Re: [PATCH 9/9] perf tests: Use arch__compare_symbol_names to compare symbols

From: Naveen N. Rao
Date: Thu Feb 15 2018 - 09:49:12 EST


Arnaldo Carvalho de Melo wrote:
Em Thu, Feb 15, 2018 at 01:26:35PM +0100, Jiri Olsa escreveu:
The symbol search called by machine__find_kernel_symbol_by_name
is using internally arch__compare_symbol_names function to compare
2 symbol names, because different archs have different ways of
comparing symbols. Mostly for skipping '.' prefixes and similar.

In test 1 when we try to find matching symbols in kallsyms and
vmlinux, by address and by symbol name. When either is found
we compare the pair symbol names by simple strcmp, which is not
good enough for reasons explained in previous paragraph.

On powerpc this can cause lockup, because even thought we found
the pair, the compared names are different and don't match
simple strcmp. Following code path is executed, that leads
to lockup:

Added a:

Fixes: 031b84c407c3 ("perf probe ppc: Enable matching against dot symbols automatically")

And CCed Naveen, the author of that patch, so that gets notified of this
fix.

Thanks! This does fix the test on ppc64 BE. So:
Acked-and-Tested-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>

- Naveen