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References: <20210112091403.10458-1-gilad.reti@gmail.com>
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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Tue, 12 Jan 2021 11:46:42 -0800
Message-ID: <CAEf4BzY2ezxxeUbhMy-kw-zRv974JG2NAQ+2g5_rtVSn8EmNcw@mail.gmail.com>
Subject: Re: [PATCH bpf 1/2] bpf: support PTR_TO_MEM{,_OR_NULL} register spilling
To:     Gilad Reti <gilad.reti@gmail.com>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Networking <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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On Tue, Jan 12, 2021 at 1:14 AM Gilad Reti <gilad.reti@gmail.com> wrote:
>
> Add support for pointer to mem register spilling, to allow the verifier
> to track pointer to valid memory addresses. Such pointers are returned
> for example by a successful call of the bpf_ringbuf_reserve helper.
>
> This patch was suggested as a solution by Yonghong Song.
>
> The patch was partially contibuted by CyberArk Software, Inc.
>
> Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier
> support for it")

Surprised no one mentioned this yet. Fixes tag should always be on a
single unwrapped line, however long it is, please fix.


> Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
> ---
>  kernel/bpf/verifier.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 17270b8404f1..36af69fac591 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -2217,6 +2217,8 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
>         case PTR_TO_RDWR_BUF:
>         case PTR_TO_RDWR_BUF_OR_NULL:
>         case PTR_TO_PERCPU_BTF_ID:
> +       case PTR_TO_MEM:
> +       case PTR_TO_MEM_OR_NULL:
>                 return true;
>         default:
>                 return false;
> --
> 2.27.0
>