Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 878 insertions, 0 deletions

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
new file mode 100644
index 000000000..8525f2876
--- /dev/null
+++ b/arch/x86/mm/pgtable.c
@@ -0,0 +1,878 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/hugetlb.h>
+#include <asm/pgalloc.h>
+#include <asm/tlb.h>
+#include <asm/fixmap.h>
+#include <asm/mtrr.h>
+
+#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
+phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
+EXPORT_SYMBOL(physical_mask);
+#endif
+
+#ifdef CONFIG_HIGHPTE
+#define PGTABLE_HIGHMEM __GFP_HIGHMEM
+#else
+#define PGTABLE_HIGHMEM 0
+#endif
+
+#ifndef CONFIG_PARAVIRT
+static inline
+void paravirt_tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+	tlb_remove_page(tlb, table);
+}
+#endif
+
+gfp_t __userpte_alloc_gfp = GFP_PGTABLE_USER | PGTABLE_HIGHMEM;
+
+pgtable_t pte_alloc_one(struct mm_struct *mm)
+{
+	return __pte_alloc_one(mm, __userpte_alloc_gfp);
+}
+
+static int __init setup_userpte(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	/*
+	 * "userpte=nohigh" disables allocation of user pagetables in
+	 * high memory.
+	 */
+	if (strcmp(arg, "nohigh") == 0)
+		__userpte_alloc_gfp &= ~__GFP_HIGHMEM;
+	else
+		return -EINVAL;
+	return 0;
+}
+early_param("userpte", setup_userpte);
+
+void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
+{
+	pgtable_pte_page_dtor(pte);
+	paravirt_release_pte(page_to_pfn(pte));
+	paravirt_tlb_remove_table(tlb, pte);
+}
+
+#if CONFIG_PGTABLE_LEVELS > 2
+void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
+{
+	struct page *page = virt_to_page(pmd);
+	paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
+	/*
+	 * NOTE! For PAE, any changes to the top page-directory-pointer-table
+	 * entries need a full cr3 reload to flush.
+	 */
+#ifdef CONFIG_X86_PAE
+	tlb->need_flush_all = 1;
+#endif
+	pgtable_pmd_page_dtor(page);
+	paravirt_tlb_remove_table(tlb, page);
+}
+
+#if CONFIG_PGTABLE_LEVELS > 3
+void ___pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
+{
+	paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
+	paravirt_tlb_remove_table(tlb, virt_to_page(pud));
+}
+
+#if CONFIG_PGTABLE_LEVELS > 4
+void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d)
+{
+	paravirt_release_p4d(__pa(p4d) >> PAGE_SHIFT);
+	paravirt_tlb_remove_table(tlb, virt_to_page(p4d));
+}
+#endif	/* CONFIG_PGTABLE_LEVELS > 4 */
+#endif	/* CONFIG_PGTABLE_LEVELS > 3 */
+#endif	/* CONFIG_PGTABLE_LEVELS > 2 */
+
+static inline void pgd_list_add(pgd_t *pgd)
+{
+	struct page *page = virt_to_page(pgd);
+
+	list_add(&page->lru, &pgd_list);
+}
+
+static inline void pgd_list_del(pgd_t *pgd)
+{
+	struct page *page = virt_to_page(pgd);
+
+	list_del(&page->lru);
+}
+
+#define UNSHARED_PTRS_PER_PGD				\
+	(SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
+#define MAX_UNSHARED_PTRS_PER_PGD			\
+	max_t(size_t, KERNEL_PGD_BOUNDARY, PTRS_PER_PGD)
+
+
+static void pgd_set_mm(pgd_t *pgd, struct mm_struct *mm)
+{
+	virt_to_page(pgd)->pt_mm = mm;
+}
+
+struct mm_struct *pgd_page_get_mm(struct page *page)
+{
+	return page->pt_mm;
+}
+
+static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)
+{
+	/* If the pgd points to a shared pagetable level (either the
+	   ptes in non-PAE, or shared PMD in PAE), then just copy the
+	   references from swapper_pg_dir. */
+	if (CONFIG_PGTABLE_LEVELS == 2 ||
+	    (CONFIG_PGTABLE_LEVELS == 3 && SHARED_KERNEL_PMD) ||
+	    CONFIG_PGTABLE_LEVELS >= 4) {
+		clone_pgd_range(pgd + KERNEL_PGD_BOUNDARY,
+				swapper_pg_dir + KERNEL_PGD_BOUNDARY,
+				KERNEL_PGD_PTRS);
+	}
+
+	/* list required to sync kernel mapping updates */
+	if (!SHARED_KERNEL_PMD) {
+		pgd_set_mm(pgd, mm);
+		pgd_list_add(pgd);
+	}
+}
+
+static void pgd_dtor(pgd_t *pgd)
+{
+	if (SHARED_KERNEL_PMD)
+		return;
+
+	spin_lock(&pgd_lock);
+	pgd_list_del(pgd);
+	spin_unlock(&pgd_lock);
+}
+
+/*
+ * List of all pgd's needed for non-PAE so it can invalidate entries
+ * in both cached and uncached pgd's; not needed for PAE since the
+ * kernel pmd is shared. If PAE were not to share the pmd a similar
+ * tactic would be needed. This is essentially codepath-based locking
+ * against pageattr.c; it is the unique case in which a valid change
+ * of kernel pagetables can't be lazily synchronized by vmalloc faults.
