Commit-ID: 262b6b30087246abf09d6275eb0c0dc421bcbe38
Gitweb: https://git.kernel.org/tip/262b6b30087246abf09d6275eb0c0dc421bcbe38
Author: Dave Hansen <[email protected]>
AuthorDate: Sat, 6 Jan 2018 18:41:14 +0100
Committer: Thomas Gleixner <[email protected]>
CommitDate: Mon, 8 Jan 2018 17:29:18 +0100
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 <[email protected]>
Signed-off-by: Andrea Arcangeli <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Jon Masters <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jeff Law <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: David" <[email protected]>
Cc: Nick Clifton <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/kernel/tboot.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index a4eb279..75869a4 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;
