linux-kernel - Re: [PATCH v2 1/3] kprobes/x86: use instruction_pointer and instruction_pointer

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Date:   Tue, 20 Aug 2019 09:02:59 +0000
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 1/3] kprobes/x86: use instruction_pointer and
 instruction_pointer_set

Hi Thomas,

On Tue, 20 Aug 2019 10:53:58 +0200 (CEST) Thomas Gleixner wrote:

> 
> 
> On Tue, 20 Aug 2019, Jisheng Zhang wrote:
> 
> > This is to make the x86 kprobe_ftrace_handler() more common so that
> > the code could be reused in future.  
> 
> While I agree with the change in general, I can't find anything which
> reuses that code. So the change log is pretty useless and I have no idea
> how this is related to the rest of the series.

In v1, this code is moved from x86 to common kprobes.c [1]
But I agree with Masami, consolidation could be done when arm64 kprobes
on ftrace is stable.

In v2, actually, the arm64 version's kprobe_ftrace_handler() is the same
as x86's, the only difference is comment, e.g

/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */

while in arm64

/* Kprobe handler expects regs->pc = ip + 1 as breakpoint hit */


W/ above, any suggestion about the suitable change log?

Thanks

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2019-August/674417.html