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Date:   Mon, 21 Nov 2022 23:40:23 +0900
From:   Masami Hiramatsu (Google) <mhiramat@kernel.org>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Steven Rostedt <rostedt@goodmis.org>, Chris Mason <clm@meta.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Florent Revest <revest@chromium.org>,
        bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        KP Singh <kpsingh@kernel.org>,
        Brendan Jackman <jackmanb@google.com>, markowsky@google.com,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Xu Kuohai <xukuohai@huawei.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC 0/1] BPF tracing for arm64 using fprobe
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On Mon, 21 Nov 2022 11:09:21 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Fri, Nov 18, 2022 at 01:06:08PM -0500, Steven Rostedt wrote:
> > How do I know that a function return was modified by BPF? If I'm debugging
> > something, is it obvious to the developer that is debugging an issue
> > (perhaps unaware of what BPF programs are loaded on the users machine),
> > that the return of a function was tweaked by BPF and that could be the
> > source of the bug?
> 
> Have it taint the kernel if something is overridden ;-) Then we can all
> ignore the report until it comes back without taint.

Hmm, indeed. BTW, error injection should set that too.

Thanks,

-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>