Implement Meter extern for eBPF backend

backends/ebpf/CMakeLists.txt

@@ -48,7 +48,9 @@ set (P4C_EBPF_SRCS
   psa/externs/ebpfPsaChecksum.cpp
   psa/externs/ebpfPsaHashAlgorithm.cpp
   psa/externs/ebpfPsaTableImplementation.cpp
-  psa/externs/ebpfPsaRegister.cpp)
+  psa/externs/ebpfPsaRegister.cpp
+  psa/externs/ebpfPsaMeter.cpp
+)
 
 set (P4C_EBPF_HDRS
   codeGen.h
@@ -81,6 +83,7 @@ set (P4C_EBPF_HDRS
   psa/externs/ebpfPsaHashAlgorithm.h
   psa/externs/ebpfPsaTableImplementation.h
   psa/externs/ebpfPsaRegister.h
+  psa/externs/ebpfPsaMeter.h
 )
 
 add_cpplint_files(${CMAKE_CURRENT_SOURCE_DIR} "${P4C_EBPF_SRCS};${P4C_EBPF_HDRS}")

backends/ebpf/psa/README.md

@@ -270,6 +270,21 @@ If a deparser triggers the `pack()` method, an eBPF program inserts data defined
 A user space application is responsible for performing periodic queries to this map to read a Digest message. It can use either
 `psabpf-ctl digest get pipe`, `psabpf_digest_get_next` from psabpf C API or `bpf_map_lookup_and_delete_elem` from `libbpf` API.
 
+### Meters
+
+[Meters](https://p4.org/p4-spec/docs/PSA.html#sec-meters) are a mechanism for "marking" packets that exceed an average packet or bit rate.
+Meters implement Dual Token Bucket Algorithm with both "color aware" and "color blind" modes. The PSA-eBPF implementation uses a BPF hash map
+to store a Meter state. The current implementation in eBPF uses BPF spinlocks to make operations on Meters atomic. The `bpf_ktime_get_ns()` helper is used to get a packet arrival timestamp. 
+
+The best way to configure a Meter is to use `psabpf-ctl meter` tool as in the following example:
+```bash
+# 1Mb/s -> 128 000 bytes/s (132 kbytes/s PIR, 128 kbytes/s CIR), let CBS, PBS -> 10 kbytes
+$ psabpf-ctl meter update pipe "$PIPELINE" DemoIngress_meter index 0 132000:10000 128000:10000
+```
+
+`psabpf-ctl` accepts PIR and CIR values in bytes/s units or packets/s. PBS and CBS in bytes or packets.
+
+
 # Getting started
 
 ## Installation 

backends/ebpf/psa/ebpfPipeline.h

@@ -118,6 +118,9 @@ class EBPFPipeline : public EBPFProgram {
     void emitHeadersFromCPUMAP(CodeBuilder* builder);
     void emitMetadataFromCPUMAP(CodeBuilder *builder);
 
+    bool hasAnyMeter() const {
+        return !control->meters.empty();
+    }
     /*
      * Returns whether the compiler should generate
      * timestamp retrieved by bpf_ktime_get_ns().
@@ -126,7 +129,7 @@ class EBPFPipeline : public EBPFProgram {
      * if the timestamp field is not used within a pipeline.
      */
     bool shouldEmitTimestamp() const {
-        return control->timestampIsUsed;
+        return hasAnyMeter() || control->timestampIsUsed;
     }
 };
 

backends/ebpf/psa/ebpfPsaControl.cpp

@@ -46,6 +46,11 @@ bool ControlBodyTranslatorPSA::preorder(const IR::AssignmentStatement* a) {
             // Then the hash value is stored in a registerVar variable.
             hash->calculateHash(builder, ext->expr, this);
             builder->emitIndent();
+        } else if (ext->originalExternType->name.name == "Meter") {
+            // It is just for trace message before meter execution
+            cstring name = EBPFObject::externalName(ext->object);
+            auto msgStr = Util::printf_format("Executing meter: %s", name);
+            builder->target->emitTraceMessage(builder, msgStr.c_str());
         }
     }
 
@@ -61,6 +66,10 @@ void ControlBodyTranslatorPSA::processMethod(const P4::ExternMethod* method) {
         auto counterMap = control->getCounter(name);
         counterMap->to<EBPFCounterPSA>()->emitMethodInvocation(builder, method, this);
         return;
+    } else if (declType->name.name == "Meter") {
+        auto meter = control->to<EBPFControlPSA>()->getMeter(name);
+        meter->emitExecute(builder, method, this);
+        return;
     } else if (declType->name.name == "Hash") {
         auto hash = control->to<EBPFControlPSA>()->getHash(name);
         hash->processMethod(builder, method->method->name.name, method->expr, this);
@@ -95,6 +104,13 @@ void EBPFControlPSA::emitTableTypes(CodeBuilder *builder) {
 
