On Tue, Apr 11, 2017 at 09:52:19AM +0200, Peter Zijlstra wrote:
> On Tue, Apr 11, 2017 at 06:56:30PM +0800, Jin Yao wrote:
> > @@ -960,6 +1006,11 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc)
> > cpuc->lbr_entries[i].from = 0;
> > compress = true;
> > }
> > +
> > + if ((br_sel & X86_BR_TYPE_SAVE) == X86_BR_TYPE_SAVE)
> > + cpuc->lbr_entries[i].type = common_branch_type(type);
> > + else
> > + cpuc->lbr_entries[i].type = PERF_BR_NONE;
> > }
I was wondering WTH you did that else; because it should already be 0
(aka, BR_NONE). Then I found intel_pmu_lbr_read_32() is already broken,
and you just broke intel_pmu_lbr_read_64().
Arguably we should add a union on the last __u64 with a name for the
entire thing, but the below is the minimal fix.
---
Subject: perf,x86: Avoid exposing wrong/stale data in intel_pmu_lbr_read_32()
From: Peter Zijlstra <pet...@infradead.org>
Date: Tue Apr 11 10:10:28 CEST 2017
When the perf_branch_entry::{in_tx,abort,cycles} fields were added,
intel_pmu_lbr_read_32() wasn't updated to initialize them.
Fixes: 135c5612c460 ("perf/x86/intel: Support Haswell/v4 LBR format")
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
--- 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;
