netdev - [PATCH RESEND bpf-next v3 5/6] riscv, bpf: Optimize sign-extention mov insns with Zbb support

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Date: Mon, 15 Jan 2024 13:12:34 +0000
From: Pu Lehui <pulehui@...weicloud.com>
To: bpf@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	netdev@...r.kernel.org
Cc: Björn Töpel <bjorn@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Conor Dooley <conor@...nel.org>,
	Luke Nelson <luke.r.nels@...il.com>,
	Pu Lehui <pulehui@...wei.com>,
	Pu Lehui <pulehui@...weicloud.com>
Subject: [PATCH RESEND bpf-next v3 5/6] riscv, bpf: Optimize sign-extention mov insns with Zbb support

From: Pu Lehui <pulehui@...wei.com>

Add 8-bit and 16-bit sign-extention wraper with Zbb support to optimize
sign-extension mov instructions.

Signed-off-by: Pu Lehui <pulehui@...wei.com>
Acked-by: Björn Töpel <bjorn@...nel.org>
---
 arch/riscv/net/bpf_jit.h        | 22 ++++++++++++++++++++++
 arch/riscv/net/bpf_jit_comp64.c |  5 +++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
index 51f6d214086f..b00c5c0591d2 100644
--- a/arch/riscv/net/bpf_jit.h
+++ b/arch/riscv/net/bpf_jit.h
@@ -1119,6 +1119,28 @@ static inline void emit_subw(u8 rd, u8 rs1, u8 rs2, struct rv_jit_context *ctx)
 		emit(rv_subw(rd, rs1, rs2), ctx);
 }
 
+static inline void emit_sextb(u8 rd, u8 rs, struct rv_jit_context *ctx)
+{
+	if (rvzbb_enabled()) {
+		emit(rvzbb_sextb(rd, rs), ctx);
+		return;
+	}
+
+	emit_slli(rd, rs, 56, ctx);
+	emit_srai(rd, rd, 56, ctx);
+}
+
+static inline void emit_sexth(u8 rd, u8 rs, struct rv_jit_context *ctx)
+{
+	if (rvzbb_enabled()) {
+		emit(rvzbb_sexth(rd, rs), ctx);
+		return;
+	}
+
+	emit_slli(rd, rs, 48, ctx);
+	emit_srai(rd, rd, 48, ctx);
+}
+
 static inline void emit_sextw(u8 rd, u8 rs, struct rv_jit_context *ctx)
 {
 	emit_addiw(rd, rs, 0, ctx);
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index d90784674677..18bbf8122eb3 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1073,9 +1073,10 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 			emit_mv(rd, rs, ctx);
 			break;
 		case 8:
+			emit_sextb(rd, rs, ctx);
+			break;
 		case 16:
-			emit_slli(RV_REG_T1, rs, 64 - insn->off, ctx);
-			emit_srai(rd, RV_REG_T1, 64 - insn->off, ctx);
+			emit_sexth(rd, rs, ctx);
 			break;
 		case 32:
 			emit_sextw(rd, rs, ctx);
-- 
2.34.1