Re: [PATCH] perf: unwind: fix segbase for libunwind.

From: Ingo Molnar
Date: Wed Apr 01 2015 - 10:48:49 EST



* Wang Nan <wangnan0@xxxxxxxxxx> wrote:

> Perf passes incorrect segbase and table_data to libunwind when
> map->pgoff != 0, causes unwind failure. This patch fixes this
> problem.
>
> segbase is an absolute offset from the head of object file, directly
> read from ELF file. Original code computes corresponding virtual
> address using map->start + segbase, doesn't consider map->pgoff.
> Which causes libunwind read from incorrect offset.

What's the effect of this bug in practice?

Is there any before/after output you can show that demonstrates the
fix?

Thanks,

Ingo
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