[PATCH 3/3] perf, x86, lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

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We should always have proper privileges when requesting kernel data.

Cc: Andi Kleen <ak@linux.intel.com>
Cc: eranian@google.com
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org
---
 arch/x86/kernel/cpu/perf_event_intel_lbr.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -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 */