Re: [Libunwind-devel] [PATCH 0/8] libunwind accuracy improvements for x86-64

[Lassi Tuura]

Hi,

I forgot to mention two things about this patch set:

1. The new signal frame detection code has a potential issue. The dwarf frame 
information is only available after calling unw_step(), so if you chance to set 
things up so you start unwinding at the kernel signal return frame, it will get 
confused. I don't know how to fix this without major change how unw_init_* work 
relative to unw_is_signal_frame(). I don't think it's significant, as chances 
of constructing such a stack frame are slim; I don't think it's possible with 
local unwind at all, and I don't even know how to create the situation with 
remote (ptrace) unwinding.

2. As previously discussed the changes are partially based on earlier work in 
frysk. The final code isn't really the same - libunwind has changed, I did many 
things differently, and code in frysk wasn't a complete solution in my tests - 
but it was useful to look at the frysk version for ideas! Sorry I forgot to add 
the credit in the original mail; if someone from frysk cares they might want to 
ask to be added to copyright list.

Regards,
Lassi