From: Florian Weimer <fweimer@redhat.com>
To: Rich Felker <dalias@libc.org>
Cc: musl@lists.openwall.com
Subject: Re: libexecinfo with musl
Date: Fri, 23 Aug 2019 16:21:44 +0200 [thread overview]
Message-ID: <87k1b4rmh3.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <20190822030739.GH9017@brightrain.aerifal.cx>
* 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
next prev parent reply other threads:[~2019-08-23 14:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 0:32 Guillaume Quintard
2019-08-22 3:07 ` Rich Felker
2019-08-23 14:21 ` Florian Weimer [this message]
2019-08-26 21:56 ` Guillaume Quintard
2019-08-28 8:06 ` Tuan Hoang
2019-08-28 19:07 ` Guillaume Quintard
2019-08-22 17:17 ` Tuan Hoang
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