linux-kernel - Re: [PATCH 03/23] perf: Add ability to attach user level registers dump to sample

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1340810729.10063.66.camel@twins>
Date:	Wed, 27 Jun 2012 17:25:29 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Stephane Eranian <eranian@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>, acme@...hat.com, mingo@...e.hu,
	paulus@...ba.org, cjashfor@...ux.vnet.ibm.com, gorcunov@...nvz.org,
	tzanussi@...il.com, mhiramat@...hat.com, robert.richter@....com,
	fche@...hat.com, linux-kernel@...r.kernel.org,
	masami.hiramatsu.pt@...achi.com, drepper@...il.com, asharma@...com,
	benjamin.redelings@...cent.org,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: [PATCH 03/23] perf: Add ability to attach user level registers
 dump to sample

On Wed, 2012-06-27 at 17:24 +0200, Frederic Weisbecker wrote:
> On Wed, Jun 27, 2012 at 05:13:44PM +0200, Stephane Eranian wrote:
> > On Wed, Jun 27, 2012 at 5:11 PM, Frederic Weisbecker <fweisbec@...il.com> wrote:
> > > On Tue, Jun 19, 2012 at 05:47:54PM +0200, Jiri Olsa wrote:
> > >> @@ -4061,6 +4105,19 @@ void perf_prepare_sample(struct perf_event_header *header,
> > >>               }
> > >>               header->size += size;
> > >>       }
> > >> +
> > >> +     if (sample_type & PERF_SAMPLE_REGS_USER) {
> > >> +             /* regs dump available bool */
> > >> +             int size = sizeof(u64);
> > >> +
> > >> +             data->regs_user = perf_sample_regs_user(regs);
> > >> +             if (data->regs_user) {
> > >> +                     u64 mask = event->attr.sample_regs_user;
> > >> +                     size += hweight64(mask) * sizeof(u64);
> > >> +             }
> > >> +
> > >> +             header->size += size;
> > >
> > > We'll need to remove the 64 bits registers for compat tasks but other than
> > > that, it looks ok.
> > You cannot do this. You cannot remove register values from under the hood.
> > The only way the user has to parse the sample is the sample_regs_users bitmask.
> > You have to return 0 for those unexisting regs for compat tasks.
> 
> You mean fill unexisting reg values with 0? Yeah that works.

What does x32 look like? Is that still reported as a compat task? If so,
we should record all registers and not 0 out anything.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/