From: Dave Hansen <dave.hansen@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 08/10] x86, mpx: add prctl commands PR_MPX_REGISTER, PR_MPX_UNREGISTER
Date: Fri, 12 Sep 2014 13:35:12 -0700 [thread overview]
Message-ID: <54135900.6010606@intel.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1409122038590.4178@nanos>
On 09/12/2014 11:42 AM, Thomas Gleixner wrote:
> On Fri, 12 Sep 2014, Thomas Gleixner wrote:
>> On Fri, 12 Sep 2014, Dave Hansen wrote:
>> The proper solution to this problem is:
>>
>> do_bounds()
>> bd_addr = get_bd_addr_from_xsave();
>> bd_entry = bndstatus & ADDR_MASK:
>
> Just for clarification. You CANNOT avoid the xsave here because it's
> the only way to access BNDSTATUS according to the manual.
>
> "The BNDCFGU and BNDSTATUS registers are accessible only with
> XSAVE/XRSTOR family of instructions"
>
> So there is no point to cache BNDCFGU as you get it anyway when you
> need to retrieve the invalid BD entry.
Agreed. It serves no purpose during a bounds fault.
However, it does keep you from having to do an xsave during the bounds
table free operations, like at unmap() time. That is actually a much
more critical path than bounds faults.
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next prev parent reply other threads:[~2014-09-12 20:36 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
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 [this message]
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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