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References: <20220110165208.1826-1-jszhang@kernel.org> <Ydxljv2Q4YNDYRTx@xhacker>
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From:   =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@gmail.com>
Date:   Wed, 19 Jan 2022 11:24:16 +0100
Message-ID: <CAJ+HfNiS7Ss0FJowPUrrKvuC+1Kn9gXb=VqNoqh3eWJDu=m4Mg@mail.gmail.com>
Subject: Re: [PATCH riscv-next] riscv: bpf: Fix eBPF's exception tables
To:     Jisheng Zhang <jszhang@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>, palmer@rivosinc.com,
        Daniel Borkmann <daniel@iogearbox.net>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexei Starovoitov <ast@kernel.org>,
        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>, Netdev <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Tong Tiangen <tongtiangen@huawei.com>
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Jisheng/Palmer,

On Mon, 10 Jan 2022 at 18:05, Jisheng Zhang <jszhang@kernel.org> wrote:
>
> On Tue, Jan 11, 2022 at 12:52:08AM +0800, Jisheng Zhang wrote:
> > eBPF's exception tables needs to be modified to relative synchronously.
> >
> > Suggested-by: Tong Tiangen <tongtiangen@huawei.com>
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>

Nice catch, and apologies for the slow response.

Acked-by: Bj=C3=B6rn T=C3=B6pel <bjorn@kernel.org>

> > ---
> >  arch/riscv/net/bpf_jit_comp64.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_c=
omp64.c
> > index 69bab7e28f91..44c97535bc15 100644
> > --- a/arch/riscv/net/bpf_jit_comp64.c
> > +++ b/arch/riscv/net/bpf_jit_comp64.c
> > @@ -498,7 +498,7 @@ static int add_exception_handler(const struct bpf_i=
nsn *insn,
> >       offset =3D pc - (long)&ex->insn;
> >       if (WARN_ON_ONCE(offset >=3D 0 || offset < INT_MIN))
> >               return -ERANGE;
> > -     ex->insn =3D pc;
> > +     ex->insn =3D offset;
>
> Hi Palmer,
>
> Tong pointed out this issue but there was something wrong with my email
> forwarding address, so I didn't get his reply. Today, I searched on
> lore.kernel.org just found his reply, sorry for inconvenience.
>

AFAIK, Jisheng's extable work is still in Palmer's for-next tree.

Daniel/Alexei: This eBPF must follow commit 1f77ed9422cb ("riscv:
switch to relative extable and other improvements"), which is in
Palmer's tree. It cannot go via bpf-next.

Palmer, please pull this to your for-next tree.


Thanks,
Bj=C3=B6rn