From patchwork Sun Feb 23 05:43:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 1242582 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=R4oeECZU; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48QDdG4Vvyz9sR4 for ; Sun, 23 Feb 2020 16:43:29 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726057AbgBWFn2 (ORCPT ); Sun, 23 Feb 2020 00:43:28 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:29266 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725978AbgBWFn1 (ORCPT ); Sun, 23 Feb 2020 00:43:27 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01N5ecef032263 for ; Sat, 22 Feb 2020 21:43:27 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=facebook; bh=5msdfc5zTsOWmdjJR5YR1UV6gjvJTYboucuH+CcrOsQ=; b=R4oeECZU0MDkt3TuJh0SQUzEU6yUZVHeoI8cg56Fwy8MTMWBreHnUX7LnD+Nrcf631um 14O7IeebRBjR8IP+v22UDRLyq8lV+rHZ+e0wETuGXLTw+YrdL+7i7utAkS1+4cbbuMhX tSAVyGN99ahBhMwB8HGaEw1QbkVxWPCJ8Ms= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 2yb2x1tgdh-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sat, 22 Feb 2020 21:43:26 -0800 Received: from intmgw003.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1779.2; Sat, 22 Feb 2020 21:43:25 -0800 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 1B6082EC2D58; Sat, 22 Feb 2020 21:43:24 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Andrii Nakryiko Smtp-Origin-Hostname: devbig012.ftw2.facebook.com To: , , , CC: , , Andrii Nakryiko Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next] selftests/bpf: print backtrace on SIGSEGV in test_progs Date: Sat, 22 Feb 2020 21:43:19 -0800 Message-ID: <20200223054320.2006995-1-andriin@fb.com> X-Mailer: git-send-email 2.17.1 X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-02-22_08:2020-02-21,2020-02-22 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 clxscore=1015 lowpriorityscore=0 adultscore=0 malwarescore=0 bulkscore=0 phishscore=0 priorityscore=1501 impostorscore=0 mlxlogscore=950 spamscore=0 suspectscore=8 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002230048 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Due to various bugs in test clean up code (usually), if host system is misconfigured, it happens that test_progs will just crash in the middle of running a test with little to no indication of where and why the crash happened. For cases where coredump is not readily available (e.g., inside a CI), it's very helpful to have a stack trace, which lead to crash, to be printed out. This change adds a signal handler that will capture and print out symbolized backtrace: $ sudo ./test_progs -t mmap test_mmap:PASS:skel_open_and_load 0 nsec test_mmap:PASS:bss_mmap 0 nsec test_mmap:PASS:data_mmap 0 nsec Caught signal #11! Stack trace: ./test_progs(crash_handler+0x18)[0x42a888] /lib64/libpthread.so.0(+0xf5d0)[0x7f2aab5175d0] ./test_progs(test_mmap+0x3c0)[0x41f0a0] ./test_progs(main+0x160)[0x407d10] /lib64/libc.so.6(__libc_start_main+0xf5)[0x7f2aab15d3d5] ./test_progs[0x407ebc] [1] 1988412 segmentation fault (core dumped) sudo ./test_progs -t mmap Unfortunately, glibc's symbolization support is unable to symbolize static functions, only global ones will be present in stack trace. But it's still a step forward without adding extra libraries to get a better symbolization. Signed-off-by: Andrii Nakryiko --- tools/testing/selftests/bpf/Makefile | 2 +- tools/testing/selftests/bpf/test_progs.c | 26 ++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 2a583196fa51..50c63c21e6fd 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -20,7 +20,7 @@ CLANG ?= clang LLC ?= llc LLVM_OBJCOPY ?= llvm-objcopy BPF_GCC ?= $(shell command -v bpf-gcc;) -CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(CURDIR) -I$(APIDIR) \ +CFLAGS += -g -rdynamic -Wall -O2 $(GENFLAGS) -I$(CURDIR) -I$(APIDIR) \ -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR) -I$(TOOLSINCDIR) \ -Dbpf_prog_load=bpf_prog_test_load \ -Dbpf_load_program=bpf_test_load_program diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index bab1e6f1d8f1..531ab3e7e5e5 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -6,6 +6,8 @@ #include "bpf_rlimit.h" #include #include +#include +#include /* backtrace */ /* defined in test_progs.h */ struct test_env env = {}; @@ -617,6 +619,22 @@ int cd_flavor_subdir(const char *exec_name) return chdir(flavor); } +#define MAX_BACKTRACE_SZ 128 +void crash_handler(int signum) +{ + void *bt[MAX_BACKTRACE_SZ]; + size_t sz; + + sz = backtrace(bt, ARRAY_SIZE(bt)); + + if (env.test) + dump_test_log(env.test, true); + stdio_restore(); + + fprintf(stderr, "Caught signal #%d!\nStack trace:\n", signum); + backtrace_symbols_fd(bt, sz, STDERR_FILENO); +} + int main(int argc, char **argv) { static const struct argp argp = { @@ -624,8 +642,16 @@ int main(int argc, char **argv) .parser = parse_arg, .doc = argp_program_doc, }; + struct sigaction sigact = { + .sa_handler = crash_handler, + .sa_flags = SA_RESETHAND, + }; int err, i; + env.stdout = stdout; + env.stderr = stderr; + sigaction(SIGSEGV, &sigact, NULL); + err = argp_parse(&argp, argc, argv, 0, NULL, &env); if (err) return err;