+ * vmalloc faults work because attached pagetables are never freed.
+ * -- nyc
+ */
+
+#ifdef CONFIG_X86_PAE
+/*
+ * In PAE mode, we need to do a cr3 reload (=tlb flush) when
+ * updating the top-level pagetable entries to guarantee the
+ * processor notices the update.  Since this is expensive, and
+ * all 4 top-level entries are used almost immediately in a
+ * new process's life, we just pre-populate them here.
+ *
+ * Also, if we're in a paravirt environment where the kernel pmd is
+ * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
+ * and initialize the kernel pmds here.
+ */
+#define PREALLOCATED_PMDS	UNSHARED_PTRS_PER_PGD
+#define MAX_PREALLOCATED_PMDS	MAX_UNSHARED_PTRS_PER_PGD
+
+/*
+ * We allocate separate PMDs for the kernel part of the user page-table
+ * when PTI is enabled. We need them to map the per-process LDT into the
+ * user-space page-table.
+ */
+#define PREALLOCATED_USER_PMDS	 (boot_cpu_has(X86_FEATURE_PTI) ? \
+					KERNEL_PGD_PTRS : 0)
+#define MAX_PREALLOCATED_USER_PMDS KERNEL_PGD_PTRS
+
+void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
+{
+	paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
+
+	/* Note: almost everything apart from _PAGE_PRESENT is
+	   reserved at the pmd (PDPT) level. */
+	set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT));
+
+	/*
+	 * According to Intel App note "TLBs, Paging-Structure Caches,
+	 * and Their Invalidation", April 2007, document 317080-001,
+	 * section 8.1: in PAE mode we explicitly have to flush the
+	 * TLB via cr3 if the top-level pgd is changed...
+	 */
+	flush_tlb_mm(mm);
+}
+#else  /* !CONFIG_X86_PAE */
+
+/* No need to prepopulate any pagetable entries in non-PAE modes. */
+#define PREALLOCATED_PMDS	0
+#define MAX_PREALLOCATED_PMDS	0
+#define PREALLOCATED_USER_PMDS	 0
+#define MAX_PREALLOCATED_USER_PMDS 0
+#endif	/* CONFIG_X86_PAE */
+
+static void free_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		if (pmds[i]) {
+			pgtable_pmd_page_dtor(virt_to_page(pmds[i]));
+			free_page((unsigned long)pmds[i]);
+			mm_dec_nr_pmds(mm);
+		}
+}
+
+static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
+{
+	int i;
+	bool failed = false;
+	gfp_t gfp = GFP_PGTABLE_USER;
+
+	if (mm == &init_mm)
+		gfp &= ~__GFP_ACCOUNT;
+
+	for (i = 0; i < count; i++) {
+		pmd_t *pmd = (pmd_t *)__get_free_page(gfp);
+		if (!pmd)
+			failed = true;
+		if (pmd && !pgtable_pmd_page_ctor(virt_to_page(pmd))) {
+			free_page((unsigned long)pmd);
+			pmd = NULL;
+			failed = true;
+		}
+		if (pmd)
+			mm_inc_nr_pmds(mm);
+		pmds[i] = pmd;
+	}
+
+	if (failed) {
+		free_pmds(mm, pmds, count);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/*
+ * Mop up any pmd pages which may still be attached to the pgd.
+ * Normally they will be freed by munmap/exit_mmap, but any pmd we
+ * preallocate which never got a corresponding vma will need to be
+ * freed manually.
