[mirror_ubuntu-hirsute-kernel.git] / tools / objtool / elf.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#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 "builtin.h"

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

#define MAX_NAME_LEN 128

static inline u32 str_hash(const char *str)
{
	return jhash(str, strlen(str), 0);
}

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

	hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
		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;

	hash_for_each_possible(elf->section_hash, sec, hash, idx)
		if (sec->idx == idx)
			return sec;

	return NULL;
}

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

	hash_for_each_possible(elf->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_func_by_offset(struct section *sec, unsigned long offset)
{
	struct symbol *sym;

	list_for_each_entry(sym, &sec->symbol_list, list)
		if (sym->type == STT_FUNC && 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);

		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;

		list_add_tail(&sec->list, &elf->sections);
		hash_add(elf->section_hash, &sec->hash, sec->idx);
		hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
	}

	if (stats)
		printf("nr_sections: %lu\n", (unsigned long)sections_nr);

	/* 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, *alias;
	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));
		alias = 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) {
				if (sym->len && sym->len == s->len && alias == sym)
					alias = s;

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

	if (stats)
		printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);

	/* 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) {
			char pname[MAX_NAME_LEN + 1];
			size_t pnamelen;
			if (sym->type != STT_FUNC)
				continue;
			sym->pfunc = sym->cfunc = sym;
			coldstr = strstr(sym->name, ".cold");
			if (!coldstr)
				continue;

			pnamelen = coldstr - sym->name;
			if (pnamelen > MAX_NAME_LEN) {
				WARN("%s(): parent function name exceeds maximum length of %d characters",
				     sym->name, MAX_NAME_LEN);
				return -1;
			}

			strncpy(pname, sym->name, pnamelen);
			pname[pnamelen] = '\0';
			pfunc = find_symbol_by_name(elf, pname);

			if (!pfunc) {
				WARN("%s(): can't find parent function",
				     sym->name);
				return -1;
			}

			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;
	unsigned long nr_rela, max_rela = 0, tot_rela = 0;

	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;

		nr_rela = 0;
		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);
			rela->sec = sec;
			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);
			nr_rela++;
		}
		max_rela = max(max_rela, nr_rela);
		tot_rela += nr_rela;
	}

	if (stats) {
		printf("max_rela: %lu\n", max_rela);
		printf("tot_rela: %lu\n", tot_rela);
	}

	return 0;
}

struct elf *elf_read(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));

	hash_init(elf->symbol_hash);
	hash_init(elf->section_hash);
	hash_init(elf->section_name_hash);
	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;
	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);

	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;

	list_add_tail(&sec->list, &elf->sections);
	hash_add(elf->section_hash, &sec->hash, sec->idx);
	hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));

