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From: Dave Hansen <dave.hansen@intel.com>
To: "Ren, Qiaowei" <qiaowei.ren@intel.com>,
	One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "x86@kernel.org" <x86@kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 08/10] x86, mpx: add prctl commands PR_MPX_REGISTER, PR_MPX_UNREGISTER
Date: Mon, 15 Sep 2014 21:17:02 -0700	[thread overview]
Message-ID: <5417B9BE.1030209@intel.com> (raw)
In-Reply-To: <9E0BE1322F2F2246BD820DA9FC397ADE017AE183@shsmsx102.ccr.corp.intel.com>

On 09/15/2014 08:20 PM, Ren, Qiaowei wrote:
>> What are the semantics across execve() ?
>> 
> This will not impact on the semantics of execve(). One runtime
> library
> for MPX will be provided (or merged into Glibc), and when the
> application starts, this runtime will be called to initialize MPX
> runtime environment, including calling prctl() to notify the kernel to
> start managing the bounds directories. You can see the discussion
> about exec(): https://lkml.org/lkml/2014/1/26/199

I think he's asking what happens to the kernel value at execve() time.

The short answer is that it is zero'd along with the rest of a new mm.
It probably _shouldn't_ be, though.  It's actually valid to have a bound
directory at 0x0.  We probably need to initialize it to -1 instead, and
that means initializing to -1 at execve() time.

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WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: "Ren, Qiaowei" <qiaowei.ren@intel.com>,
	One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "x86@kernel.org" <x86@kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 08/10] x86, mpx: add prctl commands PR_MPX_REGISTER, PR_MPX_UNREGISTER
Date: Mon, 15 Sep 2014 21:17:02 -0700	[thread overview]
Message-ID: <5417B9BE.1030209@intel.com> (raw)
In-Reply-To: <9E0BE1322F2F2246BD820DA9FC397ADE017AE183@shsmsx102.ccr.corp.intel.com>

On 09/15/2014 08:20 PM, Ren, Qiaowei wrote:
>> What are the semantics across execve() ?
>> 
> This will not impact on the semantics of execve(). One runtime
> library
> for MPX will be provided (or merged into Glibc), and when the
> application starts, this runtime will be called to initialize MPX
> runtime environment, including calling prctl() to notify the kernel to
> start managing the bounds directories. You can see the discussion
> about exec(): https://lkml.org/lkml/2014/1/26/199

I think he's asking what happens to the kernel value at execve() time.

The short answer is that it is zero'd along with the rest of a new mm.
It probably _shouldn't_ be, though.  It's actually valid to have a bound
directory at 0x0.  We probably need to initialize it to -1 instead, and
that means initializing to -1 at execve() time.

  reply	other threads:[~2014-09-16  4:17 UTC|newest]

