Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 pti updates from Thomas Gleixner:
 "Two small PTI updates:

   - Handle unaligned addresses gracefully in pti_clone_pagetable(). Not
     an issue with current callers, but a correctness problem. Adds a
     warning so any caller which hands in an unaligned address gets
     pointed out clearly.

   - Prevent PTI functions from being invoked when PTI is disabled at
     boottime. While this does not cause any harm today, it's pointless
     code executed and prone to cause subtle issues if the PTI
     implementation changes internally over time"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm/pti: Do not invoke PTI functions when PTI is disabled
  x86/mm/pti: Handle unaligned address gracefully in pti_clone_pagetable()

Author: torvalds

arch/x86/mm/pti.c

@@ -330,13 +330,15 @@ pti_clone_pgtable(unsigned long start, unsigned long end,
 
 		pud = pud_offset(p4d, addr);
 		if (pud_none(*pud)) {
-			addr += PUD_SIZE;
+			WARN_ON_ONCE(addr & ~PUD_MASK);
+			addr = round_up(addr + 1, PUD_SIZE);
 			continue;
 		}
 
 		pmd = pmd_offset(pud, addr);
 		if (pmd_none(*pmd)) {
-			addr += PMD_SIZE;
+			WARN_ON_ONCE(addr & ~PMD_MASK);
+			addr = round_up(addr + 1, PMD_SIZE);
 			continue;
 		}
 
@@ -666,6 +668,8 @@ void __init pti_init(void)
  */
 void pti_finalize(void)
 {
+	if (!boot_cpu_has(X86_FEATURE_PTI))
+		return;
 	/*
 	 * We need to clone everything (again) that maps parts of the
 	 * kernel image.