linux-kernel - Re: [PATCH v8 08/28] x86/mpx, x86/insn: Relocate insn util functions to a new insn-eval file

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Message-ID: <1504726041.19040.10.camel@ranerica-desktop>
Date:   Wed, 06 Sep 2017 12:27:21 -0700
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Borislav Petkov <bp@...e.de>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Adam Buchbinder <adam.buchbinder@...il.com>,
        Colin Ian King <colin.king@...onical.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Qiaowei Ren <qiaowei.ren@...el.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kees Cook <keescook@...omium.org>,
        Thomas Garnier <thgarnie@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v8 08/28] x86/mpx, x86/insn: Relocate insn util
 functions to a new insn-eval file

On Wed, 2017-09-06 at 17:54 +0200, Borislav Petkov wrote:
> On Fri, Aug 18, 2017 at 05:27:49PM -0700, Ricardo Neri wrote:
> > Other kernel submodules can benefit from using the utility functions
> > defined in mpx.c to obtain the addresses and values of operands contained
> > in the general purpose registers. An instance of this is the emulation code
> > used for instructions protected by the Intel User-Mode Instruction
> > Prevention feature.
> > 
> > Thus, these functions are relocated to a new insn-eval.c file. The reason
> > to not relocate these utilities into insn.c is that the latter solely
> > analyses instructions given by a struct insn without any knowledge of the
> > meaning of the values of instruction operands. This new utility insn-
> > eval.c aims to be used to resolve and userspace linear addresses based on
> 				   ^
> 				   |
> 
> something's missing there - "kernel" maybe?

I have updated this line to read "This new utility insn-eval.c aims to
be used to resolve userspace linear addresses based on the contents of
the instruction operands as well as the contents of pt_regs structure."

> 
> > the contents of the instruction operands as well as the contents of pt_regs
> > structure.
> > 
> > These utilities come with a separate header. This is to avoid taking insn.c
> > out of sync from the instructions decoders under tools/obj and tools/perf.
> > This also avoids adding cumbersome #ifdef's for the #include'd files
> > required to decode instructions in a kernel context.
> > 
> > Functions are simply relocated. There are not functional or indentation
> > changes.
> 
> That text below you don't need to have in the commit message. Patch
> handling and other modalities are usually put after the "---" and before
> the diffstat below...
> 
> > The checkpatch script issues the following warning with this
> > commit:
> > 
> > WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code
> > rather than BUG() or BUG_ON()
> > +               BUG();
> > 
> > This warning will be fixed in a subsequent patch.
> > 
> > Cc: Borislav Petkov <bp@...e.de>
> > Cc: Andy Lutomirski <luto@...nel.org>
> > Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> > Cc: Adam Buchbinder <adam.buchbinder@...il.com>
> > Cc: Colin Ian King <colin.king@...onical.com>
> > Cc: Lorenzo Stoakes <lstoakes@...il.com>
> > Cc: Qiaowei Ren <qiaowei.ren@...el.com>
> > Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Cc: Masami Hiramatsu <mhiramat@...nel.org>
> > Cc: Adrian Hunter <adrian.hunter@...el.com>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: Thomas Garnier <thgarnie@...gle.com>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Dmitry Vyukov <dvyukov@...gle.com>
> > Cc: Ravi V. Shankar <ravi.v.shankar@...el.com>
> > Cc: x86@...nel.org
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
> > ---
> 
> <--- ... here. Put such notes here.

Thanks for explaining this to me. I will move the note about the warning
here.
> 
> >  arch/x86/include/asm/insn-eval.h |  16 ++++
> >  arch/x86/lib/Makefile            |   2 +-
> >  arch/x86/lib/insn-eval.c         | 163 +++++++++++++++++++++++++++++++++++++++
> >  arch/x86/mm/mpx.c                | 156 +------------------------------------
> >  4 files changed, 182 insertions(+), 155 deletions(-)
> >  create mode 100644 arch/x86/include/asm/insn-eval.h
> >  create mode 100644 arch/x86/lib/insn-eval.c
> 
> Reviewed-by: Borislav Petkov <bp@...e.de>

Thanks you!

BR,
Ricardo