Commit-ID: 1ac228a7c87f697d1d01eb6362a6b5246705b0dd Gitweb: https://git.kernel.org/tip/1ac228a7c87f697d1d01eb6362a6b5246705b0dd Author: Joerg Roedel <jroe...@suse.de> AuthorDate: Wed, 18 Jul 2018 11:41:05 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Fri, 20 Jul 2018 01:11:45 +0200
x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text() Mapping the kernel text area to user-space makes only sense if it has the same permissions as in the kernel page-table. If permissions are different this will cause a TLB reload when using the kernel page-table, which is as good as not mapping it at all. On 64-bit kernels this patch makes no difference, as the whole range cloned by pti_clone_kernel_text() is mapped RO anyway. On 32 bit there are writeable mappings in the range, so just keep the permissions as they are. Signed-off-by: Joerg Roedel <jroe...@suse.de> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Tested-by: Pavel Machek <pa...@ucw.cz> Cc: "H . Peter Anvin" <h...@zytor.com> Cc: linux...@kvack.org Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Dave Hansen <dave.han...@intel.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Juergen Gross <jgr...@suse.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Jiri Kosina <jkos...@suse.cz> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com> Cc: Brian Gerst <brge...@gmail.com> Cc: David Laight <david.lai...@aculab.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: Eduardo Valentin <edu...@amazon.com> Cc: Greg KH <gre...@linuxfoundation.org> Cc: Will Deacon <will.dea...@arm.com> Cc: aligu...@amazon.com Cc: daniel.gr...@iaik.tugraz.at Cc: hu...@google.com Cc: keesc...@google.com Cc: Andrea Arcangeli <aarca...@redhat.com> Cc: Waiman Long <ll...@redhat.com> Cc: "David H . Gutteridge" <dhgutteri...@sympatico.ca> Cc: j...@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-29-git-send-email-j...@8bytes.org --- arch/x86/mm/pti.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 453d23760941..e41ee93c430d 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -482,7 +482,7 @@ void pti_clone_kernel_text(void) * pti_set_kernel_image_nonglobal() did to clear the * global bit. */ - pti_clone_pmds(start, end, _PAGE_RW); + pti_clone_pmds(start, end, 0); } /*
