linux-kernel - Re: Why do kprobes and uprobes singlestep?

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Date:   Wed, 3 Mar 2021 14:27:50 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Andy Lutomirski <luto@...nel.org>, bpf <bpf@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>, X86 ML <x86@...nel.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>
Subject: Re: Why do kprobes and uprobes singlestep?

On 03/02, Alexei Starovoitov wrote:
>
> Especially if such tightening will come with performance boost for
> uprobe on a nop and unprobe at the start (which is typically push or
> alu on %sp).
> That would be a great step forward.

Just in case, nop and push are emulated without additional overhead.

Oleg.