netdev - [PATCH net-next 00/13] nfp: bpf: jump resolution and memcpy update

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Date:   Thu, 30 Nov 2017 21:32:47 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     netdev@...r.kernel.org
Cc:     oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH net-next 00/13] nfp: bpf: jump resolution and memcpy update

Hi!

Jiong says:

Currently, compiler will lower memcpy function call in XDP/eBPF C program
into a sequence of eBPF load/store pairs for some scenarios.

Compiler is thinking this "inline" optimiation is beneficial as it could
avoid function call and also increase code locality.

However, Netronome NPU is not an tranditional load/store architecture that
doing a sequence of individual load/store actions are not efficient.

This patch set tries to identify the load/store sequences composed of
load/store pairs that comes from memcpy lowering, then accelerates them
through NPU's Command Push Pull (CPP) instruction.

This patch set registered an new optimization pass before doing the actual
JIT work, it traverse through eBPF IR, once found candidate sequence then
record the memory copy source, destination and length information in the
first load instruction starting the sequence and marks all remaining
instructions in the sequence into skipable status. Later, when JITing the
first load instructoin, optimal instructions will be generated using those
record information.

For this safety of this transformation:

  - jump into the middle of the sequence will cancel the optimization.

  - overlapped memory access will cancel the optimization.

  - the load destination register still contains the same value as before
    the transformation.

Jakub Kicinski (2):
  nfp: fix old kdoc issues
  nfp: bpf: encode indirect commands

Jiong Wang (11):
  nfp: bpf: support backward jump
  nfp: bpf: record jump destination to simplify jump fixup
  nfp: bpf: flag jump destination to guide insn combine optimizations
  nfp: bpf: don't do ld/mask combination if mask is jump destination
  nfp: bpf: don't do ld/shifts combination if shifts are jump
    destination
  nfp: bpf: relax source operands check
  nfp: bpf: correct the encoding for No-Dest immed
  nfp: bpf: factor out is_mbpf_load & is_mbpf_store
  nfp: bpf: implement memory bulk copy for length within 32-bytes
  nfp: bpf: implement memory bulk copy for length bigger than 32-bytes
  nfp: bpf: detect load/store sequences lowered from memory copy

 drivers/net/ethernet/netronome/nfp/bpf/jit.c       | 489 ++++++++++++++++++---
 drivers/net/ethernet/netronome/nfp/bpf/main.h      |  35 +-
 drivers/net/ethernet/netronome/nfp/bpf/offload.c   |  23 +-
 drivers/net/ethernet/netronome/nfp/bpf/verifier.c  |   8 +-
 drivers/net/ethernet/netronome/nfp/nfp_asm.c       |   7 +-
 drivers/net/ethernet/netronome/nfp/nfp_asm.h       |   7 +-
 drivers/net/ethernet/netronome/nfp/nfp_net.h       |   2 +
 .../ethernet/netronome/nfp/nfpcore/nfp_cppcore.c   |   9 +-
 8 files changed, 505 insertions(+), 75 deletions(-)

-- 
2.15.0