x86, bts: correctly report invalid bts records

Impact: change the reporting of empty BTS records

Correctly report a cleared BTS record as invalid. Used to be reported
as branch from 0 to 0.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 0dc795951d73..98d271e60e08 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -484,6 +484,9 @@ static int bts_read(struct bts_tracer *tracer, const void *at,
                 out->qualifier = bts_branch;
                 out->variant.lbr.from = bts_get(at, bts_from);
                 out->variant.lbr.to   = bts_get(at, bts_to);
+
+                if (!out->variant.lbr.from && !out->variant.lbr.to)
+                        out->qualifier = bts_invalid;
         }
 
         return ds_cfg.sizeof_rec[ds_bts];