From: Eduard Zingerman <eddyz87@gmail.com>
To: Kui-Feng Lee <sinquersw@gmail.com>,
Kui-Feng Lee <thinker.li@gmail.com>,
bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev,
song@kernel.org, kernel-team@meta.com, andrii@kernel.org
Cc: kuifeng@meta.com
Subject: Re: [PATCH bpf-next v5 7/9] selftests/bpf: Test kptr arrays and kptrs in nested struct fields.
Date: Fri, 10 May 2024 16:29:38 -0700 [thread overview]
Message-ID: <e3dcfcf4a40cb9ee2f5a7c84b1df59eec1992664.camel@gmail.com> (raw)
In-Reply-To: <cfe0145e88727ccb23be8728671649eb0ffb61ae.camel@gmail.com>
On Fri, 2024-05-10 at 16:17 -0700, Eduard Zingerman wrote:
> On Fri, 2024-05-10 at 16:04 -0700, Kui-Feng Lee wrote:
>
> [...]
>
>
> > I am not sure if I read you question correctly.
> >
> > For example, we have 3 correct info.
> >
> > [info(offset=0x8), info(offset=0x10), info(offset=0x18)]
> >
> > And We have program that includes 3 instructions to access the offset
> > 0x8, 0x10, and 0x18. (let's assume these load instructions would be
> > checked against infos)
> >
> > load r1, [0x8]
> > load r1, [0x10]
> > load r1, [0x18]
> >
> > If everything works as expected, the verifier would accept the program.
> >
> > Otherwise, like you said, all 3 info are pointing to the same offset.
> >
> > [info(0offset=0x8), info(offset=0x8), info(offset=0x8)]
> >
> > Then, the later two instructions should fail the check.
Ok, what you are saying is possible not with load but with some kfunc
that accepts a special pointer. E.g. when verifier.c:check_kfunc_args()
expects an argument of KF_ARG_PTR_TO_LIST_HEAD type it would report an
error if special field is not found.
So the structure of the test would be:
- define a nested data structure with list head at some leafs;
- in the BPF program call a kfunc accessing each of the list heads;
- if all offsets are computed correctly there would be no load time error;
- this is a load time test, no need to actually run the BPF program.
[...]
next prev parent reply other threads:[~2024-05-10 23:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 1:13 [PATCH bpf-next v5 0/9] Enable BPF programs to declare arrays of kptr, bpf_rb_root, and bpf_list_head Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 1/9] bpf: Remove unnecessary checks on the offset of btf_field Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 2/9] bpf: Remove unnecessary call to btf_field_type_size() Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 3/9] bpf: refactor btf_find_struct_field() and btf_find_datasec_var() Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 4/9] bpf: create repeated fields for arrays Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 5/9] bpf: look into the types of the fields of a struct type recursively Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 6/9] bpf: limit the number of levels of a nested struct type Kui-Feng Lee
2024-05-10 2:37 ` Eduard Zingerman
2024-05-10 1:13 ` [PATCH bpf-next v5 7/9] selftests/bpf: Test kptr arrays and kptrs in nested struct fields Kui-Feng Lee
2024-05-10 10:03 ` Eduard Zingerman
2024-05-10 21:59 ` Kui-Feng Lee
2024-05-10 22:08 ` Eduard Zingerman
2024-05-10 22:25 ` Kui-Feng Lee
2024-05-10 22:31 ` Eduard Zingerman
2024-05-10 22:53 ` Kui-Feng Lee
2024-05-10 22:57 ` Eduard Zingerman
2024-05-10 23:04 ` Kui-Feng Lee
2024-05-10 23:17 ` Eduard Zingerman
2024-05-10 23:29 ` Eduard Zingerman [this message]
2024-05-20 15:55 ` Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 8/9] selftests/bpf: Test global bpf_rb_root arrays and fields in nested struct types Kui-Feng Lee
2024-05-10 1:13 ` [PATCH bpf-next v5 9/9] selftests/bpf: Test global bpf_list_head arrays Kui-Feng Lee
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