linux-kernel - Re: [PATCH ipsec-next v3 5/9] libbpf: selftests: Add verifier tests for CO-RE bitfield writes

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Message-ID: <d2fe8b0593a1009305e90d98a8bff984c1314748.camel@gmail.com>
Date:   Sat, 02 Dec 2023 02:20:15 +0200
From:   Eduard Zingerman <eddyz87@...il.com>
To:     Daniel Xu <dxu@...uu.xyz>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, shuah@...nel.org,
        andrii@...nel.org, steffen.klassert@...unet.com,
        antony.antony@...unet.com, alexei.starovoitov@...il.com,
        yonghong.song@...ux.dev, mykolal@...com, martin.lau@...ux.dev,
        song@...nel.org, john.fastabend@...il.com, kpsingh@...nel.org,
        sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org, devel@...ux-ipsec.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH ipsec-next v3 5/9] libbpf: selftests: Add verifier tests
 for CO-RE bitfield writes

On Fri, 2023-12-01 at 17:10 -0700, Daniel Xu wrote:
[...]
> > > +SEC("tc")
> > > +__description("single CO-RE bitfield roundtrip")
> > > +__btf_path("btf__core_reloc_bitfields.bpf.o")
> > > +__success __failure_unpriv
> > 
> > do we want __failure_unpriv at all? Is this failure related to
> > *bitfield* logic at all?
> 
> Oh, I pre-emptively added it. From the docs, I thought __failure_unpriv
> meant "don't try to load this as an unprivileged used cuz it'll fail".
> And since I used the tc hook, I figured it'd fail.

Actually it means:
"try to load as unprivileged user and expect failure,
 report error on successful load".

In general, the meaning of "___xxx" and "___xxx_unpriv" annotations
is identical, except first instructs to run the test in privileged mode,
while second instructs to run test in unprivileged mode:
- if only annotations w/o "*_unpriv" suffix are present the test would
  be executed as privileged;
- if only annotations with "*_unpriv" suffix are present the test would
  be executed as unprivileged;
- if both kinds of annotations are present the test would be executed
  in both modes.

[...]