[PATCH 4.9 15/69] perf/x86: Avoid exposing wrong/stale data in intel_pmu_lbr_read_32()

From: Greg Kroah-Hartman
Date: Wed Apr 19 2017 - 11:16:17 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

commit f2200ac311302fcdca6556fd0c5127eab6c65a3e upstream.

When the perf_branch_entry::{in_tx,abort,cycles} fields were added,
intel_pmu_lbr_read_32() wasn't updated to initialize them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Fixes: 135c5612c460 ("perf/x86/intel: Support Haswell/v4 LBR format")
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/x86/events/intel/lbr.c | 3 +++
1 file changed, 3 insertions(+)

--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -507,6 +507,9 @@ static void intel_pmu_lbr_read_32(struct
cpuc->lbr_entries[i].to = msr_lastbranch.to;
cpuc->lbr_entries[i].mispred = 0;
cpuc->lbr_entries[i].predicted = 0;
+ cpuc->lbr_entries[i].in_tx = 0;
+ cpuc->lbr_entries[i].abort = 0;
+ cpuc->lbr_entries[i].cycles = 0;
cpuc->lbr_entries[i].reserved = 0;
}
cpuc->lbr_stack.nr = i;