[PATCH bpf-next v2 5/7] riscv, bpf: Support signed div/mod insns

From: Pu Lehui
Date: Wed Aug 23 2023 - 21:47:02 EST


From: Pu Lehui <pulehui@xxxxxxxxxx>

Add support signed div/mod instructions for RV64.

Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
Acked-by: Björn Töpel <bjorn@xxxxxxxxxx>
---
arch/riscv/net/bpf_jit.h | 20 ++++++++++++++++++++
arch/riscv/net/bpf_jit_comp64.c | 26 ++++++++++++++++++++------
2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
index a52a3dda18c3..d21c6c92a683 100644
--- a/arch/riscv/net/bpf_jit.h
+++ b/arch/riscv/net/bpf_jit.h
@@ -431,11 +431,21 @@ static inline u32 rv_mulhu(u8 rd, u8 rs1, u8 rs2)
return rv_r_insn(1, rs2, rs1, 3, rd, 0x33);
}

+static inline u32 rv_div(u8 rd, u8 rs1, u8 rs2)
+{
+ return rv_r_insn(1, rs2, rs1, 4, rd, 0x33);
+}
+
static inline u32 rv_divu(u8 rd, u8 rs1, u8 rs2)
{
return rv_r_insn(1, rs2, rs1, 5, rd, 0x33);
}

+static inline u32 rv_rem(u8 rd, u8 rs1, u8 rs2)
+{
+ return rv_r_insn(1, rs2, rs1, 6, rd, 0x33);
+}
+
static inline u32 rv_remu(u8 rd, u8 rs1, u8 rs2)
{
return rv_r_insn(1, rs2, rs1, 7, rd, 0x33);
@@ -776,11 +786,21 @@ static inline u32 rv_mulw(u8 rd, u8 rs1, u8 rs2)
return rv_r_insn(1, rs2, rs1, 0, rd, 0x3b);
}

+static inline u32 rv_divw(u8 rd, u8 rs1, u8 rs2)
+{
+ return rv_r_insn(1, rs2, rs1, 4, rd, 0x3b);
+}
+
static inline u32 rv_divuw(u8 rd, u8 rs1, u8 rs2)
{
return rv_r_insn(1, rs2, rs1, 5, rd, 0x3b);
}

+static inline u32 rv_remw(u8 rd, u8 rs1, u8 rs2)
+{
+ return rv_r_insn(1, rs2, rs1, 6, rd, 0x3b);
+}
+
static inline u32 rv_remuw(u8 rd, u8 rs1, u8 rs2)
{
return rv_r_insn(1, rs2, rs1, 7, rd, 0x3b);
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 076619f4aa82..ba4535ac194f 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1107,13 +1107,19 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
break;
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU64 | BPF_DIV | BPF_X:
- emit(is64 ? rv_divu(rd, rd, rs) : rv_divuw(rd, rd, rs), ctx);
+ if (off)
+ emit(is64 ? rv_div(rd, rd, rs) : rv_divw(rd, rd, rs), ctx);
+ else
+ emit(is64 ? rv_divu(rd, rd, rs) : rv_divuw(rd, rd, rs), ctx);
if (!is64 && !aux->verifier_zext)
emit_zext_32(rd, ctx);
break;
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU64 | BPF_MOD | BPF_X:
- emit(is64 ? rv_remu(rd, rd, rs) : rv_remuw(rd, rd, rs), ctx);
+ if (off)
+ emit(is64 ? rv_rem(rd, rd, rs) : rv_remw(rd, rd, rs), ctx);
+ else
+ emit(is64 ? rv_remu(rd, rd, rs) : rv_remuw(rd, rd, rs), ctx);
if (!is64 && !aux->verifier_zext)
emit_zext_32(rd, ctx);
break;
@@ -1284,16 +1290,24 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
case BPF_ALU | BPF_DIV | BPF_K:
case BPF_ALU64 | BPF_DIV | BPF_K:
emit_imm(RV_REG_T1, imm, ctx);
- emit(is64 ? rv_divu(rd, rd, RV_REG_T1) :
- rv_divuw(rd, rd, RV_REG_T1), ctx);
+ if (off)
+ emit(is64 ? rv_div(rd, rd, RV_REG_T1) :
+ rv_divw(rd, rd, RV_REG_T1), ctx);
+ else
+ emit(is64 ? rv_divu(rd, rd, RV_REG_T1) :
+ rv_divuw(rd, rd, RV_REG_T1), ctx);
if (!is64 && !aux->verifier_zext)
emit_zext_32(rd, ctx);
break;
case BPF_ALU | BPF_MOD | BPF_K:
case BPF_ALU64 | BPF_MOD | BPF_K:
emit_imm(RV_REG_T1, imm, ctx);
- emit(is64 ? rv_remu(rd, rd, RV_REG_T1) :
- rv_remuw(rd, rd, RV_REG_T1), ctx);
+ if (off)
+ emit(is64 ? rv_rem(rd, rd, RV_REG_T1) :
+ rv_remw(rd, rd, RV_REG_T1), ctx);
+ else
+ emit(is64 ? rv_remu(rd, rd, RV_REG_T1) :
+ rv_remuw(rd, rd, RV_REG_T1), ctx);
if (!is64 && !aux->verifier_zext)
emit_zext_32(rd, ctx);
break;
--
2.39.2