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

Jin Yao
2018-06-15T02:10:02Z

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(+)

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2.7.4