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Commit Graph

58 Commits

Author SHA1 Message Date
Andrey Konovalov
9577dd7486 kasan: rename kasan_zero_page to kasan_early_shadow_page
With tag based KASAN mode the early shadow value is 0xff and not 0x00, so
this patch renames kasan_zero_(page|pte|pmd|pud|p4d) to
kasan_early_shadow_(page|pte|pmd|pud|p4d) to avoid confusion.

Link: http://lkml.kernel.org/r/3fed313280ebf4f88645f5b89ccbc066d320e177.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:43 -08:00
Kirill A. Shutemov
254eb5505c x86/dump_pagetables: Fix LDT remap address marker
The LDT remap placement has been changed. It's now placed before the direct
mapping in the kernel virtual address space for both paging modes.

Change address markers order accordingly.

Fixes: d52888aa27 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: peterz@infradead.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: bhe@redhat.com
Cc: hans.van.kranenburg@mendix.com
Cc: linux-mm@kvack.org
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20181130202328.65359-3-kirill.shutemov@linux.intel.com
2018-12-11 11:19:24 +01:00
Kirill A. Shutemov
16877a5570 x86/mm: Fix guard hole handling
There is a guard hole at the beginning of the kernel address space, also
used by hypervisors. It occupies 16 PGD entries.

This reserved range is not defined explicitely, it is calculated relative
to other entities: direct mapping and user space ranges.

The calculation got broken by recent changes of the kernel memory layout:
LDT remap range is now mapped before direct mapping and makes the
calculation invalid.

The breakage leads to crash on Xen dom0 boot[1].

Define the reserved range explicitely. It's part of kernel ABI (hypervisors
expect it to be stable) and must not depend on changes in the rest of
kernel memory layout.

[1] https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03313.html

Fixes: d52888aa27 ("x86/mm: Move LDT remap out of KASLR region on 5-level paging")
Reported-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: peterz@infradead.org
Cc: boris.ostrovsky@oracle.com
Cc: bhe@redhat.com
Cc: linux-mm@kvack.org
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20181130202328.65359-2-kirill.shutemov@linux.intel.com
2018-12-11 11:19:24 +01:00
Thomas Gleixner
c200dac78f x86/mm: Do not warn about PCI BIOS W+X mappings
PCI BIOS requires the BIOS area 0x0A0000-0x0FFFFFF to be mapped W+X for
various legacy reasons. When CONFIG_DEBUG_WX is enabled, this triggers the
WX warning, but this is misleading because the mapping is required and is
not a result of an accidental oversight.

Prevent the full warning when PCI BIOS is enabled and the detected WX
mapping is in the BIOS area. Just emit a pr_warn() which denotes the
fact. This is partially duplicating the info which the PCI BIOS code emits
when it maps the area as executable, but that info is not in the context of
the WX checking output.

Remove the extra %p printout in the WARN_ONCE() while at it. %pS is enough.

Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1810082151160.2455@nanos.tec.linutronix.de
2018-10-10 15:16:13 +02:00
Joerg Roedel
d878efce73 x86/mm/pti: Move user W+X check into pti_finalize()
The user page-table gets the updated kernel mappings in pti_finalize(),
which runs after the RO+X permissions got applied to the kernel page-table
in mark_readonly().

But with CONFIG_DEBUG_WX enabled, the user page-table is already checked in
mark_readonly() for insecure mappings.  This causes false-positive
warnings, because the user page-table did not get the updated mappings yet.

Move the W+X check for the user page-table into pti_finalize() after it
updated all required mappings.

[ tglx: Folded !NX supported fix ]

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1533727000-9172-1-git-send-email-joro@8bytes.org
2018-08-10 21:12:45 +02:00
Joerg Roedel
f3e48e546c x86/ldt: Reserve address-space range on 32 bit for the LDT
Reserve 2MB/4MB of address-space for mapping the LDT to user-space on 32
bit PTI kernels.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-34-git-send-email-joro@8bytes.org
2018-07-20 01:11:47 +02:00
Joerg Roedel
4e8537e4a7 x86/mm/dump_pagetables: Define INIT_PGD
Define INIT_PGD to point to the correct initial page-table for 32 and 64
bit and use it where needed. This fixes the build on 32 bit with
CONFIG_PAGE_TABLE_ISOLATION enabled.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-32-git-send-email-joro@8bytes.org
2018-07-20 01:11:46 +02:00
Kirill A. Shutemov
ed7588d5dc x86/mm: Stop pretending pgtable_l5_enabled is a variable
pgtable_l5_enabled is defined using cpu_feature_enabled() but we refer
to it as a variable. This is misleading.

Make pgtable_l5_enabled() a function.

We cannot literally define it as a function due to circular dependencies
between header files. Function-alike macros is close enough.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180518103528.59260-4-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-19 11:56:57 +02:00
Joerg Roedel
d6ef1f194b x86/mm: Prevent kernel Oops in PTDUMP code with HIGHPTE=y
The walk_pte_level() function just uses __va to get the virtual address of
the PTE page, but that breaks when the PTE page is not in the direct
mapping with HIGHPTE=y.

