From: Eduard Zingerman <eddyz87@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Hao Sun <sunhao.th@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>, bpf <bpf@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [Bug Report] bpf: incorrectly pruning runtime execution path
Date: Thu, 14 Dec 2023 01:47:35 +0200 [thread overview]
Message-ID: <3ba67d3e220c19c4a921e20f06e26bfe70ae8c80.camel@gmail.com> (raw)
In-Reply-To: <CAEf4BzbfF=aNa-jAkka6YrK6Vbisi=v7PFsEDR-RFuHtAub2Xw@mail.gmail.com>
On Wed, 2023-12-13 at 15:40 -0800, Andrii Nakryiko wrote:
[...]
> > 24: (18) r2 = 0x4 ; R2_w=4
> > 26: (7e) if w8 s>= w0 goto pc+5
> > mark_precise: frame0: last_idx 26 first_idx 22 subseq_idx -1
> > mark_precise: frame0: regs=r5,r8 stack= before 24: (18) r2 = 0x4
> > ... ^^^^^^^^^^
> > ^^^^^^^^^^
> > Here w8 == 15, w0 in range [0, 2], so the jump is being predicted,
> > but for some reason R0 is not among the registers that would be marked precise.
>
> It is, as a second step. There are two concatenated precision logs:
>
> mark_precise: frame0: last_idx 26 first_idx 22 subseq_idx -1
> mark_precise: frame0: regs=r0 stack= before 24: (18) r2 = 0x4
> mark_precise: frame0: regs=r0 stack= before 23: (bf) r5 = r8
> mark_precise: frame0: regs=r0 stack= before 22: (67) r4 <<= 2
>
>
> The issue is elsewhere, see my last email.
Oh, right, there are two calls to mark_chain_precision in a row, thanks
next prev parent reply other threads:[~2023-12-13 23:47 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-11 15:31 [Bug Report] bpf: incorrectly pruning runtime execution path Hao Sun
2023-12-13 0:51 ` Andrii Nakryiko
2023-12-13 10:25 ` Hao Sun
2023-12-13 23:30 ` Andrii Nakryiko
2023-12-14 0:08 ` Eduard Zingerman
2023-12-14 0:36 ` Andrii Nakryiko
2023-12-13 23:35 ` Eduard Zingerman
2023-12-13 23:40 ` Andrii Nakryiko
2023-12-13 23:47 ` Eduard Zingerman [this message]
2023-12-13 23:50 ` Andrii Nakryiko
2023-12-14 9:38 ` Hao Sun
2023-12-14 15:10 ` Eduard Zingerman
2023-12-14 16:26 ` Eduard Zingerman
2023-12-15 0:06 ` Andrii Nakryiko
2023-12-15 0:16 ` Eduard Zingerman
2023-12-15 0:49 ` Eduard Zingerman
2023-12-15 1:24 ` Eduard Zingerman
2023-12-15 1:43 ` Eduard Zingerman
2023-12-15 2:16 ` Alexei Starovoitov
2023-12-15 2:28 ` Eduard Zingerman
2023-12-15 5:20 ` Andrii Nakryiko
2023-12-15 16:22 ` Eduard Zingerman
2023-12-15 17:01 ` Andrii Nakryiko
2023-12-15 20:55 ` Eduard Zingerman
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