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Message-ID: <CAPhsuW6h+ospj-_b1mX16OZFV1p-2v54ymr+yF-ztoO869Qy-w@mail.gmail.com>
Date: Tue, 26 Jun 2018 15:23:48 -0700
From: Song Liu <liu.song.a23@...il.com>
To: Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>,
Daniel Borkmann <daniel@...earbox.net>,
oss-drivers@...ronome.com, Networking <netdev@...r.kernel.org>,
Jiong Wang <jiong.wang@...ronome.com>
Subject: Re: [PATCH bpf-next 5/7] nfp: bpf: support u16 and u32 multiplications
On Sun, Jun 24, 2018 at 8:54 PM, Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
> From: Jiong Wang <jiong.wang@...ronome.com>
>
> NFP supports u16 and u32 multiplication. Multiplication is done 8-bits per
> step, therefore we need 2 steps for u16 and 4 steps for u32.
>
> We also need one start instruction to initialize the sequence and one or
> two instructions to fetch the result depending on either you need the high
> halve of u32 multiplication.
>
> For ALU64, if either operand is beyond u32's value range, we reject it. One
> thing to note, if the source operand is BPF_K, then we need to check "imm"
> field directly, and we'd reject it if it is negative. Because for ALU64,
> "imm" (with s32 type) is expected to be sign extended to s64 which NFP mul
> doesn't support. For ALU32, it is fine for "imm" be negative though,
> because the result is 32-bits and here is no difference on the low halve
> of result for signed/unsigned mul, so we will get correct result.
>
> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
> Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Acked-by: Song Liu <songliubraving@...com>
> ---
> drivers/net/ethernet/netronome/nfp/bpf/jit.c | 137 ++++++++++++++++++
> drivers/net/ethernet/netronome/nfp/bpf/main.h | 5 +
> .../net/ethernet/netronome/nfp/bpf/verifier.c | 58 ++++++--
> drivers/net/ethernet/netronome/nfp/nfp_asm.h | 28 ++++
> 4 files changed, 217 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
> index 4a629e9b5c0f..7d7061d93358 100644
> --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
> +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
> @@ -415,6 +415,60 @@ emit_alu(struct nfp_prog *nfp_prog, swreg dst,
> reg.dst_lmextn, reg.src_lmextn);
> }
>
> +static void
> +__emit_mul(struct nfp_prog *nfp_prog, enum alu_dst_ab dst_ab, u16 areg,
> + enum mul_type type, enum mul_step step, u16 breg, bool swap,
> + bool wr_both, bool dst_lmextn, bool src_lmextn)
> +{
> + u64 insn;
> +
> + insn = OP_MUL_BASE |
> + FIELD_PREP(OP_MUL_A_SRC, areg) |
> + FIELD_PREP(OP_MUL_B_SRC, breg) |
> + FIELD_PREP(OP_MUL_STEP, step) |
> + FIELD_PREP(OP_MUL_DST_AB, dst_ab) |
> + FIELD_PREP(OP_MUL_SW, swap) |
> + FIELD_PREP(OP_MUL_TYPE, type) |
> + FIELD_PREP(OP_MUL_WR_AB, wr_both) |
> + FIELD_PREP(OP_MUL_SRC_LMEXTN, src_lmextn) |
> + FIELD_PREP(OP_MUL_DST_LMEXTN, dst_lmextn);
> +
> + nfp_prog_push(nfp_prog, insn);
> +}
> +
> +static void
> +emit_mul(struct nfp_prog *nfp_prog, swreg lreg, enum mul_type type,
> + enum mul_step step, swreg rreg)
> +{
> + struct nfp_insn_ur_regs reg;
> + u16 areg;
> + int err;
> +
> + if (type == MUL_TYPE_START && step != MUL_STEP_NONE) {
> + nfp_prog->error = -EINVAL;
> + return;
> + }
> +
> + if (step == MUL_LAST || step == MUL_LAST_2) {
> + /* When type is step and step Number is LAST or LAST2, left
> + * source is used as destination.
