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[213.102.90.208]) by smtp.gmail.com with ESMTPSA id g14sm409580lja.120.2021.01.22.02.54.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Jan 2021 02:54:00 -0800 (PST) From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= To: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, bpf@vger.kernel.org Cc: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, kuba@kernel.org, jonathan.lemon@gmail.com, maximmi@nvidia.com, davem@davemloft.net, hawk@kernel.org, john.fastabend@gmail.com, ciara.loftus@intel.com, weqaar.a.janjua@intel.com, andrii@kernel.org, Marek Majtyka Subject: [PATCH bpf-next 3/3] libbpf, xsk: select AF_XDP BPF program based on kernel version Date: Fri, 22 Jan 2021 11:53:51 +0100 Message-Id: <20210122105351.11751-4-bjorn.topel@gmail.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210122105351.11751-1-bjorn.topel@gmail.com> References: <20210122105351.11751-1-bjorn.topel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Björn Töpel Add detection for kernel version, and adapt the BPF program based on kernel support. This way, users will get the best possible performance from the BPF program. Reviewed-by: Maciej Fijalkowski Acked-by: Maciej Fijalkowski Signed-off-by: Björn Töpel Signed-off-by: Marek Majtyka --- tools/lib/bpf/xsk.c | 82 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 79 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index e3e41ceeb1bc..1df8c133a5bc 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -46,6 +46,11 @@ #define PF_XDP AF_XDP #endif +enum xsk_prog { + XSK_PROG_FALLBACK, + XSK_PROG_REDIRECT_FLAGS, +}; + struct xsk_umem { struct xsk_ring_prod *fill_save; struct xsk_ring_cons *comp_save; @@ -351,6 +356,55 @@ int xsk_umem__create_v0_0_2(struct xsk_umem **umem_ptr, void *umem_area, COMPAT_VERSION(xsk_umem__create_v0_0_2, xsk_umem__create, LIBBPF_0.0.2) DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, LIBBPF_0.0.4) + +static enum xsk_prog get_xsk_prog(void) +{ + enum xsk_prog detected = XSK_PROG_FALLBACK; + struct bpf_load_program_attr prog_attr; + struct bpf_create_map_attr map_attr; + __u32 size_out, retval, duration; + char data_in = 0, data_out; + struct bpf_insn insns[] = { + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_3, XDP_PASS), + BPF_EMIT_CALL(BPF_FUNC_redirect_map), + BPF_EXIT_INSN(), + }; + int prog_fd, map_fd, ret; + + memset(&map_attr, 0, sizeof(map_attr)); + map_attr.map_type = BPF_MAP_TYPE_XSKMAP; + map_attr.key_size = sizeof(int); + map_attr.value_size = sizeof(int); + map_attr.max_entries = 1; + + map_fd = bpf_create_map_xattr(&map_attr); + if (map_fd < 0) + return detected; + + insns[0].imm = map_fd; + + memset(&prog_attr, 0, sizeof(prog_attr)); + prog_attr.prog_type = BPF_PROG_TYPE_XDP; + prog_attr.insns = insns; + prog_attr.insns_cnt = ARRAY_SIZE(insns); + prog_attr.license = "GPL"; + + prog_fd = bpf_load_program_xattr(&prog_attr, NULL, 0); + if (prog_fd < 0) { + close(map_fd); + return detected; + } + + ret = bpf_prog_test_run(prog_fd, 0, &data_in, 1, &data_out, &size_out, &retval, &duration); + if (!ret && retval == XDP_PASS) + detected = XSK_PROG_REDIRECT_FLAGS; + close(prog_fd); + close(map_fd); + return detected; +} + static int xsk_load_xdp_prog(struct xsk_socket *xsk) { static const int log_buf_size = 16 * 1024; @@ -358,7 +412,7 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk) char log_buf[log_buf_size]; int err, prog_fd; - /* This is the C-program: + /* This is the fallback C-program: * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx) * { * int ret, index = ctx->rx_queue_index; @@ -414,9 +468,31 @@ static int xsk_load_xdp_prog(struct xsk_socket *xsk) /* The jumps are to this instruction */ BPF_EXIT_INSN(), }; - size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn); - prog_fd = bpf_load_program(BPF_PROG_TYPE_XDP, prog, insns_cnt, + /* This is the post-5.3 kernel C-program: + * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx) + * { + * return bpf_redirect_map(&xsks_map, ctx->rx_queue_index, XDP_PASS); + * } + */ + struct bpf_insn prog_redirect_flags[] = { + /* r2 = *(u32 *)(r1 + 16) */ + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 16), + /* r1 = xskmap[] */ + BPF_LD_MAP_FD(BPF_REG_1, ctx->xsks_map_fd), + /* r3 = XDP_PASS */ + BPF_MOV64_IMM(BPF_REG_3, 2), + /* call bpf_redirect_map */ + BPF_EMIT_CALL(BPF_FUNC_redirect_map), + BPF_EXIT_INSN(), + }; + size_t insns_cnt[] = {sizeof(prog) / sizeof(struct bpf_insn), + sizeof(prog_redirect_flags) / sizeof(struct bpf_insn), + }; + struct bpf_insn *progs[] = {prog, prog_redirect_flags}; + enum xsk_prog option = get_xsk_prog(); + + prog_fd = bpf_load_program(BPF_PROG_TYPE_XDP, progs[option], insns_cnt[option], "LGPL-2.1 or BSD-2-Clause", 0, log_buf, log_buf_size); if (prog_fd < 0) { -- 2.27.0