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Subject[PATCH 4.14 095/118] x86/tboot: Unbreak tboot with PTI enabled
4.14-stable review patch.  If anyone has any objections, please let me know.


From: Dave Hansen <>

commit 262b6b30087246abf09d6275eb0c0dc421bcbe38 upstream.

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 <>
Signed-off-by: Andrea Arcangeli <>
Signed-off-by: Thomas Gleixner <>
Cc: Alan Cox <>
Cc: Tim Chen <>
Cc: Jon Masters <>
Cc: Dave Hansen <>
Cc: Andi Kleen <>
Cc: Jeff Law <>
Cc: Paolo Bonzini <>
Cc: Linus Torvalds <>
Cc: Greg Kroah-Hartman <>
Cc: David <>
Cc: Nick Clifton <>
Signed-off-by: Greg Kroah-Hartman <>

arch/x86/kernel/tboot.c | 1 +
1 file changed, 1 insertion(+)

--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -127,6 +127,7 @@ static int map_tboot_page(unsigned long
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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