ebpfBackend.cpp

/*
Copyright 2013-present Barefoot Networks, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include "ebpfBackend.h"

#include "ebpfProgram.h"
#include "ebpfType.h"
#include "frontends/p4/evaluator/evaluator.h"
#include "lib/error.h"
#include "lib/nullstream.h"
#include "psa/backend.h"
#include "psa/ebpfPsaGen.h"
#include "target.h"

namespace P4::EBPF {

void emitFilterModel(const EbpfOptions &options, Target *target, const IR::ToplevelBlock *toplevel,
                     P4::ReferenceMap *refMap, P4::TypeMap *typeMap) {
    CodeBuilder c(target);
    CodeBuilder h(target);

    EBPFTypeFactory::createFactory(typeMap);
    auto ebpfprog = new EBPFProgram(options, toplevel->getProgram(), refMap, typeMap, toplevel);
    if (!ebpfprog->build()) return;

    if (options.outputFile.empty()) return;

    auto *cstream = openFile(options.outputFile, false);
    if (cstream == nullptr) return;

    std::filesystem::path hfile = options.outputFile;
    hfile.replace_extension(".h");
    auto *hstream = openFile(hfile, false);
    if (hstream == nullptr) return;

    ebpfprog->emitH(&h, hfile);
    ebpfprog->emitC(&c, hfile);
    *cstream << c.toString();
    *hstream << h.toString();
    cstream->flush();
    hstream->flush();
}

void run_ebpf_backend(const EbpfOptions &options, const IR::ToplevelBlock *toplevel,
                      P4::ReferenceMap *refMap, P4::TypeMap *typeMap) {
    if (toplevel == nullptr) return;

    auto main = toplevel->getMain();
    if (main == nullptr) {
        ::P4::warning(ErrorType::WARN_MISSING,
                      "Could not locate top-level block; is there a %1% module?",
                      IR::P4Program::main);
        return;
    }

    // We don't require --xdp option to be used if we can auto-detect it.
    bool mainIsXdp = (main->type->name == "xdp");

    Target *target;
    if (options.target.isNullOrEmpty() || options.target == "kernel") {
        if (!options.generateToXDP && !mainIsXdp)
            target = new KernelSamplesTarget(options.emitTraceMessages);
        else
            target = new XdpTarget(options.emitTraceMessages);
    } else if (options.target == "bcc") {
        target = new BccTarget();
    } else if (options.target == "test") {
        target = new TestTarget();
    } else {
        ::P4::error(ErrorType::ERR_UNKNOWN,
                    "Unknown target %s; legal choices are 'bcc', 'kernel', and test",
                    options.target);
        return;
    }

    if (options.arch.isNullOrEmpty() || options.arch == "filter") {
        emitFilterModel(options, target, toplevel, refMap, typeMap);
    } else if (options.arch == "psa") {
        auto backend = new EBPF::PSASwitchBackend(options, target, refMap, typeMap);
        backend->convert(toplevel);

        if (options.outputFile.empty()) return;

        auto cstream = openFile(options.outputFile, false);
        if (cstream == nullptr) return;

        backend->codegen(*cstream);
        cstream->flush();
    } else {
        ::P4::error(ErrorType::ERR_UNKNOWN,
                    "Unknown architecture %s; legal choices are 'filter', and 'psa'", options.arch);
        return;
    }
}

}  // namespace P4::EBPF