linux-kernel - Re: [RFC PATCH 15/20] coresight: etm-perf: implementing 'setup

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: <87si5t3mcu.fsf@ashishki-desk.ger.corp.intel.com>
Date:	Fri, 02 Oct 2015 07:50:25 +0300
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:	Greg KH <gregkh@...uxfoundation.org>, a.p.zijlstra@...llo.nl,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...hat.com>, Jon Corbet <corbet@....net>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Chunyan Zhang <zhang.chunyan@...aro.org>,
	Mike Leach <mike.leach@....com>, Tor Jeremiassen <tor@...com>,
	Al Grant <al.grant@....com>,
	Paweł Moll <pawel.moll@....com>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-doc@...r.kernel.org,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 15/20] coresight: etm-perf: implementing 'setup_aux()' API

Mathieu Poirier <mathieu.poirier@...aro.org> writes:

> On 30 September 2015 at 05:50, Alexander Shishkin
> <alexander.shishkin@...ux.intel.com> wrote:
>> Mathieu Poirier <mathieu.poirier@...aro.org> writes:
>>
>>> +static void *etm_setup_aux(int cpu, void **pages,
>>> +                           int nr_pages, bool overwrite)
>>> +{
>>> +     struct coresight_device *csdev;
>>> +
>>> +     if (cpu == -1)
>>> +             cpu = smp_processor_id();
>>> +
>>> +     csdev = per_cpu(csdev_sink, cpu);
>>> +     if (!csdev)
>>> +             return NULL;
>>> +
>>> +     return sink_ops(csdev)->setup_aux(csdev, cpu, pages,
>>> +                                       nr_pages, overwrite);
>>
>> Is it guaranteed that this sink would always have .setup_aux()?
>
> A setup_aux() is vital to the design, both on Intel and ARM.  I really
> don't see how one could go without it.  I can return NULL if it hasn't
> been provided - that way the setup will fail without triggering a core
> dump.

It wasn't clear to me that the sink that ends up in csdev_sink will
always be the one that does have .setup_aux(). And if it indeed doesn't,
it's better to refuse to setup a buffer than crash.

Regards,
--
Alex
--
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/