netdev - Re: [PATCH bpf-next 1/3] libbpf: add asm/unistd.h to xsk to get __NR

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Message-ID: <CAEf4BzbyAHkL5pFoBCKPY7ia3voj7t2OkFDNKYqdyE1Fiuy4nQ@mail.gmail.com>
Date:   Wed, 14 Aug 2019 12:56:32 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Björn Töpel <bjorn.topel@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        john fastabend <john.fastabend@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        xdp-newbies@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH bpf-next 1/3] libbpf: add asm/unistd.h to xsk to get __NR_mmap2

On Wed, Aug 14, 2019 at 2:24 AM Ivan Khoronzhuk
<ivan.khoronzhuk@...aro.org> wrote:
>
> On Tue, Aug 13, 2019 at 04:38:13PM -0700, Andrii Nakryiko wrote:
>
> Hi, Andrii
>
> >On Tue, Aug 13, 2019 at 3:24 AM Ivan Khoronzhuk
> ><ivan.khoronzhuk@...aro.org> wrote:
> >>
> >> That's needed to get __NR_mmap2 when mmap2 syscall is used.
> >>
> >> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
> >> ---
> >>  tools/lib/bpf/xsk.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> >> index 5007b5d4fd2c..f2fc40f9804c 100644
> >> --- a/tools/lib/bpf/xsk.c
> >> +++ b/tools/lib/bpf/xsk.c
> >> @@ -12,6 +12,7 @@
> >>  #include <stdlib.h>
> >>  #include <string.h>
> >>  #include <unistd.h>
> >> +#include <asm/unistd.h>
> >
> >asm/unistd.h is not present in Github libbpf projection. Is there any
>
> Look on includes from
> tools/lib/bpf/libpf.c
> tools/lib/bpf/bpf.c
>

Yeah, sorry for the noise. I missed that this is system header that's
expected to be present, not internal kernel header, parts of which we
need to re-implement for Github projection. Never mind my concerns.


> That's how it's done... Copping headers to arch/arm will not
> solve this, it includes both of them anyway, and anyway it needs
> asm/unistd.h inclusion here, only because xsk.c needs __NR_*
>
>
> >way to avoid including this header? Generally, libbpf can't easily use
> >all of kernel headers, we need to re-implemented all the extra used
> >stuff for Github version of libbpf, so we try to minimize usage of new
> >headers that are not just plain uapi headers from include/uapi.
>
> Yes I know, it's far away from real number of changes needed.
> I faced enough about this already and kernel headers, especially
> for arm32 it's a bit decency problem. But this patch it's part of
> normal one. I have couple issues despite this normally fixed mmap2
> that is the same even if uapi includes are coppied to tools/arch/arm.
>
> In continuation of kernel headers inclusion and arm build:
>
> For instance, what about this rough "kernel headers" hack:
> https://github.com/ikhorn/af_xdp_stuff/commit/aa645ccca4d844f404ec3c2b27402d4d7848d1b5
>
> or this one related for arm32 only:
> https://github.com/ikhorn/af_xdp_stuff/commit/2c6c6d538605aac39600dcb3c9b66de11c70b963
>
> I have more...
>
> >
> >>  #include <arpa/inet.h>
> >>  #include <asm/barrier.h>
> >>  #include <linux/compiler.h>
> >> --
> >> 2.17.1
> >>
>
> --
> Regards,
> Ivan Khoronzhuk