The result is an unhandled kernel paging request at some random address
when accessing the current_kernel or current_user file.

Use the correct API to access PTE pages.

Fixes: fe770bf031 ('x86: clean up the page table dumper and add 32-bit support')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Cc: jgross@suse.com
Cc: JBeulich@suse.com
Cc: hpa@zytor.com
Cc: aryabinin@virtuozzo.com
Cc: kirill.shutemov@linux.intel.com
Link: https://lkml.kernel.org/r/1523971636-4137-1-git-send-email-joro@8bytes.org
2018-04-17 15:43:01 +02:00
Jan Beulich
672c0ae09b x86/mm: Consider effective protection attributes in W+X check
Using just the leaf page table entry flags would cause a false warning
in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry.
Hand through both the current entry's flags as well as the accumulated
effective value (the latter as pgprotval_t instead of pgprot_t, as it's
not an actual entry's value).

This in particular eliminates the false W+X warning when running under
Xen, as commit:

  2cc42bac1c ("x86-64/Xen: eliminate W+X mappings")

had to make the necessary adjustment in L2 rather than L1 (the reason is
explained there). I.e. _PAGE_RW is clear there in L1, but _PAGE_NX is
set in L2.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5A8FDE8902000078001AABBB@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-26 08:43:21 +01:00
Kirill A. Shutemov
91f606a8fa x86/mm: Replace compile-time checks for 5-level paging with runtime-time checks
This patch converts the of CONFIG_X86_5LEVEL check to runtime checks for
p4d folding.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214182542.69302-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-16 10:48:49 +01:00
Kirill A. Shutemov
09e61a779e x86/mm: Make __VIRTUAL_MASK_SHIFT dynamic
For boot-time switching between paging modes, we need to be able to
adjust virtual mask shifts.

The change doesn't affect the kernel image size much:

   text	   data	    bss	    dec	    hex	filename
8628892	4734340	1368064	14731296	 e0c820	vmlinux.before
8628966	4734340	1368064	14731370	 e0c86a	vmlinux.after

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214111656.88514-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-14 13:11:15 +01:00
Kirill A. Shutemov
c65e774fb3 x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable
For boot-time switching between 4- and 5-level paging we need to be able
to fold p4d page table level at runtime. It requires variable
PGDIR_SHIFT and PTRS_PER_P4D.

The change doesn't affect the kernel image size much:

   text	   data	    bss	    dec	    hex	filename
8628091	4734304	1368064	14730459	 e0c4db	vmlinux.before
8628393	4734340	1368064	14730797	 e0c62d	vmlinux.after

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214111656.88514-7-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-14 13:11:14 +01:00
Kirill A. Shutemov
5c7919bb19 x86/mm: Make LDT_BASE_ADDR dynamic
LDT_BASE_ADDR has different value in 4- and 5-level paging
configurations.

We need to make it dynamic in preparation for boot-time switching
between paging modes.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214111656.88514-6-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-14 13:11:14 +01:00
Thomas Gleixner
f207890481 x86/mm: Map cpu_entry_area at the same place on 4/5 level
There is no reason for 4 and 5 level pagetables to have a different
layout. It just makes determining vaddr_end for KASLR harder than
necessary.

Fixes: 92a0f81d89 ("x86/cpu_entry_area: Move it out of the fixmap")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Gilbert <benjamin.gilbert@coreos.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Garnier <thgarnie@google.com>,
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801041320360.1771@nanos
2018-01-04 23:04:57 +01:00
Thomas Gleixner
a4b51ef655 x86/mm/dump_pagetables: Allow dumping current pagetables
Add two debugfs files which allow to dump the pagetable of the current
task.

current_kernel dumps the regular page table. This is the page table which
is normally shared between kernel and user space. If kernel page table
isolation is enabled this is the kernel space mapping.

If kernel page table isolation is enabled the second file, current_user,
dumps the user space page table.

These files allow to verify the resulting page tables for page table
isolation, but even in the normal case its useful to be able to inspect
user space page tables of current for debugging purposes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23 21:13:01 +01:00
Thomas Gleixner
b4bf4f924b x86/mm/dump_pagetables: Check user space page table for WX pages
ptdump_walk_pgd_level_checkwx() checks the kernel page table for WX pages,
but does not check the PAGE_TABLE_ISOLATION user space page table.

Restructure the code so that dmesg output is selected by an explicit
argument and not implicit via checking the pgd argument for !NULL.

Add the check for the user space page table.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23 21:13:01 +01:00
Andy Lutomirski
f55f0501cb x86/pti: Put the LDT in its own PGD if PTI is on
With PTI enabled, the LDT must be mapped in the usermode tables somewhere.
The LDT is per process, i.e. per mm.

