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From: Lorenz Bauer <lmb@isovalent.com>
To: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	martin.lau@kernel.org, timo@incline.eu,
	robin.goegge@isovalent.com, kernel-team@meta.com
Subject: Re: [PATCH v2 bpf-next 6/6] selftests/bpf: add fixed vs rotating verifier log tests
Date: Thu, 30 Mar 2023 18:12:57 +0100	[thread overview]
Message-ID: <CAN+4W8ju8Bdqe59QXbX+eQWARfiy2-zqgkD5N0rMpmRn9-W4Vg@mail.gmail.com> (raw)
In-Reply-To: <20230328235610.3159943-8-andrii@kernel.org>

On Wed, Mar 29, 2023 at 12:56 AM Andrii Nakryiko <andrii@kernel.org> wrote:
>
> Add selftests validating BPF_LOG_FIXED behavior, which used to be the
> only behavior, and now default rotating BPF verifier log, which returns
> just up to last N bytes of full verifier log, instead of returning
> -ENOSPC.
>
> To stress test correctness of in-kernel verifier log logic, we force it
> to truncate program's verifier log to all lengths from 1 all the way to
> its full size (about 450 bytes today). This was a useful stress test
> while developing the feature.
>
> For both fixed and rotating log modes we expect -ENOSPC if log contents
> doesn't fit in user-supplied log buffer.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Acked-by: Lorenz Bauer <lmb@isovalent.com>

> +       /* validate BPF_LOG_FIXED works as verifier log used to work, that is:
> +        * we get -ENOSPC and beginning of the full verifier log. This only
> +        * works for log_level 2 and log_level 1 + failed program. For log
> +        * level 2 we don't reset log at all. For log_level 1 + failed program
> +        * we don't get to verification stats output. With log level 1
> +        * for successful program  final result will be just verifier stats.
> +        * But if provided too short log buf, kernel will NULL-out log->ubuf

Out of curiousity: why is ubuf NULLed? Is that something we could change?

  reply	other threads:[~2023-03-30 17:13 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-28 23:56 [PATCH v2 bpf-next 0/6] BPF verifier rotating log Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 1/6] bpf: split off basic BPF verifier log into separate file Andrii Nakryiko
2023-03-30 17:12   ` Lorenz Bauer
2023-03-28 23:56 ` [PATCH v2 bpf-next 2/6] bpf: remove minimum size restrictions on verifier log buffer Andrii Nakryiko
2023-03-30 17:12   ` Lorenz Bauer
2023-03-30 20:48     ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 3/6] bpf: switch BPF verifier log to be a rotating log by default Andrii Nakryiko
2023-03-30 17:12   ` Lorenz Bauer
2023-03-30 20:48     ` Andrii Nakryiko
2023-04-05 17:29       ` Lorenz Bauer
2023-04-05 18:03         ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 4/6] libbpf: don't enforce verifier log levels on libbpf side Andrii Nakryiko
2023-03-30 17:12   ` Lorenz Bauer
2023-03-30 21:05     ` Andrii Nakryiko
2023-03-31  9:39       ` Timo Beckers
2023-03-31 15:59         ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH bpf-next 4/6] libbpf: don't enfore " Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 5/6] selftests/bpf: add more veristat control over verifier log options Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 6/6] selftests/bpf: add fixed vs rotating verifier log tests Andrii Nakryiko
2023-03-30 17:12   ` Lorenz Bauer [this message]
2023-03-30 21:07     ` Andrii Nakryiko
2023-03-28 23:59 ` [PATCH v2 bpf-next 0/6] BPF verifier rotating log Andrii Nakryiko
2023-03-30  5:38   ` Alexei Starovoitov
2023-03-30  9:31     ` Lorenz Bauer

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