From: Xin Liu <liuxin350@huawei.com>
To: <alan.maguire@oracle.com>
Cc: <andrii@kernel.org>, <arnaldo.melo@gmail.com>, <ast@kernel.org>,
<bpf@vger.kernel.org>, <daniel@iogearbox.net>,
<dwarves@vger.kernel.org>, <kernel-team@fb.com>,
<liuxin350@huawei.com>, <ndesaulniers@google.com>,
<yonghong.song@linux.dev>, <yanan@huawei.com>,
<wuchangye@huawei.com>, <xiesongyang@huawei.com>,
<kongweibin2@huawei.com>, <zhangmingyi5@huawei.com>,
<liwei883@huawei.com>
Subject: Re: [PATCH dwarves] btf_encoder: Fix dwarf int type with greater-than-16 byte issue
Date: Thu, 25 Apr 2024 21:43:40 +0800 [thread overview]
Message-ID: <20240425134340.750289-1-liuxin350@huawei.com> (raw)
In-Reply-To: <686d2f65-0d6d-43e6-83fe-a9eb2eb6149e@oracle.com>
On Wed, 24 Apr 2024 15:35:38 -0700 Yonghong Song <yonghong.song@linux.dev> wrote:
> Nick Desaulniers and Xin Liu separately reported that int type might
> have greater-than-16 byte size ([1] and [2]). More specifically, the
> reported int type sizes are 1024 and 64 bytes.
>
> The libbpf and bpf program does not really support any int type greater
> than 16 bytes. Therefore, with current pahole, btf encoding will fail
> with greater-than-16 byte int types.
>
> Since for now bpf does not support '> 16' bytes int type, the simplest
> way is to sanitize such types, similar to existing conditions like
> '!byte_sz' and 'byte_sz & (byte_sz - 1)'. This way, pahole won't
> call libbpf with an unsupported int type size. The patch [3] was
> proposed before. Now I resubmitted this patch as there are another
> failure due to the same issue.
>
> [1] https://github.com/libbpf/libbpf/pull/680
> [2] https://lore.kernel.org/bpf/20240422144538.351722-1-liuxin350@huawei.com/
> [3] https://lore.kernel.org/bpf/20230426055030.3743074-1-yhs@fb.com/
>
> Cc: Xin Liu <liuxin350@huawei.com>
> Cc: Alan Maguire <alan.maguire@oracle.com>
> Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Reviewed-by: Xin Liu <liuxin350@huawei.com>
> ---
> btf_encoder.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index e1e3529..19e9d90 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -393,7 +393,7 @@ static int32_t btf_encoder__add_base_type(struct btf_encoder *encoder, const str
> * these non-regular int types to avoid libbpf/kernel complaints.
> */
> byte_sz = BITS_ROUNDUP_BYTES(bt->bit_size);
> - if (!byte_sz || (byte_sz & (byte_sz - 1))) {
> + if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16) {
> name = "__SANITIZED_FAKE_INT__";
> byte_sz = 4;
> }
next prev parent reply other threads:[~2024-04-25 13:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-24 22:35 [PATCH dwarves] btf_encoder: Fix dwarf int type with greater-than-16 byte issue Yonghong Song
2024-04-25 8:17 ` Alan Maguire
2024-04-25 13:43 ` Xin Liu [this message]
2024-04-25 14:19 ` Arnaldo Carvalho de Melo
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