Re: [PATCH bpf-next] selftests/bpf: Add arena direct-value one-past-end reject test

[Emil Tsalapatis]

On Thu Jun 4, 2026 at 11:37 AM EDT, Woojin Ji wrote:
> Thanks for the review.
>
> I tried moving this into verifier_arena.c, but this test needs to set the
> second BPF_PSEUDO_MAP_VALUE ldimm64 immediate to arena_size exactly. The
> __arena C forms I checked materialize the arena-end offset as a separate ALU
> add or memory access offset instead, so they do not exercise
> arena_map_direct_value_addr() with off == arena_size.
>
> So v2 keeps the userspace raw-instruction test and expands the commit message
> to explain why it is needed.

This sounds like the problem is that we can't really get BPF C to be
compiled down to problematic code. Can't we still use inline assembly
in the BPF C file to do so? I don't see why not.

>
> v2: https://lore.kernel.org/all/20260605-arena-direct-value-v1-v2-1-a92cb281e376@xxxxxxxxx/