From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf] bpf_trace: bail out from bpf_kprobe_multi_link_attach when in compat
Date: Tue, 10 May 2022 11:10:35 -0700 [thread overview]
Message-ID: <CAADnVQKNkEX-caBjozegRaOb67g1HNOHn1e-enRk_s-7Gtt=gg@mail.gmail.com> (raw)
In-Reply-To: <20220506142148.GA24802@asgard.redhat.com>
On Fri, May 6, 2022 at 7:22 AM Eugene Syromiatnikov <esyr@redhat.com> wrote:
>
> Since bpf_kprobe_multi_link_attach doesn't support 32-bit kernels
> for whatever reason,
Jiri,
why did you add this restriction?
> having it enabled for compat processes on 64-bit
> kernels makes even less sense due to discrepances in the type sizes
> that it does not handle.
I don't follow this logic.
bpf progs are always 64-bit. Even when user space is 32-bit.
Jiri's check is for the kernel.
> Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
> Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
> ---
> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index d8553f4..9560af6 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2410,7 +2410,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> int err;
>
> /* no support for 32bit archs yet */
> - if (sizeof(u64) != sizeof(void *))
> + if (sizeof(u64) != sizeof(void *) || in_compat_syscall())
> return -EOPNOTSUPP;
>
> if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI)
> --
> 2.1.4
>
next prev parent reply other threads:[~2022-05-10 18:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 14:21 [PATCH bpf] bpf_trace: bail out from bpf_kprobe_multi_link_attach when in compat Eugene Syromiatnikov
2022-05-10 18:10 ` Alexei Starovoitov [this message]
2022-05-10 18:41 ` Eugene Syromiatnikov
2022-05-10 22:30 ` Alexei Starovoitov
2022-05-16 20:38 ` Jiri Olsa
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