From 1653192f510bd8114b7b133d7289e6e5c3e95046 Mon Sep 17 00:00:00 2001 From: "markus.t.metzger@intel.com" Date: Wed, 2 Sep 2009 16:04:48 +0200 Subject: [PATCH] x86, perf_counter, bts: Do not allow kernel BTS tracing for now 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 Acked-by: Peter Zijlstra 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 --- arch/x86/kernel/cpu/perf_counter.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 3776b0b630c8..f9cd0849bd42 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -984,8 +984,15 @@ 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()) - return -EOPNOTSUPP; + (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; -- 2.11.0