+ */
+static void mop_up_one_pmd(struct mm_struct *mm, pgd_t *pgdp)
+{
+	pgd_t pgd = *pgdp;
+
+	if (pgd_val(pgd) != 0) {
+		pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
+
+		pgd_clear(pgdp);
+
+		paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
+		pmd_free(mm, pmd);
+		mm_dec_nr_pmds(mm);
+	}
+}
+
+static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
+{
+	int i;
+
+	for (i = 0; i < PREALLOCATED_PMDS; i++)
+		mop_up_one_pmd(mm, &pgdp[i]);
+
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+
+	if (!boot_cpu_has(X86_FEATURE_PTI))
+		return;
+
+	pgdp = kernel_to_user_pgdp(pgdp);
+
+	for (i = 0; i < PREALLOCATED_USER_PMDS; i++)
+		mop_up_one_pmd(mm, &pgdp[i + KERNEL_PGD_BOUNDARY]);
+#endif
+}
+
+static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
+{
+	p4d_t *p4d;
+	pud_t *pud;
+	int i;
+
+	if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */
+		return;
+
+	p4d = p4d_offset(pgd, 0);
+	pud = pud_offset(p4d, 0);
+
+	for (i = 0; i < PREALLOCATED_PMDS; i++, pud++) {
+		pmd_t *pmd = pmds[i];
+
+		if (i >= KERNEL_PGD_BOUNDARY)
+			memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
+			       sizeof(pmd_t) * PTRS_PER_PMD);
+
+		pud_populate(mm, pud, pmd);
+	}
+}
+
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
+				     pgd_t *k_pgd, pmd_t *pmds[])
+{
+	pgd_t *s_pgd = kernel_to_user_pgdp(swapper_pg_dir);
+	pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+	p4d_t *u_p4d;
+	pud_t *u_pud;
+	int i;
+
+	u_p4d = p4d_offset(u_pgd, 0);
+	u_pud = pud_offset(u_p4d, 0);
+
+	s_pgd += KERNEL_PGD_BOUNDARY;
+	u_pud += KERNEL_PGD_BOUNDARY;
+
+	for (i = 0; i < PREALLOCATED_USER_PMDS; i++, u_pud++, s_pgd++) {
+		pmd_t *pmd = pmds[i];
+
+		memcpy(pmd, (pmd_t *)pgd_page_vaddr(*s_pgd),
+		       sizeof(pmd_t) * PTRS_PER_PMD);
+
+		pud_populate(mm, u_pud, pmd);
+	}
+
+}
+#else
+static void pgd_prepopulate_user_pmd(struct mm_struct *mm,
+				     pgd_t *k_pgd, pmd_t *pmds[])
+{
+}
+#endif
+/*
+ * Xen paravirt assumes pgd table should be in one page. 64 bit kernel also
+ * assumes that pgd should be in one page.
+ *
+ * But kernel with PAE paging that is not running as a Xen domain
+ * only needs to allocate 32 bytes for pgd instead of one page.
+ */
+#ifdef CONFIG_X86_PAE
+
+#include <linux/slab.h>
+
+#define PGD_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
+#define PGD_ALIGN	32
+
+static struct kmem_cache *pgd_cache;
+
+void __init pgtable_cache_init(void)
+{
+	/*
+	 * When PAE kernel is running as a Xen domain, it does not use
+	 * shared kernel pmd. And this requires a whole page for pgd.
+	 */
+	if (!SHARED_KERNEL_PMD)
+		return;
+
+	/*
+	 * when PAE kernel is not running as a Xen domain, it uses
+	 * shared kernel pmd. Shared kernel pmd does not require a whole
+	 * page for pgd. We are able to just allocate a 32-byte for pgd.
+	 * During boot time, we create a 32-byte slab for pgd table allocation.
+	 */
+	pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_ALIGN,
+				      SLAB_PANIC, NULL);
+}
+
+static inline pgd_t *_pgd_alloc(void)
+{
+	/*
+	 * If no SHARED_KERNEL_PMD, PAE kernel is running as a Xen domain.
+	 * We allocate one page for pgd.
+	 */
+	if (!SHARED_KERNEL_PMD)
+		return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
+						 PGD_ALLOCATION_ORDER);
+
+	/*
+	 * Now PAE kernel is not running as a Xen domain. We can allocate
+	 * a 32-byte slab for pgd to save memory space.
+	 */
+	return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_USER);
+}
+
+static inline void _pgd_free(pgd_t *pgd)
+{
+	if (!SHARED_KERNEL_PMD)
+		free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
+	else
+		kmem_cache_free(pgd_cache, pgd);
+}
+#else
+
+static inline pgd_t *_pgd_alloc(void)
+{
+	return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
+					 PGD_ALLOCATION_ORDER);
+}
+
+static inline void _pgd_free(pgd_t *pgd)
+{
+	free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
+}
+#endif /* CONFIG_X86_PAE */
+
+pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *pgd;
+	pmd_t *u_pmds[MAX_PREALLOCATED_USER_PMDS];
+	pmd_t *pmds[MAX_PREALLOCATED_PMDS];
+
+	pgd = _pgd_alloc();
+
+	if (pgd == NULL)
+		goto out;
+
+	mm->pgd = pgd;
+
+	if (preallocate_pmds(mm, pmds, PREALLOCATED_PMDS) != 0)
+		goto out_free_pgd;
+
+	if (preallocate_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS) != 0)
+		goto out_free_pmds;
+
+	if (paravirt_pgd_alloc(mm) != 0)
+		goto out_free_user_pmds;
+
+	/*
+	 * Make sure that pre-populating the pmds is atomic with
+	 * respect to anything walking the pgd_list, so that they
+	 * never see a partially populated pgd.
+	 */
+	spin_lock(&pgd_lock);
+
+	pgd_ctor(mm, pgd);
+	pgd_prepopulate_pmd(mm, pgd, pmds);
+	pgd_prepopulate_user_pmd(mm, pgd, u_pmds);
+
+	spin_unlock(&pgd_lock);
+
+	return pgd;
+
+out_free_user_pmds:
+	free_pmds(mm, u_pmds, PREALLOCATED_USER_PMDS);
+out_free_pmds:
+	free_pmds(mm, pmds, PREALLOCATED_PMDS);
+out_free_pgd:
+	_pgd_free(pgd);
+out:
+	return NULL;
+}
+
+void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+	pgd_mop_up_pmds(mm, pgd);
+	pgd_dtor(pgd);
+	paravirt_pgd_free(mm, pgd);
+	_pgd_free(pgd);
+}
+
+/*
+ * Used to set accessed or dirty bits in the page table entries
+ * on other architectures. On x86, the accessed and dirty bits
+ * are tracked by hardware. However, do_wp_page calls this function
+ * to also make the pte writeable at the same time the dirty bit is
+ * set. In that case we do actually need to write the PTE.
+ */
+int ptep_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pte_t *ptep,
+			  pte_t entry, int dirty)
+{
+	int changed = !pte_same(*ptep, entry);
+
+	if (changed && dirty)
+		set_pte(ptep, entry);
+
+	return changed;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp,
+			  pmd_t entry, int dirty)
+{
+	int changed = !pmd_same(*pmdp, entry);
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	if (changed && dirty) {
+		set_pmd(pmdp, entry);
+		/*
+		 * We had a write-protection fault here and changed the pmd
+		 * to to more permissive. No need to flush the TLB for that,
+		 * #PF is architecturally guaranteed to do that and in the
+		 * worst-case we'll generate a spurious fault.
+		 */
+	}
+
+	return changed;
+}
+
+int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
+			  pud_t *pudp, pud_t entry, int dirty)
+{
+	int changed = !pud_same(*pudp, entry);
+
+	VM_BUG_ON(address & ~HPAGE_PUD_MASK);
+
+	if (changed && dirty) {
+		set_pud(pudp, entry);
+		/*
+		 * We had a write-protection fault here and changed the pud
+		 * to to more permissive. No need to flush the TLB for that,
+		 * #PF is architecturally guaranteed to do that and in the
+		 * worst-case we'll generate a spurious fault.
