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unwind: add libdw as an unwinder

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Implement alternative libdw-based unwinder for stack tracing.
Add --with-libdw configure option to control whether libdw can be used
as an unwinder.

* m4/st_libdw.m4: New file.
* m4/st_stacktrace.m4 (st_STACKTRACE): Invoke st_ARG_LIBDW and st_LIBDW,
check for mutually exclusive configure options,
(AM_CONDITIONAL): Add USE_LIBDW.
* unwind-libdw.c: New file.
* Makefile.am [USE_LIBDW] (strace_SOURCES): Append unwind-libdw.c.
[USE_LIBDW] (strace_CPPFLAGS): Append $(libdw_CPPFLAGS).
[USE_LIBDW] (strace_CFLAGS): Append $(libdw_CFLAGS).
[USE_LIBDW] (strace_LDFLAGS): Append $(libdw_LDFLAGS).
[USE_LIBDW] (strace_LDADD): Append $(libdw_LIBS).
* NEWS: Mention this improvement.

Closes: https://github.com/strace/strace/issues/12
Closes: https://github.com/strace/strace/issues/13
Co-Authored-by: Mark Wielaard <mjw@redhat.com>
Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Masatake YAMATO <yamato@redhat.com>
This commit is contained in:
Masatake YAMATO 2018-03-14 02:28:12 +09:00 committed by Dmitry V. Levin
parent c78af2c9cf
commit ddb5a4ba73
5 changed files with 328 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Makefile.am
View File

@ -353,6 +353,13 @@ strace_SOURCES_check = bpf_attr_check.c
if ENABLE_STACKTRACE
strace_SOURCES += unwind.c unwind.h
if USE_LIBDW
strace_SOURCES += unwind-libdw.c
strace_CPPFLAGS += $(libdw_CPPFLAGS)
strace_CFLAGS += $(libdw_CFLAGS)
strace_LDFLAGS += $(libdw_LDFLAGS)
strace_LDADD += $(libdw_LIBS)
endif
if USE_LIBUNWIND
strace_SOURCES += unwind-libunwind.c
strace_CPPFLAGS += $(libunwind_CPPFLAGS)

6
NEWS
View File

@ -1,6 +1,12 @@
Noteworthy changes in release ?.?? (????-??-??)
===============================================
* Improvements
* Implemented libdw backend for -k option, configured at build time
using --with-libdw option.
Whether -k option is compiled is now configured at build time
using --enable-stacktrace option.
Noteworthy changes in release 4.22 (2018-04-05)
===============================================

