x86/mm/pti: Allow NX poison to be set in p4d/pgd
authorDave Hansen <dave.hansen@linux.intel.com>
Mon, 4 Dec 2017 14:07:38 +0000 (15:07 +0100)
committerIngo Molnar <mingo@kernel.org>
Sat, 23 Dec 2017 20:13:00 +0000 (21:13 +0100)
commit1c4de1ff4fe50453b968579ee86fac3da80dd783
tree60f596c7ba981b3f77b8c083bfa6ec9018ce8878
parent61e9b3671007a5da8127955a1a3bda7e0d5f42e8
x86/mm/pti: Allow NX poison to be set in p4d/pgd

With PAGE_TABLE_ISOLATION the user portion of the kernel page tables is
poisoned with the NX bit so if the entry code exits with the kernel page
tables selected in CR3, userspace crashes.

But doing so trips the p4d/pgd_bad() checks.  Make sure it does not do
that.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/include/asm/pgtable.h