[PATCHES] Fix 'perf top' breakage on architectures not providing get_cpuid() Re: perf top for arm64?

[Arnaldo Carvalho de Melo]

Em Tue, Dec 10, 2019 at 04:51:13PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Dec 10, 2019 at 05:17:56PM +0000, John Garry escreveu:
> > On 10/12/2019 17:08, Jiri Olsa wrote:
> > > On Tue, Dec 10, 2019 at 04:52:52PM +0000, John Garry wrote:
> > > > On 10/12/2019 16:36, Jiri Olsa wrote:
> > > > > On Tue, Dec 10, 2019 at 04:13:49PM +0000, John Garry wrote:
> > > > > > I find to my surprise that "perf top" does not work for arm64:

> > > > > > root@ubuntu:/home/john/linux# tools/perf/perf top
> > > > > > Couldn't read the cpuid for this machine: No such file or directory

> > > > > there was recent change that check on cpuid and quits:
> > > > >     608127f73779 perf top: Initialize perf_env->cpuid, needed by the per arch annotation init routine

> > > > ok, this is new code. I obviously didn't check the git history...

> > > > But, apart from this, there are many other places where get_cpuid() is
> > > > called. I wonder what else we're missing out on, and whether we should still
> > > > add it.

> > > right, I was just wondering how come vendor events are working for you,
> > > but realized we have get_cpuid_str being called in there ;-)

> > > I think we should add it as you have it prepared already,
> > > could you post it with bigger changelog that would explain
> > > where it's being used for arm?

> > ok, I can look to do that.

> > But, as you know, we still need to fix perf top for other architectures
> > affected.

> Right, I need to make that just a pr_debug() message and then check in
> the annotation code when that is needed to see if it is set, if not,
> then show a popup error message and refuse to do whatever annotation
> feature requires that.

> Anyway, your patch should make sense and provide info that the ARM64
> annotation may use now or in the future.

So can you take a look at the two patches below and provide me Acked-by
and/or Reviewed-by and/or Tested-by?