netdev - Re: [PATCH v8 bpf-next 05/16] bpf: introduce new bpf prog load flags "BPF_F_TEST_RND

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Message-ID: <20190524204343.kprqtget3pwireak@ast-mbp.dhcp.thefacebook.com>
Date:   Fri, 24 May 2019 13:43:45 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Jiong Wang <jiong.wang@...ronome.com>
Cc:     daniel@...earbox.net, bpf@...r.kernel.org, netdev@...r.kernel.org,
        oss-drivers@...ronome.com, davem@...emloft.net,
        paul.burton@...s.com, udknight@...il.com, zlim.lnx@...il.com,
        illusionist.neo@...il.com, naveen.n.rao@...ux.ibm.com,
        sandipan@...ux.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, jakub.kicinski@...ronome.com,
        andriin@...com
Subject: Re: [PATCH v8 bpf-next 05/16] bpf: introduce new bpf prog load flags
 "BPF_F_TEST_RND_HI32"

On Fri, May 24, 2019 at 12:35:15PM +0100, Jiong Wang wrote:
> x86_64 and AArch64 perhaps are two arches that running bpf testsuite
> frequently, however the zero extension insertion pass is not enabled for
> them because of their hardware support.
> 
> It is critical to guarantee the pass correction as it is supposed to be
> enabled at default for a couple of other arches, for example PowerPC,
> SPARC, arm, NFP etc. Therefore, it would be very useful if there is a way
> to test this pass on for example x86_64.
> 
> The test methodology employed by this set is "poisoning" useless bits. High
> 32-bit of a definition is randomized if it is identified as not used by any
> later insn. Such randomization is only enabled under testing mode which is
> gated by the new bpf prog load flags "BPF_F_TEST_RND_HI32".
> 
> Suggested-by: Alexei Starovoitov <ast@...nel.org>
> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
> ---
>  include/uapi/linux/bpf.h       | 18 ++++++++++++++++++
>  kernel/bpf/syscall.c           |  4 +++-
>  tools/include/uapi/linux/bpf.h | 18 ++++++++++++++++++
>  3 files changed, 39 insertions(+), 1 deletion(-)

one more nit:
could you please split this patch into two?
Our mostly automatic sync of kernel/libbpf into github/libbpf will fail
when tools/../bpf.h is not a separate commit.