asm-generic: pgalloc: provide generic pmd_alloc_one() and pmd_free_one()

For most architectures that support >2 levels of page tables,
pmd_alloc_one() is a wrapper for __get_free_pages(), sometimes with
__GFP_ZERO and sometimes followed by memset(0) instead.

More elaborate versions on arm64 and x86 account memory for the user page
tables and call to pgtable_pmd_page_ctor() as the part of PMD page
initialization.

Move the arm64 version to include/asm-generic/pgalloc.h and use the
generic version on several architectures.

The pgtable_pmd_page_ctor() is a NOP when ARCH_ENABLE_SPLIT_PMD_PTLOCK is
not enabled, so there is no functional change for most architectures
except of the addition of __GFP_ACCOUNT for allocation of user page
tables.

The pmd_free() is a wrapper for free_page() in all the cases, so no
functional change here.

Signed-off-by: Mike Rapoport <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Reviewed-by: Pekka Enberg <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Abdul Haleem <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: Joerg Roedel <[e-mail]>
Cc: Joerg Roedel <[e-mail]>
Cc: Max Filippov <[e-mail]>
Cc: Peter Zijlstra (Intel) <[e-mail]>
Cc: Satheesh Rajendran <[e-mail]>
Cc: Stafford Horne <[e-mail]>
Cc: Stephen Rothwell <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Linus Torvalds <[e-mail]>

arch/alpha/include/asm/pgalloc.h

···
 #include <linux/mm.h>
 #include <linux/mmzone.h>
 
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#include <asm-generic/pgalloc.h>
 
 /*      
  * Allocate and free page tables. The xxx_kernel() versions are
···
 pgd_free(struct mm_struct *mm, pgd_t *pgd)
 {
 	free_page((unsigned long)pgd);
-}
-
-static inline pmd_t *
-pmd_alloc_one(struct mm_struct *mm, unsigned long address)
-{
-	pmd_t *ret = (pmd_t *)__get_free_page(GFP_PGTABLE_USER);
-	return ret;
-}
-
-static inline void
-pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	free_page((unsigned long)pmd);
 }
 
 #endif /* _ALPHA_PGALLOC_H */

arch/arm/include/asm/pgalloc.h

···
 
 #ifdef CONFIG_ARM_LPAE
 
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
-	return (pmd_t *)get_zeroed_page(GFP_KERNEL);
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
-	free_page((unsigned long)pmd);
-}
-
 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 {
 	set_pud(pud, __pud(__pa(pmd) | PMD_TYPE_TABLE));

arch/arm64/include/asm/pgalloc.h

···
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#include <asm-generic/pgalloc.h>
 
 #define PGD_SIZE	(PTRS_PER_PGD * sizeof(pgd_t))
 
 #if CONFIG_PGTABLE_LEVELS > 2
-
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
-	gfp_t gfp = GFP_PGTABLE_USER;
-	struct page *page;
-
-	if (mm == &init_mm)
-		gfp = GFP_PGTABLE_KERNEL;
-
-	page = alloc_page(gfp);
-	if (!page)
-		return NULL;
-	if (!pgtable_pmd_page_ctor(page)) {
-		__free_page(page);
-		return NULL;
-	}
-	return page_address(page);
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmdp)
-{
-	BUG_ON((unsigned long)pmdp & (PAGE_SIZE-1));
-	pgtable_pmd_page_dtor(virt_to_page(pmdp));
-	free_page((unsigned long)pmdp);
-}
 
 static inline void __pud_populate(pud_t *pudp, phys_addr_t pmdp, pudval_t prot)
 {

arch/ia64/include/asm/pgalloc.h

···
 	pud_val(*pud_entry) = __pa(pmd);
 }
 
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
-	return (pmd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	free_page((unsigned long)pmd);
-}
-
 #define __pmd_free_tlb(tlb, pmd, address)	pmd_free((tlb)->mm, pmd)
 
 static inline void

arch/mips/include/asm/pgalloc.h

···
 #include <linux/mm.h>
 #include <linux/sched.h>
 
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#define __HAVE_ARCH_PMD_ALLOC_ONE
+#include <asm-generic/pgalloc.h>
 
 static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
 	pte_t *pte)
···
 	if (pmd)
 		pmd_init((unsigned long)pmd, (unsigned long)invalid_pte_table);
 	return pmd;
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	free_pages((unsigned long)pmd, PMD_ORDER);
 }
 
 #define __pmd_free_tlb(tlb, x, addr)	pmd_free((tlb)->mm, x)

arch/parisc/include/asm/pgalloc.h

···
 
 #include <asm/cache.h>
 
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#define __HAVE_ARCH_PMD_FREE
+#include <asm-generic/pgalloc.h>
 
