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From:   =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
To:     Pu Lehui <pulehui@huaweicloud.com>, bpf@vger.kernel.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Pu Lehui <pulehui@huawei.com>
Subject: Re: [PATCH bpf v2] riscv, bpf: Emit fixed-length instructions for
 BPF_PSEUDO_FUNC
In-Reply-To: <0620000f-4d06-de15-09d9-24b5b0c47410@huaweicloud.com>
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 <0ade59ea-6863-4d68-607c-22e4b9405a0d@huaweicloud.com>
 <87359t3r0h.fsf@all.your.base.are.belong.to.us>
 <0620000f-4d06-de15-09d9-24b5b0c47410@huaweicloud.com>
Date:   Tue, 06 Dec 2022 09:42:52 +0100
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Pu Lehui <pulehui@huaweicloud.com> writes:

>> Wouldn't that work?
>> 
>
> It definitely works. But auipc+addi may be some holes, while 
> lui+addi+slli support all the address of kernel and module. And this 
> might be help for the future feature porting.

We're already using auipc/jalr for calls, and I'd say it *very* unlikely
that we'll hit the non-covered range. I'd say go with auipc/addi +
error, and we can change if this really is a problem.