[ 092/136 ] perf/x86/intel/lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL

Steven Rostedt
2013-05-18T03:09:26Z

[-- Attachment #1: 0092-perf-x86-intel-lbr-Demand-proper-privileges-for-PERF.patch --]
[-- Type: text/plain, Size: 2299 bytes --]

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

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

From: Peter Zijlstra <a.p.zijlstra@chello.nl>

[ Upstream commit 7cc23cd6c0c7d7f4bee057607e7ce01568925717 ]

We should always have proper privileges when requesting kernel
data.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20130503121256.230745028@chello.nl
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
[ Fix build error reported by fengguang.wu@intel.com, propagate error code back. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
---
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 de341d4..d978353 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
--
1.7.10.4