linux-kernel - [PATCH 3.16 152/178] perf/x86: Avoid exposing wrong/stale data in intel_pmu_lbr_read

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Message-ID: <lsq.1500213406.314100234@decadent.org.uk>
Date:   Sun, 16 Jul 2017 14:56:46 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ingo Molnar" <mingo@...nel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 152/178] perf/x86: Avoid exposing wrong/stale data in
 intel_pmu_lbr_read_32()

3.16.46-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Peter Zijlstra <peterz@...radead.org>

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@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Fixes: 135c5612c460 ("perf/x86/intel: Support Haswell/v4 LBR format")
Signed-off-by: Ingo Molnar <mingo@...nel.org>
[bwh: Backported to 3.16:
 - There's no perf_branch_entry::cycles field
 - Adjust filename]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -268,6 +268,8 @@ 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].reserved	= 0;
 	}
 	cpuc->lbr_stack.nr = i;