From: "H. Peter Anvin" <hpa@zytor.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@intel.com>,
Qiaowei Ren <qiaowei.ren@intel.com>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 07/10] x86, mpx: decode MPX instruction to get bound violation information
Date: Fri, 12 Sep 2014 12:07:16 -0700 [thread overview]
Message-ID: <54134464.1010809@zytor.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1409121949460.4178@nanos>
On 09/12/2014 10:52 AM, Thomas Gleixner wrote:
>
> Well, I did not see the trainwreck which tried to use the generic
> decoder, but as I explained in the other mail, there is no reason not
> to use it and I can't see any complexity in retrieving the data beyond
> calling insn_get_length(insn);
>
Looking at how complex the state machine ended up being, it probably was
the wrong direction. It is safe to copy_from_user() 15 bytes, decode
what we get (which may be less than 15 bytes) and then verify with
insn_get_length() that what we decoded is actually what we copied if the
copy_from_user() length is < 15.
My intent was to explore a state machine limited to the restricted "mib"
encodings that are valid for BNDSTX and BNDLDX only, but in the end it
really doesn't make enough difference that it is worth messing with, I
don't think.
-hpa
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next prev parent reply other threads:[~2014-09-12 19:07 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-11 8:46 [PATCH v8 00/10] Intel MPX support Qiaowei Ren
2014-09-11 8:46 ` [PATCH v8 01/10] x86, mpx: introduce VM_MPX to indicate that a VMA is MPX specific Qiaowei Ren
2014-09-11 8:46 ` [PATCH v8 02/10] x86, mpx: add MPX specific mmap interface Qiaowei Ren
2014-09-11 8:46 ` [PATCH v8 03/10] x86, mpx: add macro cpu_has_mpx Qiaowei Ren
2014-09-11 8:46 ` [PATCH v8 04/10] x86, mpx: hook #BR exception handler to allocate bound tables Qiaowei Ren
2014-09-12 22:58 ` Dave Hansen
2014-09-13 7:24 ` Ren, Qiaowei
2014-09-24 14:40 ` Dave Hansen
2014-09-11 8:46 ` [PATCH v8 05/10] x86, mpx: extend siginfo structure to include bound violation information Qiaowei Ren
2014-09-11 8:46 ` [PATCH v8 06/10] mips: sync struct siginfo with general version Qiaowei Ren
2014-09-11 22:13 ` Thomas Gleixner
2014-09-12 2:54 ` Ren, Qiaowei
2014-09-12 8:17 ` Thomas Gleixner
2014-09-13 7:13 ` Ren, Qiaowei
2014-09-11 8:46 ` [PATCH v8 07/10] x86, mpx: decode MPX instruction to get bound violation information Qiaowei Ren
2014-09-11 22:18 ` Thomas Gleixner
2014-09-11 22:32 ` Dave Hansen
2014-09-11 22:35 ` H. Peter Anvin
2014-09-11 23:37 ` Thomas Gleixner
2014-09-12 4:44 ` H. Peter Anvin
2014-09-12 13:10 ` Thomas Gleixner
2014-09-12 13:39 ` H. Peter Anvin
2014-09-12 17:48 ` Thomas Gleixner
2014-09-12 17:52 ` Thomas Gleixner
2014-09-12 19:07 ` H. Peter Anvin [this message]
2014-09-11 8:46 ` [PATCH v8 08/10] x86, mpx: add prctl commands PR_MPX_REGISTER, PR_MPX_UNREGISTER Qiaowei Ren
2014-09-11 15:03 ` Dave Hansen
2014-09-12 3:10 ` Ren, Qiaowei
2014-09-11 23:28 ` Thomas Gleixner
2014-09-12 0:10 ` Dave Hansen
2014-09-12 8:11 ` Thomas Gleixner
2014-09-12 9:24 ` Thomas Gleixner
2014-09-12 14:36 ` Dave Hansen
2014-09-12 17:34 ` Thomas Gleixner
2014-09-12 18:42 ` Thomas Gleixner
2014-09-12 20:35 ` Dave Hansen
2014-09-12 20:18 ` Dave Hansen
2014-09-13 9:01 ` Thomas Gleixner
2014-09-12 15:22 ` Dave Hansen
2014-09-12 17:42 ` Thomas Gleixner
2014-09-12 20:33 ` Dave Hansen
2014-09-15 0:00 ` One Thousand Gnomes
2014-09-16 3:20 ` Ren, Qiaowei
2014-09-16 4:17 ` Dave Hansen
2014-09-16 7:50 ` Kevin Easton
2014-09-18 0:40 ` Ren, Qiaowei
2014-09-18 3:23 ` Kevin Easton
2014-09-18 2:37 ` Ren, Qiaowei
2014-09-18 4:43 ` Dave Hansen
2014-09-18 7:17 ` Kevin Easton
2014-09-18 6:20 ` Dave Hansen
2014-09-11 8:46 ` [PATCH v8 09/10] x86, mpx: cleanup unused bound tables Qiaowei Ren
2014-09-11 14:59 ` Dave Hansen
2014-09-12 3:02 ` Ren, Qiaowei
2014-09-12 4:59 ` Dave Hansen
2014-09-15 20:53 ` Dave Hansen
2014-09-16 8:06 ` Ren, Qiaowei
2014-09-11 8:46 ` [PATCH v8 10/10] x86, mpx: add documentation on Intel MPX Qiaowei Ren
2014-09-12 0:51 ` [PATCH v8 00/10] Intel MPX support Dave Hansen
2014-09-12 19:21 ` Thomas Gleixner
2014-09-12 21:23 ` Dave Hansen
2014-09-13 9:25 ` Thomas Gleixner
2014-09-12 21:31 ` Dave Hansen
2014-09-12 22:08 ` Dave Hansen
2014-09-13 9:39 ` Thomas Gleixner
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