> + */
> + err = swreg_to_unrestricted(lreg, reg_none(), rreg, ®);
> + areg = reg.dst;
> + } else {
> + err = swreg_to_unrestricted(reg_none(), lreg, rreg, ®);
> + areg = reg.areg;
> + }
> +
> + if (err) {
> + nfp_prog->error = err;
> + return;
> + }
> +
> + __emit_mul(nfp_prog, reg.dst_ab, areg, type, step, reg.breg, reg.swap,
> + reg.wr_both, reg.dst_lmextn, reg.src_lmextn);
> +}
> +
> static void
> __emit_ld_field(struct nfp_prog *nfp_prog, enum shf_sc sc,
> u8 areg, u8 bmask, u8 breg, u8 shift, bool imm8,
> @@ -1380,6 +1434,65 @@ static void wrp_end32(struct nfp_prog *nfp_prog, swreg reg_in, u8 gpr_out)
> SHF_SC_R_ROT, 16);
> }
>
> +static void
> +wrp_mul_u32(struct nfp_prog *nfp_prog, swreg dst_hi, swreg dst_lo, swreg lreg,
> + swreg rreg, bool gen_high_half)
> +{
> + emit_mul(nfp_prog, lreg, MUL_TYPE_START, MUL_STEP_NONE, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_32x32, MUL_STEP_1, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_32x32, MUL_STEP_2, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_32x32, MUL_STEP_3, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_32x32, MUL_STEP_4, rreg);
> + emit_mul(nfp_prog, dst_lo, MUL_TYPE_STEP_32x32, MUL_LAST, reg_none());
> + if (gen_high_half)
> + emit_mul(nfp_prog, dst_hi, MUL_TYPE_STEP_32x32, MUL_LAST_2,
> + reg_none());
> + else
> + wrp_immed(nfp_prog, dst_hi, 0);
> +}
> +
> +static void
> +wrp_mul_u16(struct nfp_prog *nfp_prog, swreg dst_hi, swreg dst_lo, swreg lreg,
> + swreg rreg)
> +{
> + emit_mul(nfp_prog, lreg, MUL_TYPE_START, MUL_STEP_NONE, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_16x16, MUL_STEP_1, rreg);
> + emit_mul(nfp_prog, lreg, MUL_TYPE_STEP_16x16, MUL_STEP_2, rreg);
> + emit_mul(nfp_prog, dst_lo, MUL_TYPE_STEP_16x16, MUL_LAST, reg_none());
> +}
> +
> +static int
> +wrp_mul(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
> + bool gen_high_half, bool ropnd_from_reg)
> +{
> + swreg multiplier, multiplicand, dst_hi, dst_lo;
> + const struct bpf_insn *insn = &meta->insn;
> + u32 lopnd_max, ropnd_max;
> + u8 dst_reg;
> +
> + dst_reg = insn->dst_reg;
> + multiplicand = reg_a(dst_reg * 2);
> + dst_hi = reg_both(dst_reg * 2 + 1);
> + dst_lo = reg_both(dst_reg * 2);
> + lopnd_max = meta->umax_dst;
> + if (ropnd_from_reg) {
> + multiplier = reg_b(insn->src_reg * 2);
> + ropnd_max = meta->umax_src;
> + } else {
> + u32 imm = insn->imm;
> +
> + multiplier = re_load_imm_any(nfp_prog, imm, imm_b(nfp_prog));
> + ropnd_max = imm;
> + }
> + if (lopnd_max > U16_MAX || ropnd_max > U16_MAX)
> + wrp_mul_u32(nfp_prog, dst_hi, dst_lo, multiplicand, multiplier,
> + gen_high_half);
> + else
> + wrp_mul_u16(nfp_prog, dst_hi, dst_lo, multiplicand, multiplier);
> +
> + return 0;
> +}
> +
> static int adjust_head(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> {
> swreg tmp = imm_a(nfp_prog), tmp_len = imm_b(nfp_prog);
> @@ -1684,6 +1797,16 @@ static int sub_imm64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> return 0;
> }
>
> +static int mul_reg64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> +{
> + return wrp_mul(nfp_prog, meta, true, true);
> +}
> +
> +static int mul_imm64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> +{
