From: Andrea Righi <arighi@nvidia.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP
Date: Tue, 17 Dec 2024 20:53:30 +0100 [thread overview]
Message-ID: <Z2HWuv6o86W5yY7j@gpd3> (raw)
In-Reply-To: <CAEf4BzbKZ3JL7FigJ1aRDJSiRYBA8wYjh0+TYNfnsNVHd30j7g@mail.gmail.com>
On Tue, Dec 17, 2024 at 10:38:04AM -0800, Andrii Nakryiko wrote:
...
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index f7f892a52a37..761c70899754 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -21281,11 +21281,15 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> > * changed in some incompatible and hard to support
> > * way, it's fine to back out this inlining logic
> > */
> > +#ifdef CONFIG_SMP
> > insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number);
> > insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
> > insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
> > cnt = 3;
> > -
> > +#else
> > + BPF_ALU32_REG(BPF_XOR, BPF_REG_0, BPF_REG_0),
>
> um... shouldn't this be `insns_buf[0] = ` assignment? And that comma
> instead of semicolon at the end?
Yeah.. my bad, I tested it with the wrong .config that has CONFIG_SMP
enabled.
I'll send a v3 with the proper code, sorry for the noise.
-Andrea
>
> pw-bot: cr
>
> > + cnt = 1;
> > +#endif
> > new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
> > if (!new_prog)
> > return -ENOMEM;
> > --
> > 2.47.1
> >
next prev parent reply other threads:[~2024-12-17 19:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-16 21:00 [PATCH v2] bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP Andrea Righi
2024-12-17 18:38 ` Andrii Nakryiko
2024-12-17 19:53 ` Andrea Righi [this message]
-- strict thread matches above, loose matches on Subject: below --
2024-12-17 19:58 Andrea Righi
2024-12-18 0:20 ` patchwork-bot+netdevbpf
2024-12-18 12:22 ` Daniel Borkmann
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