2023-08-24 02:09:29

by Pu Lehui

[permalink] [raw]
Subject: [PATCH bpf-next v2 2/7] riscv, bpf: Support sign-extension load insns

From: Pu Lehui <[email protected]>

Add Support sign-extension load instructions for RV64.

Signed-off-by: Pu Lehui <[email protected]>
Acked-by: Björn Töpel <[email protected]>
---
arch/riscv/net/bpf_jit.h | 10 +++++++
arch/riscv/net/bpf_jit_comp64.c | 46 +++++++++++++++++++++++++++------
2 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
index 2717f5490428..a52a3dda18c3 100644
--- a/arch/riscv/net/bpf_jit.h
+++ b/arch/riscv/net/bpf_jit.h
@@ -501,6 +501,16 @@ static inline u32 rv_ble(u8 rs1, u8 rs2, u16 imm12_1)
return rv_bge(rs2, rs1, imm12_1);
}

+static inline u32 rv_lb(u8 rd, u16 imm11_0, u8 rs1)
+{
+ return rv_i_insn(imm11_0, rs1, 0, rd, 0x03);
+}
+
+static inline u32 rv_lh(u8 rd, u16 imm11_0, u8 rs1)
+{
+ return rv_i_insn(imm11_0, rs1, 1, rd, 0x03);
+}
+
static inline u32 rv_lw(u8 rd, u16 imm11_0, u8 rs1)
{
return rv_i_insn(imm11_0, rs1, 2, rd, 0x03);
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index f2644e7ea6b5..fd36cb17101a 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -580,7 +580,8 @@ static int add_exception_handler(const struct bpf_insn *insn,
unsigned long pc;
off_t offset;

- if (!ctx->insns || !ctx->prog->aux->extable || BPF_MODE(insn->code) != BPF_PROBE_MEM)
+ if (!ctx->insns || !ctx->prog->aux->extable ||
+ (BPF_MODE(insn->code) != BPF_PROBE_MEM && BPF_MODE(insn->code) != BPF_PROBE_MEMSX))
return 0;

if (WARN_ON_ONCE(ctx->nexentries >= ctx->prog->aux->num_exentries))
@@ -1486,7 +1487,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
return 1;
}

- /* LDX: dst = *(size *)(src + off) */
+ /* LDX: dst = *(unsigned size *)(src + off) */
case BPF_LDX | BPF_MEM | BPF_B:
case BPF_LDX | BPF_MEM | BPF_H:
case BPF_LDX | BPF_MEM | BPF_W:
@@ -1495,14 +1496,28 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
case BPF_LDX | BPF_PROBE_MEM | BPF_H:
case BPF_LDX | BPF_PROBE_MEM | BPF_W:
case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
+ /* LDSX: dst = *(signed size *)(src + off) */
+ case BPF_LDX | BPF_MEMSX | BPF_B:
+ case BPF_LDX | BPF_MEMSX | BPF_H:
+ case BPF_LDX | BPF_MEMSX | BPF_W:
+ case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
+ case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
+ case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
{
int insn_len, insns_start;
+ bool sign_ext;
+
+ sign_ext = BPF_MODE(insn->code) == BPF_MEMSX ||
+ BPF_MODE(insn->code) == BPF_PROBE_MEMSX;

switch (BPF_SIZE(code)) {
case BPF_B:
if (is_12b_int(off)) {
insns_start = ctx->ninsns;
- emit(rv_lbu(rd, off, rs), ctx);
+ if (sign_ext)
+ emit(rv_lb(rd, off, rs), ctx);
+ else
+ emit(rv_lbu(rd, off, rs), ctx);
insn_len = ctx->ninsns - insns_start;
break;
}
@@ -1510,13 +1525,19 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
emit_imm(RV_REG_T1, off, ctx);
emit_add(RV_REG_T1, RV_REG_T1, rs, ctx);
insns_start = ctx->ninsns;
- emit(rv_lbu(rd, 0, RV_REG_T1), ctx);
+ if (sign_ext)
+ emit(rv_lb(rd, 0, RV_REG_T1), ctx);
+ else
+ emit(rv_lbu(rd, 0, RV_REG_T1), ctx);
insn_len = ctx->ninsns - insns_start;
break;
case BPF_H:
if (is_12b_int(off)) {
insns_start = ctx->ninsns;
- emit(rv_lhu(rd, off, rs), ctx);
+ if (sign_ext)
+ emit(rv_lh(rd, off, rs), ctx);
+ else
+ emit(rv_lhu(rd, off, rs), ctx);
insn_len = ctx->ninsns - insns_start;
break;
}
@@ -1524,13 +1545,19 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
emit_imm(RV_REG_T1, off, ctx);
emit_add(RV_REG_T1, RV_REG_T1, rs, ctx);
insns_start = ctx->ninsns;
- emit(rv_lhu(rd, 0, RV_REG_T1), ctx);
+ if (sign_ext)
+ emit(rv_lh(rd, 0, RV_REG_T1), ctx);
+ else
+ emit(rv_lhu(rd, 0, RV_REG_T1), ctx);
insn_len = ctx->ninsns - insns_start;
break;
case BPF_W:
if (is_12b_int(off)) {
insns_start = ctx->ninsns;
- emit(rv_lwu(rd, off, rs), ctx);
+ if (sign_ext)
+ emit(rv_lw(rd, off, rs), ctx);
+ else
+ emit(rv_lwu(rd, off, rs), ctx);
insn_len = ctx->ninsns - insns_start;
break;
}
@@ -1538,7 +1565,10 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
emit_imm(RV_REG_T1, off, ctx);
emit_add(RV_REG_T1, RV_REG_T1, rs, ctx);
insns_start = ctx->ninsns;
- emit(rv_lwu(rd, 0, RV_REG_T1), ctx);
+ if (sign_ext)
+ emit(rv_lw(rd, 0, RV_REG_T1), ctx);
+ else
+ emit(rv_lwu(rd, 0, RV_REG_T1), ctx);
insn_len = ctx->ninsns - insns_start;
break;
case BPF_DW:
--
2.39.2