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libbpf, xsk: Select AF_XDP BPF program based on kernel version

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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.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Marek Majtyka  <alardam@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210122105351.11751-4-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel 2021-01-22 11:53:51 +01:00 committed by Daniel Borkmann
parent f0863eab96
commit 78ed404591
1 changed files with 78 additions and 3 deletions
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81
tools/lib/bpf/xsk.c
View file

@ -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 +356,54 @@ 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 +411,7 @@ 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 +467,31 @@ 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) {