	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
1ccea77e	1	// SPDX-License-Identifier: GPL-2.0-or-later
442f04c3 JP	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>
442f04c3 JP	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>
385d11b1	17	#include <errno.h>
1e11f3fd	18	#include "builtin.h"
442f04c3 JP	19
	20	#include "elf.h"
	21	#include "warn.h"
	22
22566c16 AS	23	#define MAX_NAME_LEN 128
22566c16 AS	24
ae358196 PZ	25	static inline u32 str_hash(const char *str)
	26	{
	27	return jhash(str, strlen(str), 0);
	28	}
	29
442f04c3 JP	30	struct section find_section_by_name(struct elf elf, const char *name)
	31	{
	32	struct section *sec;
	33
ae358196	34	hash_for_each_possible(elf->section_name_hash, sec, name_hash, str_hash(name))
442f04c3 JP	35	if (!strcmp(sec->name, name))
	36	return sec;
	37
	38	return NULL;
	39	}
	40
	41	static struct section find_section_by_index(struct elf elf,
	42	unsigned int idx)
	43	{
	44	struct section *sec;
	45
53038996	46	hash_for_each_possible(elf->section_hash, sec, hash, idx)
442f04c3 JP	47	if (sec->idx == idx)
	48	return sec;
	49
	50	return NULL;
	51	}
	52
	53	static struct symbol find_symbol_by_index(struct elf elf, unsigned int idx)
	54	{
442f04c3 JP	55	struct symbol *sym;
442f04c3 JP	56
65fb11a7 PZ	57	hash_for_each_possible(elf->symbol_hash, sym, hash, idx)
	58	if (sym->idx == idx)
	59	return sym;
442f04c3 JP	60
	61	return NULL;
	62	}
	63
	64	struct symbol find_symbol_by_offset(struct section sec, unsigned long offset)
	65	{
	66	struct symbol *sym;
	67
a196e171	68	list_for_each_entry(sym, &sec->symbol_list, list)
7acfe531 JP	69	if (sym->type != STT_SECTION && sym->offset == offset)
	70	return sym;
	71
	72	return NULL;
	73	}
	74
	75	struct symbol find_func_by_offset(struct section sec, unsigned long offset)
	76	{
	77	struct symbol *sym;
	78
	79	list_for_each_entry(sym, &sec->symbol_list, list)
	80	if (sym->type == STT_FUNC && sym->offset == offset)
442f04c3 JP	81	return sym;
	82
	83	return NULL;
	84	}
	85
13810435 JP	86	struct symbol find_symbol_by_name(struct elf elf, const char *name)
	87	{
	88	struct section *sec;
	89	struct symbol *sym;
	90
	91	list_for_each_entry(sec, &elf->sections, list)
	92	list_for_each_entry(sym, &sec->symbol_list, list)
	93	if (!strcmp(sym->name, name))
	94	return sym;
	95
	96	return NULL;
	97	}
	98
5c51f4ae JP	99	struct symbol find_symbol_containing(struct section sec, unsigned long offset)
	100	{
	101	struct symbol *sym;
	102
	103	list_for_each_entry(sym, &sec->symbol_list, list)
	104	if (sym->type != STT_SECTION &&
	105	offset >= sym->offset && offset < sym->offset + sym->len)
	106	return sym;
	107
	108	return NULL;
	109	}
	110
442f04c3 JP	111	struct rela find_rela_by_dest_range(struct section sec, unsigned long offset,
	112	unsigned int len)
	113	{
	114	struct rela *rela;
042ba73f	115	unsigned long o;
442f04c3 JP	116
	117	if (!sec->rela)
	118	return NULL;
	119
042ba73f JP	120	for (o = offset; o < offset + len; o++)
	121	hash_for_each_possible(sec->rela->rela_hash, rela, hash, o)
	122	if (rela->offset == o)
	123	return rela;
442f04c3 JP	124
	125	return NULL;
	126	}
