riscv, bpf: Unify 32-bit sign-extension to emit_sextw

For code unification, add emit_sextw wrapper to unify all the 32-bit
sign-extension operations.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20240115131235.2914289-2-pulehui@huaweicloud.com

arch/riscv/net/bpf_jit.h

@@ -1087,6 +1087,11 @@ 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_sextw(u8 rd, u8 rs, struct rv_jit_context *ctx)
+{
+	emit_addiw(rd, rs, 0, ctx);
+}
+
 #endif /* __riscv_xlen == 64 */
 
 void bpf_jit_build_prologue(struct rv_jit_context *ctx);

arch/riscv/net/bpf_jit_comp64.c

@@ -417,8 +417,8 @@ static void emit_zext_32_rd_rs(u8 *rd, u8 *rs, struct rv_jit_context *ctx)
 
 static void emit_sext_32_rd_rs(u8 *rd, u8 *rs, struct rv_jit_context *ctx)
 {
-	emit_addiw(RV_REG_T2, *rd, 0, ctx);
-	emit_addiw(RV_REG_T1, *rs, 0, ctx);
+	emit_sextw(RV_REG_T2, *rd, ctx);
+	emit_sextw(RV_REG_T1, *rs, ctx);
 	*rd = RV_REG_T2;
 	*rs = RV_REG_T1;
 }
@@ -433,7 +433,7 @@ static void emit_zext_32_rd_t1(u8 *rd, struct rv_jit_context *ctx)
 
 static void emit_sext_32_rd(u8 *rd, struct rv_jit_context *ctx)
 {
-	emit_addiw(RV_REG_T2, *rd, 0, ctx);
+	emit_sextw(RV_REG_T2, *rd, ctx);
 	*rd = RV_REG_T2;
 }
 
@@ -1104,7 +1104,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 			emit_srai(rd, RV_REG_T1, 64 - insn->off, ctx);
 			break;
 		case 32:
-			emit_addiw(rd, rs, 0, ctx);
+			emit_sextw(rd, rs, ctx);
 			break;
 		}
 		if (!is64 && !aux->verifier_zext)
@@ -1504,7 +1504,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 		 * as t1 is used only in comparison against zero.
 		 */
 		if (!is64 && imm < 0)
-			emit_addiw(RV_REG_T1, RV_REG_T1, 0, ctx);
+			emit_sextw(RV_REG_T1, RV_REG_T1, ctx);
 		e = ctx->ninsns;
 		rvoff -= ninsns_rvoff(e - s);
 		emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff, ctx);