3 files changed, 115 insertions, 44 deletions

diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index a281e61ec60c..29aa7859bdee 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -6,6 +6,9 @@
 #include <linux/mm.h>           /* for struct page */
 #include <linux/pagemap.h>
 
+#define __HAVE_ARCH_PTE_ALLOC_ONE
+#include <asm-generic/pgalloc.h>        /* for pte_{alloc,free}_one */
+
 static inline int  __paravirt_pgd_alloc(struct mm_struct *mm) { return 0; }
 
 #ifdef CONFIG_PARAVIRT_XXL
@@ -47,24 +50,8 @@ extern gfp_t __userpte_alloc_gfp;
 extern pgd_t *pgd_alloc(struct mm_struct *);
 extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);
 
-extern pte_t *pte_alloc_one_kernel(struct mm_struct *);
 extern pgtable_t pte_alloc_one(struct mm_struct *);
 
-/* Should really implement gc for free page table pages. This could be
-   done with a reference count in struct page. */
-
-static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
-{
-        BUG_ON((unsigned long)pte & (PAGE_SIZE-1));
-        free_page((unsigned long)pte);
-}
-
-static inline void pte_free(struct mm_struct *mm, struct page *pte)
-{
-        pgtable_page_dtor(pte);
-        __free_page(pte);
-}
-
 extern void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte);
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte,
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 1f67b1e15bf6..44816ff6411f 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -13,33 +13,17 @@ phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
 EXPORT_SYMBOL(physical_mask);
 #endif
 
-#define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO)
-
 #ifdef CONFIG_HIGHPTE
-#define PGALLOC_USER_GFP __GFP_HIGHMEM
+#define PGTABLE_HIGHMEM __GFP_HIGHMEM
 #else
-#define PGALLOC_USER_GFP 0
+#define PGTABLE_HIGHMEM 0
 #endif
 
-gfp_t __userpte_alloc_gfp = PGALLOC_GFP | PGALLOC_USER_GFP;
-
-pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
-{
-        return (pte_t *)__get_free_page(PGALLOC_GFP & ~__GFP_ACCOUNT);
-}
+gfp_t __userpte_alloc_gfp = GFP_PGTABLE_USER | PGTABLE_HIGHMEM;
 
 pgtable_t pte_alloc_one(struct mm_struct *mm)
 {
-        struct page *pte;
-
-        pte = alloc_pages(__userpte_alloc_gfp, 0);
-        if (!pte)
-                return NULL;
-        if (!pgtable_page_ctor(pte)) {
-                __free_page(pte);
-                return NULL;
-        }
-        return pte;
+        return __pte_alloc_one(mm, __userpte_alloc_gfp);
 }
 
 static int __init setup_userpte(char *arg)
@@ -235,7 +219,7 @@ static int preallocate_pmds(struct mm_struct *mm, pmd_t *pmds[], int count)
 {
         int i;
         bool failed = false;
-        gfp_t gfp = PGALLOC_GFP;
+        gfp_t gfp = GFP_PGTABLE_USER;
 
         if (mm == &init_mm)
                 gfp &= ~__GFP_ACCOUNT;
@@ -399,14 +383,14 @@ static inline pgd_t *_pgd_alloc(void)
          * We allocate one page for pgd.
          */
         if (!SHARED_KERNEL_PMD)
-                return (pgd_t *)__get_free_pages(PGALLOC_GFP,
+                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, PGALLOC_GFP);
+        return kmem_cache_alloc(pgd_cache, GFP_PGTABLE_USER);
 }
 
 static inline void _pgd_free(pgd_t *pgd)
@@ -424,7 +408,8 @@ void __init pgd_cache_init(void)
 
 static inline pgd_t *_pgd_alloc(void)
 {
-        return (pgd_t *)__get_free_pages(PGALLOC_GFP, PGD_ALLOCATION_ORDER);
+        return (pgd_t *)__get_free_pages(GFP_PGTABLE_USER,
+                                         PGD_ALLOCATION_ORDER);
 }
 
 static inline void _pgd_free(pgd_t *pgd)
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 948714c1535a..8476175c07e7 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -1,13 +1,112 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __ASM_GENERIC_PGALLOC_H
 #define __ASM_GENERIC_PGALLOC_H
-/*
- * an empty file is enough for a nommu architecture
- */
+
 #ifdef CONFIG_MMU
-#error need to implement an architecture specific asm/pgalloc.h
+
+#define GFP_PGTABLE_KERNEL      (GFP_KERNEL | __GFP_ZERO)
+#define GFP_PGTABLE_USER        (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
+
+/**
+ * __pte_alloc_one_kernel - allocate a page for PTE-level kernel page table
+ * @mm: the mm_struct of the current context
+ *
+ * This function is intended for architectures that need
+ * anything beyond simple page allocation.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+static inline pte_t *__pte_alloc_one_kernel(struct mm_struct *mm)
+{
+        return (pte_t *)__get_free_page(GFP_PGTABLE_KERNEL);
+}
+
+#ifndef __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
+/**
+ * pte_alloc_one_kernel - allocate a page for PTE-level kernel page table
+ * @mm: the mm_struct of the current context
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
+{
+        return __pte_alloc_one_kernel(mm);
+}
+#endif
+
+/**
+ * pte_free_kernel - free PTE-level kernel page table page
+ * @mm: the mm_struct of the current context
+ * @pte: pointer to the memory containing the page table
+ */
+static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+        free_page((unsigned long)pte);
+}
+
+/**
+ * __pte_alloc_one - allocate a page for PTE-level user page table
+ * @mm: the mm_struct of the current context
+ * @gfp: GFP flags to use for the allocation
+ *
+ * Allocates a page and runs the pgtable_page_ctor().
+ *
+ * This function is intended for architectures that need
+ * anything beyond simple page allocation or must have custom GFP flags.
+ *
+ * Return: `struct page` initialized as page table or %NULL on error
+ */
+static inline pgtable_t __pte_alloc_one(struct mm_struct *mm, gfp_t gfp)
+{
+        struct page *pte;
+
+        pte = alloc_page(gfp);
+        if (!pte)
+                return NULL;
+        if (!pgtable_page_ctor(pte)) {
+                __free_page(pte);
+                return NULL;
+        }
+
+        return pte;
+}
+
+#ifndef __HAVE_ARCH_PTE_ALLOC_ONE
+/**
+ * pte_alloc_one - allocate a page for PTE-level user page table
+ * @mm: the mm_struct of the current context
+ *
+ * Allocates a page and runs the pgtable_page_ctor().
+ *
+ * Return: `struct page` initialized as page table or %NULL on error
+ */
+static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
+{
+        return __pte_alloc_one(mm, GFP_PGTABLE_USER);
+}
 #endif
 
+/*
+ * Should really implement gc for free page table pages. This could be
+ * done with a reference count in struct page.
+ */
+
+/**
+ * pte_free - free PTE-level user page table page
+ * @mm: the mm_struct of the current context
+ * @pte_page: the `struct page` representing the page table
+ */
+static inline void pte_free(struct mm_struct *mm, struct page *pte_page)
+{
+        pgtable_page_dtor(pte_page);
+        __free_page(pte_page);
+}
+
+#else /* CONFIG_MMU */
+
+/* This is enough for a nommu architecture */
 #define check_pgt_cache()          do { } while (0)
 
+#endif /* CONFIG_MMU */
+
 #endif /* __ASM_GENERIC_PGALLOC_H */