+		 */
+	}
+
+	return changed;
+}
+#endif
+
+int ptep_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pte_t *ptep)
+{
+	int ret = 0;
+
+	if (pte_young(*ptep))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *) &ptep->pte);
+
+	return ret;
+}
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)
+int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pmd_t *pmdp)
+{
+	int ret = 0;
+
+	if (pmd_young(*pmdp))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *)pmdp);
+
+	return ret;
+}
+#endif
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pudp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pud_t *pudp)
+{
+	int ret = 0;
+
+	if (pud_young(*pudp))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *)pudp);
+
+	return ret;
+}
+#endif
+
+int ptep_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pte_t *ptep)
+{
+	/*
+	 * On x86 CPUs, clearing the accessed bit without a TLB flush
+	 * doesn't cause data corruption. [ It could cause incorrect
+	 * page aging and the (mistaken) reclaim of hot pages, but the
+	 * chance of that should be relatively low. ]
+	 *
+	 * So as a performance optimization don't flush the TLB when
+	 * clearing the accessed bit, it will eventually be flushed by
+	 * a context switch or a VM operation anyway. [ In the rare
+	 * event of it not getting flushed for a long time the delay
+	 * shouldn't really matter because there's no real memory
+	 * pressure for swapout to react to. ]
+	 */
+	return ptep_test_and_clear_young(vma, address, ptep);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pmd_t *pmdp)
+{
+	int young;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	young = pmdp_test_and_clear_young(vma, address, pmdp);
+	if (young)
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+
+	return young;
+}
+
+pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
+			 pmd_t *pmdp)
+{
+	/*
+	 * No flush is necessary. Once an invalid PTE is established, the PTE's
+	 * access and dirty bits cannot be updated.
+	 */
+	return pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp));
+}
+#endif
+
+/**
+ * reserve_top_address - reserves a hole in the top of kernel address space
+ * @reserve - size of hole to reserve
+ *
+ * Can be used to relocate the fixmap area and poke a hole in the top
+ * of kernel address space to make room for a hypervisor.
+ */
+void __init reserve_top_address(unsigned long reserve)
+{
+#ifdef CONFIG_X86_32
+	BUG_ON(fixmaps_set > 0);
+	__FIXADDR_TOP = round_down(-reserve, 1 << PMD_SHIFT) - PAGE_SIZE;
+	printk(KERN_INFO "Reserving virtual address space above 0x%08lx (rounded to 0x%08lx)\n",
+	       -reserve, __FIXADDR_TOP + PAGE_SIZE);
+#endif
+}
+
+int fixmaps_set;
+
+void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
+{
+	unsigned long address = __fix_to_virt(idx);
+
+#ifdef CONFIG_X86_64
+       /*
+	* Ensure that the static initial page tables are covering the
+	* fixmap completely.
+	*/
+	BUILD_BUG_ON(__end_of_permanent_fixed_addresses >
+		     (FIXMAP_PMD_NUM * PTRS_PER_PTE));
+#endif
+
+	if (idx >= __end_of_fixed_addresses) {
+		BUG();
+		return;
+	}
+	set_pte_vaddr(address, pte);
+	fixmaps_set++;
+}
+
+void native_set_fixmap(unsigned /* enum fixed_addresses */ idx,
+		       phys_addr_t phys, pgprot_t flags)
+{
+	/* Sanitize 'prot' against any unsupported bits: */
+	pgprot_val(flags) &= __default_kernel_pte_mask;
+
+	__native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
+}
+
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+#ifdef CONFIG_X86_5LEVEL
+/**
+ * p4d_set_huge - setup kernel P4D mapping
+ *
+ * No 512GB pages yet -- always return 0
+ */
+int p4d_set_huge(p4d_t *p4d, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+
+/**
+ * p4d_clear_huge - clear kernel P4D mapping when it is set
+ *
+ * No 512GB pages yet -- always return 0
+ */
+void p4d_clear_huge(p4d_t *p4d)
+{
+}
+#endif
+
+/**
+ * pud_set_huge - setup kernel PUD mapping
+ *
+ * MTRRs can override PAT memory types with 4KiB granularity. Therefore, this
+ * function sets up a huge page only if any of the following conditions are met:
+ *
+ * - MTRRs are disabled, or
+ *
+ * - MTRRs are enabled and the range is completely covered by a single MTRR, or
+ *
+ * - MTRRs are enabled and the corresponding MTRR memory type is WB, which
+ *   has no effect on the requested PAT memory type.
+ *
+ * Callers should try to decrease page size (1GB -> 2MB -> 4K) if the bigger
+ * page mapping attempt fails.
+ *
+ * Returns 1 on success and 0 on failure.
+ */
+int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	u8 mtrr, uniform;
+
+	mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
+	if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
+	    (mtrr != MTRR_TYPE_WRBACK))
+		return 0;
+
+	/* Bail out if we are we on a populated non-leaf entry: */
+	if (pud_present(*pud) && !pud_huge(*pud))
+		return 0;
+
+	set_pte((pte_t *)pud, pfn_pte(
+		(u64)addr >> PAGE_SHIFT,
+		__pgprot(protval_4k_2_large(pgprot_val(prot)) | _PAGE_PSE)));
+
+	return 1;
+}
+
+/**
+ * pmd_set_huge - setup kernel PMD mapping
+ *
+ * See text over pud_set_huge() above.
