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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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;
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 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;
 }
 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 */

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