linux-kernel - [PATCH v1 0/2] perf: Drop leaked kernel samples

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Date:   Fri, 15 Jun 2018 18:03:21 +0800
From:   Jin Yao <yao.jin@...ux.intel.com>
To:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        me@...ehuey.com
Cc:     Linux-kernel@...r.kernel.org, vincent.weaver@...ne.edu,
        will.deacon@....com, eranian@...gle.com, namhyung@...nel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com,
        Jin Yao <yao.jin@...ux.intel.com>
Subject: [PATCH v1 0/2] perf: Drop leaked kernel samples

On workloads that do a lot of kernel entry/exits we see kernel
samples, even though :u is specified. This is due to skid existing.

This might be a security issue because it can leak kernel addresses even
though kernel sampling support is disabled.

One patch "perf/core: Drop kernel samples even though :u is specified"
was posted in last year but it was reverted because it introduced a
regression issue that broke the rr-project.

Now this patch set uses sysctl to control the dropping of leaked
kernel samples.

/sys/devices/cpu/perf_allow_sample_leakage:

0 - default, drop the leaked kernel samples.
1 - don't drop the leaked kernel samples.

For rr it can write 1 to /sys/devices/cpu/perf_allow_sample_leakage to
keep original system behavior.

Jin Yao (2):
  perf/core: Use sysctl to turn on/off dropping leaked kernel samples
  perf Documentation: Introduce the sysctl perf_allow_sample_leakage

 kernel/events/core.c                     | 58 ++++++++++++++++++++++++++++++++
 tools/perf/Documentation/perf-record.txt | 14 ++++++++
 2 files changed, 72 insertions(+)

-- 
2.7.4