[PATCH 1/4] ldv/unwind: enable cache feature of libunwind

Masatake YAMATO yamato at redhat.com
Wed Apr 16 07:46:52 UTC 2014


> i don't know whether you care, but Android recently switched to
> libunwind and we had to rewrite the caching because it's so leaky.
> we've also found libunwind copes badly with processes that are
> crashed/crashing --- there are no sanity checks before dereferences.
> we [think we've] fixed this locally, but we haven't managed to get
> much upstreamed yet.
> you can see our local changes here:
> https://android-review.googlesource.com/#/q/project:platform/external/libunwind

Do you mean dwarf cache or mmap cache?

As far as trying dwarf cache(with strace), it works fine. I have never
got crashing. For me you are talking about mmap cache.

As far as I know there is no mmap cache API in libunwind.  I proposed
mmap cache API but I got requests to improve from reviewer. A person
at google also submmited a patch about similar area.

BTW, I was notified that elfutils has good unwinder.
It has good mmap cache mechanism. It can show source file name 
and line number in stacktrace. 

Thank you for notifying. Many interesting patches in the repository.
I hope the patches are merged to upstream:)

Masatake YAMATO

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