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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
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: Wed, 2 Mar 2022 14:13:56 -0800	[thread overview]
Message-ID: <CAADnVQLEbDrKt-ehyR=FqMfxcWLL0Tg6i7cKY+jjybBJLn+E0w@mail.gmail.com> (raw)
In-Reply-To: <d4e589ac-db4d-b721-580c-120ee524084d@iogearbox.net>

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.

  reply	other threads:[~2022-03-02 22:14 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 [this message]
2022-03-03 15:51       ` Daniel Borkmann

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