xdpHelpProgram.h

/*
 * SPDX-FileCopyrightText: 2022 Open Networking Foundation
 * SPDX-FileCopyrightText: 2022 Orange
 *
 * SPDX-License-Identifier: Apache-2.0
 */
#ifndef BACKENDS_EBPF_PSA_XDPHELPPROGRAM_H_
#define BACKENDS_EBPF_PSA_XDPHELPPROGRAM_H_
 
#include "backends/ebpf/ebpfProgram.h"
 
namespace P4::EBPF {
 
class XDPHelpProgram : public EBPFProgram {
    const char *XDPProgUsingMetaForXDP2TC =
        "    void *data_end = (void *)(long)skb->data_end;\n"
        "    struct ethhdr *eth = (struct ethhdr *)(long)skb->data;\n"
        "    if ((void *)((struct ethhdr *) eth + 1) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    if (eth->h_proto == bpf_htons(0x0800) || eth->h_proto == bpf_htons(0x86DD)) {\n"
        "        return XDP_PASS;\n"
        "    }\n"
        "\n"
        "    struct internal_metadata *meta;\n"
        "    int ret = bpf_xdp_adjust_meta(skb, -(int)sizeof(*meta));\n"
        "    if (ret < 0) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    meta = (struct internal_metadata *)(unsigned long)skb->data_meta;\n"
        "    eth = (void *)(long)skb->data;\n"
        "    data_end = (void *)(long)skb->data_end;\n"
        "    if ((void *) ((struct internal_metadata *) meta + 1) > (void *)(long)skb->data)\n"
        "        return XDP_ABORTED;\n"
        "    if ((void *)((struct ethhdr *) eth + 1) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    meta->pkt_ether_type = eth->h_proto;\n"
        "    eth->h_proto = bpf_htons(0x0800);\n"
        "\n"
        "    return XDP_PASS;";
 
    const char *XDPProgUsingHeadForXDP2TC =
        "    void *data = (void *)(long)skb->data;\n"
        "    void *data_end = (void *)(long)skb->data_end;\n"
        "    struct ethhdr *eth = data;\n"
        "    if ((void *)((struct ethhdr *) eth + 1) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    __u16 orig_ethtype = eth->h_proto;\n"
        "    int ret = bpf_xdp_adjust_head(skb, -2);\n"
        "    if (ret < 0) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "\n"
        "    data = (void *)(long)skb->data;\n"
        "    data_end = (void *)(long)skb->data_end;\n"
        "\n"
        "    if ((void *)(data + 16) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    __builtin_memmove(data, data + 2, 14);\n"
        "    eth = data;\n"
        "    if ((void *)((struct ethhdr *) eth + 1) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    eth->h_proto = bpf_htons(0x0800);\n"
        "    __builtin_memcpy((char *)data + 14, &orig_ethtype, 2);\n"
        "    "
        "\n"
        "    return XDP_PASS;";
 
    const char *XDPProgUsingCPUMAPForXDP2TC =
        "    void *data = (void *)(long)skb->data;\n"
        "    void *data_end = (void *)(long)skb->data_end;\n"
        "    struct ethhdr *eth = data;\n"
        "    if ((void *)((struct ethhdr *) eth + 1) > data_end) {\n"
        "        return XDP_ABORTED;\n"
        "    }\n"
        "    u16 orig_ethtype = eth->h_proto;\n"
        "    eth->h_proto = bpf_htons(0x0800);\n"
        "    u32 zero = 0;\n"
        "    BPF_MAP_UPDATE_ELEM(xdp2tc_cpumap, &zero, &orig_ethtype, BPF_ANY);\n"
        "    return XDP_PASS;";
 
 public:
    cstring sectionName;
    explicit XDPHelpProgram(const EbpfOptions &options)
        : EBPFProgram(options, nullptr, nullptr, nullptr, nullptr) {
        sectionName = "xdp/xdp-ingress"_cs;
        functionName = "xdp_func"_cs;
    }
 
    void emit(CodeBuilder *builder) {
        builder->target->emitCodeSection(builder, sectionName);
        builder->emitIndent();
        builder->appendFormat("int %v(struct xdp_md *%s)", functionName, model.CPacketName.str());
        builder->spc();
        builder->blockStart();
        builder->emitIndent();
        // This is static program, so we can just paste a piece of code.
        if (options.xdp2tcMode == XDP2TC_META) {
            builder->appendLine(XDPProgUsingMetaForXDP2TC);
        } else if (options.xdp2tcMode == XDP2TC_HEAD) {
            builder->appendLine(XDPProgUsingHeadForXDP2TC);
        } else if (options.xdp2tcMode == XDP2TC_CPUMAP) {
            builder->appendLine(XDPProgUsingCPUMAPForXDP2TC);
        }
        builder->blockEnd(true);
    }
};
 
}  // namespace P4::EBPF
 
#endif /* BACKENDS_EBPF_PSA_XDPHELPPROGRAM_H_ */