linux-kernel - Re: [PATCH -tip v3 0/2] kprobes/x86: Another way to make insn buffer RO and cleanup

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Message-Id: <20170911192818.d71f33c94cd235b74446cd5f@kernel.org>
Date:   Mon, 11 Sep 2017 19:28:18 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Ananth N Mavinakayanahalli <ananth@...ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -tip v3 0/2] kprobes/x86: Another way to make insn
 buffer RO and cleanup

Hello Ingo,

Ping?

Could you give me a comment? Since current code has an obvious bug, it should be fixed anyway.

Thank you,

On Mon, 28 Aug 2017 11:28:04 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Hi Ingo,
> 
> What would you think about fixing this way?
> This makes the instruction buffer always RO and
> poke it via text_poke.
> 
> Thank you,
> 
> On Fri, 18 Aug 2017 17:22:54 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > Hi,
> > 
> > This series modifies how to handle RO insn buffer and
> > cleans up addressof operators.
> > 
> > The 1st patch changes the RO insn buffer handling: instead
> > of using set_memory_ro/rw to modify the buffer, it prepares
> > new instructions in another buffer and write it with
> > text_poke() as suggested by Ingo Molnar (Thanks!).
> > Since the text_poke() is safely modifying code by
> > mapping alias pages, it can write RO pages.
> > This also override alloc_insn_page() so that it returns
> > ROX page directly.
> > 
> > The 2nd one is not changed. It is a cleanup patch
> > to remove addressof operators ("&") since
> > it is meaningless anymore.
> > 
> > V3 has just a following update:
> >  - [1/2] Not to just add set_memory_ro(), introduce new
> >    patch to change the way to handle RO pages.
> > 
> > Thanks,
> > 
> > ---
> > 
> > Masami Hiramatsu (2):
> >       kprobes/x86: Make insn buffer always ROX and use text_poke
> >       kprobes/x86: Remove addressof operators
> > 
> > 
> >  arch/x86/include/asm/kprobes.h   |    4 +-
> >  arch/x86/kernel/kprobes/common.h |    6 ++-
> >  arch/x86/kernel/kprobes/core.c   |   61 +++++++++++++++++++++------------
> >  arch/x86/kernel/kprobes/opt.c    |   71 +++++++++++++++++++++-----------------
> >  kernel/kprobes.c                 |    2 +
> >  5 files changed, 86 insertions(+), 58 deletions(-)
> > 
> > --
> > Masami Hiramatsu <mhiramat@...nel.org>
> 
> 
> -- 
> Masami Hiramatsu <mhiramat@...nel.org>


-- 
Masami Hiramatsu <mhiramat@...nel.org>