From: Gianluca Borello <g.borello@gmail.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Yonghong Song <yhs@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
David Miller <davem@davemloft.net>,
Linux Networking Development Mailing List
<netdev@vger.kernel.org>
Subject: Re: len = bpf_probe_read_str(); bpf_perf_event_output(... len) == FAIL
Date: Wed, 22 Nov 2017 10:42:22 -0800 [thread overview]
Message-ID: <CAJWsiu=psGT41fk6y9YE14UCwGd+Fq4_CBMOkiJ8fC-pMq1b5Q@mail.gmail.com> (raw)
In-Reply-To: <20171121223157.v3nodaugpuzl5dwg@ast-mbp.dhcp.thefacebook.com>
On Tue, Nov 21, 2017 at 2:31 PM, Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> yeah sorry about this hack. Gianluca reported this issue as well.
> Yonghong fixed it for bpf_probe_read only. We will extend
> the fix to bpf_probe_read_str() and bpf_perf_event_output() asap.
> The above workaround gets too much into llvm and verifier details
> we should strive to make bpf program writing as easy as possible.
>
Hi Arnaldo
With the help of Alexei, Daniel and Yonghong I just submitted a new
series ("bpf: fix semantics issues with helpers receiving NULL
arguments") that includes a fix in bpf_perf_event_output. This should
simplify the way you write your bpf programs, so you shouldn't be
required to write those convoluted branches anymore (there are a few
usage examples in the commit log).
In my case it made writing the code much easier, after applying it I
haven't been surprised by the compiler output in a while, and I hope
your experience will be improved as well.
Thanks
next prev parent reply other threads:[~2017-11-22 18:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-13 14:30 len = bpf_probe_read_str(); bpf_perf_event_output(... len) == FAIL Arnaldo Carvalho de Melo
2017-11-13 14:56 ` Daniel Borkmann
2017-11-13 15:08 ` Arnaldo Carvalho de Melo
2017-11-14 0:09 ` Daniel Borkmann
2017-11-14 12:58 ` Arnaldo Carvalho de Melo
2017-11-14 13:09 ` Daniel Borkmann
2017-11-14 13:42 ` Arnaldo Carvalho de Melo
2017-11-14 14:19 ` Daniel Borkmann
2017-11-14 14:58 ` Arnaldo Carvalho de Melo
2017-11-14 18:15 ` Yonghong Song
2017-11-14 20:25 ` Daniel Borkmann
2017-11-14 22:58 ` Yonghong Song
2017-11-21 14:29 ` Arnaldo Carvalho de Melo
2017-11-21 22:31 ` Alexei Starovoitov
2017-11-22 18:42 ` Gianluca Borello [this message]
2018-01-22 15:06 ` Arnaldo Carvalho de Melo
2018-01-22 18:28 ` Yonghong Song
2018-01-22 20:52 ` Arnaldo Carvalho de Melo
2017-11-20 13:31 ` Arnaldo Carvalho de Melo
2017-11-20 16:47 ` Yonghong Song
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