123
m4/st_libdw.m4 Normal file
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@ -0,0 +1,123 @@
#!/usr/bin/m4
#
# Copyright (c) 2018 The strace developers.
# 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.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
AC_DEFUN([st_ARG_LIBDW], [dnl
AC_ARG_WITH([libdw],
[AS_HELP_STRING([--with-libdw],
[use libdw to implement stack tracing support]
)
],
[case "${withval}" in
yes|no|check) ;;
*)
AC_MSG_ERROR([Use pkg-config variables instead of giving path to --with-libdw])
;;
esac
],
[with_libdw=check]
)
])
AC_DEFUN([st_LIBDW], [dnl
: ${libdw_CPPFLAGS=}
: ${libdw_CFLAGS=}
: ${libdw_LDFLAGS=}
: ${libdw_LIBS=}
have_libdw=
AS_IF([test "x$with_libdw" != xno],
[
dnl If libdw.pc is not available, then libdw is not new enough
dnl to be used for stack tracing.
AS_IF([test "x$with_libdw" = xyes],
[PKG_CHECK_MODULES([libdw], [libdw], [have_libdw=yes])],
[PKG_CHECK_MODULES([libdw], [libdw], [have_libdw=yes], [:])]
)
]
)
AS_IF([test "x$have_libdw" = xyes],
[
dnl If libdw.pc is available, check whether libdw can be used
dnl for stack tracing.
saved_CPPFLAGS="$CPPFLAGS"
saved_CFLAGS="$CFLAGS"
CPPFLAGS="$CPPFLAGS $libdw_CPPFLAGS"
CFLAGS="$CFLAGS $libdw_CFLAGS"
AC_CHECK_HEADERS([elfutils/libdwfl.h],
[
AC_MSG_CHECKING([for dwfl_linux_proc_attach in libdw])
saved_LDFLAGS="$LDFLAGS"
saved_LIBS="$LIBS"
LDFLAGS="$LDFLAGS $libdw_LDFLAGS"
LIBS="$LIBS $libdw_LIBS"
AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <elfutils/libdwfl.h>]],
[[return dwfl_linux_proc_attach(0, 0, 0)]]
)
],
[AC_MSG_RESULT([yes])],
[AC_MSG_RESULT([no])
AS_IF([test "x$with_libdw" = xyes],
[AC_MSG_FAILURE([failed to find dwfl_linux_proc_attach in libdw])],
)
have_libdw=
]
)
LIBS="$saved_LIBS"
LDFLAGS="$saved_LDFLAGS"
],
[AS_IF([test "x$with_libdw" = xyes],
[AC_MSG_FAILURE([failed to find elfutils/libdwfl.h])]
)
have_libdw=
]
)
CFLAGS="$saved_CFLAGS"
CPPFLAGS="$saved_CPPFLAGS"
]
)
AS_IF([test "x$have_libdw" = xyes],
[use_unwinder=libdw
AC_DEFINE([USE_LIBDW], 1,
[Whether to use libdw for stack tracing]
)
AC_SUBST(libdw_CPPFLAGS)
AC_SUBST(libdw_CFLAGS)
AC_SUBST(libdw_LDFLAGS)
AC_SUBST(libdw_LIBS)
]
)
])

15
m4/st_stacktrace.m4
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@ -42,13 +42,24 @@ use_unwinder=
dnl Whether to enable stack tracing support?
AS_IF([test x"$enable_stacktrace" != xno],
[st_ARG_LIBUNWIND
[st_ARG_LIBDW
st_ARG_LIBUNWIND
AS_IF([test "x$with_libdw" = xyes && test "x$with_libunwind" = xyes],
[AC_MSG_ERROR([--with-libdw=yes and --with-libunwind=yes are mutually exclusive])],
[test "x$with_libdw" = xyes], [with_libunwind=no],
[test "x$with_libunwind" = xyes], [with_libdw=no]
)
AS_IF([test "x$use_unwinder" = x], [st_LIBDW])
AS_IF([test "x$use_unwinder" = x], [st_LIBUNWIND])
AS_IF([test x"$enable_stacktrace$use_unwinder" = xyes],
[AC_MSG_ERROR([stack tracing support requires an unwinder])])])
[AC_MSG_ERROR([stack tracing support requires an unwinder])]
)
]
)
AC_MSG_CHECKING([whether to enable stack tracing support])
AM_CONDITIONAL([ENABLE_STACKTRACE], [test "x$use_unwinder" != x])
AM_CONDITIONAL([USE_LIBDW], [test "x$use_unwinder" = xlibdw])
AM_CONDITIONAL([USE_LIBUNWIND], [test "x$use_unwinder" = xlibunwind])
use_libiberty=

