summaryrefslogtreecommitdiff
path: root/findtextrel
diff options
context:
space:
mode:
Diffstat (limited to 'findtextrel')
-rw-r--r--findtextrel/Makefile15
-rw-r--r--findtextrel/findtextrel.1104
-rw-r--r--findtextrel/findtextrel.c417
3 files changed, 536 insertions, 0 deletions
diff --git a/findtextrel/Makefile b/findtextrel/Makefile
new file mode 100644
index 000000000000..4c316eb0b42a
--- /dev/null
+++ b/findtextrel/Makefile
@@ -0,0 +1,15 @@
+# $Id: Makefile 2069 2011-10-26 15:53:48Z jkoshy $
+
+TOP= ..
+
+PROG= findtextrel
+SRCS= findtextrel.c
+
+WARNS?= 6
+
+DPADD= ${LIBELFTC} ${LIBDWARF} ${LIBELF}
+LDADD= -lelftc -ldwarf -lelf
+
+MAN1= findtextrel.1
+
+.include "${TOP}/mk/elftoolchain.prog.mk"
diff --git a/findtextrel/findtextrel.1 b/findtextrel/findtextrel.1
new file mode 100644
index 000000000000..ee88b8ecba00
--- /dev/null
+++ b/findtextrel/findtextrel.1
@@ -0,0 +1,104 @@
+.\" Copyright (c) 2010,2011 Joseph Koshy <jkoshy@users.sourceforge.net>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer
+.\" in this position and unchanged.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.\" $Id: findtextrel.1 2069 2011-10-26 15:53:48Z jkoshy $
+.\"
+.Dd August 25, 2011
+.Os
+.Dt FINDTEXTREL 1
+.Sh NAME
+.Nm findtextrel
+.Nd locate text relocation entries in position independent ELF executables
+.Sh SYNOPSIS
+.Nm
+.Op Fl V
+.Op Fl H
+.Op Ar
+.Sh DESCRIPTION
+The
+.Nm
+utility displays information about text relocations in ELF objects
+containing position independent code.
+.Pp
+Text relocations are usually undesirable because they require that the
+text sections of objects be modified at load time, preventing the
+sharing of text sections across multiple processes using a dynamic
+shared object.
+.Pp
+Arguments
+.Ar
+name ELF executables to be examined.
+If no files are specified, the
+.Nm
+utility will examine the file
+.Pa a.out
+in the current directory.
+.Pp
+The
+.Nm
+utility recognizes the following options:
+.Bl -tag -width indent
+.It Fl H
+Print a brief help message.
+.It Fl V
+Print a version identifier and exit.
+.El
+.Sh EXIT STATUS
+.Ex -std
+.Sh EXAMPLES
+To list text relocations in an object, use:
+.Bd -literal -offset indent
+% findtextrel a.out
+a.out: ELF object contains text relocation records:
+a.out: off: 0x530, func: main, file: a.c, line: 5
+.Ed
+.Sh DIAGNOSTICS
+The
+.Nm
+may issue the following diagnostics:
+.Bl -diag
+.It "ELF object is not a DSO/PIE"
+The ELF executable specified by argument
+.Ar object
+was not a position independent executable.
+.It "ELF object does not contain a text relocation"
+The ELF executable specified by argument
+.Ar object
+contained no text relocations.
+.El
+.Sh SEE ALSO
+.Xr addr2line 1 ,
+.Xr nm 1 ,
+.Xr readelf 1
+.Sh HISTORY
+A
+.Nm
+utility first appeared in the
+.Nm elfutils
+toolset from Red Hat, Inc.
