Commit 262b6b30 authored by Dave Hansen's avatar Dave Hansen Committed by Thomas Gleixner

x86/tboot: Unbreak tboot with PTI enabled

This is another case similar to what EFI does: create a new set of
page tables, map some code at a low address, and jump to it.  PTI
mistakes this low address for userspace and mistakenly marks it
non-executable in an effort to make it unusable for userspace.

Undo the poison to allow execution.

Fixes: 385ce0ea ("x86/mm/pti: Add Kconfig")
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jeff Law <law@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: David" <dwmw@amazon.co.uk>
Cc: Nick Clifton <nickc@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180108102805.GK25546@redhat.com
parent 61dc0f55
......@@ -127,6 +127,7 @@ static int map_tboot_page(unsigned long vaddr, unsigned long pfn,
p4d = p4d_alloc(&tboot_mm, pgd, vaddr);
if (!p4d)
return -1;
pgd->pgd &= ~_PAGE_NX;
pud = pud_alloc(&tboot_mm, p4d, vaddr);
if (!pud)
return -1;
......
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