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Commit 747b50aa authored by markus.t.metzger@intel.com's avatar markus.t.metzger@intel.com Committed by Ingo Molnar
Browse files

x86, perf_counter, bts: Fail if BTS is not available 



Reserve PERF_COUNT_HW_BRANCH_INSTRUCTIONS with sample_period ==
1 for BTS tracing and fail, if BTS is not available.

Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090902140612.943801000@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dc86cabe

arch/x86/kernel/cpu/perf_counter.c

+11 −14
Original line number Diff line number Diff line
@@ -769,7 +769,7 @@ static int reserve_bts_hardware(void) 
	int cpu, err = 0;



	if (!bts_available())

		return -EOPNOTSUPP;

		return 0;



	get_online_cpus();
@@ -914,7 +914,7 @@ static int __hw_perf_counter_init(struct perf_counter *counter) 
			if (!reserve_pmc_hardware())

				err = -EBUSY;

			else

				reserve_bts_hardware();

				err = reserve_bts_hardware();

		}

		if (!err)

			atomic_inc(&active_counters);
@@ -979,6 +979,13 @@ static int __hw_perf_counter_init(struct perf_counter *counter) 
	if (config == -1LL)

		return -EINVAL;



	/*

	 * Branch tracing:

	 */

	if ((attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) &&

	    (hwc->sample_period == 1) && !bts_available())

		return -EOPNOTSUPP;



	hwc->config |= config;



	return 0;
@@ -1355,19 +1362,9 @@ static int x86_pmu_enable(struct perf_counter *counter) 


	idx = fixed_mode_idx(counter, hwc);

	if (idx == X86_PMC_IDX_FIXED_BTS) {

		/*

		 * Try to use BTS for branch tracing. If that is not

		 * available, try to get a generic counter.

		 */

		if (unlikely(!cpuc->ds))

			goto try_generic;



		/*

		 * Try to get the fixed counter, if that is already taken

		 * then try to get a generic counter:

		 */

		/* BTS is already occupied. */

		if (test_and_set_bit(idx, cpuc->used_mask))

			goto try_generic;

			return -EAGAIN;



		hwc->config_base	= 0;

		hwc->counter_base	= 0;