netdev - Re: [PATCH v2 bpf-next] selftests/bpf: print backtrace on SIGSEGV in test

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Message-ID: <CAPhsuW6xrw=5X-HzgQ++ZEJO-5VmbrzhEXvAOYnhc4bYG0B8PA@mail.gmail.com>
Date:   Mon, 24 Feb 2020 21:51:42 -0800
From:   Song Liu <song@...nel.org>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v2 bpf-next] selftests/bpf: print backtrace on SIGSEGV in test_progs

On Mon, Feb 24, 2020 at 4:09 PM Andrii Nakryiko <andriin@...com> wrote:
>
> Due to various bugs in tests 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 <andriin@...com>

Acked-by: Song Liu <songliubraving@...com>