[ 3.5.y.z extended stable ] Patch "perf/x86/intel/lbr: Demand proper privileges for" has been added to staging queue

[Luis Henriques]

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

    perf/x86/intel/lbr: Demand proper privileges for

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

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

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
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From bc03682e09c9909ec48a8ee3697e19434a96a7a5 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra at chello.nl>
Date: Fri, 3 May 2013 14:11:25 +0200
Subject: [PATCH] perf/x86/intel/lbr: Demand proper privileges for
 PERF_SAMPLE_BRANCH_KERNEL

commit 7cc23cd6c0c7d7f4bee057607e7ce01568925717 upstream.

We should always have proper privileges when requesting kernel
data.

Signed-off-by: Peter Zijlstra <a.p.zijlstra at chello.nl>
Cc: Andi Kleen <ak at linux.intel.com>
Cc: eranian at google.com
Link: http://lkml.kernel.org/r/20130503121256.230745028@chello.nl
[ Fix build error reported by fengguang.wu at intel.com, propagate error code back. ]
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/kernel/cpu/perf_event_intel_lbr.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 62a93a4..fd1a099 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -310,7 +310,7 @@ void intel_pmu_lbr_read(void)
  * - in case there is no HW filter
  * - in case the HW filter has errata or limitations
  */
-static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
+static int intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
 {
 	u64 br_type = event->attr.branch_sample_type;
 	int mask = 0;
@@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
 	if (br_type & PERF_SAMPLE_BRANCH_USER)
 		mask |= X86_BR_USER;

-	if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
+	if (br_type & PERF_SAMPLE_BRANCH_KERNEL) {
+		if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+			return -EACCES;
 		mask |= X86_BR_KERNEL;
+	}

 	/* we ignore BRANCH_HV here */

@@ -339,6 +342,8 @@ static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
 	 * be used by fixup code for some CPU
 	 */
 	event->hw.branch_reg.reg = mask;
+
+	return 0;
 }

 /*
@@ -386,7 +391,9 @@ int intel_pmu_setup_lbr_filter(struct perf_event *event)
 	/*
 	 * setup SW LBR filter
 	 */
-	intel_pmu_setup_sw_lbr_filter(event);
+	ret = intel_pmu_setup_sw_lbr_filter(event);
+	if (ret)
+		return ret;

 	/*
 	 * setup HW LBR filter, if any
--
1.8.1.2