Commit e65650f2 authored by Maciej Fijalkowski's avatar Maciej Fijalkowski Committed by Daniel Borkmann
Browse files

bpf: Implement map_gen_lookup() callback for XSKMAP 



Inline the xsk_map_lookup_elem() via implementing the map_gen_lookup()
callback. This results in emitting the bpf instructions in place of
bpf_map_lookup_elem() helper call and better performance of bpf
programs.

Signed-off-by: default avatarMaciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/bpf/20191101110346.15004-3-bjorn.topel@gmail.com
parent 64fe8c06

kernel/bpf/xskmap.c

+17 −0
Original line number Diff line number Diff line
@@ -163,6 +163,22 @@ struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) 
	return xs;

}



static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)

{

	const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;

	struct bpf_insn *insn = insn_buf;



	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);

	*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);

	*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));

	*insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));

	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);

	*insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);

	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);

	*insn++ = BPF_MOV64_IMM(ret, 0);

	return insn - insn_buf;

}



int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,

		       struct xdp_sock *xs)

{
@@ -303,6 +319,7 @@ const struct bpf_map_ops xsk_map_ops = { 
	.map_free = xsk_map_free,

	.map_get_next_key = xsk_map_get_next_key,

	.map_lookup_elem = xsk_map_lookup_elem,

	.map_gen_lookup = xsk_map_gen_lookup,

	.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,

	.map_update_elem = xsk_map_update_elem,

	.map_delete_elem = xsk_map_delete_elem,

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