From: Peter Zijlstra <peterz@infradead.org>
To: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Leo Yan <leo.yan@linaro.org>,
coresight@lists.linaro.org, Stephen Boyd <swboyd@chromium.org>,
Denis Nikitin <denik@chromium.org>,
Mattias Nissler <mnissler@chromium.org>,
Al Grant <al.grant@arm.com>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, jannh@google.com
Subject: Re: [PATCH 1/4] perf/core: Add support to exclude kernel mode instruction tracing
Date: Mon, 1 Feb 2021 14:41:33 +0100 [thread overview]
Message-ID: <YBgFDXgX57y5XzOn@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <3c96026b544c2244e57b46119427b8a0@codeaurora.org>
On Mon, Feb 01, 2021 at 01:11:04PM +0530, Sai Prakash Ranjan wrote:
> Ok I suppose you mean CONFIG_SECURITY_LOCKDOWN_LSM? But I don't see
> how this new config has to depend on that? This can work independently
> whether complete lockdown is enforced or not since it applies to only
> hardware instruction tracing. Ideally this depends on several hardware
> tracing configs such as ETMs and others but we don't need them because
> we are already exposing PERF_PMU_CAP_ITRACE check in the events core.
If you don't have lockdown, root pretty much owns the kernel, or am I
missing something?
> be used for some speculative execution based attacks. Which other
> kernel level PMUs can be used to get a full branch trace that is not
> locked down? If there is one, then this should probably be applied to
> it as well.
Just the regular counters. The information isn't as accurate, but given
enough goes you can infer plenty.
Just like all the SMT size-channel attacks.
Sure, PT and friends make it even easier, but I don't see a fundamental
distinction.
next prev parent reply other threads:[~2021-02-01 13:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-29 19:05 [PATCH 0/4] Add support to exclude kernel mode hardware assisted instruction tracing Sai Prakash Ranjan
2021-01-29 19:05 ` [PATCH 1/4] perf/core: Add support to exclude kernel mode " Sai Prakash Ranjan
2021-01-29 19:30 ` Peter Zijlstra
2021-02-01 7:41 ` Sai Prakash Ranjan
2021-02-01 13:41 ` Peter Zijlstra [this message]
2021-02-02 6:11 ` Sai Prakash Ranjan
2021-02-10 7:38 ` Sai Prakash Ranjan
2021-01-29 19:05 ` [PATCH 2/4] perf evsel: Print warning for excluding " Sai Prakash Ranjan
2021-01-29 19:05 ` [PATCH 3/4] coresight: etm4x: Add support to exclude kernel mode tracing Sai Prakash Ranjan
2021-02-22 20:14 ` Doug Anderson
2021-02-24 14:51 ` Sai Prakash Ranjan
2021-01-29 19:05 ` [PATCH 4/4] coresight: etm3x: " Sai Prakash Ranjan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YBgFDXgX57y5XzOn@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=acme@kernel.org \
--cc=al.grant@arm.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=coresight@lists.linaro.org \
--cc=denik@chromium.org \
--cc=jannh@google.com \
--cc=jolsa@redhat.com \
--cc=leo.yan@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mathieu.poirier@linaro.org \
--cc=mike.leach@linaro.org \
--cc=mingo@redhat.com \
--cc=mnissler@chromium.org \
--cc=namhyung@kernel.org \
--cc=saiprakash.ranjan@codeaurora.org \
--cc=suzuki.poulose@arm.com \
--cc=swboyd@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox