From: Dave Hansen <dave@sr71.net>
To: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
linux-arch <linux-arch@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Mel Gorman <mgorman@techsingularity.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Hugh Dickins <hughd@google.com>, "H. Peter Anvin" <hpa@zytor.com>,
X86 ML <x86@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls
Date: Tue, 12 Jul 2016 08:39:07 -0700 [thread overview]
Message-ID: <57850F1B.4080306@sr71.net> (raw)
In-Reply-To: <20160712071305.GA13444@gmail.com>
On 07/12/2016 12:13 AM, Ingo Molnar wrote:
>> > Remember, PKRU is just a *bitmap*. The only place keys are stored is in the
>> > page tables.
> A pkey is an index *and* a protection mask. So by representing it as a bitmask we
> lose per thread information. This is what I meant by 'incomplete shadowing' - for
> example the debug code couldn't work: if we cleared a pkey in a task we wouldn't
> know what to restore it to with the current data structures, right?
Right. I actually have some code to do the shadowing that I wrote to
explore how to do different PKRU values in signal handlers. The code
only shadowed the keys that were currently allocated, and used the
(mm-wide) allocation map to figure that out. It did not have a separate
per-thread concept of which parts of PKRU need to be shadowed.
It essentially populated the shadow value on all pkru_set() calls.
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@sr71.net>
To: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
linux-arch <linux-arch@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Mel Gorman <mgorman@techsingularity.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Hugh Dickins <hughd@google.com>, "H. Peter Anvin" <hpa@zytor.com>,
X86 ML <x86@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH 6/9] x86, pkeys: add pkey set/get syscalls
Date: Tue, 12 Jul 2016 08:39:07 -0700 [thread overview]
Message-ID: <57850F1B.4080306@sr71.net> (raw)
In-Reply-To: <20160712071305.GA13444@gmail.com>
On 07/12/2016 12:13 AM, Ingo Molnar wrote:
>> > Remember, PKRU is just a *bitmap*. The only place keys are stored is in the
>> > page tables.
> A pkey is an index *and* a protection mask. So by representing it as a bitmask we
> lose per thread information. This is what I meant by 'incomplete shadowing' - for
> example the debug code couldn't work: if we cleared a pkey in a task we wouldn't
> know what to restore it to with the current data structures, right?
Right. I actually have some code to do the shadowing that I wrote to
explore how to do different PKRU values in signal handlers. The code
only shadowed the keys that were currently allocated, and used the
(mm-wide) allocation map to figure that out. It did not have a separate
per-thread concept of which parts of PKRU need to be shadowed.
It essentially populated the shadow value on all pkru_set() calls.
--
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next prev parent reply other threads:[~2016-07-12 15:39 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-07 12:47 [PATCH 0/9] [REVIEW-REQUEST] [v4] System Calls for Memory Protection Keys Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 1/9] x86, pkeys: add fault handling for PF_PK page fault bit Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 14:40 ` Mel Gorman
2016-07-07 14:40 ` Mel Gorman
2016-07-07 15:42 ` Dave Hansen
2016-07-07 15:42 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 2/9] mm: implement new pkey_mprotect() system call Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 14:40 ` Mel Gorman
2016-07-07 14:40 ` Mel Gorman
2016-07-07 16:51 ` Dave Hansen
2016-07-07 16:51 ` Dave Hansen
2016-07-08 10:15 ` Mel Gorman
2016-07-08 10:15 ` Mel Gorman