	127
	128	struct rela find_rela_by_dest(struct section sec, unsigned long offset)
	129	{
	130	return find_rela_by_dest_range(sec, offset, 1);
	131	}
	132
	133	struct symbol find_containing_func(struct section sec, unsigned long offset)
	134	{
	135	struct symbol *func;
	136
a196e171	137	list_for_each_entry(func, &sec->symbol_list, list)
442f04c3 JP	138	if (func->type == STT_FUNC && offset >= func->offset &&
	139	offset < func->offset + func->len)
	140	return func;
	141
	142	return NULL;
	143	}
	144
	145	static int read_sections(struct elf *elf)
	146	{
	147	Elf_Scn *s = NULL;
	148	struct section *sec;
	149	size_t shstrndx, sections_nr;
	150	int i;
	151
	152	if (elf_getshdrnum(elf->elf, &sections_nr)) {
baa41469	153	WARN_ELF("elf_getshdrnum");
442f04c3 JP	154	return -1;
	155	}
	156
	157	if (elf_getshdrstrndx(elf->elf, &shstrndx)) {
baa41469	158	WARN_ELF("elf_getshdrstrndx");
442f04c3 JP	159	return -1;
	160	}
	161
	162	for (i = 0; i < sections_nr; i++) {
	163	sec = malloc(sizeof(*sec));
	164	if (!sec) {
	165	perror("malloc");
	166	return -1;
	167	}
	168	memset(sec, 0, sizeof(*sec));
	169
a196e171 JP	170	INIT_LIST_HEAD(&sec->symbol_list);
a196e171 JP	171	INIT_LIST_HEAD(&sec->rela_list);
042ba73f	172	hash_init(sec->rela_hash);
442f04c3	173
442f04c3 JP	174	s = elf_getscn(elf->elf, i);
442f04c3 JP	175	if (!s) {
baa41469	176	WARN_ELF("elf_getscn");
442f04c3 JP	177	return -1;
	178	}
	179
	180	sec->idx = elf_ndxscn(s);
	181
	182	if (!gelf_getshdr(s, &sec->sh)) {
baa41469	183	WARN_ELF("gelf_getshdr");
442f04c3 JP	184	return -1;
	185	}
	186
	187	sec->name = elf_strptr(elf->elf, shstrndx, sec->sh.sh_name);
	188	if (!sec->name) {
baa41469	189	WARN_ELF("elf_strptr");
442f04c3 JP	190	return -1;
	191	}
	192
df968c93 PV	193	if (sec->sh.sh_size != 0) {
	194	sec->data = elf_getdata(s, NULL);
	195	if (!sec->data) {
	196	WARN_ELF("elf_getdata");
	197	return -1;
	198	}
	199	if (sec->data->d_off != 0 \|\|
	200	sec->data->d_size != sec->sh.sh_size) {
	201	WARN("unexpected data attributes for %s",
	202	sec->name);
	203	return -1;
	204	}
442f04c3	205	}
df968c93	206	sec->len = sec->sh.sh_size;
53038996 PZ	207
	208	list_add_tail(&sec->list, &elf->sections);
	209	hash_add(elf->section_hash, &sec->hash, sec->idx);
ae358196	210	hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
442f04c3 JP	211	}
442f04c3 JP	212
1e11f3fd PZ	213	if (stats)
	214	printf("nr_sections: %lu\n", (unsigned long)sections_nr);
	215
442f04c3 JP	216	/* sanity check, one more call to elf_nextscn() should return NULL */
	217	if (elf_nextscn(elf->elf, s)) {
	218	WARN("section entry mismatch");
	219	return -1;
	220	}
	221
	222	return 0;
	223	}
	224
	225	static int read_symbols(struct elf *elf)
	226	{
13810435	227	struct section symtab, sec;
09f30d83	228	struct symbol sym, pfunc, *alias;
442f04c3 JP	229	struct list_head entry, tmp;
442f04c3 JP	230	int symbols_nr, i;
13810435	231	char *coldstr;
442f04c3 JP	232
	233	symtab = find_section_by_name(elf, ".symtab");
	234	if (!symtab) {
	235	WARN("missing symbol table");
	236	return -1;
	237	}
	238
	239	symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
