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Commit-ID: 747b50aaf728987732e6ff3ba10aba4acc4e0277
Gitweb: http://git.kernel.org/tip/747b50aaf728987732e6ff3ba10aba4acc4e0277
Author: [email protected] <[email protected]>
AuthorDate: Wed, 2 Sep 2009 16:04:46 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Fri, 4 Sep 2009 09:26:39 +0200
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: Markus Metzger <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/cpu/perf_counter.c | 25 +++++++++++--------------
1 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 396e35d..2f41874 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -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;