Thread overview: 130+ 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 ` 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   ` 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   ` 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   ` Qiaowei Ren
2014-09-11  8:46 ` [PATCH v8 04/10] x86, mpx: hook #BR exception handler to allocate bound tables Qiaowei Ren
2014-09-11  8:46   ` Qiaowei Ren
2014-09-12 22:58   ` Dave Hansen
2014-09-12 22:58     ` Dave Hansen
2014-09-13  7:24     ` Ren, Qiaowei
2014-09-13  7:24       ` Ren, Qiaowei
2014-09-24 14:40   ` Dave Hansen
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   ` Qiaowei Ren
2014-09-11  8:46 ` [PATCH v8 06/10] mips: sync struct siginfo with general version Qiaowei Ren
2014-09-11  8:46   ` Qiaowei Ren
2014-09-11 22:13   ` Thomas Gleixner
2014-09-11 22:13     ` Thomas Gleixner
2014-09-12  2:54     ` Ren, Qiaowei
2014-09-12  2:54       ` Ren, Qiaowei
2014-09-12  8:17       ` Thomas Gleixner
2014-09-12  8:17         ` Thomas Gleixner
2014-09-13  7:13         ` Ren, Qiaowei
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  8:46   ` Qiaowei Ren
2014-09-11 22:18   ` Thomas Gleixner
2014-09-11 22:18     ` Thomas Gleixner
2014-09-11 22:32     ` Dave Hansen
2014-09-11 22:32       ` Dave Hansen
2014-09-11 22:35       ` H. Peter Anvin
2014-09-11 22:35         ` H. Peter Anvin
2014-09-11 23:37         ` Thomas Gleixner
2014-09-11 23:37           ` Thomas Gleixner
2014-09-12  4:44           ` H. Peter Anvin
2014-09-12  4:44             ` H. Peter Anvin
2014-09-12 13:10             ` Thomas Gleixner
2014-09-12 13:10               ` Thomas Gleixner
2014-09-12 13:39               ` H. Peter Anvin
2014-09-12 13:39                 ` H. Peter Anvin
2014-09-12 17:48                 ` Thomas Gleixner
2014-09-12 17:48                   ` Thomas Gleixner
2014-09-12 17:52         ` Thomas Gleixner
2014-09-12 17:52           ` Thomas Gleixner
2014-09-12 19:07           ` H. Peter Anvin
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  8:46   ` Qiaowei Ren
2014-09-11 15:03   ` Dave Hansen
2014-09-11 15:03     ` Dave Hansen
2014-09-12  3:10     ` Ren, Qiaowei
2014-09-12  3:10       ` Ren, Qiaowei
2014-09-11 23:28   ` Thomas Gleixner
2014-09-11 23:28     ` Thomas Gleixner
2014-09-12  0:10     ` Dave Hansen
2014-09-12  0:10       ` Dave Hansen
2014-09-12  8:11       ` Thomas Gleixner
2014-09-12  8:11         ` Thomas Gleixner
2014-09-12  9:24         ` Thomas Gleixner
2014-09-12  9:24           ` Thomas Gleixner
2014-09-12 14:36           ` Dave Hansen
2014-09-12 14:36             ` Dave Hansen
2014-09-12 17:34             ` Thomas Gleixner
2014-09-12 17:34               ` Thomas Gleixner
2014-09-12 18:42               ` Thomas Gleixner
2014-09-12 18:42                 ` Thomas Gleixner
2014-09-12 20:35                 ` Dave Hansen
2014-09-12 20:35                   ` Dave Hansen
2014-09-12 20:18               ` Dave Hansen
2014-09-12 20:18                 ` Dave Hansen
2014-09-13  9:01                 ` Thomas Gleixner
2014-09-13  9:01                   ` Thomas Gleixner
2014-09-12 15:22         ` Dave Hansen
2014-09-12 15:22           ` Dave Hansen
2014-09-12 17:42           ` Thomas Gleixner
2014-09-12 17:42             ` Thomas Gleixner
2014-09-12 20:33             ` Dave Hansen
2014-09-12 20:33               ` Dave Hansen
2014-09-15  0:00   ` One Thousand Gnomes
2014-09-15  0:00     ` One Thousand Gnomes
2014-09-16  3:20     ` Ren, Qiaowei
2014-09-16  3:20       ` Ren, Qiaowei
2014-09-16  4:17       ` Dave Hansen [this message]
2014-09-16  4:17         ` Dave Hansen
2014-09-16  7:50   ` Kevin Easton
2014-09-16  7:50     ` Kevin Easton
2014-09-18  0:40     ` Ren, Qiaowei
2014-09-18  0:40       ` Ren, Qiaowei
2014-09-18  3:23       ` Kevin Easton
2014-09-18  3:23         ` Kevin Easton
2014-09-18  2:37         ` Ren, Qiaowei
2014-09-18  2:37           ` Ren, Qiaowei
2014-09-18  4:43         ` Dave Hansen
2014-09-18  4:43           ` Dave Hansen
2014-09-18  7:17           ` Kevin Easton
2014-09-18  7:17             ` Kevin Easton
2014-09-18  6:20             ` Dave Hansen
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  8:46   ` Qiaowei Ren
2014-09-11 14:59   ` Dave Hansen
2014-09-11 14:59     ` Dave Hansen
2014-09-12  3:02     ` Ren, Qiaowei
2014-09-12  3:02       ` Ren, Qiaowei
2014-09-12  4:59       ` Dave Hansen
2014-09-12  4:59         ` Dave Hansen
2014-09-15 20:53   ` Dave Hansen
2014-09-15 20:53     ` Dave Hansen
2014-09-16  8:06     ` Ren, Qiaowei
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
2014-09-11  8:46   ` Qiaowei Ren
2014-09-12  0:51 ` [PATCH v8 00/10] Intel MPX support Dave Hansen
2014-09-12  0:51   ` Dave Hansen
2014-09-12 19:21   ` Thomas Gleixner
2014-09-12 19:21     ` Thomas Gleixner
2014-09-12 21:23     ` Dave Hansen
2014-09-12 21:23       ` Dave Hansen
2014-09-13  9:25       ` Thomas Gleixner
2014-09-13  9:25         ` Thomas Gleixner
2014-09-12 21:31     ` Dave Hansen
2014-09-12 21:31       ` Dave Hansen
2014-09-12 22:08     ` Dave Hansen
2014-09-12 22:08       ` Dave Hansen
2014-09-13  9:39       ` Thomas Gleixner
2014-09-13  9:39         ` Thomas Gleixner

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