elf.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 4. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#if 0
33/* From: */
34#ifndef lint
35static char sccsid[] = "@(#)gprof.c	8.1 (Berkeley) 6/6/93";
36#endif /* not lint */
37#endif
38
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: stable/11/usr.bin/gprof/elf.c 330897 2018-03-14 03:19:51Z eadler $");
41
42#include <sys/types.h>
43#include <sys/mman.h>
44#include <sys/stat.h>
45#include <machine/elf.h>
46
47#include <err.h>
48#include <fcntl.h>
49#include <string.h>
50#include <unistd.h>
51
52#include "gprof.h"
53
54static bool wantsym(const Elf_Sym *, const char *);
55
56/* Things which get -E excluded by default. */
57static char	*excludes[] = { ".mcount", "_mcleanup", NULL };
58
59int
60elf_getnfile(const char *filename, char ***defaultEs)
61{
62    int fd;
63    Elf_Ehdr h;
64    struct stat s;
65    void *mapbase;
66    const char *base;
67    const Elf_Shdr *shdrs;
68    const Elf_Shdr *sh_symtab;
69    const Elf_Shdr *sh_strtab;
70    const char *strtab;
71    const Elf_Sym *symtab;
72    int symtabct;
73    int i;
74
75    if ((fd = open(filename, O_RDONLY)) == -1)
76	err(1, "%s", filename);
77    if (read(fd, &h, sizeof h) != sizeof h || !IS_ELF(h)) {
78	close(fd);
79	return -1;
80    }
81    if (fstat(fd, &s) == -1)
82	err(1, "cannot fstat %s", filename);
83    if ((mapbase = mmap(0, s.st_size, PROT_READ, MAP_SHARED, fd, 0)) ==
84      MAP_FAILED)
85	err(1, "cannot mmap %s", filename);
86    close(fd);
87
88    base = (const char *)mapbase;
89    shdrs = (const Elf_Shdr *)(base + h.e_shoff);
90
91    /* Find the symbol table and associated string table section. */
92    for (i = 1;  i < h.e_shnum;  i++)
93	if (shdrs[i].sh_type == SHT_SYMTAB)
94	    break;
95    if (i == h.e_shnum)
96	errx(1, "%s has no symbol table", filename);
97    sh_symtab = &shdrs[i];
98    sh_strtab = &shdrs[sh_symtab->sh_link];
99
100    symtab = (const Elf_Sym *)(base + sh_symtab->sh_offset);
101    symtabct = sh_symtab->sh_size / sh_symtab->sh_entsize;
102    strtab = (const char *)(base + sh_strtab->sh_offset);
103
104    /* Count the symbols that we're interested in. */
105    nname = 0;
106    for (i = 1;  i < symtabct;  i++)
107	if (wantsym(&symtab[i], strtab))
108	    nname++;
109
110    /* Allocate memory for them, plus a terminating entry. */
111    if ((nl = (nltype *)calloc(nname + 1, sizeof(nltype))) == NULL)
112	errx(1, "insufficient memory for symbol table");
113
114    /* Read them in. */
115    npe = nl;
116    for (i = 1;  i < symtabct;  i++) {
117	const Elf_Sym *sym = &symtab[i];
118
119	if (wantsym(sym, strtab)) {
120	    npe->value = sym->st_value;
121	    npe->name = strtab + sym->st_name;
122	    npe++;
123	}
124    }
125    npe->value = -1;
126
127    *defaultEs = excludes;
128    return 0;
129}
130
131static bool
132wantsym(const Elf_Sym *sym, const char *strtab)
133{
134    int type;
135    int bind;
136
137    type = ELF_ST_TYPE(sym->st_info);
138    bind = ELF_ST_BIND(sym->st_info);
139
140    if (type != STT_FUNC ||
141      (aflag && bind == STB_LOCAL) ||
142      (uflag && strchr(strtab + sym->st_name, '.') != NULL))
143	return 0;
144
145    return 1;
146}
147