From: Eduard Zingerman <eddyz87@gmail.com>
To: Emil Tsalapatis <emil@etsalapatis.com>, bpf@vger.kernel.org
Cc: andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net,
john.fastabend@gmail.com, memxor@gmail.com,
yonghong.song@linux.dev
Subject: Re: [PATCH v3 4/5] libbpf: move arena globals to the end of the arena
Date: Mon, 15 Dec 2025 13:12:12 -0800 [thread overview]
Message-ID: <bce8c7063b11fa8136a796fedc24b7fc7866f832.camel@gmail.com> (raw)
In-Reply-To: <20251215161313.10120-5-emil@etsalapatis.com>
On Mon, 2025-12-15 at 11:13 -0500, Emil Tsalapatis wrote:
> Arena globals are currently placed at the beginning of the arena
> by libbpf. This is convenient, but prevents users from reserving
> guard pages in the beginning of the arena to identify NULL pointer
> dereferences. Adjust the load logic to place the globals at the
> end of the arena instead.
>
> Also modify bpftool to set the arena pointer in the program's BPF
> skeleton to point to the globals. Users now call bpf_map__initial_value()
> to find the beginning of the arena mapping and use the arena pointer
> in the skeleton to determine which part of the mapping holds the
> arena globals and which part is free.
>
> Suggested-by: Andrii Nakryiko <andrii@kernel.org>
> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2025-12-15 21:12 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-15 16:13 [PATCH v3 0/5] libbpf: move arena variables out of the zero page Emil Tsalapatis
2025-12-15 16:13 ` [PATCH v3 1/5] selftests/bpf: explicitly account for globals in verifier_arena_large Emil Tsalapatis
2025-12-15 16:13 ` [PATCH v3 2/5] bpf/verifier: do not limit maximum direct offset into arena map Emil Tsalapatis
2025-12-15 20:19 ` Eduard Zingerman
2025-12-16 17:25 ` Emil Tsalapatis
2025-12-16 20:13 ` Eduard Zingerman
2025-12-16 21:48 ` Emil Tsalapatis
2025-12-15 16:13 ` [PATCH v3 3/5] libbpf: turn relo_core->sym_off unsigned Emil Tsalapatis
2025-12-15 16:37 ` bot+bpf-ci
2025-12-15 17:08 ` Emil Tsalapatis
2025-12-15 20:05 ` Eduard Zingerman
2025-12-15 16:13 ` [PATCH v3 4/5] libbpf: move arena globals to the end of the arena Emil Tsalapatis
2025-12-15 21:12 ` Eduard Zingerman [this message]
2025-12-15 16:13 ` [PATCH v3 5/5] selftests/bpf: add tests for the arena offset of globals Emil Tsalapatis
2025-12-15 21:26 ` Eduard Zingerman
2025-12-16 2:28 ` Emil Tsalapatis
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