perf top breakage.

From: Dave Jones
Date: Fri Mar 14 2014 - 16:20:13 EST


On Fri, Mar 14, 2014 at 12:41:41PM -0700, Linus Torvalds wrote:
> On Fri, Mar 14, 2014 at 12:32 PM, Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hmm. Do you have CONFIG_KALLSYMS enabled?
>
> Just to clarify. KALLSYMS is required to figure out the symbol
> addresses on a kaslr system. There's no way to look them up in a
> System.map file or the object file, since the addresses aren't going
> to match.
>
> Your symptoms really sound like you might not have KALLSYMS enabled.
>
> I wonder if we have a "select KALLSYMS" as part of RANDOMIZE_BASE,
> since you need it for debug messages too (random hex numbers aren't
> too useful ;)

Ok, I've figured out the cause. kaslr is a red herring.

This works :

# su - root
$ tools/perf/perf top

This doesn't:

# sudo tools/perf/perf top

Neither does:

# su - root
$ sudo tools/perf/perf top

So somehow sudo+perf broke. fun.

The 3.13 binary works regardless of how I call it.

Dave

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