	240
	241	for (i = 0; i < symbols_nr; i++) {
	242	sym = malloc(sizeof(*sym));
	243	if (!sym) {
	244	perror("malloc");
	245	return -1;
	246	}
	247	memset(sym, 0, sizeof(*sym));
09f30d83	248	alias = sym;
442f04c3 JP	249
	250	sym->idx = i;
	251
baa41469 JP	252	if (!gelf_getsym(symtab->data, i, &sym->sym)) {
baa41469 JP	253	WARN_ELF("gelf_getsym");
442f04c3 JP	254	goto err;
	255	}
	256
	257	sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
	258	sym->sym.st_name);
	259	if (!sym->name) {
baa41469	260	WARN_ELF("elf_strptr");
442f04c3 JP	261	goto err;
	262	}
	263
	264	sym->type = GELF_ST_TYPE(sym->sym.st_info);
	265	sym->bind = GELF_ST_BIND(sym->sym.st_info);
	266
	267	if (sym->sym.st_shndx > SHN_UNDEF &&
	268	sym->sym.st_shndx < SHN_LORESERVE) {
	269	sym->sec = find_section_by_index(elf,
	270	sym->sym.st_shndx);
	271	if (!sym->sec) {
	272	WARN("couldn't find section for symbol %s",
	273	sym->name);
	274	goto err;
	275	}
	276	if (sym->type == STT_SECTION) {
	277	sym->name = sym->sec->name;
	278	sym->sec->sym = sym;
	279	}
	280	} else
	281	sym->sec = find_section_by_index(elf, 0);
	282
	283	sym->offset = sym->sym.st_value;
	284	sym->len = sym->sym.st_size;
	285
	286	/* sorted insert into a per-section list */
a196e171 JP	287	entry = &sym->sec->symbol_list;
a196e171 JP	288	list_for_each_prev(tmp, &sym->sec->symbol_list) {
442f04c3 JP	289	struct symbol *s;
	290
	291	s = list_entry(tmp, struct symbol, list);
	292
	293	if (sym->offset > s->offset) {
	294	entry = tmp;
	295	break;
	296	}
	297
09f30d83	298	if (sym->offset == s->offset) {
e10cd8fe	299	if (sym->len && sym->len == s->len && alias == sym)
09f30d83 PZ	300	alias = s;
	301
	302	if (sym->len >= s->len) {
	303	entry = tmp;
	304	break;
	305	}
442f04c3 JP	306	}
442f04c3 JP	307	}
09f30d83	308	sym->alias = alias;
442f04c3	309	list_add(&sym->list, entry);
65fb11a7	310	hash_add(elf->symbol_hash, &sym->hash, sym->idx);
442f04c3 JP	311	}
442f04c3 JP	312
1e11f3fd PZ	313	if (stats)
	314	printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
	315
13810435 JP	316	/* Create parent/child links for any cold subfunctions */
	317	list_for_each_entry(sec, &elf->sections, list) {
	318	list_for_each_entry(sym, &sec->symbol_list, list) {
22566c16 AS	319	char pname[MAX_NAME_LEN + 1];
22566c16 AS	320	size_t pnamelen;
13810435 JP	321	if (sym->type != STT_FUNC)
	322	continue;
	323	sym->pfunc = sym->cfunc = sym;
bcb6fb5d	324	coldstr = strstr(sym->name, ".cold");
08b393d0 JP	325	if (!coldstr)
	326	continue;
	327
22566c16 AS	328	pnamelen = coldstr - sym->name;
	329	if (pnamelen > MAX_NAME_LEN) {
	330	WARN("%s(): parent function name exceeds maximum length of %d characters",
	331	sym->name, MAX_NAME_LEN);
	332	return -1;
	333	}
	334
	335	strncpy(pname, sym->name, pnamelen);
	336	pname[pnamelen] = '\0';
	337	pfunc = find_symbol_by_name(elf, pname);
08b393d0 JP	338
	339	if (!pfunc) {
	340	WARN("%s(): can't find parent function",
	341	sym->name);
0b9301fb	342	return -1;
08b393d0 JP	343	}
	344
	345	sym->pfunc = pfunc;
	346	pfunc->cfunc = sym;
	347
	348	/*
	349	* Unfortunately, -fnoreorder-functions puts the child