An earlier approach mapped the LDT on context switch into a fixmap area,
but that's a big overhead and exhausted the fixmap space when NR_CPUS got
big.

Take advantage of the fact that there is an address space hole which
provides a completely unused pgd. Use this pgd to manage per-mm LDT
mappings.

This has a down side: the LDT isn't (currently) randomized, and an attack
that can write the LDT is instant root due to call gates (thanks, AMD, for
leaving call gates in AMD64 but designing them wrong so they're only useful
for exploits).  This can be mitigated by making the LDT read-only or
randomizing the mapping, either of which is strightforward on top of this
patch.

This will significantly slow down LDT users, but that shouldn't matter for
important workloads -- the LDT is only used by DOSEMU(2), Wine, and very
old libc implementations.

[ tglx: Cleaned it up. ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-23 21:13:00 +01:00
Thomas Gleixner
92a0f81d89 x86/cpu_entry_area: Move it out of the fixmap
Put the cpu_entry_area into a separate P4D entry. The fixmap gets too big
and 0-day already hit a case where the fixmap PTEs were cleared by
cleanup_highmap().

Aside of that the fixmap API is a pain as it's all backwards.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-22 20:13:05 +01:00
Thomas Gleixner
146122e24b x86/mm/dump_pagetables: Make the address hints correct and readable
The address hints are a trainwreck. The array entry numbers have to kept
magically in sync with the actual hints, which is doomed as some of the
array members are initialized at runtime via the entry numbers.

Designated initializers have been around before this code was
implemented....

Use the entry numbers to populate the address hints array and add the
missing bits and pieces. Split 32 and 64 bit for readability sake.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-22 20:13:00 +01:00
Thomas Gleixner
c05344947b x86/mm/dump_pagetables: Check PAGE_PRESENT for real
The check for a present page in printk_prot():

       if (!pgprot_val(prot)) {
                /* Not present */

is bogus. If a PTE is set to PAGE_NONE then the pgprot_val is not zero and
the entry is decoded in bogus ways, e.g. as RX GLB. That is confusing when
analyzing mapping correctness. Check for the present bit to make an
informed decision.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-22 20:13:00 +01:00
Andrey Ryabinin
04b67022fb x86/mm/dump_pagetables: Speed up page tables dump for CONFIG_KASAN=y
KASAN fills kernel page tables with repeated values to map several
TBs of the virtual memory to the single kasan_zero_page:
  kasan_zero_p4d ->
    kasan_zero_pud ->
        kasan_zero_pmd->
            kasan_zero_pte->
                kasan_zero_page

Walking the whole KASAN shadow range takes a lot of time, especially
with 5-level page tables. Since we already know that all kasan page tables
eventually point to the kasan_zero_page we could call note_page()
right and avoid walking lower levels of the page tables.
This will not affect the output of the kernel_page_tables file,
but let us avoid spending time in page table walkers:

Before:

  $ time cat /sys/kernel/debug/kernel_page_tables > /dev/null

  real    0m55.855s
  user    0m0.000s
  sys     0m55.840s

After:

  $ time cat /sys/kernel/debug/kernel_page_tables > /dev/null

  real    0m0.054s
  user    0m0.000s
  sys     0m0.054s

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170724152558.24689-1-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-25 11:22:09 +02:00
Kirill A. Shutemov
45dcd20913 x86/mm/dump_pagetables: Fix printout of p4d level
Modify printk_prot() and callers to print out additional page table
level correctly.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170716225954.74185-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-21 10:05:17 +02:00
Kirill A. Shutemov
3a366f791d x86/mm/dump_pagetables: Generalize address normalization
Modify normalize_addr to handle different sizes of virtual address
space.

It's preparation for enabling 5-level paging.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170716225954.74185-2-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-21 10:05:17 +02:00
Kirill A. Shutemov
65ade2f872 x86/boot/64: Rename init_level4_pgt and early_level4_pgt
With CONFIG_X86_5LEVEL=y, level 4 is no longer top level of page tables.

Let's give these variable more generic names: init_top_pgt and
early_top_pgt.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170606113133.22974-9-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-13 08:56:55 +02:00
Juergen Gross
84bbabc3a4 x86/mm: Fix dump pagetables for 4 levels of page tables
Commit fdd3d8ce0e ("x86/dump_pagetables: Add support for 5-level
paging") introduced an error for dumping with only 4 levels by setting
PGD_LEVEL_MULT to a wrong value.