+ *
+ * Returns 1 on success and 0 on failure.
+ */
+int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	u8 mtrr, uniform;
+
+	mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE, &uniform);
+	if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
+	    (mtrr != MTRR_TYPE_WRBACK)) {
+		pr_warn_once("%s: Cannot satisfy [mem %#010llx-%#010llx] with a huge-page mapping due to MTRR override.\n",
+			     __func__, addr, addr + PMD_SIZE);
+		return 0;
+	}
+
+	/* Bail out if we are we on a populated non-leaf entry: */
+	if (pmd_present(*pmd) && !pmd_huge(*pmd))
+		return 0;
+
+	set_pte((pte_t *)pmd, pfn_pte(
+		(u64)addr >> PAGE_SHIFT,
+		__pgprot(protval_4k_2_large(pgprot_val(prot)) | _PAGE_PSE)));
+
+	return 1;
+}
+
+/**
+ * pud_clear_huge - clear kernel PUD mapping when it is set
+ *
+ * Returns 1 on success and 0 on failure (no PUD map is found).
+ */
+int pud_clear_huge(pud_t *pud)
+{
+	if (pud_large(*pud)) {
+		pud_clear(pud);
+		return 1;
+	}
+
+	return 0;
+}
+
+/**
+ * pmd_clear_huge - clear kernel PMD mapping when it is set
+ *
+ * Returns 1 on success and 0 on failure (no PMD map is found).
+ */
+int pmd_clear_huge(pmd_t *pmd)
+{
+	if (pmd_large(*pmd)) {
+		pmd_clear(pmd);
+		return 1;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_X86_64
+/**
+ * pud_free_pmd_page - Clear pud entry and free pmd page.
+ * @pud: Pointer to a PUD.
+ * @addr: Virtual address associated with pud.
+ *
+ * Context: The pud range has been unmapped and TLB purged.
+ * Return: 1 if clearing the entry succeeded. 0 otherwise.
+ *
+ * NOTE: Callers must allow a single page allocation.
+ */
+int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+{
+	pmd_t *pmd, *pmd_sv;
+	pte_t *pte;
+	int i;
+
+	pmd = pud_pgtable(*pud);
+	pmd_sv = (pmd_t *)__get_free_page(GFP_KERNEL);
+	if (!pmd_sv)
+		return 0;
+
+	for (i = 0; i < PTRS_PER_PMD; i++) {
+		pmd_sv[i] = pmd[i];
+		if (!pmd_none(pmd[i]))
+			pmd_clear(&pmd[i]);
+	}
+
+	pud_clear(pud);
+
+	/* INVLPG to clear all paging-structure caches */
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
+
+	for (i = 0; i < PTRS_PER_PMD; i++) {
+		if (!pmd_none(pmd_sv[i])) {
+			pte = (pte_t *)pmd_page_vaddr(pmd_sv[i]);
+			free_page((unsigned long)pte);
+		}
+	}
+
+	free_page((unsigned long)pmd_sv);
+
+	pgtable_pmd_page_dtor(virt_to_page(pmd));
+	free_page((unsigned long)pmd);
+
+	return 1;
+}
+
+/**
+ * pmd_free_pte_page - Clear pmd entry and free pte page.
+ * @pmd: Pointer to a PMD.
+ * @addr: Virtual address associated with pmd.
+ *
+ * Context: The pmd range has been unmapped and TLB purged.
+ * Return: 1 if clearing the entry succeeded. 0 otherwise.
+ */
+int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+{
+	pte_t *pte;
+
+	pte = (pte_t *)pmd_page_vaddr(*pmd);
+	pmd_clear(pmd);
+
+	/* INVLPG to clear all paging-structure caches */
+	flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
+
+	free_page((unsigned long)pte);
+
+	return 1;
+}
+
+#else /* !CONFIG_X86_64 */
+
+/*
+ * Disable free page handling on x86-PAE. This assures that ioremap()
+ * does not update sync'd pmd entries. See vmalloc_sync_one().
+ */
+int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+{
+	return pmd_none(*pmd);
+}
+
+#endif /* CONFIG_X86_64 */
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */