Re: [dpdk-dev] [PATCH v6 03/10] bpf: add function to convert classic BPF to DPDK BPF

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2021-09-09 16:33 (UTC-0700), Stephen Hemminger:
[...]
> +	prm = rte_zmalloc("bpf_filter",
> +			  sizeof(*prm) + ebpf_len * sizeof(*ebpf), 0);
> +	if (prm == NULL) {
> +		rte_errno = ENOMEM;
> +		return NULL;
> +	}
> +
> +	/* The EPBF instructions in this case are right after the header */
> +	ebpf = (void *)(prm + 1);
> +
> +	/* 2nd pass: remap cBPF to eBPF instructions  */
> +	ret = bpf_convert_filter(prog->bf_insns, prog->bf_len, ebpf, &ebpf_len);
> +	if (ret < 0) {
> +		RTE_BPF_LOG(ERR, "%s: cannot convert cBPF to eBPF\n", __func__);
> +		free(prm);

free -> rte_free

> +		rte_errno = -ret;
> +		return NULL;
> +	}
[...]
> diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
> index 69116f36ba8b..2f23e272a376 100644
> --- a/lib/bpf/rte_bpf.h
> +++ b/lib/bpf/rte_bpf.h
> @@ -198,6 +198,31 @@ rte_bpf_exec_burst(const struct rte_bpf *bpf, void *ctx[], uint64_t rc[],
>  int
>  rte_bpf_get_jit(const struct rte_bpf *bpf, struct rte_bpf_jit *jit);
>  
> +#ifdef RTE_PORT_PCAP

In libre_bpf the function for ELF loading is always declared, and defined as a
stub when libelf is unavailable. The app using it can link to DPDK with or
without ELF support. No strong opinion here, but using different approaches
is a bit messy.

> +
> +struct bpf_program;
> +
> +/**
> + * Convert a Classic BPF program from libpcap into a DPDK BPF code.
> + *
> + * @param prog
> + *  Classic BPF program from pcap_compile().
> + * @param prm
> + *  Result Extended BPF program.
> + * @return
> + *   Pointer to BPF program (allocated with *rte_malloc*)
> + *   that is used in future BPF operations,
> + *   or NULL on error, with error code set in rte_errno.
> + *   Possible rte_errno errors include:
> + *   - EINVAL - invalid parameter passed to function
> + *   - ENOMEM - can't reserve enough memory
> + */
> +__rte_experimental
> +struct rte_bpf_prm *
> +rte_bpf_convert(const struct bpf_program *prog);
> +
> +#endif
> +
>  #ifdef __cplusplus
>  }
>  #endif