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x86, perf_counter, bts: Do not allow kernel BTS tracing for now

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Kernel BTS tracing generates too much data too fast for us to
handle, causing the kernel to hang.

Fail for BTS requests for kernel code.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Acked-by: Peter Zijlstra <a.p.zjilstra@chello.nl>
LKML-Reference: <20090902140616.901253000@intel.com>
[ This is really a workaround - but we want BTS tracing in .32
  so make sure we dont regress. The lockup should be fixed
  ASAP. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
markus.t.metzger@intel.com 2009-09-02 16:04:48 +02:00 committed by Ingo Molnar
parent 596da17f94
commit 1653192f51
1 changed files with 9 additions and 2 deletions
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9
arch/x86/kernel/cpu/perf_counter.c
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@ -984,9 +984,16 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
* Branch tracing:
*/
if ((attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) &&
(hwc->sample_period == 1) && !bts_available())
(hwc->sample_period == 1)) {
/* BTS is not supported by this architecture. */
if (!bts_available())
return -EOPNOTSUPP;
/* BTS is currently only allowed for user-mode. */
if (hwc->config & ARCH_PERFMON_EVENTSEL_OS)
return -EOPNOTSUPP;
}
hwc->config |= config;
return 0;