 /* Allocate the top level pgd (page directory)
  *
···
 {
 	set_pud(pud, __pud((PxD_FLAG_PRESENT | PxD_FLAG_VALID) +
 			(__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT)));
-}
-
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
-{
-	pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER);
-	if (pmd)
-		memset(pmd, 0, PAGE_SIZE<<PMD_ORDER);
-	return pmd;
 }
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)

arch/riscv/include/asm/pgalloc.h

···
 #include <asm/tlb.h>
 
 #ifdef CONFIG_MMU
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#include <asm-generic/pgalloc.h>
 
 static inline void pmd_populate_kernel(struct mm_struct *mm,
 	pmd_t *pmd, pte_t *pte)
···
 }
 
 #ifndef __PAGETABLE_PMD_FOLDED
-
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
-	return (pmd_t *)__get_free_page(
-		GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	free_page((unsigned long)pmd);
-}
 
 #define __pmd_free_tlb(tlb, pmd, addr)  pmd_free((tlb)->mm, pmd)
 

arch/sh/include/asm/pgalloc.h

···
 #define __ASM_SH_PGALLOC_H
 
 #include <asm/page.h>
+
+#define __HAVE_ARCH_PMD_ALLOC_ONE
+#define __HAVE_ARCH_PMD_FREE
 #include <asm-generic/pgalloc.h>
 
 extern pgd_t *pgd_alloc(struct mm_struct *);

arch/um/include/asm/pgalloc.h

···
 
 #include <linux/mm.h>
 
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#include <asm-generic/pgalloc.h>
 
 #define pmd_populate_kernel(mm, pmd, pte) \
 	set_pmd(pmd, __pmd(_PAGE_TABLE + (unsigned long) __pa(pte)))
···
 } while (0)
 
 #ifdef CONFIG_3_LEVEL_PGTABLES
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	free_page((unsigned long)pmd);
-}
-
 #define __pmd_free_tlb(tlb,x, address)   tlb_remove_page((tlb),virt_to_page(x))
 #endif
 

arch/um/include/asm/pgtable-3level.h

···
 #define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
 #endif
 
-struct mm_struct;
-extern pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address);
-
 static inline void pud_clear (pud_t *pud)
 {
 	set_pud(pud, __pud(_PAGE_NEWPAGE));

arch/um/kernel/mem.c

···
 	free_page((unsigned long) pgd);
 }
 
-#ifdef CONFIG_3_LEVEL_PGTABLES
-pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
-{
-	pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
-
-	if (pmd)
-		memset(pmd, 0, PAGE_SIZE);
-
-	return pmd;
-}
-#endif
-
 void *uml_kmalloc(int size, int flags)
 {
 	return kmalloc(size, flags);

arch/x86/include/asm/pgalloc.h

···
 #include <linux/pagemap.h>
 
 #define __HAVE_ARCH_PTE_ALLOC_ONE
-#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+#include <asm-generic/pgalloc.h>
 
 static inline int  __paravirt_pgd_alloc(struct mm_struct *mm) { return 0; }
 
···
 #define pmd_pgtable(pmd) pmd_page(pmd)
 
 #if CONFIG_PGTABLE_LEVELS > 2
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
-{
-	struct page *page;
-	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO;
-
-	if (mm == &init_mm)
-		gfp &= ~__GFP_ACCOUNT;
-	page = alloc_pages(gfp, 0);
-	if (!page)
-		return NULL;
-	if (!pgtable_pmd_page_ctor(page)) {
-		__free_pages(page, 0);
-		return NULL;
-	}
-	return (pmd_t *)page_address(page);
-}
-
-static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
-{
-	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
-	pgtable_pmd_page_dtor(virt_to_page(pmd));
-	free_page((unsigned long)pmd);
-}
-
 extern void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd);
 
 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,

include/asm-generic/pgalloc.h

···
 	__free_page(pte_page);
 }
 
+
+#if CONFIG_PGTABLE_LEVELS > 2
+
+#ifndef __HAVE_ARCH_PMD_ALLOC_ONE
+/**
+ * pmd_alloc_one - allocate a page for PMD-level page table
+ * @mm: the mm_struct of the current context
+ *
+ * Allocates a page and runs the pgtable_pmd_page_ctor().
+ * Allocations use %GFP_PGTABLE_USER in user context and
+ * %GFP_PGTABLE_KERNEL in kernel context.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
+{
+	struct page *page;
+	gfp_t gfp = GFP_PGTABLE_USER;
+
+	if (mm == &init_mm)
+		gfp = GFP_PGTABLE_KERNEL;
+	page = alloc_pages(gfp, 0);
+	if (!page)
+		return NULL;
+	if (!pgtable_pmd_page_ctor(page)) {
+		__free_pages(page, 0);
+		return NULL;
+	}
+	return (pmd_t *)page_address(page);
+}
+#endif
+
+#ifndef __HAVE_ARCH_PMD_FREE
+static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
+{
+	BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
+	pgtable_pmd_page_dtor(virt_to_page(pmd));
+	free_page((unsigned long)pmd);
+}
+#endif
+
+#endif /* CONFIG_PGTABLE_LEVELS > 2 */
+
 #endif /* CONFIG_MMU */
 
 #endif /* __ASM_GENERIC_PGALLOC_H */