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Subject[ 12/73] perf/x86/intel/lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL
Date
3.8-stable review patch.  If anyone has any objections, please let me know.

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

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

commit 7cc23cd6c0c7d7f4bee057607e7ce01568925717 upstream.

We should always have proper privileges when requesting kernel
data.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20130503121256.230745028@chello.nl
[ 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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/perf_event_intel_lbr.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- 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_filte
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_filte
* 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 pe
/*
* 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



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