+.Sh AUTHORS
+This implementation of the
+.Nm
+utility was created by
+.An "Kai Wang" Aq kaiwang27@users.sourceforge.net .
diff --git a/findtextrel/findtextrel.c b/findtextrel/findtextrel.c
new file mode 100644
index 000000000000..a744ca5b0b13
--- /dev/null
+++ b/findtextrel/findtextrel.c
@@ -0,0 +1,417 @@
+/*-
+ * Copyright (c) 2010 Kai Wang
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+#include <sys/param.h>
+#include <err.h>
+#include <dwarf.h>
+#include <fcntl.h>
+#include <gelf.h>
+#include <getopt.h>
+#include <libdwarf.h>
+#include <libelftc.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "_elftc.h"
+
+ELFTC_VCSID("$Id: findtextrel.c 2185 2011-11-19 16:07:16Z jkoshy $");
+
+static struct option longopts[] = {
+ {"help", no_argument, NULL, 'H'},
+ {"version", no_argument, NULL, 'V'},
+ {NULL, 0, NULL, 0}
+};
+
+#define USAGE_MESSAGE "\
+Usage: %s [options] [files...]\n\
+ Show text relocations present in position independent code.\n\n\
+ Options:\n\
+ -H Print a help message.\n\
+ -V Print a version identifier and exit.\n"
+
+static void
+usage(void)
+{
+ (void) fprintf(stderr, USAGE_MESSAGE, ELFTC_GETPROGNAME());
+ exit(1);
+}
+
+static void
+version(void)
+{
+ (void) printf("%s (%s)\n", ELFTC_GETPROGNAME(), elftc_version());
+ exit(0);
+}
+
+static const char *
+find_symbol(const char *fn, Elf *e, Elf_Data *d, GElf_Shdr *sh, uintmax_t off)
+{
+ GElf_Sym sym;
+ const char *name;
+ int i, len;
+
+ len = d->d_size / sh->sh_entsize;
+ for (i = 0; i < len; i++) {
+ if (gelf_getsym(d, i, &sym) != &sym) {
+ warnx("%s: gelf_getsym() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
+ continue;
+ if (off >= sym.st_value && off < sym.st_value + sym.st_size) {
+ name = elf_strptr(e, sh->sh_link, sym.st_name);
+ if (name == NULL)
+ warnx("%s: elf_strptr() failed: %s", fn,
+ elf_errmsg(-1));
+ return (name);
+ }
+ }
+
+ return (NULL);
+}
+
+static void
+report_textrel(const char *fn, Elf *e, Dwarf_Debug dbg, uintmax_t off,
+ int *textrel)
+{
+ Dwarf_Die die;
+ Dwarf_Line *lbuf;
+ Dwarf_Error de;
+ Dwarf_Half tag;
+ Dwarf_Unsigned lopc, hipc, lineno, plineno;
+ Dwarf_Signed lcount;
+ Dwarf_Addr lineaddr, plineaddr;
+ Elf_Scn *scn;
+ Elf_Data *d;
+ GElf_Shdr sh;
+ const char *name;
+ char *file, *pfile;
+ int elferr, found, i, ret;
+
+ if (!*textrel) {
+ printf("%s: ELF object contains text relocation records:\n",
+ fn);
+ *textrel = 1;
+ }
+
+ printf("%s: off: %#jx", fn, off);
+
+ found = 0;
+ scn = NULL;
+ while ((scn = elf_nextscn(e, scn)) != NULL) {
+ if (gelf_getshdr(scn, &sh) == NULL) {
+ warnx("%s: gelf_getshdr() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ if (sh.sh_type != SHT_DYNSYM &&
+ sh.sh_type != SHT_SYMTAB)
+ continue;
+ (void) elf_errno();
+ if ((d = elf_getdata(scn, NULL)) == NULL) {
+ elferr = elf_errno();
+ if (elferr != 0)
+ warnx("%s: elf_getdata() failed: %s",
+ fn, elf_errmsg(-1));
+ continue;
+ }
+ if (d->d_size <= 0)
+ continue;
+ if ((name = find_symbol(fn, e, d, &sh, off)) != NULL) {
+ printf(", func: %s", name);
+ break;
+ }
+ }
+ elferr = elf_errno();
+ if (elferr != 0)
+ warnx("%s: elf_nextscn() failed: %s", fn,
+ elf_errmsg(elferr));
+
+ if (dbg == NULL)
+ goto done;
+
+ /*
+ * More verbose output if debugging information is available.
