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| author | Ingo Molnar <mingo@kernel.org> | 2017-07-11 10:56:54 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-27 15:03:28 -0700 |
| commit | ad74bba6c16803b3c393353bfc96ea116079ac4f (patch) | |
| tree | ca81e640c8b49f879e2eda9b800f2bfade4ba77b /kernel | |
| parent | 827ac4ceda9e7766392dedc80a8ac582284e6bda (diff) | |
| download | linux-stable-ad74bba6c16803b3c393353bfc96ea116079ac4f.tar.gz linux-stable-ad74bba6c16803b3c393353bfc96ea116079ac4f.tar.bz2 linux-stable-ad74bba6c16803b3c393353bfc96ea116079ac4f.zip | |
Revert "perf/core: Drop kernel samples even though :u is specified"
commit 6a8a75f3235724c5941a33e287b2f98966ad14c5 upstream.
This reverts commit cc1582c231ea041fbc68861dfaf957eaf902b829.
This commit introduced a regression that broke rr-project, which uses sampling
events to receive a signal on overflow (but does not care about the contents
of the sample). These signals are critical to the correct operation of rr.
There's been some back and forth about how to fix it - but to not keep
applications in limbo queue up a revert.
Reported-by: Kyle Huey <me@kylehuey.com>
Acked-by: Kyle Huey <me@kylehuey.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20170628105600.GC5981@leverpostej
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 21 |
1 files changed, 0 insertions, 21 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 050b4e399738..4886c0e97bbd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5761,21 +5761,6 @@ static void perf_log_throttle(struct perf_event *event, int enable) perf_output_end(&handle); } -static bool sample_is_allowed(struct perf_event *event, struct pt_regs *regs) -{ - /* - * Due to interrupt latency (AKA "skid"), we may enter the - * kernel before taking an overflow, even if the PMU is only - * counting user events. - * To avoid leaking information to userspace, we must always - * reject kernel samples when exclude_kernel is set. - */ - if (event->attr.exclude_kernel && !user_mode(regs)) - return false; - - return true; -} - /* * Generic event overflow handling, sampling. */ @@ -5823,12 +5808,6 @@ static int __perf_event_overflow(struct perf_event *event, } /* - * For security, drop the skid kernel samples if necessary. - */ - if (!sample_is_allowed(event, regs)) - return ret; - - /* * XXX event_limit might not quite work as expected on inherited * events */ |