[bpf-next] arm64: bpf: optimize modulo operation
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Message ID 20190902061448.28252-1-jerinj@marvell.com
State Accepted
Commit 504792e07a44844f24e9d79913e4a2f8373cd332
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Series
  • [bpf-next] arm64: bpf: optimize modulo operation
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Commit Message

jerinj@marvell.com Sept. 2, 2019, 6:14 a.m. UTC
From: Jerin Jacob <jerinj@marvell.com>

Optimize modulo operation instruction generation by
using single MSUB instruction vs MUL followed by SUB
instruction scheme.

Signed-off-by: Jerin Jacob <jerinj@marvell.com>
---
 arch/arm64/net/bpf_jit.h      | 3 +++
 arch/arm64/net/bpf_jit_comp.c | 6 ++----
 2 files changed, 5 insertions(+), 4 deletions(-)

Comments

Daniel Borkmann Sept. 3, 2019, 2:05 p.m. UTC | #1
On 9/2/19 8:14 AM, jerinj@marvell.com wrote:
> From: Jerin Jacob <jerinj@marvell.com>
> 
> Optimize modulo operation instruction generation by
> using single MSUB instruction vs MUL followed by SUB
> instruction scheme.
> 
> Signed-off-by: Jerin Jacob <jerinj@marvell.com>

Applied, thanks!

Patch
diff mbox series

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: