From: Will Deacon <will@kernel.org>
To: German Gomez <german.gomez@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
james.clark@arm.com, leo.yan@linaro.org
Subject: Re: [RFC PATCH 2/2] perf: arm_spe: Enable CONTEXT packets in SPE traces if the profiler runs in CPU mode.
Date: Tue, 18 Jan 2022 09:52:58 +0000 [thread overview]
Message-ID: <20220118095258.GA16547@willie-the-truck> (raw)
In-Reply-To: <20220117124432.3119132-3-german.gomez@arm.com>
On Mon, Jan 17, 2022 at 12:44:32PM +0000, German Gomez wrote:
> Enable CONTEXT packets in SPE traces if the profiler runs in CPU mode.
> This is no less permissive than the existing behavior for the following
> reason:
>
> If perf_event_paranoid <= 0, then non perfmon_capable() users can open
> a per-CPU event. With a per-CPU event, unpriviledged users are allowed
> to profile _all_ processes, even ones owned by root.
>
> Without this change, users could see kernel addresses, root processes,
> etc, but not gather the PIDs of those processes. The PID is probably the
> least sensitive of all the information.
>
> It would be more idiomatic to check the perf_event_paranoid level with
> perf_allow_cpu(), but this function is not exported so cannot be used
> from a module. Looking for cpu != -1 is the indirect way of checking
> the same thing as it could never get to arm_spe_pmu_event_init() without
> perf_event_paranoid <= 0.
perf_allow_cpu() is a static inline so there's no need to export it. What's
missing?
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-01-18 9:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-17 12:44 [RFC PATCH 0/2] perf: arm_spe: Fix consistency of CONTEXT packets in SPE driver German Gomez
2022-01-17 12:44 ` [RFC PATCH 1/2] perf: arm_spe: Fix consistency of PMSCR register bit CX German Gomez
2022-01-18 10:07 ` Will Deacon
2022-01-18 14:04 ` German Gomez
2022-01-19 11:27 ` German Gomez
2022-01-18 16:28 ` James Clark
2022-02-05 15:39 ` Leo Yan
2022-02-07 12:06 ` German Gomez
2022-02-08 13:00 ` Leo Yan
2022-02-10 17:23 ` German Gomez
2022-02-11 10:45 ` Leo Yan
2022-02-15 14:29 ` German Gomez
2022-02-16 13:22 ` Leo Yan
2022-02-16 15:16 ` German Gomez
2022-01-17 12:44 ` [RFC PATCH 2/2] perf: arm_spe: Enable CONTEXT packets in SPE traces if the profiler runs in CPU mode German Gomez
2022-01-17 14:04 ` German Gomez
2022-01-18 9:52 ` Will Deacon [this message]
2022-01-18 14:13 ` German Gomez
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=20220118095258.GA16547@willie-the-truck \
--to=will@kernel.org \
--cc=german.gomez@arm.com \
--cc=james.clark@arm.com \
--cc=leo.yan@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
/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