This is leading to e.g. addresses printed as "(null)" for ranges:

  x86/mm: Found insecure W+X mapping at address (null)/(null)

Make PGD_LEVEL_MULT a multiple of PTRS_PER_P4D instead of PTRS_PER_PUD

Fixes: fdd3d8ce0e ("x86/dump_pagetables: Add support for 5-level paging")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20170412143634.6846-1-jgross@suse.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-13 00:26:30 +02:00
Kirill A. Shutemov
fdd3d8ce0e x86/dump_pagetables: Add support for 5-level paging
Simple extension to support one more page table level.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170328104806.41711-1-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-30 08:20:17 +02:00
Thomas Garnier
f991376e44 x86/mm: Correct fixmap header usage on adaptable MODULES_END
This patch removes fixmap header usage on non-x86 code that was
introduced by the adaptable MODULE_END change.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170317175034.4701-1-thgarnie@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-18 09:48:00 +01:00
Thomas Garnier
f06bdd4001 x86/mm: Adapt MODULES_END based on fixmap section size
This patch aligns MODULES_END to the beginning of the fixmap section.
It optimizes the space available for both sections. The address is
pre-computed based on the number of pages required by the fixmap
section.

It will allow GDT remapping in the fixmap section. The current
MODULES_END static address does not provide enough space for the kernel
to support a large number of processors.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Luis R . Rodriguez <mcgrof@kernel.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kasan-dev@googlegroups.com
Cc: kernel-hardening@lists.openwall.com
Cc: kvm@vger.kernel.org
Cc: lguest@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-pm@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Cc: zijun_hu <zijun_hu@htc.com>
Link: http://lkml.kernel.org/r/20170314170508.100882-1-thgarnie@google.com
[ Small build fix. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16 09:06:24 +01:00
Andrey Ryabinin
025205f8f3 x86/mm/ptdump: Add address marker for KASAN shadow region
Annotate the KASAN shadow with address markers in page table
dump output:

$ cat /sys/kernel/debug/kernel_page_tables
...

---[ Vmemmap ]---
0xffffea0000000000-0xffffea0003000000          48M     RW         PSE     GLB NX pmd
0xffffea0003000000-0xffffea0004000000          16M                               pmd
0xffffea0004000000-0xffffea0005000000          16M     RW         PSE     GLB NX pmd
0xffffea0005000000-0xffffea0040000000         944M                               pmd
0xffffea0040000000-0xffffea8000000000         511G                               pud
0xffffea8000000000-0xffffec0000000000        1536G                               pgd
---[ KASAN shadow ]---
0xffffec0000000000-0xffffed0000000000           1T     ro                 GLB NX pte
0xffffed0000000000-0xffffed0018000000         384M     RW         PSE     GLB NX pmd
0xffffed0018000000-0xffffed0020000000         128M                               pmd
0xffffed0020000000-0xffffed0028200000         130M     RW         PSE     GLB NX pmd
0xffffed0028200000-0xffffed0040000000         382M                               pmd
0xffffed0040000000-0xffffed8000000000         511G                               pud
0xffffed8000000000-0xfffff50000000000        7680G                               pgd
0xfffff50000000000-0xfffffbfff0000000     7339776M     ro                 GLB NX pte
0xfffffbfff0000000-0xfffffbfff0200000           2M                               pmd
0xfffffbfff0200000-0xfffffbfff0a00000           8M     RW         PSE     GLB NX pmd
0xfffffbfff0a00000-0xfffffbffffe00000         244M                               pmd
0xfffffbffffe00000-0xfffffc0000000000           2M     ro                 GLB NX pte
---[ KASAN shadow end ]---
0xfffffc0000000000-0xffffff0000000000           3T                               pgd
---[ ESPfix Area ]---
...

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Link: http://lkml.kernel.org/r/20170214100839.17186-2-aryabinin@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-02-16 19:53:25 +01:00
Andrey Ryabinin
243b72aae2 x86/mm/ptdump: Optimize check for W+X mappings for CONFIG_KASAN=y
Enabling both DEBUG_WX=y and KASAN=y options significantly increases
boot time (dozens of seconds at least).
KASAN fills kernel page tables with repeated values to map several
TBs of the virtual memory to the single kasan_zero_page:

    kasan_zero_pud ->
        kasan_zero_pmd->
            kasan_zero_pte->
                kasan_zero_page

So, the page table walker used to find W+X mapping check the same
kasan_zero_p?d page table entries a lot more than once.
With patch pud walker will skip the pud if it has the same value as
the previous one . Skipping done iff we search for W+X mappings,
so this optimization won't affect the page table dump via debugfs.

This dropped time spend in W+X check from ~30 sec to reasonable 0.1 sec:

Before:
[    4.579991] Freeing unused kernel memory: 1000K
[   35.257523] x86/mm: Checked W+X mappings: passed, no W+X pages found.