+ */
+
+ while ((ret = dwarf_next_cu_header(dbg, NULL, NULL, NULL, NULL, NULL,
+ &de)) == DW_DLV_OK) {
+ die = NULL;
+ while (dwarf_siblingof(dbg, die, &die, &de) == DW_DLV_OK) {
+ if (dwarf_tag(die, &tag, &de) != DW_DLV_OK)
+ goto out;
+ /* XXX: What about DW_TAG_partial_unit? */
+ if (tag == DW_TAG_compile_unit)
+ break;
+ }
+ if (die == NULL) {
+ /* Could not find DW_TAG_compile_unit DIE. */
+ goto out;
+ }
+ if (!dwarf_attrval_unsigned(die, DW_AT_low_pc, &lopc, &de) &&
+ !dwarf_attrval_unsigned(die, DW_AT_high_pc, &hipc, &de)) {
+ /*
+ * Check if the address falls into the PC range of
+ * this CU.
+ */
+ if (off < lopc || off >= hipc)
+ continue;
+ } else
+ continue;
+
+ if (dwarf_srclines(die, &lbuf, &lcount, &de) != DW_DLV_OK)
+ continue;
+
+ found = 0;
+ plineaddr = ~0ULL;
+ plineno = 0;
+ pfile = NULL;
+ for (i = 0; i < lcount; i++) {
+ if (dwarf_lineaddr(lbuf[i], &lineaddr, &de))
+ continue;
+ if (dwarf_lineno(lbuf[i], &lineno, &de))
+ continue;
+ if (dwarf_linesrc(lbuf[i], &file, &de))
+ continue;
+ if (off == lineaddr) {
+ found = 1;
+ goto out;
+ } else if (off < lineaddr && off > plineaddr) {
+ lineno = plineno;
+ file = pfile;
+ found = 1;
+ goto out;
+ }
+ plineaddr = lineaddr;
+ plineno = lineno;
+ pfile = file;
+ }
+ }
+
+out:
+ if (found)
+ printf(", file: %s, line: %ju", file, lineno);
+
+ /*
+ * Reset internal CU pointer, so we will start from the first CU
+ * next round.
+ */
+ while (ret != DW_DLV_NO_ENTRY) {
+ if (ret == DW_DLV_ERROR)
+ break;
+ ret = dwarf_next_cu_header(dbg, NULL, NULL, NULL, NULL, NULL,
+ &de);
+ }
+
+done:
+ putchar('\n');
+}
+
+static void
+examine_reloc(const char *fn, Elf *e, Elf_Data *d, GElf_Shdr *sh, GElf_Phdr *ph,
+ int phnum, Dwarf_Debug dbg, int *textrel)
+{
+ GElf_Rel rel;
+ GElf_Rela rela;
+ int i, j, len;
+
+ len = d->d_size / sh->sh_entsize;
+ for (i = 0; i < len; i++) {
+ if (sh->sh_type == SHT_REL) {
+ if (gelf_getrel(d, i, &rel) != &rel) {
+ warnx("%s: gelf_getrel() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ } else {
+ if (gelf_getrela(d, i, &rela) != &rela) {
+ warnx("%s: gelf_getrela() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ }
+ for (j = 0; j < phnum; j++) {
+ if (sh->sh_type == SHT_REL) {
+ if (rel.r_offset >= ph[j].p_offset &&
+ rel.r_offset < ph[j].p_offset +
+ ph[j].p_filesz)
+ report_textrel(fn, e, dbg,
+ (uintmax_t) rel.r_offset, textrel);
+ } else {
+ if (rela.r_offset >= ph[j].p_offset &&
+ rela.r_offset < ph[j].p_offset +
+ ph[j].p_filesz)
+ report_textrel(fn, e, dbg,
+ (uintmax_t) rela.r_offset, textrel);
+ }
+ }
+ }
+}
+
+static void
+find_textrel(const char *fn)
+{
+ Elf *e;
+ Elf_Scn *scn;
+ Elf_Data *d;
+ GElf_Ehdr eh;
+ GElf_Phdr *ph;
+ GElf_Shdr sh;
+ Dwarf_Debug dbg;
+ Dwarf_Error de;
+ int elferr, fd, i, phnum, textrel;
+
+ e = NULL;
+ ph = NULL;
+ dbg = NULL;
+
+ if ((fd = open(fn, O_RDONLY)) < 0) {
+ warn("%s", fn);
+ return;
+ }
+
+ if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
+ warnx("%s: elf_begin() failed: %s", fn, elf_errmsg(-1));
+ goto exit;
+ }
+
+ if (gelf_getehdr(e, &eh) != &eh) {
+ warnx("%s: gelf_getehdr() failed: %s", fn, elf_errmsg(-1));
+ goto exit;
+ }
+
+ if (eh.e_type != ET_DYN) {
+ printf("%s: ELF object is not a DSO/PIE\n", fn);
+ goto exit;
+ }
+
+ /*
+ * Search program header for executable segments.
