From: Yang Jihong <yangjihong1@huawei.com>
To: Martin KaFai Lau <martin.lau@linux.dev>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<song@kernel.org>, <yhs@fb.com>, <john.fastabend@gmail.com>,
<kpsingh@kernel.org>, <sdf@google.com>, <haoluo@google.com>,
<jolsa@kernel.org>, <illusionist.neo@gmail.com>,
<linux@armlinux.org.uk>, <davem@davemloft.net>,
<edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
<mykolal@fb.com>, <shuah@kernel.org>,
<benjamin.tissoires@redhat.com>, <memxor@gmail.com>,
<asavkov@redhat.com>, <delyank@fb.com>, <bpf@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH bpf v2 1/5] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension
Date: Sat, 26 Nov 2022 17:45:57 +0800 [thread overview]
Message-ID: <db99b2c7-3798-b7d5-e0b9-00ce454f47c6@huawei.com> (raw)
In-Reply-To: <62bf28ac-c1fa-fc60-ce52-6d993a8a4bbf@linux.dev>
Hello,
On 2022/11/9 7:12, Martin KaFai Lau wrote:
> On 11/7/22 1:20 AM, Yang Jihong wrote:
>> For ARM32 architecture, if data width of kfunc return value is 32 bits,
>> need to do explicit zero extension for high 32-bit, insn_def_regno should
>> return dst_reg for BPF_JMP type of BPF_PSEUDO_KFUNC_CALL. Otherwise,
>> opt_subreg_zext_lo32_rnd_hi32 returns -EFAULT, resulting in BPF failure.
>>
>> Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
>> ---
>> kernel/bpf/verifier.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
>> index 7f0a9f6cb889..bac37757ffca 100644
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
>> @@ -2404,6 +2404,9 @@ static int insn_def_regno(const struct bpf_insn
>> *insn)
>> {
>> switch (BPF_CLASS(insn->code)) {
>> case BPF_JMP:
>> + if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL)
>> + return insn->dst_reg;
>
> This does not look right. A kfunc can return void. The btf type of the
> kfunc's return value needs to be checked against "void" first?
OK, will add the check in next version.
> Also, this will affect insn_has_def32(), does is_reg64 (called from
> insn_has_def32) need to be adjusted also?
Yes, is_reg64 need to be adjusted, will fix in next version.
>
>
> For patch 2, as replied earlier in v1, I would separate out the prog
> that does __sk_buff->sk and use the uapi's bpf.h instead of vmlinux.h
> since it does not need CO-RE.
OK, will remove adjust sk check patches in next verion.
As mentioned in v1:
"bpf-tc program can take'struct sk_buff *skb' instead of'struct
__sk_buff *skb' but it will be a separate topic."
It is a separate topic, only the lskel test cases are affected.
The ARM32 kfunc function is not affected.
>
> This set should target for bpf-next instead of bpf.
OK, will send to bpf-next in next version.
Thanks,
Yang
next prev parent reply other threads:[~2022-11-26 9:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-07 9:20 [PATCH bpf v2 0/5] bpf: Support kernel function call in 32-bit ARM Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 1/5] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension Yang Jihong
2022-11-08 23:12 ` Martin KaFai Lau
2022-11-26 9:45 ` Yang Jihong [this message]
2022-11-07 9:20 ` [PATCH bpf v2 2/5] bpf: Adjust sk size check for sk in bpf_skb_is_valid_access for CO_RE in 32-bit arch Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 3/5] libbpf: Skip adjust mem size for load pointer in 32-bit arch in CO_RE Yang Jihong
2022-11-08 1:22 ` Andrii Nakryiko
2022-11-08 2:44 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 4/5] bpf: Add kernel function call support in 32-bit ARM for EABI Yang Jihong
2022-11-07 12:33 ` Russell King (Oracle)
2022-11-08 0:52 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 5/5] bpf:selftests: Add kfunc_call test for mixing 32-bit and 64-bit parameters Yang Jihong
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