From a80857822b0c2ed608c93504bd3687b78f20c619 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Dec 2014 15:06:38 -0800 Subject: samples: bpf: trivial eBPF program in C this example does the same task as previous socket example in assembler, but this one does it in C. eBPF program in kernel does: /* assume that packet is IPv4, load one byte of IP->proto */ int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)); long *value; value = bpf_map_lookup_elem(&my_map, &index); if (value) __sync_fetch_and_add(value, 1); Corresponding user space reads map[tcp], map[udp], map[icmp] and prints protocol stats every second Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/Makefile | 14 +++++++++++++ samples/bpf/libbpf.h | 2 +- samples/bpf/sockex1_kern.c | 25 +++++++++++++++++++++++ samples/bpf/sockex1_user.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 89 insertions(+), 1 deletion(-) create mode 100644 samples/bpf/sockex1_kern.c create mode 100644 samples/bpf/sockex1_user.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index f46d3492d032..770d145186c3 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -4,12 +4,26 @@ obj- := dummy.o # List of programs to build hostprogs-y := test_verifier test_maps hostprogs-y += sock_example +hostprogs-y += sockex1 test_verifier-objs := test_verifier.o libbpf.o test_maps-objs := test_maps.o libbpf.o sock_example-objs := sock_example.o libbpf.o +sockex1-objs := bpf_load.o libbpf.o sockex1_user.o # Tell kbuild to always build the programs always := $(hostprogs-y) +always += sockex1_kern.o HOSTCFLAGS += -I$(objtree)/usr/include + +HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable +HOSTLOADLIBES_sockex1 += -lelf + +# point this to your LLVM backend with bpf support +LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc + +%.o: %.c + clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \ + -D__KERNEL__ -Wno-unused-value -Wno-pointer-sign \ + -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@ diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h index cc62ad4d95de..58c5fe1bdba1 100644 --- a/samples/bpf/libbpf.h +++ b/samples/bpf/libbpf.h @@ -15,7 +15,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_len, const char *license); -#define LOG_BUF_SIZE 8192 +#define LOG_BUF_SIZE 65536 extern char bpf_log_buf[LOG_BUF_SIZE]; /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */ diff --git a/samples/bpf/sockex1_kern.c b/samples/bpf/sockex1_kern.c new file mode 100644 index 000000000000..066892662915 --- /dev/null +++ b/samples/bpf/sockex1_kern.c @@ -0,0 +1,25 @@ +#include +#include +#include +#include "bpf_helpers.h" + +struct bpf_map_def SEC("maps") my_map = { + .type = BPF_MAP_TYPE_ARRAY, + .key_size = sizeof(u32), + .value_size = sizeof(long), + .max_entries = 256, +}; + +SEC("socket1") +int bpf_prog1(struct sk_buff *skb) +{ + int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)); + long *value; + + value = bpf_map_lookup_elem(&my_map, &index); + if (value) + __sync_fetch_and_add(value, 1); + + return 0; +} +char _license[] SEC("license") = "GPL"; diff --git a/samples/bpf/sockex1_user.c b/samples/bpf/sockex1_user.c new file mode 100644 index 000000000000..34a443ff3831 --- /dev/null +++ b/samples/bpf/sockex1_user.c @@ -0,0 +1,49 @@ +#include +#include +#include +#include "libbpf.h" +#include "bpf_load.h" +#include +#include + +int main(int ac, char **argv) +{ + char filename[256]; + FILE *f; + int i, sock; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + + sock = open_raw_sock("lo"); + + assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, prog_fd, + sizeof(prog_fd[0])) == 0); + + f = popen("ping -c5 localhost", "r"); + (void) f; + + for (i = 0; i < 5; i++) { + long long tcp_cnt, udp_cnt, icmp_cnt; + int key; + + key = IPPROTO_TCP; + assert(bpf_lookup_elem(map_fd[0], &key, &tcp_cnt) == 0); + + key = IPPROTO_UDP; + assert(bpf_lookup_elem(map_fd[0], &key, &udp_cnt) == 0); + + key = IPPROTO_ICMP; + assert(bpf_lookup_elem(map_fd[0], &key, &icmp_cnt) == 0); + + printf("TCP %lld UDP %lld ICMP %lld packets\n", + tcp_cnt, udp_cnt, icmp_cnt); + sleep(1); + } + + return 0; +} -- cgit v1.2.3