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authorDave Hansen <dave.hansen@linux.intel.com>2018-01-06 18:41:14 +0100
committerThomas Gleixner <tglx@linutronix.de>2018-01-08 17:29:18 +0100
commit262b6b30087246abf09d6275eb0c0dc421bcbe38 (patch)
treeea807ff4377f68fa4c1d66f7577895503e2c4869 /arch/x86/kernel/tboot.c
parent61dc0f555b5c761cdafb0ba5bd41ecf22d68a4c4 (diff)
downloadlinux-262b6b30087246abf09d6275eb0c0dc421bcbe38.tar.bz2
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: 385ce0ea4c07 ("x86/mm/pti: Add Kconfig") Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Thomas 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
Diffstat (limited to 'arch/x86/kernel/tboot.c')
-rw-r--r--arch/x86/kernel/tboot.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index a4eb27918ceb..75869a4b6c41 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -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;