After:
[    5.138756] Freeing unused kernel memory: 1000K
[    5.266496] x86/mm: Checked W+X mappings: passed, no W+X pages found.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kasan-dev@googlegroups.com
Cc: Tobias Regnery <tobias.regnery@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Link: http://lkml.kernel.org/r/20170214100839.17186-1-aryabinin@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-02-16 19:53:25 +01:00
Andrey Ryabinin
146fbb7669 x86/mm/ptdump: Fix soft lockup in page table walker
CONFIG_KASAN=y needs a lot of virtual memory mapped for its shadow.
In that case ptdump_walk_pgd_level_core() takes a lot of time to
walk across all page tables and doing this without
a rescheduling causes soft lockups:

 NMI watchdog: BUG: soft lockup - CPU#3 stuck for 23s! [swapper/0:1]
 ...
 Call Trace:
  ptdump_walk_pgd_level_core+0x40c/0x550
  ptdump_walk_pgd_level_checkwx+0x17/0x20
  mark_rodata_ro+0x13b/0x150
  kernel_init+0x2f/0x120
  ret_from_fork+0x2c/0x40

I guess that this issue might arise even without KASAN on huge machines
with several terabytes of RAM.

Stick cond_resched() in pgd loop to fix this.

Reported-by: Tobias Regnery <tobias.regnery@gmail.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Alexander Potapenko <glider@google.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170210095405.31802-1-aryabinin@virtuozzo.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-02-10 11:00:23 +01:00
Linus Torvalds
aeb35d6b74 Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 header cleanups from Ingo Molnar:
 "This tree is a cleanup of the x86 tree reducing spurious uses of
  module.h - which should improve build performance a bit"

* 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, crypto: Restore MODULE_LICENSE() to glue_helper.c so it loads
  x86/apic: Remove duplicated include from probe_64.c
  x86/ce4100: Remove duplicated include from ce4100.c
  x86/headers: Include spinlock_types.h in x8664_ksyms_64.c for missing spinlock_t
  x86/platform: Delete extraneous MODULE_* tags fromm ts5500
  x86: Audit and remove any remaining unnecessary uses of module.h
  x86/kvm: Audit and remove any unnecessary uses of module.h
  x86/xen: Audit and remove any unnecessary uses of module.h
  x86/platform: Audit and remove any unnecessary uses of module.h
  x86/lib: Audit and remove any unnecessary uses of module.h
  x86/kernel: Audit and remove any unnecessary uses of module.h
  x86/mm: Audit and remove any unnecessary uses of module.h
  x86: Don't use module.h just for AUTHOR / LICENSE tags
2016-08-01 14:23:42 -04:00
Paul Gortmaker
84e629b668 x86: Don't use module.h just for AUTHOR / LICENSE tags
The Kconfig controlling compilation of these files are:

 arch/x86/Kconfig.debug:config DEBUG_RODATA_TEST
 arch/x86/Kconfig.debug: bool "Testcase for the marking rodata read-only"

 arch/x86/Kconfig.debug:config X86_PTDUMP_CORE
 arch/x86/Kconfig.debug: def_bool n

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.

We delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-2-paul.gortmaker@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14 13:04:20 +02:00
Thomas Garnier
0483e1fa6e x86/mm: Implement ASLR for kernel memory regions
Randomizes the virtual address space of kernel memory regions for
x86_64. This first patch adds the infrastructure and does not randomize
any region. The following patches will randomize the physical memory
mapping, vmalloc and vmemmap regions.

This security feature mitigates exploits relying on predictable kernel
addresses. These addresses can be used to disclose the kernel modules
base addresses or corrupt specific structures to elevate privileges
bypassing the current implementation of KASLR. This feature can be
enabled with the CONFIG_RANDOMIZE_MEMORY option.

The order of each memory region is not changed. The feature looks at the
available space for the regions based on different configuration options
and randomizes the base and space between each. The size of the physical
memory mapping is the available physical memory. No performance impact
was detected while testing the feature.

Entropy is generated using the KASLR early boot functions now shared in
the lib directory (originally written by Kees Cook). Randomization is
done on PGD & PUD page table levels to increase possible addresses. The
physical memory mapping code was adapted to support PUD level virtual
addresses. This implementation on the best configuration provides 30,000
possible virtual addresses in average for each memory region.  An
additional low memory page is used to ensure each CPU can start with a
PGD aligned virtual address (for realmode).

x86/dump_pagetable was updated to correctly display each region.

Updated documentation on x86_64 memory layout accordingly.

Performance data, after all patches in the series:

Kernbench shows almost no difference (-+ less than 1%):

Before:

Average Optimal load -j 12 Run (std deviation): Elapsed Time 102.63 (1.2695)
User Time 1034.89 (1.18115) System Time 87.056 (0.456416) Percent CPU 1092.9
(13.892) Context Switches 199805 (3455.33) Sleeps 97907.8 (900.636)

After:

Average Optimal load -j 12 Run (std deviation): Elapsed Time 102.489 (1.10636)
User Time 1034.86 (1.36053) System Time 87.764 (0.49345) Percent CPU 1095
(12.7715) Context Switches 199036 (4298.1) Sleeps 97681.6 (1031.11)

Hackbench shows 0% difference on average (hackbench 90 repeated 10 times):

attemp,before,after 1,0.076,0.069 2,0.072,0.069 3,0.066,0.066 4,0.066,0.068
5,0.066,0.067 6,0.066,0.069 7,0.067,0.066 8,0.063,0.067 9,0.067,0.065
10,0.068,0.071 average,0.0677,0.0677

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1466556426-32664-6-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-08 17:33:46 +02:00
Borislav Petkov
b176862fca x86/mm/ptdump: Remove paravirt_enabled()
is_hypervisor_range() can simply check if the PGD index is
within ffff800000000000 - ffff87ffffffffff which is the range
reserved for a hypervisor. That range is practically an ABI, see
Documentation/x86/x86_64/mm.txt.

Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Under Xen, as PV guest
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1455825641-19585-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-20 12:25:45 +01:00
Linus Torvalds
0ffedcda63 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar:
 "The main changes in this cycle were:

   - make the debugfs 'kernel_page_tables' file read-only, as it only
     has read ops.  (Borislav Petkov)

   - micro-optimize clflush_cache_range() (Chris Wilson)

   - swiotlb enhancements, which fixes certain KVM emulated devices
     (Igor Mammedov)

   - fix an LDT related debug message (Jan Beulich)

   - modularize CONFIG_X86_PTDUMP (Kees Cook)

   - tone down an overly alarming warning (Laura Abbott)

   - Mark variable __initdata (Rasmus Villemoes)

   - PAT additions (Toshi Kani)"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm: Micro-optimise clflush_cache_range()
  x86/mm/pat: Change free_memtype() to support shrinking case
  x86/mm/pat: Add untrack_pfn_moved for mremap
  x86/mm: Drop WARN from multi-BAR check
  x86/LDT: Print the real LDT base address
  x86/mm/64: Enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN
  x86/mm: Introduce max_possible_pfn
  x86/mm/ptdump: Make (debugfs)/kernel_page_tables read-only
  x86/mm/mtrr: Mark the 'range_new' static variable in mtrr_calc_range_state() as __initdata
  x86/mm: Turn CONFIG_X86_PTDUMP into a module
2016-01-11 17:16:01 -08:00
Linus Torvalds
173ae9ba63 Fix user-visible spelling error
Pavel Machek reports a warning about W+X pages found in the "Persisent"
kmap area.  After grepping for it (using the correct spelling), and not
finding it, I noticed how the debug printk was just misspelled.  Fix it.

The actual mapping bug that Pavel reported is still open.  It's
apparently a separate issue from the known EFI page tables, looks like
it's related to the HIGHMEM mappings.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-15 10:15:57 -08:00
Kees Cook
8609d1b5da x86/mm: Turn CONFIG_X86_PTDUMP into a module
Being able to examine page tables is handy, so make this a
module that can be loaded as needed.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20151120010755.GA9060@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23 10:50:13 +01:00
Boris Ostrovsky
f4e342c877 x86/mm: Skip the hypervisor range when walking PGD
The range between 0xffff800000000000 and 0xffff87ffffffffff is reserved
for hypervisor and therefore we should not try to follow PGD's indexes
corresponding to those addresses.

While this has always been a problem, with the new W+X warning
mechanism ptdump_walk_pgd_level_core() can now be called during boot,
causing a PV Xen guest to crash.

[ tglx: Replaced the macro with a readable inline ]

Fixes: e1a58320a3 "x86/mm: Warn on W^X mappings"
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel@lists.xen.org
Link: http://lkml.kernel.org/r/1446749795-27764-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-11-07 10:39:39 +01:00
Stephen Smalley
e1a58320a3 x86/mm: Warn on W^X mappings
Warn on any residual W+X mappings after setting NX
if DEBUG_WX is enabled.  Introduce a separate
X86_PTDUMP_CORE config that enables the code for
dumping the page tables without enabling the debugfs
interface, so that DEBUG_WX can be enabled without
exposing the debugfs interface.  Switch EFI_PGT_DUMP
to using X86_PTDUMP_CORE so that it also does not require
enabling the debugfs interface.

On success it prints this to the kernel log:

  x86/mm: Checked W+X mappings: passed, no W+X pages found.

On failure it prints a warning and a count of the failed pages:

