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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: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/bpf/20191101110346.15004-3-bjorn.topel@gmail.com
This commit is contained in:
Maciej Fijalkowski 2019-11-01 12:03:45 +01:00 committed by Daniel Borkmann
parent 64fe8c061d
commit e65650f291
1 changed files with 17 additions and 0 deletions
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17
kernel/bpf/xskmap.c
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@ -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,