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![Conrad Meyer](/assets/img/avatar_default.png)
Drop portions that are unlit or redundant with llvm-libunwind: builtin.c, unwind.h, and unwind_arm_ehabi_stub.c. This code should now work with -fPIE binaries, should we choose to build any that way. When backtrace() array is full, signal an error so the underlying Itanium-style C++ exception handling library (llvm-libunwind) knows to stop tracing instead of continuing. (It should stop on its own when it finishes unwinding, so this is mostly an extra seatbelt against an infinite loop bug in the unwinder.)
226 lines
5.5 KiB
C
226 lines
5.5 KiB
C
/* $NetBSD: symtab.c,v 1.5 2016/04/20 14:00:16 christos Exp $ */
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/*-
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* Copyright (c) 2012 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Christos Zoulas.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: symtab.c,v 1.5 2016/04/20 14:00:16 christos Exp $");
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <err.h>
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#include <dlfcn.h>
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#include <libelf.h>
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#include <gelf.h>
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#ifndef ELF_ST_BIND
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#define ELF_ST_BIND(x) ((x) >> 4)
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#endif
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#ifndef ELF_ST_TYPE
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#define ELF_ST_TYPE(x) (((unsigned int)x) & 0xf)
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#endif
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#include "symtab.h"
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struct symbol {
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char *st_name;
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uintptr_t st_value;
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uintptr_t st_info;
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};
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struct symtab {
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size_t nsymbols;
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struct symbol *symbols;
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bool ispie;
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};
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static int
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address_compare(const void *a, const void *b)
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{
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const struct symbol *sa = a;
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const struct symbol *sb = b;
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return (int)(intmax_t)(sa->st_value - sb->st_value);
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}
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void
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symtab_destroy(symtab_t *s)
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{
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if (s == NULL)
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return;
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for (size_t i = 0; i < s->nsymbols; i++)
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free(s->symbols[i].st_name);
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free(s->symbols);
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free(s);
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}
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symtab_t *
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symtab_create(int fd, int bind, int type)
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{
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Elf *elf;
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symtab_t *st;
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Elf_Scn *scn = NULL;
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GElf_Ehdr ehdr;
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if (elf_version(EV_CURRENT) == EV_NONE) {
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warnx("Elf Library is out of date.");
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return NULL;
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}
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elf = elf_begin(fd, ELF_C_READ, NULL);
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if (elf == NULL) {
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warnx("Error opening elf file: %s", elf_errmsg(elf_errno()));
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return NULL;
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}
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st = calloc(1, sizeof(*st));
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if (st == NULL) {
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warnx("Error allocating symbol table");
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elf_end(elf);
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return NULL;
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}
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if (gelf_getehdr(elf, &ehdr) == NULL) {
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warnx("Error getting ELF Ehdr");
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elf_end(elf);
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return NULL;
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}
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st->ispie = ehdr.e_type == ET_DYN;
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while ((scn = elf_nextscn(elf, scn)) != NULL) {
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GElf_Shdr shdr;
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Elf_Data *edata;
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size_t ns;
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struct symbol *s;
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gelf_getshdr(scn, &shdr);
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if(shdr.sh_type != SHT_SYMTAB)
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continue;
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edata = elf_getdata(scn, NULL);
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ns = shdr.sh_size / shdr.sh_entsize;
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s = calloc(ns, sizeof(*s));
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if (s == NULL) {
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warn("Cannot allocate %zu symbols", ns);
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goto out;
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}
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st->symbols = s;
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for (size_t i = 0; i < ns; i++) {
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GElf_Sym sym;
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gelf_getsym(edata, (int)i, &sym);
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#ifdef SYMTAB_DEBUG
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fprintf(stderr, "%s: %s@%#jx=%d,%d\n", __func__,
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elf_strptr(elf, shdr.sh_link, sym.st_name),
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(uintmax_t)sym.st_value, ELF_ST_BIND(sym.st_info),
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ELF_ST_TYPE(sym.st_info));
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#endif
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if (bind != -1 &&
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(unsigned)bind != ELF_ST_BIND(sym.st_info))
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continue;
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if (type != -1 &&
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(unsigned)type != ELF_ST_TYPE(sym.st_info))
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continue;
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s->st_value = sym.st_value;
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s->st_info = sym.st_info;
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s->st_name = strdup(
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elf_strptr(elf, shdr.sh_link, sym.st_name));
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if (s->st_name == NULL)
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goto out;
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s++;
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}
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st->nsymbols = s - st->symbols;
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if (st->nsymbols == 0) {
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warnx("No symbols found");
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goto out;
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}
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qsort(st->symbols, st->nsymbols, sizeof(*st->symbols),
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address_compare);
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elf_end(elf);
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return st;
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}
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out:
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symtab_destroy(st);
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elf_end(elf);
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return NULL;
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}
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int
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symtab_find(const symtab_t *st, const void *p, Dl_info *dli)
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{
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struct symbol *s = st->symbols;
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size_t ns = st->nsymbols;
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size_t hi = ns;
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size_t lo = 0;
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size_t mid = ns / 2;
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uintptr_t fbase = st->ispie ? (uintptr_t)dli->dli_fbase : 0;
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uintptr_t dd, sd, me = (uintptr_t)p - fbase;
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uintptr_t ad = (uintptr_t)dli->dli_saddr - fbase;
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#ifdef SYMTAB_DEBUG
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fprintf(stderr, "%s: [fbase=%#jx, saddr=%p, me=%#jx ad=%#jx]\n",
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__func__, (uintmax_t)fbase, dli->dli_saddr, (uintmax_t)me,
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(uintmax_t)ad);
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#endif
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for (;;) {
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if (s[mid].st_value < me)
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lo = mid;
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else if (s[mid].st_value > me)
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hi = mid;
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else
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break;
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if (hi - lo == 1) {
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mid = lo;
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break;
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}
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mid = (hi + lo) / 2;
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}
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dd = me - ad;
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sd = me - s[mid].st_value;
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if (dd > sd) {
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dli->dli_saddr = (void *)s[mid].st_value;
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dli->dli_sname = s[mid].st_name;
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#ifdef SYMTAB_DEBUG
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fprintf(stderr, "%s: me=%#jx -> [%#jx, %s]\n", __func__,
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(uintmax_t)me, (uintmax_t)sd, dli->dli_sname);
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#endif
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}
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#ifdef SYMTAB_DEBUG
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else
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fprintf(stderr, "%s: %#jx -> [%#jx, ***]\n", __func__,
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(uintmax_t)me, (uintmax_t)sd);
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#endif
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return 1;
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}
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