash);
442f04c3 JP	671	free(rela);
	672	}
	673	list_del(&sec->list);
	674	free(sec);
	675	}
baa41469	676
442f04c3 JP	677	free(elf);
442f04c3 JP	678	}