mbox series

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

Message ID 20210119102501.511-1-glin@suse.com (mailing list archive)
Headers show
Series bpf,x64: implement jump padding in jit | expand

Message

Gary Lin Jan. 19, 2021, 10:24 a.m. UTC 
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(-)

Comments

Alexei Starovoitov Jan. 19, 2021, 8:54 p.m. UTC | #1 
On Tue, Jan 19, 2021 at 2:25 AM Gary Lin <glin@suse.com> wrote:
>
> 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

Applied. Thanks a ton for all the hard work you put into it.