ebpf: fix percpu hash handling

An alignement issue was preventing the code to work properly.
We introduce macros taken from Linux source code sample to get
something that should work on the long term.

diff --git a/src/source-af-packet.c b/src/source-af-packet.c
index d770050c00fbe3f71b05fa05213dc1c4716cdec0..d87776f56c7ed2e8cbbea594cebc0d8be08aebfe 100644 (file)
--- a/src/source-af-packet.c
+++ b/src/source-af-packet.c
@@ -2299,7 +2299,7 @@ static int AFPInsertHalfFlow(int mapd, void *key, uint32_t hash,
                              uint64_t pkts_cnt, uint64_t bytes_cnt,
                              unsigned int nr_cpus)
 {
-    struct pair value[nr_cpus];
+    BPF_DECLARE_PERCPU(struct pair, value, nr_cpus);
     unsigned int i;
 
     if (mapd == -1) {
@@ -2310,12 +2310,13 @@ static int AFPInsertHalfFlow(int mapd, void *key, uint32_t hash,
      * is not duplicating the data on each CPU by itself. We set the first entry to
      * the actual flow pkts and bytes count as we need to continue from actual point
      * to detect an absence of packets in the future. */
-    value[0].packets = pkts_cnt;
-    value[0].bytes = bytes_cnt;
-    value[0].hash = hash;
+    BPF_PERCPU(value,0).packets = pkts_cnt;
+    BPF_PERCPU(value,0).bytes = bytes_cnt;
+    BPF_PERCPU(value,0).hash = hash;
     for (i = 1; i < nr_cpus; i++) {
-        value[i].packets = 0;
-        value[i].bytes = 0;
+        BPF_PERCPU(value, i).packets = 0;
+        BPF_PERCPU(value, i).bytes = 0;
+        BPF_PERCPU(value, i).hash = hash;
     }
     if (bpf_map_update_elem(mapd, key, value, BPF_NOEXIST) != 0) {
         switch (errno) {

diff --git a/src/util-ebpf.c b/src/util-ebpf.c
index 7774b25163a439df1a64854303032651704024fa..4a5f25bd0a61f78e8836dc87818241b2f3b92ef0 100644 (file)
--- a/src/util-ebpf.c
+++ b/src/util-ebpf.c
@@ -560,7 +560,7 @@ static int EBPFForEachFlowV4Table(LiveDevice *dev, const char *name,
         pkts_cnt = 0;
         /* We use a per CPU structure so we will get a array of values. But if nr_cpus
          * is 1 then we have a global hash. */
-        struct pair values_array[tcfg->cpus_count];
+        BPF_DECLARE_PERCPU(struct pair, values_array, tcfg->cpus_count);
         memset(values_array, 0, sizeof(values_array));
         int res = bpf_map_lookup_elem(mapfd, &next_key, values_array);
         if (res < 0) {
@@ -572,9 +572,10 @@ static int EBPFForEachFlowV4Table(LiveDevice *dev, const char *name,
         for (i = 0; i < tcfg->cpus_count; i++) {
             /* let's start accumulating value so we can compute the counters */
             SCLogDebug("%d: Adding pkts %lu bytes %lu", i,
-                       values_array[i].packets, values_array[i].bytes);
-            pkts_cnt += values_array[i].packets;
-            bytes_cnt += values_array[i].bytes;
+                       BPF_PERCPU(values_array, i).packets,
+                       BPF_PERCPU(values_array, i).bytes);
+            pkts_cnt += BPF_PERCPU(values_array, i).packets;
+            bytes_cnt += BPF_PERCPU(values_array, i).bytes;
         }
         /* Get the corresponding Flow in the Flow table to compare and update
          * its counters and lastseen if needed */
@@ -600,7 +601,8 @@ static int EBPFForEachFlowV4Table(LiveDevice *dev, const char *name,
         flow_key.vlan_id[1] = next_key.vlan_id[1];
         flow_key.proto = next_key.ip_proto;
         flow_key.recursion_level = 0;
-        pkts_cnt = EBPFOpFlowForKey(flowstats, &flow_key, values_array[0].hash,
+        pkts_cnt = EBPFOpFlowForKey(flowstats, &flow_key,
+                                    BPF_PERCPU(values_array, 0).hash,
                                     ctime, pkts_cnt, bytes_cnt);
         if (pkts_cnt > 0) {
             found = 1;
@@ -656,7 +658,7 @@ static int EBPFForEachFlowV6Table(LiveDevice *dev, const char *name,
         pkts_cnt = 0;
         /* We use a per CPU structure so we will get a array of values. But if nr_cpus
          * is 1 then we have a global hash. */
-        struct pair values_array[tcfg->cpus_count];
+        BPF_DECLARE_PERCPU(struct pair, values_array, tcfg->cpus_count);
         memset(values_array, 0, sizeof(values_array));
         int res = bpf_map_lookup_elem(mapfd, &next_key, values_array);
         if (res < 0) {
@@ -667,9 +669,10 @@ static int EBPFForEachFlowV6Table(LiveDevice *dev, const char *name,
         for (i = 0; i < tcfg->cpus_count; i++) {
             /* let's start accumulating value so we can compute the counters */
             SCLogDebug("%d: Adding pkts %lu bytes %lu", i,
-                       values_array[i].packets, values_array[i].bytes);
-            pkts_cnt += values_array[i].packets;
-            bytes_cnt += values_array[i].bytes;
+                       BPF_PERCPU(values_array, i).packets,
+                       BPF_PERCPU(values_array, i).bytes);
+            pkts_cnt += BPF_PERCPU(values_array, i).packets;
+            bytes_cnt += BPF_PERCPU(values_array, i).bytes;
         }
         /* Get the corresponding Flow in the Flow table to compare and update
          * its counters  and lastseen if needed */
@@ -695,7 +698,7 @@ static int EBPFForEachFlowV6Table(LiveDevice *dev, const char *name,
         flow_key.vlan_id[1] = next_key.vlan_id[1];
         flow_key.proto = next_key.ip_proto;
         flow_key.recursion_level = 0;
-        pkts_cnt = EBPFOpFlowForKey(flowstats, &flow_key, values_array[0].hash,
+        pkts_cnt = EBPFOpFlowForKey(flowstats, &flow_key, BPF_PERCPU(values_array, 0).hash,
                                     ctime, pkts_cnt, bytes_cnt);
         if (pkts_cnt > 0) {
             found = 1;

diff --git a/src/util-ebpf.h b/src/util-ebpf.h
index c66c1d9e2e2df2bd9aada7285d832e9f2522c224..078870aa4b4126c01d851aa9cf3eb73412f3a892 100644 (file)
--- a/src/util-ebpf.h
+++ b/src/util-ebpf.h
@@ -88,6 +88,14 @@ int EBPFUpdateFlow(Flow *f, Packet *p, void *data);
 TmEcode EBPFGetBypassedStats(json_t *cmd, json_t *answer, void *data);
 #endif
 
+#define __bpf_percpu_val_align  __attribute__((__aligned__(8)))
+
+#define BPF_DECLARE_PERCPU(type, name, nr_cpus)                          \
+        struct { type v; /* padding */ } __bpf_percpu_val_align \
+                name[nr_cpus]
+#define BPF_PERCPU(name, cpu) name[(cpu)].v
+
+
 #endif
 
 #endif