	350	* inside the parent. Remove the overlap so we can
	351	* have sane assumptions.
	352	*
	353	* Note that pfunc->len now no longer matches
	354	* pfunc->sym.st_size.
	355	*/
	356	if (sym->sec == pfunc->sec &&
	357	sym->offset >= pfunc->offset &&
	358	sym->offset + sym->len == pfunc->offset + pfunc->len) {
	359	pfunc->len -= sym->len;
13810435 JP	360	}
	361	}
	362	}
	363
442f04c3 JP	364	return 0;
	365
	366	err:
	367	free(sym);
	368	return -1;
	369	}
	370
	371	static int read_relas(struct elf *elf)
	372	{
	373	struct section *sec;
	374	struct rela *rela;
	375	int i;
	376	unsigned int symndx;
1e11f3fd	377	unsigned long nr_rela, max_rela = 0, tot_rela = 0;
442f04c3 JP	378
	379	list_for_each_entry(sec, &elf->sections, list) {
	380	if (sec->sh.sh_type != SHT_RELA)
	381	continue;
	382
	383	sec->base = find_section_by_name(elf, sec->name + 5);
	384	if (!sec->base) {
	385	WARN("can't find base section for rela section %s",
	386	sec->name);
	387	return -1;
	388	}
	389
	390	sec->base->rela = sec;
	391
1e11f3fd	392	nr_rela = 0;
442f04c3 JP	393	for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
	394	rela = malloc(sizeof(*rela));
	395	if (!rela) {
	396	perror("malloc");
	397	return -1;
	398	}
	399	memset(rela, 0, sizeof(*rela));
	400
baa41469 JP	401	if (!gelf_getrela(sec->data, i, &rela->rela)) {
baa41469 JP	402	WARN_ELF("gelf_getrela");
442f04c3 JP	403	return -1;
	404	}
	405
	406	rela->type = GELF_R_TYPE(rela->rela.r_info);
	407	rela->addend = rela->rela.r_addend;
	408	rela->offset = rela->rela.r_offset;
	409	symndx = GELF_R_SYM(rela->rela.r_info);
	410	rela->sym = find_symbol_by_index(elf, symndx);
e7c2bc37	411	rela->sec = sec;
442f04c3 JP	412	if (!rela->sym) {
	413	WARN("can't find rela entry symbol %d for %s",
	414	symndx, sec->name);
	415	return -1;
	416	}
042ba73f JP	417
	418	list_add_tail(&rela->list, &sec->rela_list);
	419	hash_add(sec->rela_hash, &rela->hash, rela->offset);
1e11f3fd	420	nr_rela++;
442f04c3	421	}
1e11f3fd PZ	422	max_rela = max(max_rela, nr_rela);
	423	tot_rela += nr_rela;
	424	}
	425
	426	if (stats) {
	427	printf("max_rela: %lu\n", max_rela);
	428	printf("tot_rela: %lu\n", tot_rela);
442f04c3 JP	429	}
	430
	431	return 0;
	432	}
	433
8e144797	434	struct elf elf_read(const char name, int flags)
442f04c3 JP	435	{
442f04c3 JP	436	struct elf *elf;
627fce14	437	Elf_Cmd cmd;
442f04c3 JP	438
	439	elf_version(EV_CURRENT);
	440
	441	elf = malloc(sizeof(*elf));
	442	if (!elf) {
	443	perror("malloc");
	444	return NULL;
	445	}
	446	memset(elf, 0, sizeof(*elf));
	447
65fb11a7	448	hash_init(elf->symbol_hash);
53038996	449	hash_init(elf->section_hash);
ae358196	450	hash_init(elf->section_name_hash);
442f04c3 JP	451	INIT_LIST_HEAD(&elf->sections);
442f04c3 JP	452
627fce14	453	elf->fd = open(name, flags);
442f04c3	454	if (elf->fd == -1) {
385d11b1 JP	455	fprintf(stderr, "objtool: Can't open '%s': %s\n",
385d11b1 JP	456	name, strerror(errno));
442f04c3 JP	457	goto err;
	458	}
	459
627fce14 JP	460	if ((flags & O_ACCMODE) == O_RDONLY)
	461	cmd = ELF_C_READ_MMAP;
	462	else if ((flags & O_ACCMODE) == O_RDWR)
	463	cmd = ELF_C_RDWR;
	464	else /* O_WRONLY */
