1 files changed, 68 insertions, 0 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e8b32ac75ce3..5820efdf47cd 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -118,6 +118,13 @@ static int cpu_function_call(int cpu, int (*func) (void *info), void *info)
                        PERF_FLAG_FD_OUTPUT  |\
                        PERF_FLAG_PID_CGROUP)
 
+/*
+ * branch priv levels that need permission checks
+ */
+#define PERF_SAMPLE_BRANCH_PERM_PLM \
+        (PERF_SAMPLE_BRANCH_KERNEL |\
+         PERF_SAMPLE_BRANCH_HV)
+
 enum event_type_t {
         EVENT_FLEXIBLE = 0x1,
         EVENT_PINNED = 0x2,
@@ -3907,6 +3914,24 @@ void perf_output_sample(struct perf_output_handle *handle,
                         }
                 }
         }
+
+        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                if (data->br_stack) {
+                        size_t size;
+
+                        size = data->br_stack->nr
+                             * sizeof(struct perf_branch_entry);
+
+                        perf_output_put(handle, data->br_stack->nr);
+                        perf_output_copy(handle, data->br_stack->entries, size);
+                } else {
+                        /*
+                         * we always store at least the value of nr
+                         */
+                        u64 nr = 0;
+                        perf_output_put(handle, nr);
+                }
+        }
 }
 
 void perf_prepare_sample(struct perf_event_header *header,
@@ -3949,6 +3974,15 @@ void perf_prepare_sample(struct perf_event_header *header,
                 WARN_ON_ONCE(size & (sizeof(u64)-1));
                 header->size += size;
         }
+
+        if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                int size = sizeof(u64); /* nr */
+                if (data->br_stack) {
+                        size += data->br_stack->nr
+                              * sizeof(struct perf_branch_entry);
+                }
+                header->size += size;
+        }
 }
 
 static void perf_event_output(struct perf_event *event,
@@ -5935,6 +5969,40 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
         if (attr->read_format & ~(PERF_FORMAT_MAX-1))
                 return -EINVAL;
 
+        if (attr->sample_type & PERF_SAMPLE_BRANCH_STACK) {
+                u64 mask = attr->branch_sample_type;
+
+                /* only using defined bits */
+                if (mask & ~(PERF_SAMPLE_BRANCH_MAX-1))
+                        return -EINVAL;
+
+                /* at least one branch bit must be set */
+                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)) {
+
+                        /* exclude_kernel checked on syscall entry */
+                        if (!attr->exclude_kernel)
+                                mask |= PERF_SAMPLE_BRANCH_KERNEL;
+
+                        if (!attr->exclude_user)
+                                mask |= PERF_SAMPLE_BRANCH_USER;
+
+                        if (!attr->exclude_hv)
+                                mask |= PERF_SAMPLE_BRANCH_HV;
+                        /*
+                         * adjust user setting (for HW filter setup)
+                         */
+                        attr->branch_sample_type = mask;
+                }
+        }
 out:
         return ret;