linux-kernel - Re: [RFC 0/1] BPF tracing for arm64 using fprobe

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Message-ID: <Y3tOUcOjEDJrm7w6@hirez.programming.kicks-ass.net>
Date:   Mon, 21 Nov 2022 11:09:21 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Chris Mason <clm@...a.com>, Mark Rutland <mark.rutland@....com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Florent Revest <revest@...omium.org>,
        bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        KP Singh <kpsingh@...nel.org>,
        Brendan Jackman <jackmanb@...gle.com>, markowsky@...gle.com,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Xu Kuohai <xukuohai@...wei.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [RFC 0/1] BPF tracing for arm64 using fprobe

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.