From: Stephane Eranian <eranian@google.com>
Date: Tue, 21 May 2013 10:53:37 +0000 (+0200)
Subject: perf/x86: Check branch sampling priv level in generic code
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=2b923c8;p=deliverable%2Flinux.git

perf/x86: Check branch sampling priv level in generic code

This patch moves commit 7cc23cd to the generic code:

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

The check is now implemented in generic code instead of x86 specific
code. That way we do not have to repeat the test in each arch
supporting branch sampling.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/20130521105337.GA2879@quad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index d978353c939b..de341d4ec92a 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 int intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
+static void intel_pmu_setup_sw_lbr_filter(struct perf_event *event)
 {
 	u64 br_type = event->attr.branch_sample_type;
 	int mask = 0;
@@ -318,11 +318,8 @@ static int 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 (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
+	if (br_type & PERF_SAMPLE_BRANCH_KERNEL)
 		mask |= X86_BR_KERNEL;
-	}
 
 	/* we ignore BRANCH_HV here */
 
@@ -342,8 +339,6 @@ static int 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;
 }
 
 /*
@@ -391,9 +386,7 @@ int intel_pmu_setup_lbr_filter(struct perf_event *event)
 	/*
 	 * setup SW LBR filter
 	 */
-	ret = intel_pmu_setup_sw_lbr_filter(event);
-	if (ret)
-		return ret;
+	intel_pmu_setup_sw_lbr_filter(event);
 
 	/*
 	 * setup HW LBR filter, if any
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 53d1b300116a..a0780b3a3d50 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6481,11 +6481,6 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 		if (!(mask & ~PERF_SAMPLE_BRANCH_PLM_ALL))
 			return -EINVAL;
 
-		/* kernel level capture: check permissions */
-		if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
-		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
-
 		/* propagate priv level, when not set for branch */
 		if (!(mask & PERF_SAMPLE_BRANCH_PLM_ALL)) {
 
@@ -6503,6 +6498,10 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 			 */
 			attr->branch_sample_type = mask;
 		}
+		/* kernel level capture: check permissions */
+		if ((mask & PERF_SAMPLE_BRANCH_KERNEL)
+		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+			return -EACCES;
 	}
 
 	if (attr->sample_type & PERF_SAMPLE_REGS_USER) {