From: Björn Töpel <bjorn.topel@xxxxxxxxx>
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 <maciej.fijalkowski@xxxxxxxxx>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
Signed-off-by: Björn Töpel <bjorn.topel@xxxxxxxxx>
Signed-off-by: Marek Majtyka <alardam@xxxxxxxxx>
---
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
