netdev - Re: [PATCH bpf-next] bpf: introduce BPF_JIT_ALWAYS

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Date:   Mon, 8 Jan 2018 18:23:51 -0800
From:   Alexei Starovoitov <ast@...com>
To:     Jakub Kicinski <kubakici@...pl>,
        Daniel Borkmann <daniel@...earbox.net>
CC:     Alexei Starovoitov <ast@...nel.org>, <davem@...emloft.net>,
        <torvalds@...ux-foundation.org>, <jannh@...gle.com>,
        <alan@...ux.intel.com>, <netdev@...r.kernel.org>,
        <kernel-team@...com>
Subject: Re: [PATCH bpf-next] bpf: introduce BPF_JIT_ALWAYS_ON config

On 1/8/18 4:02 PM, Jakub Kicinski wrote:
> On Mon, 8 Jan 2018 22:59:04 +0100, Daniel Borkmann wrote:
>>> @@ -1453,6 +1457,11 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
>>>  	 */
>>>  	*err = bpf_check_tail_call(fp);
>>>
>>> +#ifdef CONFIG_BPF_JIT_ALWAYS_ON
>>> +	if (!fp->jited)
>>> +		*err = -ENOTSUPP;
>>> +#endif
>
> I think programs JITed for offload won't have fp->jited set, but
> those are pretty safe from CPU bugs.  Should we set fp->jited = 1; in
> bpf_prog_offload_compile()?  Just throwing "&& !bpf_prog_is_dev_bound()"
> in here seems cleaner to me.

good catch. will fix in the v2.