> + return wrp_mul(nfp_prog, meta, true, false);
> +}
> +
> static int neg_reg64(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> {
> const struct bpf_insn *insn = &meta->insn;
> @@ -2097,6 +2220,16 @@ static int sub_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> return wrp_alu32_imm(nfp_prog, meta, ALU_OP_SUB, !meta->insn.imm);
> }
>
> +static int mul_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> +{
> + return wrp_mul(nfp_prog, meta, false, true);
> +}
> +
> +static int mul_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> +{
> + return wrp_mul(nfp_prog, meta, false, false);
> +}
> +
> static int neg_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
> {
> u8 dst = meta->insn.dst_reg * 2;
> @@ -2848,6 +2981,8 @@ static const instr_cb_t instr_cb[256] = {
> [BPF_ALU64 | BPF_ADD | BPF_K] = add_imm64,
> [BPF_ALU64 | BPF_SUB | BPF_X] = sub_reg64,
> [BPF_ALU64 | BPF_SUB | BPF_K] = sub_imm64,
> + [BPF_ALU64 | BPF_MUL | BPF_X] = mul_reg64,
> + [BPF_ALU64 | BPF_MUL | BPF_K] = mul_imm64,
> [BPF_ALU64 | BPF_NEG] = neg_reg64,
> [BPF_ALU64 | BPF_LSH | BPF_X] = shl_reg64,
> [BPF_ALU64 | BPF_LSH | BPF_K] = shl_imm64,
> @@ -2867,6 +3002,8 @@ static const instr_cb_t instr_cb[256] = {
> [BPF_ALU | BPF_ADD | BPF_K] = add_imm,
> [BPF_ALU | BPF_SUB | BPF_X] = sub_reg,
> [BPF_ALU | BPF_SUB | BPF_K] = sub_imm,
> + [BPF_ALU | BPF_MUL | BPF_X] = mul_reg,
> + [BPF_ALU | BPF_MUL | BPF_K] = mul_imm,
> [BPF_ALU | BPF_NEG] = neg_reg,
> [BPF_ALU | BPF_LSH | BPF_K] = shl_imm,
> [BPF_ALU | BPF_END | BPF_X] = end_reg32,
> diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.h b/drivers/net/ethernet/netronome/nfp/bpf/main.h
> index c985d0ac61a3..c10079b1a312 100644
> --- a/drivers/net/ethernet/netronome/nfp/bpf/main.h
> +++ b/drivers/net/ethernet/netronome/nfp/bpf/main.h
> @@ -394,6 +394,11 @@ static inline bool is_mbpf_xadd(const struct nfp_insn_meta *meta)
> return (meta->insn.code & ~BPF_SIZE_MASK) == (BPF_STX | BPF_XADD);
> }
>
> +static inline bool is_mbpf_mul(const struct nfp_insn_meta *meta)
> +{
> + return is_mbpf_alu(meta) && mbpf_op(meta) == BPF_MUL;
> +}
> +
> /**
> * struct nfp_prog - nfp BPF program
> * @bpf: backpointer to the bpf app priv structure
> diff --git a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
> index 7bd9666bd8ff..30d4f1580693 100644
> --- a/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
> +++ b/drivers/net/ethernet/netronome/nfp/bpf/verifier.c
> @@ -516,6 +516,51 @@ nfp_bpf_check_xadd(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
> return nfp_bpf_check_ptr(nfp_prog, meta, env, meta->insn.dst_reg);
> }
>
> +static int
> +nfp_bpf_check_alu(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
> + struct bpf_verifier_env *env)
> +{
> + const struct bpf_reg_state *sreg =
> + cur_regs(env) + meta->insn.src_reg;
> + const struct bpf_reg_state *dreg =
> + cur_regs(env) + meta->insn.dst_reg;
> +
> + meta->umin_src = min(meta->umin_src, sreg->umin_value);
> + meta->umax_src = max(meta->umax_src, sreg->umax_value);
> + meta->umin_dst = min(meta->umin_dst, dreg->umin_value);
> + meta->umax_dst = max(meta->umax_dst, dreg->umax_value);
> +
> + /* NFP supports u16 and u32 multiplication.
