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

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Message-ID: <Ydxljv2Q4YNDYRTx@xhacker>
Date:   Tue, 11 Jan 2022 00:57:50 +0800
From:   Jisheng Zhang <jszhang@...nel.org>
To:     Björn Töpel <bjorn@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Tong Tiangen <tongtiangen@...wei.com>
Subject: Re: [PATCH riscv-next] riscv: bpf: Fix eBPF's exception tables

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@...wei.com>
> Signed-off-by: Jisheng Zhang <jszhang@...nel.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.

Thanks

>  
>  	/*
>  	 * Since the extable follows the program, the fixup offset is always
> -- 
> 2.34.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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