RE: [PATCH v2 bpf-next 0/7] BPF register bounds logic and testing improvements

[John Fastabend <john.fastabend@gmail.com>]

Andrii Nakryiko wrote:
> This patch set adds a big set of manual and auto-generated test cases
> validating BPF verifier's register bounds tracking and deduction logic. See
> details in the last patch.
> 
> To make this approach work, BPF verifier's logic needed a bunch of
> improvements to handle some cases that previously were not covered. This had
> no implications as to correctness of verifier logic, but it was incomplete
> enough to cause significant disagreements with alternative implementation of
> register bounds logic that tests in this patch set implement. So we need BPF
> verifier logic improvements to make all the tests pass.
> 
> This is a first part of work with the end goal intended to extend register
> bounds logic to cover range vs range comparisons, which will be submitted
> later assuming changes in this patch set land.
> 
> See individual patches for details.

Nice, I'm about half way through this I'll continue on Monday. The two rounds
of convergence was interesting I didn't expect that. Looks good to me though
so far.

Thanks for doing this I've wanted this cleaned up for awhile!

> 
> v1->v2:
>   - fix compilation when building selftests with llvm-16 toolchain (CI).
> 
> Andrii Nakryiko (7):
>   bpf: improve JEQ/JNE branch taken logic
>   bpf: derive smin/smax from umin/max bounds
>   bpf: enhance subregister bounds deduction logic
>   bpf: improve deduction of 64-bit bounds from 32-bit bounds
>   bpf: try harder to deduce register bounds from different numeric
>     domains
>   bpf: drop knowledge-losing __reg_combine_{32,64}_into_{64,32} logic
>   selftests/bpf: BPF register range bounds tester
> 
>  kernel/bpf/verifier.c                         |  175 +-
>  .../selftests/bpf/prog_tests/reg_bounds.c     | 1668 +++++++++++++++++
>  2 files changed, 1791 insertions(+), 52 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/reg_bounds.c
> 
> -- 
> 2.34.1
> 
>