Re: [PATCH riscv-next] riscv: bpf: Fix eBPF's exception tables

From: "Björn Töpel" <bjorn.topel@gmail.com>
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>
Subject: Re: [PATCH riscv-next] riscv: bpf: Fix eBPF's exception tables
Date: Wed, 19 Jan 2022 11:24:16 +0100	[thread overview]
Message-ID: <CAJ+HfNiS7Ss0FJowPUrrKvuC+1Kn9gXb=VqNoqh3eWJDu=m4Mg@mail.gmail.com> (raw)
In-Reply-To: <Ydxljv2Q4YNDYRTx@xhacker>

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: Björn Töpel <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_comp64.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_insn *insn,
> >       offset = pc - (long)&ex->insn;
> >       if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
> >               return -ERANGE;
> > -     ex->insn = pc;
> > +     ex->insn = 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,
Björn

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