From: "Emil Tsalapatis" <emil@etsalapatis.com>
To: "Woojin Ji" <random6.xyz@gmail.com>,
"Emil Tsalapatis" <emil@etsalapatis.com>
Cc: <bpf@vger.kernel.org>, <linux-kselftest@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next] selftests/bpf: Add arena direct-value one-past-end reject test
Date: Thu, 04 Jun 2026 11:46:39 -0400 [thread overview]
Message-ID: <DJ0DRM980L8V.3MR51HBLAVAEP@etsalapatis.com> (raw)
In-Reply-To: <20260604153712.199362-1-random6.xyz@gmail.com>
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@gmail.com/
next prev parent reply other threads:[~2026-06-04 15:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 12:09 Woojin Ji
2026-06-03 15:47 ` Emil Tsalapatis
2026-06-04 15:37 ` Woojin Ji
2026-06-04 15:46 ` Emil Tsalapatis [this message]
2026-06-05 9:01 ` Woojin Ji
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