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

On 2/25/20 1:08 AM, Andrii Nakryiko 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 <redacted>

Applied, thanks!