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[213.102.90.208]) by smtp.gmail.com with ESMTPSA id z2sm2309075lfd.142.2021.01.19.07.37.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jan 2021 07:37:14 -0800 (PST) From: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= To: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, bpf@vger.kernel.org Cc: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= , 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, Marek Majtyka Subject: [PATCH bpf-next 5/8] libbpf, xsk: select AF_XDP BPF program based on kernel version Date: Tue, 19 Jan 2021 16:36:52 +0100 Message-Id: <20210119153655.153999-6-bjorn.topel@gmail.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210119153655.153999-1-bjorn.topel@gmail.com> References: <20210119153655.153999-1-bjorn.topel@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@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/libbpf.c | 2 +- tools/lib/bpf/libbpf_internal.h | 2 ++ tools/lib/bpf/libbpf_probes.c | 16 ------------- tools/lib/bpf/xsk.c | 41 ++++++++++++++++++++++++++++++--- 4 files changed, 41 insertions(+), 20 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 2abbc3800568..6a53adf14a9c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -693,7 +693,7 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, return 0; } -static __u32 get_kernel_version(void) +__u32 get_kernel_version(void) { __u32 major, minor, patch; struct utsname info; diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 969d0ac592ba..dafb780e2dd2 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -349,4 +349,6 @@ struct bpf_core_relo { enum bpf_core_relo_kind kind; }; +__u32 get_kernel_version(void); + #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index ecaae2927ab8..aae0231371d0 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -48,22 +48,6 @@ static int get_vendor_id(int ifindex) return strtol(buf, NULL, 0); } -static int get_kernel_version(void) -{ - int version, subversion, patchlevel; - struct utsname utsn; - - /* Return 0 on failure, and attempt to probe with empty kversion */ - if (uname(&utsn)) - return 0; - - if (sscanf(utsn.release, "%d.%d.%d", - &version, &subversion, &patchlevel) != 3) - return 0; - - return (version << 16) + (subversion << 8) + patchlevel; -} - static void probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex) diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index e3e41ceeb1bc..c8642c6cb5d6 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -46,6 +47,11 @@ #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 +357,13 @@ 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) +{ + __u32 kver = get_kernel_version(); + + return kver < KERNEL_VERSION(5, 3, 0) ? XSK_PROG_FALLBACK : XSK_PROG_REDIRECT_FLAGS; +} + static int xsk_load_xdp_prog(struct xsk_socket *xsk) { static const int log_buf_size = 16 * 1024; @@ -358,7 +371,7 @@ 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 +427,31 @@ 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) {