[PATCH bpf-next] arm64: bpf: optimize modulo operation
From: <hidden>
Date: 2019-09-02 06:15:02
Also in:
bpf, linux-arm-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), bpf jit for arm64, bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Catalin Marinas, Will Deacon, Daniel Borkmann, Alexei Starovoitov, Puranjay Mohan, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
From: Jerin Jacob <redacted> Optimize modulo operation instruction generation by using single MSUB instruction vs MUL followed by SUB instruction scheme. Signed-off-by: Jerin Jacob <redacted> --- arch/arm64/net/bpf_jit.h | 3 +++ arch/arm64/net/bpf_jit_comp.c | 6 ++---- 2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index cb7ab50b7657..eb73f9f72c46 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h@@ -171,6 +171,9 @@ /* Rd = Ra + Rn * Rm */ #define A64_MADD(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \ A64_VARIANT(sf), AARCH64_INSN_DATA3_MADD) +/* Rd = Ra - Rn * Rm */ +#define A64_MSUB(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \ + A64_VARIANT(sf), AARCH64_INSN_DATA3_MSUB) /* Rd = Rn * Rm */ #define A64_MUL(sf, Rd, Rn, Rm) A64_MADD(sf, Rd, A64_ZR, Rn, Rm)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index f5b437f8a22b..cdc79de0c794 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c@@ -409,8 +409,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, break; case BPF_MOD: emit(A64_UDIV(is64, tmp, dst, src), ctx); - emit(A64_MUL(is64, tmp, tmp, src), ctx); - emit(A64_SUB(is64, dst, dst, tmp), ctx); + emit(A64_MSUB(is64, dst, dst, tmp, src), ctx); break; } break;
@@ -516,8 +515,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_ALU64 | BPF_MOD | BPF_K: emit_a64_mov_i(is64, tmp2, imm, ctx); emit(A64_UDIV(is64, tmp, dst, tmp2), ctx); - emit(A64_MUL(is64, tmp, tmp, tmp2), ctx); - emit(A64_SUB(is64, dst, dst, tmp), ctx); + emit(A64_MSUB(is64, dst, dst, tmp, tmp2), ctx); break; case BPF_ALU | BPF_LSH | BPF_K: case BPF_ALU64 | BPF_LSH | BPF_K:
--
2.23.0