linux-kernel - Re: [PATCH v7 bpf-next 8/9] bpf: introduce bpf_jit_binary_pack

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Date:   Mon, 31 Jan 2022 16:35:23 -0800
From:   Song Liu <song@...nel.org>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Kernel Team <kernel-team@...com>,
        Peter Zijlstra <peterz@...radead.org>, X86 ML <x86@...nel.org>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Song Liu <songliubraving@...com>
Subject: Re: [PATCH v7 bpf-next 8/9] bpf: introduce bpf_jit_binary_pack_[alloc|finalize|free]

On Mon, Jan 31, 2022 at 4:21 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>
> On 1/29/22 12:45 AM, Song Liu wrote:
> [...]
[...]
> > +}
> > +
> > +/* Copy JITed text from rw_header to its final location, the ro_header. */
> > +int bpf_jit_binary_pack_finalize(struct bpf_prog *prog,
> > +                              struct bpf_binary_header *ro_header,
> > +                              struct bpf_binary_header *rw_header)
> > +{
> > +     void *ptr;
> > +
> > +     ptr = bpf_arch_text_copy(ro_header, rw_header, rw_header->size);
>
> Does this need to be wrapped with a text_mutex lock/unlock pair given
> text_poke_copy() internally relies on __text_poke() ?

Yes... Good catch. I guess we may do the lock in text_poke_copy().

Thanks,
Song