> + *
> + * For ALU64, if either operand is beyond u32's value range, we reject
> + * it. One thing to note, if the source operand is BPF_K, then we need
> + * to check "imm" field directly, and we'd reject it if it is negative.
> + * Because for ALU64, "imm" (with s32 type) is expected to be sign
> + * extended to s64 which NFP mul doesn't support.
> + *
> + * For ALU32, it is fine for "imm" be negative though, because the
> + * result is 32-bits and there is no difference on the low halve of
> + * the result for signed/unsigned mul, so we will get correct result.
> + */
> + if (is_mbpf_mul(meta)) {
> + if (meta->umax_dst > U32_MAX) {
> + pr_vlog(env, "multiplier is not within u32 value range\n");
> + return -EINVAL;
> + }
> + if (mbpf_src(meta) == BPF_X && meta->umax_src > U32_MAX) {
> + pr_vlog(env, "multiplicand is not within u32 value range\n");
> + return -EINVAL;
> + }
> + if (mbpf_class(meta) == BPF_ALU64 &&
> + mbpf_src(meta) == BPF_K && meta->insn.imm < 0) {
> + pr_vlog(env, "sign extended multiplicand won't be within u32 value range\n");
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
> +
> static int
> nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
> {
> @@ -551,17 +596,8 @@ nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
> if (is_mbpf_xadd(meta))
> return nfp_bpf_check_xadd(nfp_prog, meta, env);
>
> - if (is_mbpf_alu(meta)) {
> - const struct bpf_reg_state *sreg =
> - cur_regs(env) + meta->insn.src_reg;
> - const struct bpf_reg_state *dreg =
> - cur_regs(env) + meta->insn.dst_reg;
> -
> - meta->umin_src = min(meta->umin_src, sreg->umin_value);
> - meta->umax_src = max(meta->umax_src, sreg->umax_value);
> - meta->umin_dst = min(meta->umin_dst, dreg->umin_value);
> - meta->umax_dst = max(meta->umax_dst, dreg->umax_value);
> - }
> + if (is_mbpf_alu(meta))
> + return nfp_bpf_check_alu(nfp_prog, meta, env);
>
> return 0;
> }
> diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.h b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
> index f6677bc9875a..cdc4e065f6f5 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfp_asm.h
> +++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
> @@ -426,4 +426,32 @@ static inline u32 nfp_get_ind_csr_ctx_ptr_offs(u32 read_offset)
> return (read_offset & ~NFP_IND_ME_CTX_PTR_BASE_MASK) | NFP_CSR_CTX_PTR;
> }
>
> +enum mul_type {
> + MUL_TYPE_START = 0x00,
> + MUL_TYPE_STEP_24x8 = 0x01,
> + MUL_TYPE_STEP_16x16 = 0x02,
> + MUL_TYPE_STEP_32x32 = 0x03,
> +};
> +
> +enum mul_step {
> + MUL_STEP_1 = 0x00,
> + MUL_STEP_NONE = MUL_STEP_1,
> + MUL_STEP_2 = 0x01,
> + MUL_STEP_3 = 0x02,
> + MUL_STEP_4 = 0x03,
> + MUL_LAST = 0x04,
> + MUL_LAST_2 = 0x05,
> +};
> +
> +#define OP_MUL_BASE 0x0f800000000ULL
> +#define OP_MUL_A_SRC 0x000000003ffULL
> +#define OP_MUL_B_SRC 0x000000ffc00ULL
> +#define OP_MUL_STEP 0x00000700000ULL
> +#define OP_MUL_DST_AB 0x00000800000ULL
> +#define OP_MUL_SW 0x00040000000ULL
> +#define OP_MUL_TYPE 0x00180000000ULL
> +#define OP_MUL_WR_AB 0x20000000000ULL
> +#define OP_MUL_SRC_LMEXTN 0x40000000000ULL
> +#define OP_MUL_DST_LMEXTN 0x80000000000ULL
> +
> #endif
> --
> 2.17.1
>
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