  ------------[ cut here ]------------
  WARNING: CPU: 1 PID: 1 at arch/x86/mm/dump_pagetables.c:226 note_page+0x610/0x7b0()
  x86/mm: Found insecure W+X mapping at address ffffffff81755000/__stop___ex_table+0xfa8/0xabfa8
  [...]
  Call Trace:
   [<ffffffff81380a5f>] dump_stack+0x44/0x55
   [<ffffffff8109d3f2>] warn_slowpath_common+0x82/0xc0
   [<ffffffff8109d48c>] warn_slowpath_fmt+0x5c/0x80
   [<ffffffff8106cfc9>] ? note_page+0x5c9/0x7b0
   [<ffffffff8106d010>] note_page+0x610/0x7b0
   [<ffffffff8106d409>] ptdump_walk_pgd_level_core+0x259/0x3c0
   [<ffffffff8106d5a7>] ptdump_walk_pgd_level_checkwx+0x17/0x20
   [<ffffffff81063905>] mark_rodata_ro+0xf5/0x100
   [<ffffffff817415a0>] ? rest_init+0x80/0x80
   [<ffffffff817415bd>] kernel_init+0x1d/0xe0
   [<ffffffff8174cd1f>] ret_from_fork+0x3f/0x70
   [<ffffffff817415a0>] ? rest_init+0x80/0x80
  ---[ end trace a1f23a1e42a2ac76 ]---
  x86/mm: Checked W+X mappings: FAILED, 171 W+X pages found.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1444064120-11450-1-git-send-email-sds@tycho.nsa.gov
[ Improved the Kconfig help text and made the new option default-y
  if CONFIG_DEBUG_RODATA=y, because it already found buggy mappings,
  so we really want people to have this on by default. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-10-06 11:11:48 +02:00
Toshi Kani
da25e628c4 x86/mm: Fix page table dump to show PAT bit
/sys/kernel/debug/kernel_page_tables does not show the PAT bit for
PUD/PMD mappings.  This is because walk_pud_level(), walk_pmd_level()
and note_page() mask the flags with PTE_FLAGS_MASK, which does not
cover their PAT bit, _PAGE_PAT_LARGE.

Fix it by replacing the use of PTE_FLAGS_MASK with p?d_flags(),
which masks the flags properly.

Also change to show the PAT bit as "PAT" to be consistent with
other bits.

Reported-by: Robert Elliott <elliott@hpe.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Robert Elliot <elliott@hpe.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1442514264-12475-7-git-send-email-toshi.kani@hpe.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-22 21:27:32 +02:00
Linus Torvalds
a023748d53 Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm tree changes from Ingo Molnar:
 "The biggest change is full PAT support from Jürgen Gross:

     The x86 architecture offers via the PAT (Page Attribute Table) a
     way to specify different caching modes in page table entries.  The
     PAT MSR contains 8 entries each specifying one of 6 possible cache
     modes.  A pte references one of those entries via 3 bits:
     _PAGE_PAT, _PAGE_PWT and _PAGE_PCD.

     The Linux kernel currently supports only 4 different cache modes.
     The PAT MSR is set up in a way that the setting of _PAGE_PAT in a
     pte doesn't matter: the top 4 entries in the PAT MSR are the same
     as the 4 lower entries.

     This results in the kernel not supporting e.g. write-through mode.
     Especially this cache mode would speed up drivers of video cards
     which now have to use uncached accesses.

     OTOH some old processors (Pentium) don't support PAT correctly and
     the Xen hypervisor has been using a different PAT MSR configuration
     for some time now and can't change that as this setting is part of
     the ABI.

     This patch set abstracts the cache mode from the pte and introduces
     tables to translate between cache mode and pte bits (the default
     cache mode "write back" is hard-wired to PAT entry 0).  The tables
     are statically initialized with values being compatible to old
     processors and current usage.  As soon as the PAT MSR is changed
     (or - in case of Xen - is read at boot time) the tables are changed
     accordingly.  Requests of mappings with special cache modes are
     always possible now, in case they are not supported there will be a
     fallback to a compatible but slower mode.

     Summing it up, this patch set adds the following features:

      - capability to support WT and WP cache modes on processors with
        full PAT support

      - processors with no or uncorrect PAT support are still working as
        today, even if WT or WP cache mode are selected by drivers for
        some pages

      - reduction of Xen special handling regarding cache mode

  Another change is a boot speedup on ridiculously large RAM systems,
  plus other smaller fixes"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  x86: mm: Move PAT only functions to mm/pat.c
  xen: Support Xen pv-domains using PAT
  x86: Enable PAT to use cache mode translation tables
  x86: Respect PAT bit when copying pte values between large and normal pages
  x86: Support PAT bit in pagetable dump for lower levels
  x86: Clean up pgtable_types.h
  x86: Use new cache mode type in memtype related functions
  x86: Use new cache mode type in mm/ioremap.c
  x86: Use new cache mode type in setting page attributes
  x86: Remove looking for setting of _PAGE_PAT_LARGE in pageattr.c
  x86: Use new cache mode type in track_pfn_remap() and track_pfn_insert()
  x86: Use new cache mode type in mm/iomap_32.c
  x86: Use new cache mode type in asm/pgtable.h
  x86: Use new cache mode type in arch/x86/mm/init_64.c
  x86: Use new cache mode type in arch/x86/pci
  x86: Use new cache mode type in drivers/video/fbdev/vermilion
  x86: Use new cache mode type in drivers/video/fbdev/gbefb.c
  x86: Use new cache mode type in include/asm/fb.h
  x86: Make page cache mode a real type
  x86: mm: Use 2GB memory block size on large-memory x86-64 systems
  ...
2014-12-10 13:59:34 -08:00
Juergen Gross
f439c429c3 x86: Support PAT bit in pagetable dump for lower levels
Dumping page table protection bits is not correct for entries on levels
2 and 3 regarding the PAT bit, which is at a different position as on
level 4.

