arm64: switch to generic version of pte allocation

The PTE allocations in arm64 are identical to the generic ones modulo the
GFP flags.

Using the generic pte_alloc_one() functions ensures that the user page
tables are allocated with __GFP_ACCOUNT set.

The arm64 definition of PGALLOC_GFP is removed and replaced with
GFP_PGTABLE_USER for p[gum]d_alloc_one() for the user page tables and
GFP_PGTABLE_KERNEL for the kernel page tables. The KVM memory cache is now
using GFP_PGTABLE_USER.

The mappings created with create_pgd_mapping() are now using
GFP_PGTABLE_KERNEL.

The conversion to the generic version of pte_free_kernel() removes the NULL
check for pte.

The pte_free() version on arm64 is identical to the generic one and
can be simply dropped.

[cai@lca.pw: fix a bogus GFP flag in pgd_alloc()]
  Link: https://lore.kernel.org/r/1559656836-24940-1-git-send-email-cai@lca.pw/
[and fix it more]
  Link: https://lore.kernel.org/linux-mm/20190617151252.GF16810@rapoport-lnx/
Link: http://lkml.kernel.org/r/1557296232-15361-5-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/include/asm/pgalloc.h

@@ -13,18 +13,23 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
+#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
+
 #define check_pgt_cache()		do { } while (0)
 
-#define PGALLOC_GFP	(GFP_KERNEL | __GFP_ZERO)
 #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;
 
-	page = alloc_page(PGALLOC_GFP);
+	if (mm == &init_mm)
+		gfp = GFP_PGTABLE_KERNEL;
+
+	page = alloc_page(gfp);
 	if (!page)
 		return NULL;
 	if (!pgtable_pmd_page_ctor(page)) {
@@ -61,7 +66,7 @@ static inline void __pud_populate(pud_t *pudp, phys_addr_t pmdp, pudval_t prot)
 
 static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-	return (pud_t *)__get_free_page(PGALLOC_GFP);
+	return (pud_t *)__get_free_page(GFP_PGTABLE_USER);
 }
 
 static inline void pud_free(struct mm_struct *mm, pud_t *pudp)
@@ -89,42 +94,6 @@ static inline void __pgd_populate(pgd_t *pgdp, phys_addr_t pudp, pgdval_t prot)
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
 extern void pgd_free(struct mm_struct *mm, pgd_t *pgdp);
 
-static inline pte_t *
-pte_alloc_one_kernel(struct mm_struct *mm)
-{
-	return (pte_t *)__get_free_page(PGALLOC_GFP);
-}
-
-static inline pgtable_t
-pte_alloc_one(struct mm_struct *mm)
-{
-	struct page *pte;
-
-	pte = alloc_pages(PGALLOC_GFP, 0);
-	if (!pte)
-		return NULL;
-	if (!pgtable_page_ctor(pte)) {
-		__free_page(pte);
-		return NULL;
-	}
-	return pte;
-}
-
-/*
- * Free a PTE table.
- */
-static inline void pte_free_kernel(struct mm_struct *mm, pte_t *ptep)
-{
-	if (ptep)
-		free_page((unsigned long)ptep);
-}
-
-static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
-{
-	pgtable_page_dtor(pte);
-	__free_page(pte);
-}
-
 static inline void __pmd_populate(pmd_t *pmdp, phys_addr_t ptep,
 				  pmdval_t prot)
 {

arch/arm64/mm/mmu.c

@@ -362,7 +362,7 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
 
 static phys_addr_t __pgd_pgtable_alloc(int shift)
 {
-	void *ptr = (void *)__get_free_page(PGALLOC_GFP);
+	void *ptr = (void *)__get_free_page(GFP_PGTABLE_KERNEL);
 	BUG_ON(!ptr);
 
 	/* Ensure the zeroed page is visible to the page table walker */

arch/arm64/mm/pgd.c

@@ -19,10 +19,12 @@ static struct kmem_cache *pgd_cache __ro_after_init;
 
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
+	gfp_t gfp = GFP_PGTABLE_USER;
+
 	if (PGD_SIZE == PAGE_SIZE)
-		return (pgd_t *)__get_free_page(PGALLOC_GFP);
+		return (pgd_t *)__get_free_page(gfp);
 	else
-		return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
+		return kmem_cache_alloc(pgd_cache, gfp);
 }
 
 void pgd_free(struct mm_struct *mm, pgd_t *pgd)

virt/kvm/arm/mmu.c

@@ -129,7 +129,7 @@ static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
 	if (cache->nobjs >= min)
 		return 0;
 	while (cache->nobjs < max) {
-		page = (void *)__get_free_page(PGALLOC_GFP);
+		page = (void *)__get_free_page(GFP_PGTABLE_USER);
 		if (!page)
 			return -ENOMEM;
 		cache->objects[cache->nobjs++] = page;