[ 3.5.y.z extended stable ] Patch "perf/x86: Fix offcore_rsp valid mask for SNB/IVB" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Wed Apr 24 09:36:41 UTC 2013

This is a note to let you know that I have just added a patch titled

    perf/x86: Fix offcore_rsp valid mask for SNB/IVB

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 08c7b0a955b4287cdbea6b2e527769cba61c11c1 Mon Sep 17 00:00:00 2001
From: Stephane Eranian <eranian at google.com>
Date: Tue, 16 Apr 2013 13:51:43 +0200
Subject: [PATCH] perf/x86: Fix offcore_rsp valid mask for SNB/IVB

commit f1923820c447e986a9da0fc6bf60c1dccdf0408e upstream.

The valid mask for both offcore_response_0 and
offcore_response_1 was wrong for SNB/SNB-EP,
IVB/IVB-EP. It was possible to write to
reserved bit and cause a GP fault crashing
the kernel.

This patch fixes the problem by correctly marking the
reserved bits in the valid mask for all the processors
mentioned above.

A distinction between desktop and server parts is introduced
because bits 24-30 are only available on the server parts.

This version of the  patch is just a rebase to perf/urgent tree
and should apply to older kernels as well.

Signed-off-by: Stephane Eranian <eranian at google.com>
Cc: peterz at infradead.org
Cc: jolsa at redhat.com
Cc: gregkh at linuxfoundation.org
Cc: security at kernel.org
Cc: ak at linux.intel.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
[ luis: backport to 3.5: dropped IvyBridge changes ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 arch/x86/kernel/cpu/perf_event_intel.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 187c294..54082f7 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -126,8 +126,14 @@ static struct event_constraint intel_gen_event_constraints[] __read_mostly =

 static struct extra_reg intel_snb_extra_regs[] __read_mostly = {
-	INTEL_EVENT_EXTRA_REG(0xb7, MSR_OFFCORE_RSP_0, 0x3fffffffffull, RSP_0),
-	INTEL_EVENT_EXTRA_REG(0xbb, MSR_OFFCORE_RSP_1, 0x3fffffffffull, RSP_1),
+	INTEL_EVENT_EXTRA_REG(0xb7, MSR_OFFCORE_RSP_0, 0x3f807f8fffull, RSP_0),
+	INTEL_EVENT_EXTRA_REG(0xbb, MSR_OFFCORE_RSP_1, 0x3f807f8fffull, RSP_1),
+static struct extra_reg intel_snbep_extra_regs[] __read_mostly = {
+	INTEL_EVENT_EXTRA_REG(0xb7, MSR_OFFCORE_RSP_0, 0x3fffff8fffull, RSP_0),
+	INTEL_EVENT_EXTRA_REG(0xbb, MSR_OFFCORE_RSP_1, 0x3fffff8fffull, RSP_1),

@@ -1920,7 +1926,10 @@ __init int intel_pmu_init(void)
 		x86_pmu.event_constraints = intel_snb_event_constraints;
 		x86_pmu.pebs_constraints = intel_snb_pebs_event_constraints;
 		x86_pmu.pebs_aliases = intel_pebs_aliases_snb;
-		x86_pmu.extra_regs = intel_snb_extra_regs;
+		if (boot_cpu_data.x86_model == 45)
+			x86_pmu.extra_regs = intel_snbep_extra_regs;
+		else
+			x86_pmu.extra_regs = intel_snb_extra_regs;
 		/* all extra regs are per-cpu when HT is on */
 		x86_pmu.er_flags |= ERF_HAS_RSP_1;
 		x86_pmu.er_flags |= ERF_NO_HT_SHARING;

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