Based-on-patch-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stefan.bader@canonical.com
Cc: xen-devel@lists.xensource.com
Cc: konrad.wilk@oracle.com
Cc: ville.syrjala@linux.intel.com
Cc: david.vrabel@citrix.com
Cc: jbeulich@suse.com
Cc: toshi.kani@hp.com
Cc: plagnioj@jcrosoft.com
Cc: tomi.valkeinen@ti.com
Cc: bhelgaas@google.com
Link: http://lkml.kernel.org/r/1415019724-4317-16-git-send-email-jgross@suse.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-11-16 11:04:26 +01:00
Mathias Krause
8266e31ed0 x86, ptdump: Add section for EFI runtime services
In commit 3891a04aaf ("x86-64, espfix: Don't leak bits 31:16 of %esp
returning..") the "ESPFix Area" was added to the page table dump special
sections. That area, though, has a limited amount of entries printed.

The EFI runtime services are, unfortunately, located in-between the
espfix area and the high kernel memory mapping. Due to the enforced
limitation for the espfix area, the EFI mappings won't be printed in the
page table dump.

To make the ESP runtime service mappings visible again, provide them a
dedicated entry.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
2014-11-11 22:28:57 +00:00
Mathias Krause
8a5a5d1530 x86-64, ptdump: Mark espfix area only if existent
We should classify the espfix area as such only if we actually have
enabled the corresponding option. Otherwise the page table dump might
look confusing.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Link: http://lkml.kernel.org/r/1410114629-24523-1-git-send-email-minipli@googlemail.com
Cc: Arjan van de Ven <arjan.van.de.ven@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2014-09-08 11:57:34 -07:00
H. Peter Anvin
3891a04aaf x86-64, espfix: Don't leak bits 31:16 of %esp returning to 16-bit stack
The IRET instruction, when returning to a 16-bit segment, only
restores the bottom 16 bits of the user space stack pointer.  This
causes some 16-bit software to break, but it also leaks kernel state
to user space.  We have a software workaround for that ("espfix") for
the 32-bit kernel, but it relies on a nonzero stack segment base which
is not available in 64-bit mode.

In checkin:

    b3b42ac2cb x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

we "solved" this by forbidding 16-bit segments on 64-bit kernels, with
the logic that 16-bit support is crippled on 64-bit kernels anyway (no
V86 support), but it turns out that people are doing stuff like
running old Win16 binaries under Wine and expect it to work.

This works around this by creating percpu "ministacks", each of which
is mapped 2^16 times 64K apart.  When we detect that the return SS is
on the LDT, we copy the IRET frame to the ministack and use the
relevant alias to return to userspace.  The ministacks are mapped
readonly, so if IRET faults we promote #GP to #DF which is an IST
vector and thus has its own stack; we then do the fixup in the #DF
handler.

(Making #GP an IST exception would make the msr_safe functions unsafe
in NMI/MC context, and quite possibly have other effects.)

Special thanks to:

- Andy Lutomirski, for the suggestion of using very small stack slots
  and copy (as opposed to map) the IRET frame there, and for the
  suggestion to mark them readonly and let the fault promote to #DF.
- Konrad Wilk for paravirt fixup and testing.
- Borislav Petkov for testing help and useful comments.

Reported-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Lutomriski <amluto@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dirk Hohndel <dirk@hohndel.org>
Cc: Arjan van de Ven <arjan.van.de.ven@intel.com>
Cc: comex <comexk@gmail.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: <stable@vger.kernel.org> # consider after upstream merge
2014-04-30 14:14:28 -07:00
Borislav Petkov
ef6bea6ddf x86, ptdump: Add the functionality to dump an arbitrary pagetable
With reusing the ->trampoline_pgd page table for mapping EFI regions in
order to use them after having switched to EFI virtual mode, it is very
useful to be able to dump aforementioned page table in dmesg. This adds
that functionality through the walk_pgd_level() interface which can be
called from somewhere else.

The original functionality of dumping to debugfs remains untouched.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
2014-03-04 16:16:17 +00:00
Andres Salomon
92851e2fca x86, mm: Create symbolic index into address_markers array
Without this, adding entries into the address_markers array means adding
more and more of an #ifdef maze in pt_dump_init().  By using indices, we
can keep it a bit saner.

Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <201007202219.o6KMJkUs021052@imap1.linux-foundation.org>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-07-20 16:56:19 -07:00
Yinghai Lu
6424fb3866 x86: remove (null) in /sys kernel_page_tables
Impact: cleanup

%p prints out 0x000000000000000 as (null)
so use %lx instead.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49E43282.1090607@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-14 11:50:22 +02:00