UBUNTU: SAUCE: Add pfn_pud() and pud_mkhuge()

Both were introduced when pud size transparent hugepage support was
added and that would be too complex and dangerous to backport. The
pfn_pud() function was extended in "x86/speculation/l1tf: Protect
PROT_NONE PTEs against speculation" but not backported then since it
was not present, yet (so no users).
For the following patch, though, we will need both.

CVE-2018-3620
CVE-2018-3646
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

arch/x86/include/asm/pgtable.h

@@ -320,6 +320,14 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd)
 	return pmd_set_flags(pmd, _PAGE_RW);
 }
 
+/* Only used by arch/x86/mm/pageattr.c: populate_pmd() */
+static inline pud_t pud_mkhuge(pud_t pud)
+{
+	pudval_t v = native_pud_val(pud);
+
+	return __pud(v | _PAGE_PSE);
+}
+
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 static inline int pte_soft_dirty(pte_t pte)
 {
@@ -383,6 +391,14 @@ static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 	return __pmd(pfn | massage_pgprot(pgprot));
 }
 
+static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t pgprot)
+{
+	phys_addr_t pfn = (phys_addr_t)page_nr << PAGE_SHIFT;
+	pfn ^= protnone_mask(pgprot_val(pgprot));
+	pfn &= PHYSICAL_PUD_PAGE_MASK;
+	return __pud(pfn | massage_pgprot(pgprot));
+}
+
 static inline pmd_t pmd_mknotpresent(pmd_t pmd)
 {
 	return pfn_pmd(pmd_pfn(pmd),