perf, x86: Fixup the PEBS handler for Core2 cpus

Pull the core handler in line with the nhm one, also make sure we always
drain the buffer.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 2423694..1bfd59b 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -472,20 +472,39 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs)
        struct pt_regs regs;
        int n;
 
-       if (!event || !ds || !x86_pmu.pebs)
+       if (!ds || !x86_pmu.pebs)
                return;
 
        at  = (struct pebs_record_core *)(unsigned long)ds->pebs_buffer_base;
        top = (struct pebs_record_core *)(unsigned long)ds->pebs_index;
 
-       if (top <= at)
+       /*
+        * Whatever else happens, drain the thing
+        */
+       ds->pebs_index = ds->pebs_buffer_base;
+
+       if (!test_bit(0, cpuc->active_mask))
                return;
 
-       ds->pebs_index = ds->pebs_buffer_base;
+       WARN_ON_ONCE(!event);
+
+       if (!event->attr.precise)
+               return;
+
+       n = top - at;
+       if (n <= 0)
+               return;
 
        if (!intel_pmu_save_and_restart(event))
                return;
 
+       /*
+        * Should not happen, we program the threshold at 1 and do not
+        * set a reset value.
+        */
+       WARN_ON_ONCE(n > 1);
+       at += n - 1;
+
        perf_sample_data_init(&data, 0);
        data.period = event->hw.last_period;
 
@@ -495,14 +514,6 @@ static void intel_pmu_drain_pebs_core(struct pt_regs *iregs)
                data.raw = &raw;
        }
 
-       n = top - at;
-
-       /*
-        * Should not happen, we program the threshold at 1 and do not
-        * set a reset value.
-        */
-       WARN_ON_ONCE(n > 1);
-
        /*
         * We use the interrupt regs as a base because the PEBS record
         * does not contain a full regs set, specifically it seems to
@@ -545,12 +556,11 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
        at  = (struct pebs_record_nhm *)(unsigned long)ds->pebs_buffer_base;
        top = (struct pebs_record_nhm *)(unsigned long)ds->pebs_index;
 
-       if (top <= at)
-               return;
-
        ds->pebs_index = ds->pebs_buffer_base;
 
        n = top - at;
+       if (n <= 0)
+               return;
 
        /*
         * Should not happen, we program the threshold at 1 and do not