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Kirill A. Shutemov 4074ca7d8a x86/mm: Move LDT remap out of KASLR region on 5-level paging 
commit d52888aa2753e3063a9d3a0c9f72f94aa9809c15 upstream

On 5-level paging the LDT remap area is placed in the middle of the KASLR
randomization region and it can overlap with the direct mapping, the
vmalloc or the vmap area.

The LDT mapping is per mm, so it cannot be moved into the P4D page table
next to the CPU_ENTRY_AREA without complicating PGD table allocation for
5-level paging.

The 4 PGD slot gap just before the direct mapping is reserved for
hypervisors, so it cannot be used.

Move the direct mapping one slot deeper and use the resulting gap for the
LDT remap area. The resulting layout is the same for 4 and 5 level paging.

[ tglx: Massaged changelog ]

Fixes: f55f0501cb ("x86/pti: Put the LDT in its own PGD if PTI is on")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: peterz@infradead.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: bhe@redhat.com
Cc: willy@infradead.org
Cc: linux-mm@kvack.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181026122856.66224-2-kirill.shutemov@linux.intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2018-11-27 16:13:08 +01:00
..
00-INDEX
5level-paging.txt x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y 2018-02-16 10:48:49 +01:00
boot-options.txt Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-08-13 18:28:19 -07:00
cpu-hotplug-spec
fake-numa-for-cpusets Documenation: update cgroup's document path 2016-08-03 15:43:58 -06:00
machinecheck x86/Documentation: Fix various typos in Documentation/x86/ files 2016-07-01 10:00:10 +02:00
mm.txt x86/mm: Move LDT remap out of KASLR region on 5-level paging 2018-11-27 16:13:08 +01:00
uefi.txt x86 boot: only pick up additional EFI memmap if add_efi_memmap flag 2008-07-08 13:10:41 +02:00