     for (auto it : registers)
         it.second->emitTypes(builder);
+    for (auto it : meters)
+        it.second->emitKeyType(builder);
+
+    //  Value type for any indirect meter is the same
+    if (!meters.empty()) {
+        meters.begin()->second->emitValueType(builder);
+    }
 }
 
 void EBPFControlPSA::emitTableInstances(CodeBuilder* builder) {
@@ -104,6 +120,8 @@ void EBPFControlPSA::emitTableInstances(CodeBuilder* builder) {
         it.second->emitInstance(builder);
     for (auto it : registers)
         it.second->emitInstance(builder);
+    for (auto it : meters)
+        it.second->emitInstance(builder);
 }
 
 void EBPFControlPSA::emitTableInitializers(CodeBuilder* builder) {

backends/ebpf/psa/ebpfPsaControl.h

@@ -65,6 +65,7 @@ class EBPFControlPSA : public EBPFControl {
 
     std::map<cstring, EBPFHashPSA*> hashes;
     std::map<cstring, EBPFRegisterPSA*>  registers;
+    std::map<cstring, EBPFMeterPSA*>  meters;
 
     EBPFControlPSA(const EBPFProgram* program, const IR::ControlBlock* control,
                    const IR::Parameter* parserHeaders) :
@@ -86,6 +87,12 @@ class EBPFControlPSA : public EBPFControl {
         BUG_CHECK(result != nullptr, "No hash named %1%", name);
         return result;
     }
+
+    EBPFMeterPSA* getMeter(cstring name) const {
+        auto result = ::get(meters, name);
+        BUG_CHECK(result != nullptr, "No meter named %1%", name);
+        return result;
+    }
 };
 
 }  // namespace EBPF

backends/ebpf/psa/ebpfPsaGen.cpp

@@ -23,6 +23,7 @@ limitations under the License.
 #include "externs/ebpfPsaCounter.h"
 #include "externs/ebpfPsaHashAlgorithm.h"
 #include "externs/ebpfPsaTableImplementation.h"
+#include "externs/ebpfPsaMeter.h"
 
 namespace EBPF {
 
@@ -92,6 +93,9 @@ void PSAEbpfGenerator::emitTypes(CodeBuilder *builder) const {
         type->emit(builder);
     }
 
+    if (ingress->hasAnyMeter() || egress->hasAnyMeter())
+        EBPFMeterPSA::emitValueStruct(builder, ingress->refMap);
+
     ingress->parser->emitTypes(builder);
     ingress->control->emitTableTypes(builder);
     egress->parser->emitTypes(builder);
@@ -267,6 +271,13 @@ void PSAEbpfGenerator::emitHelperFunctions(CodeBuilder *builder) const {
 
     builder->appendLine(pktClonesFunc);
     builder->newline();
+
+    if (ingress->hasAnyMeter() || egress->hasAnyMeter()) {
+        cstring meterExecuteFunc =
+                EBPFMeterPSA::meterExecuteFunc(options.emitTraceMessages, ingress->refMap);
+        builder->appendLine(meterExecuteFunc);
+        builder->newline();
+    }
 }
 
 // =====================PSAArchTC=============================
@@ -646,6 +657,9 @@ bool ConvertToEBPFControlPSA::preorder(const IR::ExternBlock* instance) {
     } else if (typeName == "Hash") {
         auto hash = new EBPFHashPSA(program, di, name);
         control->hashes.emplace(name, hash);
+    } else if (typeName == "Meter") {
+        auto met = new EBPFMeterPSA(program, name, di, control->codeGen);
+        control->meters.emplace(name, met);
     } else {
         ::error(ErrorType::ERR_UNEXPECTED, "Unexpected block %s nested within control",
                 instance);

backends/ebpf/psa/ebpfPsaTable.h

@@ -20,6 +20,7 @@ limitations under the License.
 #include "frontends/p4/methodInstance.h"
 #include "backends/ebpf/ebpfTable.h"
 #include "backends/ebpf/psa/externs/ebpfPsaCounter.h"
+#include "backends/ebpf/psa/externs/ebpfPsaMeter.h"
 
 namespace EBPF {
 

backends/ebpf/psa/externs/ebpfPsaCounter.cpp

@@ -200,11 +200,8 @@ void EBPFCounterPSA::emitDirectMethodInvocation(CodeBuilder* builder,
 
     cstring target = valuePtr + "->" + instanceName;
     auto pipeline = dynamic_cast<const EBPFPipeline *>(program);
-    if (pipeline == nullptr) {
-        ::error(ErrorType::ERR_UNSUPPORTED,
-                "DirectCounter used outside of pipeline %1%", method->expr);
-        return;
-    }
+    CHECK_NULL(pipeline);
+
     cstring msgStr = Util::printf_format("Counter: updating %s, packets=1, bytes=%%u",
                                          instanceName.c_str());
     cstring varStr = Util::printf_format("%s", pipeline->lengthVar.c_str());