On Montag, 29. Oktober 2018 18:40:14 CET Arnaldo Carvalho de Melo wrote: > Em Mon, Oct 29, 2018 at 04:26:27PM +0100, Milian Wolff escreveu: > > On Monday, October 29, 2018 3:16:44 PM CET Milian Wolff wrote: > > > Libdwfl parses an ELF file itself and creates mappings for the > > > individual sections. Perf on the other hand sees raw mmap events which > > > represent individual sections. When we encounter an address pointing > > > into a mapping with pgoff != 0, we must take that into account and > > > report the file at the non-offset base address. > > > > > This fixes unwinding with libdwfl in some cases. E.g. for a file like: > > <snip> > > > > > Note that the backtrace is still stopping too early, when > > > compared to the nice results obtained via libunwind. It's > > > unclear so far what the reason for that is. > > > > The remaining issue is due to a bug in elfutils: > > > > https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html > > > > With both patches applied, libunwind and elfutils produce the same output > > for the above scenario. > > I'm updating the patch to remove: > > "It's unclear so far what the reason for that is." > > Adding: > > "See https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html for > a patch fixing that." > > Ok?
Yes, thanks. I figured the fix for elfutils out after I submitted the perf patch. > Or are you saying that that "unclear" part applies to both libunwind > and elfutils? No, libunwind worked fine without these patches for this specific case. Cheers -- Milian Wolff | milian.wo...@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts
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