This is an excerpt of a perf report:

Samples: 47K of event 'cycles', Event count (approx.): 22843195013
  Children      Self       Command          Shared Object         Symbol
+   97.13%     0.01%       server           server             [.] Server::runEventLoopOnce                                             ◆
-   96.70%    52.84%       server           server             [.] Server::onRecvBlock                                                               ▒
   + 46.21% 0x7fd3fa4f9253                                                                                                                                                             ▒
   + 43.86% ServerQueue::onRecvBlock                                                                                                                                             ▒
   + 6.61% __libc_start_call_main                                                                                                                                                      ▒

How is it possible that my function Server::onRecvBlock() is said to call __libc_start_call_main?

I am capturing using perf record --call-graph=fp ./server. The executable is compiled with -fno-omit-frame-pointer.