Commit db69718b authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

bpf: inline bpf_map_lookup_elem() for PERCPU_ARRAY maps 



Using new per-CPU BPF instruction implement inlining for per-CPU ARRAY
map lookup helper, if BPF JIT support is present.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240402021307.1012571-4-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 1ae69210

kernel/bpf/arraymap.c

+33 −0
Original line number Diff line number Diff line
@@ -246,6 +246,38 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key) 
	return this_cpu_ptr(array->pptrs[index & array->index_mask]);

}



/* emit BPF instructions equivalent to C code of percpu_array_map_lookup_elem() */

static int percpu_array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)

{

	struct bpf_array *array = container_of(map, struct bpf_array, map);

	struct bpf_insn *insn = insn_buf;



	if (!bpf_jit_supports_percpu_insn())

		return -EOPNOTSUPP;



	if (map->map_flags & BPF_F_INNER_MAP)

		return -EOPNOTSUPP;



	BUILD_BUG_ON(offsetof(struct bpf_array, map) != 0);

	*insn++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, offsetof(struct bpf_array, pptrs));



	*insn++ = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0);

	if (!map->bypass_spec_v1) {

		*insn++ = BPF_JMP_IMM(BPF_JGE, BPF_REG_0, map->max_entries, 6);

		*insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_0, array->index_mask);

	} else {

		*insn++ = BPF_JMP_IMM(BPF_JGE, BPF_REG_0, map->max_entries, 5);

	}



	*insn++ = BPF_ALU64_IMM(BPF_LSH, BPF_REG_0, 3);

	*insn++ = BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1);

	*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);

	*insn++ = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);

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

	*insn++ = BPF_MOV64_IMM(BPF_REG_0, 0);

	return insn - insn_buf;

}



static void *percpu_array_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)

{

	struct bpf_array *array = container_of(map, struct bpf_array, map);
@@ -776,6 +808,7 @@ const struct bpf_map_ops percpu_array_map_ops = { 
	.map_free = array_map_free,

	.map_get_next_key = array_map_get_next_key,

	.map_lookup_elem = percpu_array_map_lookup_elem,

	.map_gen_lookup = percpu_array_map_gen_lookup,

	.map_update_elem = array_map_update_elem,

	.map_delete_elem = array_map_delete_elem,

	.map_lookup_percpu_elem = percpu_array_map_lookup_percpu_elem,