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From: Daniel Borkmann <daniel@iogearbox.net>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Mykola Lysenko <mykolal@fb.com>, bpf <bpf@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v5 bpf-next] Small BPF verifier log improvements
Date: Thu, 3 Mar 2022 16:51:38 +0100	[thread overview]
Message-ID: <9449f4fa-4361-f550-5954-a855280611ce@iogearbox.net> (raw)
In-Reply-To: <CAADnVQLEbDrKt-ehyR=FqMfxcWLL0Tg6i7cKY+jjybBJLn+E0w@mail.gmail.com>

On 3/2/22 11:13 PM, Alexei Starovoitov wrote:
> On Wed, Mar 2, 2022 at 1:46 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>> On 3/2/22 10:23 PM, Alexei Starovoitov wrote:
>>> On Tue, Mar 01, 2022 at 02:27:45PM -0800, Mykola Lysenko wrote:
>>>>               .prog_type = BPF_PROG_TYPE_SCHED_CLS,
>>>>               .matches = {
>>>> -                    {6, "R3_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {7, "R4_w=inv(id=1,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {8, "R4_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {9, "R4_w=inv(id=1,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {10, "R4_w=inv(id=0,umax_value=510,var_off=(0x0; 0x1fe))"},
>>>> -                    {11, "R4_w=inv(id=1,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {12, "R4_w=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
>>>> -                    {13, "R4_w=inv(id=1,umax_value=255,var_off=(0x0; 0xff))"},
>>>> -                    {14, "R4_w=inv(id=0,umax_value=2040,var_off=(0x0; 0x7f8))"},
>>>> -                    {15, "R4_w=inv(id=0,umax_value=4080,var_off=(0x0; 0xff0))"},
>>>> +                    {6, "R3_w=scalar(umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {7, "R4_w=scalar(id=1,umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {8, "R4_w=scalar(umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {9, "R4_w=scalar(id=1,umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {10, "R4_w=scalar(umax=510,var_off=(0x0; 0x1fe))"},
>>>> +                    {11, "R4_w=scalar(id=1,umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {12, "R4_w=scalar(umax=1020,var_off=(0x0; 0x3fc))"},
>>>> +                    {13, "R4_w=scalar(id=1,umax=255,var_off=(0x0; 0xff))"},
>>>> +                    {14, "R4_w=scalar(umax=2040,var_off=(0x0; 0x7f8))"},
>>>> +                    {15, "R4_w=scalar(umax=4080,var_off=(0x0; 0xff0))"},
>>>
>>> Sorry for the later review.
>>> Would "int" be more precise and less verbose than "scalar"?
>>
>> Could work as well, although in many places today we make use of the term "scalar",
>> so developers might be more familiar with it (and more consistent towards the
>> verifier type internals).
> 
> I was focusing more on users who will see these logs and
> would have to interpret them.
> I suspect the ratio is 1 developer to 1000 users.
> The users have to fight the verifier quite a bit to make the program pass.
> I was thinking about "i64" too. That's what llvm is using,
> but it's less clear than "int", which should be obvious
> for users since they write progs in C.
> It's also shorter.
> 
> I can live with "scalar" though.

Imho, 'scalar' fits best. 'i64' would still be better then 'int' as it could imply
different width. Anyway, can push it out in a bit.

      reply	other threads:[~2022-03-03 15:51 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-01 22:27 [PATCH v5 bpf-next] Small BPF verifier log improvements Mykola Lysenko
2022-03-02 21:23 ` Alexei Starovoitov
2022-03-02 21:46   ` Daniel Borkmann
2022-03-02 22:13     ` Alexei Starovoitov
2022-03-03 15:51       ` Daniel Borkmann [this message]

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