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bpf: inline bpf_map_lookup_elem() for PERCPU_ARRAY maps

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

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240402021307.1012571-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-04-01 19:13:04 -07:00 committed by Alexei Starovoitov
parent 1ae6921009
commit db69718b8e
1 changed files with 33 additions and 0 deletions
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33
kernel/bpf/arraymap.c
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@ -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,