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bpf: inline bpf_map_lookup_elem() helper for PERCPU_HASH map

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Using new per-CPU BPF instruction, partially inline
bpf_map_lookup_elem() helper for per-CPU hashmap BPF map. Just like for
normal HASH map, we still generate a call into __htab_map_lookup_elem(),
but after that we resolve per-CPU element address using a new
instruction, saving on extra functions calls.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240402021307.1012571-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-04-01 19:13:05 -07:00 committed by Alexei Starovoitov
parent db69718b8e
commit 0b56e637f7
1 changed files with 21 additions and 0 deletions
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21
kernel/bpf/hashtab.c
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@ -2308,6 +2308,26 @@ static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
return NULL;
}
/* inline bpf_map_lookup_elem() call for per-CPU hashmap */
static int htab_percpu_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
struct bpf_insn *insn = insn_buf;
if (!bpf_jit_supports_percpu_insn())
return -EOPNOTSUPP;
BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
(void *(*)(struct bpf_map *map, void *key))NULL));
*insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
*insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3);
*insn++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_0,
offsetof(struct htab_elem, key) + map->key_size);
*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
*insn++ = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
return insn - insn_buf;
}
static void *htab_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
{
struct htab_elem *l;
@ -2436,6 +2456,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_percpu_map_lookup_elem,
.map_gen_lookup = htab_percpu_map_gen_lookup,
.map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
.map_update_elem = htab_percpu_map_update_elem,
.map_delete_elem = htab_map_delete_elem,