From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
dave.hansen@linux.intel.com, linux-api@vger.kernel.org
Subject: Re: [PATCH 28/34] x86: wire up mprotect_key() system call
Date: Tue, 8 Dec 2015 21:38:12 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1512082134470.3595@nanos> (raw)
In-Reply-To: <56672A50.4010801@sr71.net>
On Tue, 8 Dec 2015, Dave Hansen wrote:
> On 12/08/2015 10:44 AM, Thomas Gleixner wrote:
> > On Thu, 3 Dec 2015, Dave Hansen wrote:
> >> #include <asm-generic/mman.h>
> >> diff -puN mm/Kconfig~pkeys-16-x86-mprotect_key mm/Kconfig
> >> --- a/mm/Kconfig~pkeys-16-x86-mprotect_key 2015-12-03 16:21:31.114920208 -0800
> >> +++ b/mm/Kconfig 2015-12-03 16:21:31.119920435 -0800
> >> @@ -679,4 +679,5 @@ config NR_PROTECTION_KEYS
> >> # Everything supports a _single_ key, so allow folks to
> >> # at least call APIs that take keys, but require that the
> >> # key be 0.
> >> + default 16 if X86_INTEL_MEMORY_PROTECTION_KEYS
> >> default 1
> >
> > What happens if I set that to 42?
> >
> > I think we want to make this a runtime evaluated thingy. If pkeys are
> > compiled in, but the machine does not support it then we don't support
> > 16 keys, or do we?
>
> We do have runtime evaluation:
>
> #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? \
> CONFIG_NR_PROTECTION_KEYS : 1)
>
> The config option really just sets the architectural limit for how many
> are supported. So it probably needs a better name at least. Let me
> take a look at getting rid of this config option entirely.
Well, it does not set the architectural limit. It sets some random
value which the guy who configures the kernel choses.
The limit we have in the architecture is 16 because we only have 4
bits for it.
arch_max_pkey() is architecture specific, so we can make this:
#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
And when we magically get more bits in the next century, then '16' can
become a variable or whatever.
Thanks,
tglx
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
dave.hansen@linux.intel.com, linux-api@vger.kernel.org
Subject: Re: [PATCH 28/34] x86: wire up mprotect_key() system call
Date: Tue, 8 Dec 2015 21:38:12 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1512082134470.3595@nanos> (raw)
In-Reply-To: <56672A50.4010801@sr71.net>
On Tue, 8 Dec 2015, Dave Hansen wrote:
> On 12/08/2015 10:44 AM, Thomas Gleixner wrote:
> > On Thu, 3 Dec 2015, Dave Hansen wrote:
> >> #include <asm-generic/mman.h>
> >> diff -puN mm/Kconfig~pkeys-16-x86-mprotect_key mm/Kconfig
> >> --- a/mm/Kconfig~pkeys-16-x86-mprotect_key 2015-12-03 16:21:31.114920208 -0800
> >> +++ b/mm/Kconfig 2015-12-03 16:21:31.119920435 -0800
> >> @@ -679,4 +679,5 @@ config NR_PROTECTION_KEYS
> >> # Everything supports a _single_ key, so allow folks to
> >> # at least call APIs that take keys, but require that the
> >> # key be 0.
> >> + default 16 if X86_INTEL_MEMORY_PROTECTION_KEYS
> >> default 1
> >
> > What happens if I set that to 42?
> >
> > I think we want to make this a runtime evaluated thingy. If pkeys are
> > compiled in, but the machine does not support it then we don't support
> > 16 keys, or do we?
>
> We do have runtime evaluation:
>
> #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? \
> CONFIG_NR_PROTECTION_KEYS : 1)
>
> The config option really just sets the architectural limit for how many
> are supported. So it probably needs a better name at least. Let me
> take a look at getting rid of this config option entirely.
Well, it does not set the architectural limit. It sets some random
value which the guy who configures the kernel choses.
The limit we have in the architecture is 16 because we only have 4
bits for it.
arch_max_pkey() is architecture specific, so we can make this:
#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
And when we magically get more bits in the next century, then '16' can
become a variable or whatever.
Thanks,
tglx
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WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
To: Dave Hansen <dave-gkUM19QKKo4@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
dave.hansen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 28/34] x86: wire up mprotect_key() system call
Date: Tue, 8 Dec 2015 21:38:12 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.11.1512082134470.3595@nanos> (raw)
In-Reply-To: <56672A50.4010801-gkUM19QKKo4@public.gmane.org>
On Tue, 8 Dec 2015, Dave Hansen wrote:
> On 12/08/2015 10:44 AM, Thomas Gleixner wrote:
> > On Thu, 3 Dec 2015, Dave Hansen wrote:
> >> #include <asm-generic/mman.h>
> >> diff -puN mm/Kconfig~pkeys-16-x86-mprotect_key mm/Kconfig
> >> --- a/mm/Kconfig~pkeys-16-x86-mprotect_key 2015-12-03 16:21:31.114920208 -0800
> >> +++ b/mm/Kconfig 2015-12-03 16:21:31.119920435 -0800
> >> @@ -679,4 +679,5 @@ config NR_PROTECTION_KEYS
> >> # Everything supports a _single_ key, so allow folks to
> >> # at least call APIs that take keys, but require that the
> >> # key be 0.
> >> + default 16 if X86_INTEL_MEMORY_PROTECTION_KEYS
> >> default 1
> >
> > What happens if I set that to 42?
> >
> > I think we want to make this a runtime evaluated thingy. If pkeys are
> > compiled in, but the machine does not support it then we don't support
> > 16 keys, or do we?
>
> We do have runtime evaluation:
>
> #define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? \
> CONFIG_NR_PROTECTION_KEYS : 1)
>
> The config option really just sets the architectural limit for how many
> are supported. So it probably needs a better name at least. Let me
> take a look at getting rid of this config option entirely.
Well, it does not set the architectural limit. It sets some random
value which the guy who configures the kernel choses.
The limit we have in the architecture is 16 because we only have 4
bits for it.
arch_max_pkey() is architecture specific, so we can make this:
#define arch_max_pkey() (boot_cpu_has(X86_FEATURE_OSPKE) ? 16 : 1)
And when we magically get more bits in the next century, then '16' can
become a variable or whatever.
Thanks,
tglx
next prev parent reply other threads:[~2015-12-08 20:39 UTC|newest]
Thread overview: 145+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-04 1:14 [PATCH 00/34] x86: Memory Protection Keys (v5) Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 01/34] mm, gup: introduce concept of "foreign" get_user_pages() Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 02/34] x86, fpu: add placeholder for Processor Trace XSAVE state Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 03/34] x86, pkeys: Add Kconfig option Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 04/34] x86, pkeys: cpuid bit definition Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 05/34] x86, pkeys: define new CR4 bit Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 06/34] x86, pkeys: add PKRU xsave fields and data structure(s) Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 07/34] x86, pkeys: PTE bits for storing protection key Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 08/34] x86, pkeys: new page fault error code bit: PF_PK Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 09/34] x86, pkeys: store protection in high VMA flags Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 14:17 ` Thomas Gleixner
2015-12-08 14:17 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 10/34] x86, pkeys: arch-specific protection bits Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 15:15 ` [PATCH 10/34] x86, pkeys: arch-specific protection bitsy Thomas Gleixner
2015-12-08 15:15 ` Thomas Gleixner
2015-12-08 16:34 ` Dave Hansen
2015-12-08 16:34 ` Dave Hansen
2015-12-08 17:24 ` Thomas Gleixner
2015-12-08 17:24 ` Thomas Gleixner
2015-12-08 18:06 ` Dave Hansen
2015-12-08 18:29 ` Thomas Gleixner
2015-12-08 18:29 ` Thomas Gleixner
2015-12-08 18:35 ` Thomas Gleixner
2015-12-08 18:35 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 11/34] x86, pkeys: pass VMA down in to fault signal generation code Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 12/34] signals, pkeys: notify userspace about protection key faults Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 13/34] x86, pkeys: fill in pkey field in siginfo Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 14/34] x86, pkeys: add functions to fetch PKRU Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 15:18 ` Thomas Gleixner
2015-12-08 15:18 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 15/34] mm: factor out VMA fault permission checking Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 17:26 ` Thomas Gleixner