179
unwind-libdw.c Normal file
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@ -0,0 +1,179 @@
/*
* This file is based on a patch submitted by Mark Wielaard <mjw@redhat.com>
* to ltrace project:
* https://anonscm.debian.org/cgit/collab-maint/ltrace.git/commit/?id=dfefa9f057857735a073ea655f5cb34351032c8e
*
* It was re-licensed for strace by the original author:
* https://lists.strace.io/pipermail/strace-devel/2018-March/008063.html
*
* Copyright (c) 2014-2018 Mark Wielaard <mjw@redhat.com>
* Copyright (c) 2018 Masatake YAMATO <yamato@redhat.com>
* Copyright (c) 2018 The strace developers.
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
*/
#include "defs.h"
#include "unwind.h"
#include "mmap_cache.h"
#include <elfutils/libdwfl.h>
static void *
tcb_init(struct tcb *tcp)
{
static const Dwfl_Callbacks proc_callbacks = {
.find_elf = dwfl_linux_proc_find_elf,
.find_debuginfo = dwfl_standard_find_debuginfo
};
Dwfl *dwfl = dwfl_begin(&proc_callbacks);
if (dwfl == NULL) {
error_msg("dwfl_begin: %s\n", dwfl_errmsg(-1));
return NULL;
}
int r = dwfl_linux_proc_attach(dwfl, tcp->pid, true);
if (r) {
const char *msg = NULL;
if (r < 0)
msg = dwfl_errmsg(-1);
else if (r > 0)
msg = strerror(r);
error_msg("dwfl_linux_proc_attach returned an error"
" for process %d: %s\n", tcp->pid, msg);
dwfl_end(dwfl);
return NULL;
}
return dwfl;
}
static void
tcb_fin(struct tcb *tcp)
{
if (tcp->unwind_ctx)
dwfl_end(tcp->unwind_ctx);
}
struct frame_user_data {
unwind_call_action_fn call_action;
unwind_error_action_fn error_action;
void *data;
int stack_depth;
};
static int
frame_callback(Dwfl_Frame *state, void *arg)
{
struct frame_user_data *user_data = arg;
Dwarf_Addr pc;
bool isactivation;
if (!dwfl_frame_pc(state, &pc, &isactivation)) {
/* Propagate the error to the caller. */
return -1;
}
if (!isactivation)
pc--;
Dwfl *dwfl = dwfl_thread_dwfl(dwfl_frame_thread(state));
Dwfl_Module *mod = dwfl_addrmodule(dwfl, pc);
GElf_Off off = 0;
if (mod != NULL) {
const char *modname = NULL;
const char *symname = NULL;
GElf_Sym sym;
Dwarf_Addr true_offset = pc;
modname = dwfl_module_info(mod, NULL, NULL, NULL, NULL,
NULL, NULL, NULL);
symname = dwfl_module_addrinfo(mod, pc, &off, &sym,
NULL, NULL, NULL);
dwfl_module_relocate_address(mod, &true_offset);
user_data->call_action(user_data->data, modname, symname,
off, true_offset);
}
/* Max number of frames to print reached? */
if (user_data->stack_depth-- == 0)
return DWARF_CB_ABORT;
return DWARF_CB_OK;
}
static void
tcb_walk(struct tcb *tcp,
unwind_call_action_fn call_action,
unwind_error_action_fn error_action,
void *data)
{
Dwfl *dwfl = tcp->unwind_ctx;
if (!dwfl)
return;
struct frame_user_data user_data = {
.call_action = call_action,
.error_action = error_action,
.data = data,
.stack_depth = 256,
};
int r = dwfl_getthread_frames(dwfl, tcp->pid, frame_callback,
&user_data);
if (r)
error_action(data,
r < 0 ? dwfl_errmsg(-1) : "too many stack frames",
0);
}
static void
tcb_flush_cache(struct tcb *tcp)
{
Dwfl *dwfl = tcp->unwind_ctx;
if (!dwfl)
return;
int r = dwfl_linux_proc_report(dwfl, tcp->pid);
if (r < 0)
error_msg("dwfl_linux_proc_report returned an error"
" for pid %d: %s", tcp->pid, dwfl_errmsg(-1));
else if (r > 0)
error_msg("dwfl_linux_proc_report returned an error"
" for pid %d", tcp->pid);
else if (dwfl_report_end(dwfl, NULL, NULL) != 0)
error_msg("dwfl_report_end returned an error"
" for pid %d: %s", tcp->pid, dwfl_errmsg(-1));
}
const struct unwind_unwinder_t unwinder = {
.name = "libdw",
.init = NULL,
.tcb_init = tcb_init,
.tcb_fin = tcb_fin,
.tcb_walk = tcb_walk,
.tcb_flush_cache = tcb_flush_cache,
};