	465	cmd = ELF_C_WRITE;
	466
	467	elf->elf = elf_begin(elf->fd, cmd, NULL);
442f04c3	468	if (!elf->elf) {
baa41469	469	WARN_ELF("elf_begin");
442f04c3 JP	470	goto err;
	471	}
	472
	473	if (!gelf_getehdr(elf->elf, &elf->ehdr)) {
baa41469	474	WARN_ELF("gelf_getehdr");
442f04c3 JP	475	goto err;
	476	}
	477
	478	if (read_sections(elf))
	479	goto err;
	480
	481	if (read_symbols(elf))
	482	goto err;
	483
	484	if (read_relas(elf))
	485	goto err;
	486
	487	return elf;
	488
	489	err:
	490	elf_close(elf);
	491	return NULL;
	492	}
	493
627fce14 JP	494	struct section elf_create_section(struct elf elf, const char *name,
	495	size_t entsize, int nr)
	496	{
	497	struct section sec, shstrtab;
	498	size_t size = entsize * nr;
3c3ea503	499	Elf_Scn *s;
627fce14 JP	500	Elf_Data *data;
	501
	502	sec = malloc(sizeof(*sec));
	503	if (!sec) {
	504	perror("malloc");
	505	return NULL;
	506	}
	507	memset(sec, 0, sizeof(*sec));
	508
	509	INIT_LIST_HEAD(&sec->symbol_list);
	510	INIT_LIST_HEAD(&sec->rela_list);
	511	hash_init(sec->rela_hash);
627fce14	512
627fce14 JP	513	s = elf_newscn(elf->elf);
	514	if (!s) {
	515	WARN_ELF("elf_newscn");
	516	return NULL;
	517	}
	518
	519	sec->name = strdup(name);
	520	if (!sec->name) {
	521	perror("strdup");
	522	return NULL;
	523	}
	524
	525	sec->idx = elf_ndxscn(s);
	526	sec->len = size;
	527	sec->changed = true;
	528
	529	sec->data = elf_newdata(s);
	530	if (!sec->data) {
	531	WARN_ELF("elf_newdata");
	532	return NULL;
	533	}
	534
	535	sec->data->d_size = size;
	536	sec->data->d_align = 1;
	537
	538	if (size) {
	539	sec->data->d_buf = malloc(size);
	540	if (!sec->data->d_buf) {
	541	perror("malloc");
	542	return NULL;
	543	}
	544	memset(sec->data->d_buf, 0, size);
	545	}
	546
	547	if (!gelf_getshdr(s, &sec->sh)) {
	548	WARN_ELF("gelf_getshdr");
	549	return NULL;
	550	}
	551
	552	sec->sh.sh_size = size;
	553	sec->sh.sh_entsize = entsize;
	554	sec->sh.sh_type = SHT_PROGBITS;
	555	sec->sh.sh_addralign = 1;
	556	sec->sh.sh_flags = SHF_ALLOC;
	557
	558
6d77d3b4	559	/* Add section name to .shstrtab (or .strtab for Clang) */
627fce14	560	shstrtab = find_section_by_name(elf, ".shstrtab");
6d77d3b4 SS	561	if (!shstrtab)
6d77d3b4 SS	562	shstrtab = find_section_by_name(elf, ".strtab");
627fce14	563	if (!shstrtab) {
6d77d3b4	564	WARN("can't find .shstrtab or .strtab section");
627fce14 JP	565	return NULL;
	566	}
	567
	568	s = elf_getscn(elf->elf, shstrtab->idx);
	569	if (!s) {
	570	WARN_ELF("elf_getscn");
	571	return NULL;
	572	}
	573
	574	data = elf_newdata(s);
	575	if (!data) {
	576	WARN_ELF("elf_newdata");
	577	return NULL;
	578	}
	579
	580	data->d_buf = sec->name;
	581	data->d_size = strlen(name) + 1;
	582	data->d_align = 1;
	583
	584	sec->sh.sh_name = shstrtab->len;
	585
	586	shstrtab->len += strlen(name) + 1;
	587	shstrtab->changed = true;
	588
53038996 PZ	589	list_add_tail(&sec->list, &elf->sections);
53038996 PZ	590	hash_add(elf->section_hash, &sec->hash, sec->idx);
ae358196	591	hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
53038996	592
627fce14 JP	593	return sec;
	594	}
	595
	596	struct section elf_create_rela_section(struct elf elf, struct section *base)
