Date: Fri, 23 Aug 2019 16:21:44 +0200 From: Florian Weimer <fweimer@...hat.com> To: Rich Felker <dalias@...c.org> Cc: musl@...ts.openwall.com Subject: Re: libexecinfo with musl * Rich Felker: > backtrace should not require any "support from libc". My guess at > what's happening is that it fails to trace past main's stack frame > back into the call point in libc startup code, since libc lacks unwind > info. A working backtrace implementation needs to be prepared for this > possibility and stop if it reaches back to an address without unwind > info. Depending on the architecture, this is impossible because some ABIs mandate that the unwinder behaves in certain ways (other than stopping) if a frame does not have explicit unwind information. For example, they could assume that the frame has a frame pointer, or that the stack pointer has not been changed. For example, my understanding is that for POWER, the unwinder must assume that the function has a back chain if the function lacks explicit unwind data. Thanks, Florian
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