Re: [PATCH 6/9] perf tools: Don't search for active kernel start in __machine__create_kernel_maps

[Namhyung Kim]

On Mon, Feb 19, 2018 at 11:01:40AM +0100, Jiri Olsa wrote:
> On Mon, Feb 19, 2018 at 11:20:36AM +0900, Namhyung Kim wrote:
> 
> SNIP
> 
> > > +static void machine__set_kernel_mmap(struct machine *machine,
> > > +				     u64 start, u64 end)
> > > +{
> > > +	int i;
> > > +
> > > +	for (i = 0; i < MAP__NR_TYPES; i++) {
> > > +		machine->vmlinux_maps[i]->start = start;
> > > +		machine->vmlinux_maps[i]->end   = end;
> > > +
> > > +		/*
> > > +		 * Be a bit paranoid here, some perf.data file came with
> > > +		 * a zero sized synthesized MMAP event for the kernel.
> > > +		 */
> > > +		if (machine->vmlinux_maps[i]->end == 0)
> > > +			machine->vmlinux_maps[i]->end = ~0ULL;
> > 
> > Hmm.. this will make map_groups__fixup_end() below not working since
> > it only updates if the end address of a map is zero.
> > 
> > And about the paranoid check, AFAIK the only case it cares is the
> > machine__process_kernel_mmap_event() which calls it with
> > event->mmap.start and event->mmap.start + event->mmap.len.  Thus, in
> > order for the end to be zero, both start and len should be zero.  Then
> > I think this condition can be changed like below:
> > 
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index fe27ef55cbb9..c8acb603c359 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -1226,7 +1226,7 @@ static void machine__set_kernel_mmap(struct machine *machine,
> >                  * Be a bit paranoid here, some perf.data file came with
> >                  * a zero sized synthesized MMAP event for the kernel.
> >                  */
> > -               if (machine->vmlinux_maps[i]->end == 0)
> > +               if (start == 0 && end == 0)
> >                         machine->vmlinux_maps[i]->end = ~0ULL;
> >         }
> 
> right, the call from machine__create_kernel_maps will have always
> the start != 0 and there will be subsequent map_groups__fixup_end
> call..
> 
> seems ok to me.. will you send the patch?

Sure. :)