	597	{
	598	char *relaname;
	599	struct section *sec;
	600
	601	relaname = malloc(strlen(base->name) + strlen(".rela") + 1);
	602	if (!relaname) {
	603	perror("malloc");
	604	return NULL;
	605	}
	606	strcpy(relaname, ".rela");
	607	strcat(relaname, base->name);
	608
	609	sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0);
0998b7a0	610	free(relaname);
627fce14 JP	611	if (!sec)
	612	return NULL;
	613
	614	base->rela = sec;
	615	sec->base = base;
	616
	617	sec->sh.sh_type = SHT_RELA;
	618	sec->sh.sh_addralign = 8;
	619	sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
	620	sec->sh.sh_info = base->idx;
	621	sec->sh.sh_flags = SHF_INFO_LINK;
	622
	623	return sec;
	624	}
	625
	626	int elf_rebuild_rela_section(struct section *sec)
	627	{
	628	struct rela *rela;
	629	int nr, idx = 0, size;
	630	GElf_Rela *relas;
	631
	632	nr = 0;
	633	list_for_each_entry(rela, &sec->rela_list, list)
	634	nr++;
	635
	636	size = nr * sizeof(*relas);
	637	relas = malloc(size);
	638	if (!relas) {
	639	perror("malloc");
	640	return -1;
	641	}
	642
	643	sec->data->d_buf = relas;
	644	sec->data->d_size = size;
	645
	646	sec->sh.sh_size = size;
	647
	648	idx = 0;
	649	list_for_each_entry(rela, &sec->rela_list, list) {
	650	relas[idx].r_offset = rela->offset;
	651	relas[idx].r_addend = rela->addend;
	652	relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type);
	653	idx++;
	654	}
	655
	656	return 0;
	657	}
	658
	659	int elf_write(struct elf *elf)
	660	{
	661	struct section *sec;
	662	Elf_Scn *s;
	663
97dab2ae	664	/* Update section headers for changed sections: */
627fce14 JP	665	list_for_each_entry(sec, &elf->sections, list) {
	666	if (sec->changed) {
	667	s = elf_getscn(elf->elf, sec->idx);
	668	if (!s) {
	669	WARN_ELF("elf_getscn");
	670	return -1;
	671	}
97dab2ae	672	if (!gelf_update_shdr(s, &sec->sh)) {
627fce14 JP	673	WARN_ELF("gelf_update_shdr");
	674	return -1;
	675	}
	676	}
	677	}
	678
97dab2ae JP	679	/* Make sure the new section header entries get updated properly. */
	680	elf_flagelf(elf->elf, ELF_C_SET, ELF_F_DIRTY);
	681
	682	/* Write all changes to the file. */
627fce14 JP	683	if (elf_update(elf->elf, ELF_C_WRITE) < 0) {
	684	WARN_ELF("elf_update");
	685	return -1;
	686	}
	687
	688	return 0;
	689	}
	690
442f04c3 JP	691	void elf_close(struct elf *elf)
	692	{
	693	struct section sec, tmpsec;
	694	struct symbol sym, tmpsym;
	695	struct rela rela, tmprela;
	696
baa41469 JP	697	if (elf->elf)
	698	elf_end(elf->elf);
	699
	700	if (elf->fd > 0)
	701	close(elf->fd);
	702
442f04c3	703	list_for_each_entry_safe(sec, tmpsec, &elf->sections, list) {
a196e171	704	list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
442f04c3	705	list_del(&sym->list);
042ba73f	706	hash_del(&sym->hash);
442f04c3 JP	707	free(sym);
442f04c3 JP	708	}
a196e171	709	list_for_each_entry_safe(rela, tmprela, &sec->rela_list, list) {
442f04c3	710	list_del(&rela->list);
042ba73f	711	hash_del(&rela->hash);
442f04c3 JP	712	free(rela);
	713	}
	714	list_del(&sec->list);
	715	free(sec);
	716	}
baa41469	717
442f04c3 JP	718	free(elf);
442f04c3 JP	719	}