[PATCH bpf-next 4/7] nfp: bpf: implement jitting of BPF_ALU | BPF_ARSH | BPF_*

[Jiong Wang]

BPF_X support needs indirect shift mode, please see code comments for
details.

Reviewed-by: Jakub Kicinski <jakub.kicin...@netronome.com>
Signed-off-by: Jiong Wang <jiong.w...@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/jit.c | 45 ++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c 
b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index 97d33bb..662cbc2 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -2382,6 +2382,49 @@ static int neg_reg(struct nfp_prog *nfp_prog, struct 
nfp_insn_meta *meta)
        return 0;
 }
 
+static int __ashr_imm(struct nfp_prog *nfp_prog, u8 dst, u8 shift_amt)
+{
+       /* Set signedness bit (MSB of result). */
+       emit_alu(nfp_prog, reg_none(), reg_a(dst), ALU_OP_OR, reg_imm(0));
+       emit_shf(nfp_prog, reg_both(dst), reg_none(), SHF_OP_ASHR, reg_b(dst),
+                SHF_SC_R_SHF, shift_amt);
+       wrp_immed(nfp_prog, reg_both(dst + 1), 0);
+
+       return 0;
+}
+
+static int ashr_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+       const struct bpf_insn *insn = &meta->insn;
+       u64 umin, umax;
+       u8 dst, src;
+
+       dst = insn->dst_reg * 2;
+       umin = meta->umin_src;
+       umax = meta->umax_src;
+       if (umin == umax)
+               return __ashr_imm(nfp_prog, dst, umin);
+
+       src = insn->src_reg * 2;
+       /* NOTE: the first insn will set both indirect shift amount (source A)
+        * and signedness bit (MSB of result).
+        */
+       emit_alu(nfp_prog, reg_none(), reg_a(src), ALU_OP_OR, reg_b(dst));
+       emit_shf_indir(nfp_prog, reg_both(dst), reg_none(), SHF_OP_ASHR,
+                      reg_b(dst), SHF_SC_R_SHF);
+       wrp_immed(nfp_prog, reg_both(dst + 1), 0);
+
+       return 0;
+}
+
+static int ashr_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
+{
+       const struct bpf_insn *insn = &meta->insn;
+       u8 dst = insn->dst_reg * 2;
+
+       return __ashr_imm(nfp_prog, dst, insn->imm);
+}
+
 static int shl_imm(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)
 {
        const struct bpf_insn *insn = &meta->insn;
@@ -3286,6 +3329,8 @@ static const instr_cb_t instr_cb[256] = {
        [BPF_ALU | BPF_DIV | BPF_K] =   div_imm,
        [BPF_ALU | BPF_NEG] =           neg_reg,
        [BPF_ALU | BPF_LSH | BPF_K] =   shl_imm,
+       [BPF_ALU | BPF_ARSH | BPF_X] =  ashr_reg,
+       [BPF_ALU | BPF_ARSH | BPF_K] =  ashr_imm,
        [BPF_ALU | BPF_END | BPF_X] =   end_reg32,
        [BPF_LD | BPF_IMM | BPF_DW] =   imm_ld8,
        [BPF_LD | BPF_ABS | BPF_B] =    data_ld1,
-- 
2.7.4