+ */
+
+ if (eh.e_phnum == 0) {
+ printf("%s: ELF object does not contain program headers\n",
+ fn);
+ goto exit;
+ }
+ if ((ph = calloc(eh.e_phnum, sizeof(GElf_Phdr))) == NULL)
+ err(EXIT_FAILURE, "calloc failed");
+ phnum = 0;
+ for (i = 0; (unsigned) i < eh.e_phnum; i++) {
+ if (gelf_getphdr(e, i, &ph[phnum]) != &ph[phnum]) {
+ warnx("%s: gelf_getphdr() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ if (ph[phnum].p_flags & PF_X)
+ phnum++;
+ }
+ if (phnum == 0) {
+ printf("%s: ELF object does not contain any executable "
+ "segment\n", fn);
+ goto exit;
+ }
+
+ /* Check if debugging information is available. */
+ if (dwarf_elf_init(e, DW_DLC_READ, NULL, NULL, &dbg, &de))
+ dbg = NULL;
+
+ /*
+ * Search relocation records for possible text relocations.
+ */
+ textrel = 0;
+ scn = NULL;
+ while ((scn = elf_nextscn(e, scn)) != NULL) {
+ if (gelf_getshdr(scn, &sh) == NULL) {
+ warnx("%s: gelf_getshdr() failed: %s", fn,
+ elf_errmsg(-1));
+ continue;
+ }
+ if (sh.sh_type == SHT_REL || sh.sh_type == SHT_RELA) {
+ (void) elf_errno();
+ if ((d = elf_getdata(scn, NULL)) == NULL) {
+ elferr = elf_errno();
+ if (elferr != 0)
+ warnx("%s: elf_getdata() failed: %s",
+ fn, elf_errmsg(-1));
+ continue;
+ }
+ if (d->d_size <= 0)
+ continue;
+ examine_reloc(fn, e, d, &sh, ph, phnum, dbg, &textrel);
+ }
+ }
+ elferr = elf_errno();
+ if (elferr != 0)
+ warnx("%s: elf_nextscn() failed: %s", fn, elf_errmsg(elferr));
+
+ if (!textrel)
+ printf("%s: ELF object does not contain a text relocation\n",
+ fn);
+
+exit:
+ if (dbg)
+ dwarf_finish(dbg, &de);
+ if (ph)
+ free(ph);
+ if (e)
+ (void) elf_end(e);
+ close(fd);
+}
+
+int
+main(int argc, char **argv)
+{
+ int i, opt;
+
+ if (elf_version(EV_CURRENT) == EV_NONE)
+ errx(EXIT_FAILURE, "elf_version(): %s", elf_errmsg(-1));
+
+ while ((opt = getopt_long(argc, argv, "HV", longopts, NULL)) != -1) {
+ switch (opt) {
+ case 'H':
+ usage();
+ case 'V':
+ version();
+ default:
+ usage();
+ }
+ }
+
+ argv += optind;
+ argc -= optind;
+
+ if (argc > 0)
+ for (i = 0; i < argc; i++)
+ find_textrel(argv[i]);
+ else
+ find_textrel("a.out");
+
+ exit(0);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-09 23:11:45 +0000