2015-12-08 17:26 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 16/34] x86, mm: simplify get_user_pages() PTE bit handling Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:01 ` Thomas Gleixner
2015-12-08 18:01 ` Thomas Gleixner
2015-12-08 18:30 ` Dave Hansen
2015-12-08 18:30 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 17/34] x86, pkeys: check VMAs and PTEs for protection keys Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:11 ` Thomas Gleixner
2015-12-08 18:11 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 18/34] mm: add gup flag to indicate "foreign" mm access Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 19/34] x86, pkeys: optimize fault handling in access_error() Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:14 ` Thomas Gleixner
2015-12-08 18:14 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 20/34] x86, pkeys: differentiate instruction fetches Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:17 ` Thomas Gleixner
2015-12-08 18:17 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 21/34] x86, pkeys: dump PKRU with other kernel registers Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:19 ` Thomas Gleixner
2015-12-08 18:19 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 22/34] x86, pkeys: dump PTE pkey in /proc/pid/smaps Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:20 ` Thomas Gleixner
2015-12-08 18:20 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 23/34] x86, pkeys: add Kconfig prompt to existing config option Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:21 ` Thomas Gleixner
2015-12-08 18:21 ` Thomas Gleixner
2015-12-04 1:14 ` [PATCH 24/34] mm, multi-arch: pass a protection key in to calc_vm_flag_bits() Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-04 1:14 ` [PATCH 25/34] x86, pkeys: add arch_validate_pkey() Dave Hansen
2015-12-04 1:14 ` Dave Hansen
2015-12-08 18:39 ` Thomas Gleixner
2015-12-08 18:39 ` Thomas Gleixner
2015-12-04 1:15 ` [PATCH 26/34] mm: implement new mprotect_key() system call Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-05 6:50 ` Michael Kerrisk (man-pages)
2015-12-05 6:50 ` Michael Kerrisk (man-pages)
2015-12-05 6:50 ` Michael Kerrisk (man-pages)
2015-12-07 16:44 ` Dave Hansen
2015-12-07 16:44 ` Dave Hansen
2015-12-09 11:08 ` Michael Kerrisk (man-pages)
2015-12-09 11:08 ` Michael Kerrisk (man-pages)
2015-12-09 15:48 ` Dave Hansen
2015-12-09 15:48 ` Dave Hansen
2015-12-09 16:45 ` Michael Kerrisk (man-pages)
2015-12-09 16:45 ` Michael Kerrisk (man-pages)
2015-12-09 16:45 ` Michael Kerrisk (man-pages)
2015-12-09 17:05 ` Dave Hansen
2015-12-09 17:05 ` Dave Hansen
2015-12-09 17:05 ` Dave Hansen
2015-12-11 20:13 ` Michael Kerrisk (man-pages)
2015-12-11 20:13 ` Michael Kerrisk (man-pages)
2015-12-04 1:15 ` [PATCH 27/34] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-08 18:41 ` Thomas Gleixner
2015-12-08 18:41 ` Thomas Gleixner
2015-12-04 1:15 ` [PATCH 28/34] x86: wire up mprotect_key() system call Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-08 18:44 ` Thomas Gleixner
2015-12-08 18:44 ` Thomas Gleixner
2015-12-08 18:44 ` Thomas Gleixner
2015-12-08 19:06 ` Dave Hansen
2015-12-08 19:06 ` Dave Hansen
2015-12-08 20:38 ` Thomas Gleixner [this message]
2015-12-08 20:38 ` Thomas Gleixner
2015-12-08 20:38 ` Thomas Gleixner
2015-12-04 1:15 ` [PATCH 29/34] x86: separate out LDT init from context init Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-08 18:45 ` Thomas Gleixner
2015-12-08 18:45 ` Thomas Gleixner
2015-12-04 1:15 ` [PATCH 30/34] x86, fpu: allow setting of XSAVE state Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-08 18:48 ` Thomas Gleixner
2015-12-08 18:48 ` Thomas Gleixner
2015-12-04 1:15 ` [PATCH 31/34] x86, pkeys: allocation/free syscalls Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-04 1:15 ` [PATCH 32/34] x86, pkeys: add pkey set/get syscalls Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-04 1:15 ` [PATCH 33/34] x86, pkeys: actually enable Memory Protection Keys in CPU Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-04 1:15 ` [PATCH 34/34] x86, pkeys: Documentation Dave Hansen
2015-12-04 1:15 ` Dave Hansen
2015-12-04 23:31 ` [PATCH 00/34] x86: Memory Protection Keys (v5) Andy Lutomirski
2015-12-04 23:31 ` Andy Lutomirski
2015-12-04 23:38 ` Dave Hansen
2015-12-04 23:38 ` Dave Hansen
2015-12-04 23:38 ` Dave Hansen
2015-12-11 20:16 ` Andy Lutomirski
2015-12-11 20:16 ` Andy Lutomirski
2015-12-11 20:16 ` Andy Lutomirski
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