Re: [dpdk-dev] [RFC v2 6/7] net/af_xdp: load BPF file

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Thursday, March 8, 2018 9:53 PM
> To: dev@dpdk.org
> Cc: Karlsson, Magnus <magnus.karlsson@intel.com>; Topel, Bjorn
> <bjorn.topel@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>
> Subject: [RFC v2 6/7] net/af_xdp: load BPF file
> 
> Add libbpf and libelf dependency in Makefile.
> Durring initialization, a bpf prog which call imm "xdpsk_redirect"
> will be loaded. Then the driver will always try to link XDP fd with DRV mode
> first, then SKB mode if failed in previoius. Link will be released during
> dev_close.
> 
> Note: this is workaround solution, af_xdp may remove BPF dependency in
> future.
> 
> Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
> ---
>  drivers/net/af_xdp/Makefile         |   5 +-
>  drivers/net/af_xdp/bpf_load.c       | 168
> ++++++++++++++++++++++++++++++++++++
>  drivers/net/af_xdp/bpf_load.h       |  11 +++
>  drivers/net/af_xdp/rte_eth_af_xdp.c |  80 ++++++++++++++---
>  mk/rte.app.mk                       |   2 +-
>  5 files changed, 254 insertions(+), 12 deletions(-)  create mode 100644
> drivers/net/af_xdp/bpf_load.c  create mode 100644
> drivers/net/af_xdp/bpf_load.h
> 
> diff --git a/drivers/net/af_xdp/Makefile b/drivers/net/af_xdp/Makefile index
> 990073655..f16b5306b 100644
> --- a/drivers/net/af_xdp/Makefile
> +++ b/drivers/net/af_xdp/Makefile
> @@ -12,7 +12,9 @@ EXPORT_MAP := rte_pmd_af_xdp_version.map
> 
> +static char bpf_log_buf[BPF_LOG_BUF_SIZE];
> +
> +struct bpf_insn prog[] = {
> +	{
> +		.code = 0x85, //call imm
> +		.dst_reg = 0,
> +		.src_reg = 0,
> +		.off = 0,
> +		.imm = BPF_FUNC_xdpsk_redirect,
> +	},
> +	{
> +		.code = 0x95, //exit
> +		.dst_reg = 0,
> +		.src_reg = 0,
> +		.off = 0,
> +		.imm = 0,
> +	},
> +};
> +
> +int load_bpf_file(void)
> +{
> +	int fd;
> +
> +	fd = bpf_load_program(BPF_PROG_TYPE_XDP, prog,
> +			      ARRAY_SIZE(prog),
Sorry for one mistake.
checkpatch recommend to use ARRAY_SIZE here, but seems this macro is not defined by default, so compile failed here, replace with "2" is a quick fix.
> +			      "GPL", 0,
> +			      bpf_log_buf, BPF_LOG_BUF_SIZE);
> +
> +