netdev - Re: [PATCH v2] arm: eBPF JIT compiler

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Date:   Mon, 12 Jun 2017 21:11:58 +0530
From:   Shubham Bansal <illusionist.neo@...il.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Kees Cook <keescook@...omium.org>,
        Network Development <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v2] arm: eBPF JIT compiler

Hi Russel,

On Mon, Jun 12, 2017 at 4:36 PM, Russell King - ARM Linux
<linux@...linux.org.uk> wrote:
> On Mon, Jun 12, 2017 at 12:21:03PM +0200, Daniel Borkmann wrote:
>> On 05/30/2017 09:19 PM, Kees Cook wrote:
>> >On Thu, May 25, 2017 at 4:13 PM, Shubham Bansal
>> ><illusionist.neo@...il.com> wrote:
>> >>+static int validate_code(struct jit_ctx *ctx)
>> >>+{
>> >>+       int i;
>> >>+
>> >>+       for (i = 0; i < ctx->idx; i++) {
>> >>+               u32 a32_insn = le32_to_cpu(ctx->target[i]);
>>
>> Given __opcode_to_mem_arm(ARM_INST_UDF) is used to fill the image,
>> perhaps use the __mem_to_opcode_arm() helper for the check?
>>
>> >>+               if (a32_insn == ARM_INST_UDF)
>
> The following is probably better:
>
>                 if (ctx->target[i] == __opcode_to_mem_arm(ARM_INST_UDF))
>
> since then you can take advantage of the compiler optimising the
> constant rather than having to do a byte swap on an unknown 32-bit
> value.

Done. Thanks :)
Please check if you can find anymore issues with the code. I really
appreciate it.

-Shubham