Re: [PATCH 6.1.y v2 0/6] BPF selftests fixes for 6.1 branch

[Greg KH <greg@kroah.com>]

On Mon, Jul 24, 2023 at 03:42:17PM +0300, Eduard Zingerman wrote:
> Recently Luiz Capitulino reported BPF test failure for kernel version
> 6.1.36 (see [7]). The following test_verifier test failed:
> "precise: ST insn causing spi > allocated_stack".
> After back-port of the following upstream commit:
> ecdf985d7615 ("bpf: track immediate values written to stack by BPF_ST instruction")
> 
> Investigation in [8] shows that test failure is not a bug, but a
> difference in BPF verifier behavior between upstream, where commits
> [1,2,3] by Andrii Nakryiko are present, and 6.1.36, where these
> commits are absent. Both Luiz and Greg suggested back-porting [1,2,3]
> from upstream to avoid divergences.
> 
> Commits [1,2,3] break test_progs selftest "align/packet variable offset",
> commit [4] fixes this selftest.
> 
> I did some additional testing using the following compiler versions:
> - Kernel compilation
>   - gcc version 11.3.0
> - BPF tests compilation
>   - clang version 16.0.6
>   - clang version 17.0.0 (fa46feb31481)
> 
> And identified a few more failing BPF selftests:
> - Tests failing with LLVM 16:
>   - test_verifier:
>     - precise: ST insn causing spi > allocated_stack FAIL (fixed by [1,2,3])
>   - test_progs:
>     - sk_assign                                           (fixed by [6])
> - Tests failing with LLVM 17:
>   - test_verifier:
>     - precise: ST insn causing spi > allocated_stack FAIL (fixed by [1,2,3])
>   - test_progs:
>     - fexit_bpf2bpf/func_replace_verify                   (fixed by [5])
>     - fexit_bpf2bpf/func_replace_return_code              (fixed by [5])
>     - sk_assign                                           (fixed by [6])
> 
> Commits [4,5,6] only apply to BPF selftests and don't change verifier
> behavior.
> 
> After applying all of the listed commits I have test_verifier,
> test_progs, test_progs-no_alu32 and test_maps passing on my x86 setup,
> both for LLVM 16 and LLVM 17.
> 
> Upstream commits in chronological order:
> [1] be2ef8161572 ("bpf: allow precision tracking for programs with subprogs")
> [2] f63181b6ae79 ("bpf: stop setting precise in current state")
> [3] 7a830b53c17b ("bpf: aggressively forget precise markings during state checkpointing")
> [4] 4f999b767769 ("selftests/bpf: make test_align selftest more robust")
> [5] 63d78b7e8ca2 ("selftests/bpf: Workaround verification failure for fexit_bpf2bpf/func_replace_return_code")
> [6] 7ce878ca81bc ("selftests/bpf: Fix sk_assign on s390x")
> 
> Links:
> [7] https://lore.kernel.org/stable/935c4751-d368-df29-33a6-9f4fcae720fa@amazon.com/
> [8] https://lore.kernel.org/stable/c9b10a8a551edafdfec855fbd35757c6238ad258.camel@gmail.com/
> 
> Changelog:
>   V1 -> V2: added missing signed-off-by tags
>   V1: https://lore.kernel.org/stable/20230722004514.767618-1-eddyz87@gmail.com/
> 
> Reported-by: Luiz Capitulino <luizcap@amazon.com>
> 
> Andrii Nakryiko (4):
>   bpf: allow precision tracking for programs with subprogs
>   bpf: stop setting precise in current state
>   bpf: aggressively forget precise markings during state checkpointing
>   selftests/bpf: make test_align selftest more robust
> 
> Ilya Leoshkevich (1):
>   selftests/bpf: Fix sk_assign on s390x
> 
> Yonghong Song (1):
>   selftests/bpf: Workaround verification failure for
>     fexit_bpf2bpf/func_replace_return_code
> 
>  kernel/bpf/verifier.c                         | 202 ++++++++++++++++--
>  .../testing/selftests/bpf/prog_tests/align.c  |  38 ++--
>  .../selftests/bpf/prog_tests/sk_assign.c      |  25 ++-
>  .../selftests/bpf/progs/connect4_prog.c       |   2 +-
>  .../selftests/bpf/progs/test_sk_assign.c      |  11 +
>  .../bpf/progs/test_sk_assign_libbpf.c         |   3 +
>  6 files changed, 247 insertions(+), 34 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/test_sk_assign_libbpf.c
> 
> -- 
> 2.41.0
> 

All now queued up, thanks.

greg k-h