netdev - [PATCH v4 0/3] bpf,x64: implement jump padding in jit

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Message-ID: <20210119102501.511-1-glin@suse.com>
Date:   Tue, 19 Jan 2021 18:24:58 +0800
From:   Gary Lin <glin@...e.com>
To:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
CC:     Eric Dumazet <eric.dumazet@...il.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        andreas.taschner@...e.com
Subject: [PATCH v4 0/3] bpf,x64: implement jump padding in jit

This patch series implements jump padding to x64 jit to cover some
corner cases that used to consume more than 20 jit passes and caused
failure.

v4:
  - Add the detailed comments about the possible padding bytes
  - Add the second test case which triggers jmp_cond padding and imm32 nop
    jmp padding.
  - Add the new test case as another subprog

v3:
  - Copy the instructions of prologue separately or the size calculation
    of the first BPF instruction would include the prologue.
  - Replace WARN_ONCE() with pr_err() and EFAULT
  - Use MAX_PASSES in the for loop condition check
  - Remove the "padded" flag from x64_jit_data. For the extra pass of
    subprogs, padding is always enabled since it won't hurt the images
    that converge without padding.
v2:
  - Simplify the sample code in the commit description and provide the
    jit code
  - Check the expected padding bytes with WARN_ONCE
  - Move the 'padded' flag to 'struct x64_jit_data'
  - Remove the EXPECTED_FAIL flag from bpf_fill_maxinsns11() in test_bpf
  - Add 2 verifier tests

Gary Lin (3):
  bpf,x64: pad NOPs to make images converge more easily
  test_bpf: remove EXPECTED_FAIL flag from bpf_fill_maxinsns11
  selftests/bpf: Add verifier tests for x64 jit jump padding

 arch/x86/net/bpf_jit_comp.c                 | 140 ++++++++++++++++----
 lib/test_bpf.c                              |   7 +-
 tools/testing/selftests/bpf/test_verifier.c |  72 ++++++++++
 tools/testing/selftests/bpf/verifier/jit.c  |  24 ++++
 4 files changed, 209 insertions(+), 34 deletions(-)

-- 
2.29.2