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ebpf: fix percpu hash handling

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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.
pull/3952/head
Eric Leblond 6 years ago committed by Victor Julien
parent 142c69e1ef
commit 651a27e4fb
3 changed files with 28 additions and 16 deletions
Show Stats Download Patch File Download Diff File

13
src/source-af-packet.c
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@ -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) {

23
src/util-ebpf.c
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@ -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;

8
src/util-ebpf.h
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@ -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

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