linux-kernel - Re: [PATCH v5] arm64: implement KPROBES_ON

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Message-Id: <1566474733.p35psfjpl2.naveen@linux.ibm.com>
Date:   Thu, 22 Aug 2019 17:22:42 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Jonathan Corbet <corbet@....net>,
        Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v5] arm64: implement KPROBES_ON_FTRACE

Jisheng Zhang wrote:
> KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it
> eliminates the need for a trap, as well as the need to emulate or
> single-step instructions.
> 
> Tested on berlin arm64 platform.
> 
> ~ # mount -t debugfs debugfs /sys/kernel/debug/
> ~ # cd /sys/kernel/debug/
> /sys/kernel/debug # echo 'p _do_fork' > tracing/kprobe_events
> 
> before the patch:
> 
> /sys/kernel/debug # cat kprobes/list
> ffffff801009fe28  k  _do_fork+0x0    [DISABLED]
> 
> after the patch:
> 
> /sys/kernel/debug # cat kprobes/list
> ffffff801009ff54  k  _do_fork+0x4    [DISABLED][FTRACE]
> 
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@...aptics.com>

Reviewed-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>


- Naveen