2016-07-07 12:47 ` [PATCH 3/9] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 4/9] x86: wire up mprotect_key() system call Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 5/9] x86, pkeys: allocation/free syscalls Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 14:40 ` Mel Gorman
2016-07-07 14:40 ` Mel Gorman
2016-07-07 15:38 ` Dave Hansen
2016-07-07 15:38 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 14:45 ` Mel Gorman
2016-07-07 14:45 ` Mel Gorman
2016-07-07 17:33 ` Dave Hansen
2016-07-07 17:33 ` Dave Hansen
2016-07-08 7:18 ` Ingo Molnar
2016-07-08 7:18 ` Ingo Molnar
[not found] ` <20160708071810.GA27457-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-07-08 16:32 ` Dave Hansen
2016-07-08 16:32 ` Dave Hansen
2016-07-08 16:32 ` Dave Hansen
2016-07-09 8:37 ` Ingo Molnar
2016-07-09 8:37 ` Ingo Molnar
2016-07-09 8:37 ` Ingo Molnar
2016-07-11 4:25 ` Andy Lutomirski
2016-07-11 4:25 ` Andy Lutomirski
[not found] ` <CALCETrXJhVz6Za4=oidiM2Vfbb+XdggFBYiVyvOCcia+w064aQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-07-11 7:35 ` Ingo Molnar
2016-07-11 7:35 ` Ingo Molnar
2016-07-11 7:35 ` Ingo Molnar
2016-07-11 14:28 ` Dave Hansen
2016-07-11 14:28 ` Dave Hansen
2016-07-12 7:13 ` Ingo Molnar
2016-07-12 7:13 ` Ingo Molnar
2016-07-12 15:39 ` Dave Hansen [this message]
2016-07-12 15:39 ` Dave Hansen
2016-07-11 14:50 ` Andy Lutomirski
2016-07-11 14:50 ` Andy Lutomirski
2016-07-11 14:34 ` Dave Hansen
2016-07-11 14:34 ` Dave Hansen
2016-07-11 14:34 ` Dave Hansen
2016-07-11 14:45 ` Andy Lutomirski
2016-07-11 14:45 ` Andy Lutomirski
2016-07-11 15:48 ` Dave Hansen
2016-07-11 15:48 ` Dave Hansen
2016-07-12 16:32 ` Andy Lutomirski
2016-07-12 16:32 ` Andy Lutomirski
2016-07-12 17:12 ` Dave Hansen
2016-07-12 17:12 ` Dave Hansen
2016-07-12 22:55 ` Andy Lutomirski
2016-07-12 22:55 ` Andy Lutomirski
2016-07-13 7:56 ` Ingo Molnar
2016-07-13 7:56 ` Ingo Molnar
2016-07-13 18:43 ` Andy Lutomirski
2016-07-13 18:43 ` Andy Lutomirski
2016-07-14 8:07 ` Ingo Molnar
2016-07-14 8:07 ` Ingo Molnar
2016-07-18 4:43 ` Andy Lutomirski
2016-07-18 4:43 ` Andy Lutomirski
2016-07-18 9:56 ` Ingo Molnar
2016-07-18 9:56 ` Ingo Molnar
[not found] ` <20160709083715.GA29939-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-07-18 18:02 ` Dave Hansen
2016-07-18 18:02 ` Dave Hansen
2016-07-18 18:02 ` Dave Hansen
2016-07-18 20:12 ` Dave Hansen
2016-07-18 20:12 ` Dave Hansen
2016-07-18 20:12 ` Dave Hansen
2016-07-08 19:26 ` Dave Hansen
2016-07-08 19:26 ` Dave Hansen
[not found] ` <577E924C.6010406-gkUM19QKKo4@public.gmane.org>
2016-07-08 10:22 ` Mel Gorman
2016-07-08 10:22 ` Mel Gorman
2016-07-08 10:22 ` Mel Gorman
2016-07-07 12:47 ` [PATCH 7/9] generic syscalls: wire up memory protection keys syscalls Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 8/9] pkeys: add details of system call use to Documentation/ Dave Hansen
2016-07-07 12:47 ` Dave Hansen
2016-07-07 12:47 ` [PATCH 9/9] x86, pkeys: add self-tests Dave Hansen
2016-07-07 12:47 ` Dave Hansen
[not found] ` <20160707124719.3F04C882-LXbPSdftPKxrdx17CPfAsdBPR1lH4CV8@public.gmane.org>
2016-07-07 14:47 ` [PATCH 0/9] [REVIEW-REQUEST] [v4] System Calls for Memory Protection Keys Mel Gorman
2016-07-07 14:47 ` Mel Gorman
2016-07-07 14:47 ` Mel Gorman
2016-07-08 18:38 ` Hugh Dickins
2016-07-08 18:38 ` Hugh Dickins
2016-07-08 18:38 ` Hugh Dickins
-- strict thread matches above, loose matches on Subject: below --
2016-06-09 0:01 [PATCH 0/9] [v3] " Dave Hansen
2016-06-09 0:01 ` [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen
2016-06-09 0:01 ` Dave Hansen
2016-06-07 20:47 [PATCH 0/9] [v2] System Calls for Memory Protection Keys Dave Hansen
2016-06-07 20:47 ` [PATCH 6/9] x86, pkeys: add pkey set/get syscalls Dave Hansen
2016-06-07 20:47 ` Dave Hansen
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