x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32

CVE-2017-5754

Allow PTI to be compiled on x86_32.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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: 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: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-38-git-send-email-joro@8bytes.org
(backported from commit 7757d607c6b31867777de42e1fb0210b9c5d8b70)
[juergh: Require PAE for 32-bit PTI (from commit 61a6bd83abf2).]
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/security/Kconfig b/security/Kconfig
index 16803be979b247643f6082718b69eead34cf23fb..ffe994d38c23f4ee1dd0319da4900ec01a9c4544 100644 (file)
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -99,7 +99,7 @@ config SECURITY_NETWORK
 config PAGE_TABLE_ISOLATION
        bool "Remove the kernel mapping in user mode"
        default y
-       depends on X86_64 && !UML
+       depends on (X86_64 || X86_PAE) && !UML
        help
          This feature reduces the number of hardware side channels by
          ensuring that the majority of kernel addresses are not mapped