diff options
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/bpf/jit.c | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c index 1b98ef239605..3419ad495962 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c @@ -2352,12 +2352,249 @@ static void nfp_bpf_opt_ld_shift(struct nfp_prog *nfp_prog) } } +/* load/store pair that forms memory copy sould look like the following: + * + * ld_width R, [addr_src + offset_src] + * st_width [addr_dest + offset_dest], R + * + * The destination register of load and source register of store should + * be the same, load and store should also perform at the same width. + * If either of addr_src or addr_dest is stack pointer, we don't do the + * CPP optimization as stack is modelled by registers on NFP. + */ +static bool +curr_pair_is_memcpy(struct nfp_insn_meta *ld_meta, + struct nfp_insn_meta *st_meta) +{ + struct bpf_insn *ld = &ld_meta->insn; + struct bpf_insn *st = &st_meta->insn; + + if (!is_mbpf_load(ld_meta) || !is_mbpf_store(st_meta)) + return false; + + if (ld_meta->ptr.type != PTR_TO_PACKET) + return false; + + if (st_meta->ptr.type != PTR_TO_PACKET) + return false; + + if (BPF_SIZE(ld->code) != BPF_SIZE(st->code)) + return false; + + if (ld->dst_reg != st->src_reg) + return false; + + /* There is jump to the store insn in this pair. */ + if (st_meta->flags & FLAG_INSN_IS_JUMP_DST) + return false; + + return true; +} + +/* Currently, we only support chaining load/store pairs if: + * + * - Their address base registers are the same. + * - Their address offsets are in the same order. + * - They operate at the same memory width. + * - There is no jump into the middle of them. + */ +static bool +curr_pair_chain_with_previous(struct nfp_insn_meta *ld_meta, + struct nfp_insn_meta *st_meta, + struct bpf_insn *prev_ld, + struct bpf_insn *prev_st) +{ + u8 prev_size, curr_size, prev_ld_base, prev_st_base, prev_ld_dst; + struct bpf_insn *ld = &ld_meta->insn; + struct bpf_insn *st = &st_meta->insn; + s16 prev_ld_off, prev_st_off; + + /* This pair is the start pair. */ + if (!prev_ld) + return true; + + prev_size = BPF_LDST_BYTES(prev_ld); + curr_size = BPF_LDST_BYTES(ld); + prev_ld_base = prev_ld->src_reg; + prev_st_base = prev_st->dst_reg; + prev_ld_dst = prev_ld->dst_reg; + prev_ld_off = prev_ld->off; + prev_st_off = prev_st->off; + + if (ld->dst_reg != prev_ld_dst) + return false; + + if (ld->src_reg != prev_ld_base || st->dst_reg != prev_st_base) + return false; + + if (curr_size != prev_size) + return false; + + /* There is jump to the head of this pair. */ + if (ld_meta->flags & FLAG_INSN_IS_JUMP_DST) + return false; + + /* Both in ascending order. */ + if (prev_ld_off + prev_size == ld->off && + prev_st_off + prev_size == st->off) + return true; + + /* Both in descending order. */ + if (ld->off + curr_size == prev_ld_off && + st->off + curr_size == prev_st_off) + return true; + + return false; +} + +/* Return TRUE if cross memory access happens. Cross memory access means + * store area is overlapping with load area that a later load might load + * the value from previous store, for this case we can't treat the sequence + * as an memory copy. + */ +static bool +cross_mem_access(struct bpf_insn *ld, struct nfp_insn_meta *head_ld_meta, + struct nfp_insn_meta *head_st_meta) +{ + s16 head_ld_off, head_st_off, ld_off; + + /* Different pointer types does not overlap. */ + if (head_ld_meta->ptr.type != head_st_meta->ptr.type) + return false; + + /* load and store are both PTR_TO_PACKET, check ID info. */ + if (head_ld_meta->ptr.id != head_st_meta->ptr.id) + return true; + + /* Canonicalize the offsets. Turn all of them against the original + * base register. + */ + head_ld_off = head_ld_meta->insn.off + head_ld_meta->ptr.off; + head_st_off = head_st_meta->insn.off + head_st_meta->ptr.off; + ld_off = ld->off + head_ld_meta->ptr.off; + + /* Ascending order cross. */ + if (ld_off > head_ld_off && + head_ld_off < head_st_off && ld_off >= head_st_off) + return true; + + /* Descending order cross. */ + if (ld_off < head_ld_off && + head_ld_off > head_st_off && ld_off <= head_st_off) + return true; + + return false; +} + +/* This pass try to identify the following instructoin sequences. + * + * load R, [regA + offA] + * store [regB + offB], R + * load R, [regA + offA + const_imm_A] + * store [regB + offB + const_imm_A], R + * load R, [regA + offA + 2 * const_imm_A] + * store [regB + offB + 2 * const_imm_A], R + * ... + * + * Above sequence is typically generated by compiler when lowering + * memcpy. NFP prefer using CPP instructions to accelerate it. + */ +static void nfp_bpf_opt_ldst_gather(struct nfp_prog *nfp_prog) +{ + struct nfp_insn_meta *head_ld_meta = NULL; + struct nfp_insn_meta *head_st_meta = NULL; + struct nfp_insn_meta *meta1, *meta2; + struct bpf_insn *prev_ld = NULL; + struct bpf_insn *prev_st = NULL; + u8 count = 0; + + nfp_for_each_insn_walk2(nfp_prog, meta1, meta2) { + struct bpf_insn *ld = &meta1->insn; + struct bpf_insn *st = &meta2->insn; + + /* Reset record status if any of the following if true: + * - The current insn pair is not load/store. + * - The load/store pair doesn't chain with previous one. + * - The chained load/store pair crossed with previous pair. + * - The chained load/store pair has a total size of memory + * copy beyond 128 bytes which is the maximum length a + * single NFP CPP command can transfer. + */ + if (!curr_pair_is_memcpy(meta1, meta2) || + !curr_pair_chain_with_previous(meta1, meta2, prev_ld, + prev_st) || + (head_ld_meta && (cross_mem_access(ld, head_ld_meta, + head_st_meta) || + head_ld_meta->ldst_gather_len >= 128))) { + if (!count) + continue; + + if (count > 1) { + s16 prev_ld_off = prev_ld->off; + s16 prev_st_off = prev_st->off; + s16 head_ld_off = head_ld_meta->insn.off; + + if (prev_ld_off < head_ld_off) { + head_ld_meta->insn.off = prev_ld_off; + head_st_meta->insn.off = prev_st_off; + head_ld_meta->ldst_gather_len = + -head_ld_meta->ldst_gather_len; + } + + head_ld_meta->paired_st = &head_st_meta->insn; + head_st_meta->skip = true; + } else { + head_ld_meta->ldst_gather_len = 0; + } + + /* If the chain is ended by an load/store pair then this + * could serve as the new head of the the next chain. + */ + if (curr_pair_is_memcpy(meta1, meta2)) { + head_ld_meta = meta1; + head_st_meta = meta2; + head_ld_meta->ldst_gather_len = + BPF_LDST_BYTES(ld); + meta1 = nfp_meta_next(meta1); + meta2 = nfp_meta_next(meta2); + prev_ld = ld; + prev_st = st; + count = 1; + } else { + head_ld_meta = NULL; + head_st_meta = NULL; + prev_ld = NULL; + prev_st = NULL; + count = 0; + } + + continue; + } + + if (!head_ld_meta) { + head_ld_meta = meta1; + head_st_meta = meta2; + } else { + meta1->skip = true; + meta2->skip = true; + } + + head_ld_meta->ldst_gather_len += BPF_LDST_BYTES(ld); + meta1 = nfp_meta_next(meta1); + meta2 = nfp_meta_next(meta2); + prev_ld = ld; + prev_st = st; + count++; + } +} + static int nfp_bpf_optimize(struct nfp_prog *nfp_prog) { nfp_bpf_opt_reg_init(nfp_prog); nfp_bpf_opt_ld_mask(nfp_prog); nfp_bpf_opt_ld_shift(nfp_prog); + nfp_bpf_opt_ldst_gather(nfp_prog); return 0; } |