[PATCH] mm/thp: Define default pmd_pgtable()

* [PATCH] mm/thp: Define default pmd_pgtable()
@ 2021-06-08  5:32 Anshuman Khandual
  2021-06-08  6:58   ` Geert Uytterhoeven
  0 siblings, 1 reply; 4+ messages in thread
From: Anshuman Khandual @ 2021-06-08  5:32 UTC (permalink / raw)
  To: linux-mm, akpm
  Cc: Anshuman Khandual, Nick Hu, Richard Henderson, Vineet Gupta,
	Catalin Marinas, Will Deacon, Guo Ren, Brian Cain,
	Geert Uytterhoeven, Michal Simek, Thomas Bogendoerfer,
	Ley Foon Tan, Jonas Bonn, Stefan Kristiansson, Stafford Horne,
	James E.J. Bottomley, Michael Ellerman, Christophe Leroy,
	Paul Walmsley, Palmer Dabbelt, Heiko Carstens, Yoshinori Sato,
	David S. Miller, Jeff Dike, Thomas Gleixner, Chris Zankel,
	linux-arch, linux-kernel

Currently most platforms define pmd_pgtable() as pmd_page() duplicating the
same code all over. Instead just define a default value i.e pmd_page() for
pmd_pgtable() and let platforms override when required via <asm/pgtable.h>.
All the existing platform that override pmd_pgtable() have been moved into
their respective <asm/pgtable.h> header in order to precede before the new
generic definition. This makes it much cleaner with reduced code.

Cc: Nick Hu <nickhu@andestech.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This patch applies on linux-next (20210607) as there is a merge conflict
dependency on the following commit.

40762590e8be ("mm: define default value for FIRST_USER_ADDRESS").

This patch has been built tested across multiple platforms. But the m68k
changes in particular might not be optimal, followed the existing switch
from (arch/m68k/include/asm/pgalloc.h).

 arch/alpha/include/asm/pgalloc.h         | 1 -
 arch/arc/include/asm/pgalloc.h           | 2 --
 arch/arc/include/asm/pgtable.h           | 2 ++
 arch/arm/include/asm/pgalloc.h           | 1 -
 arch/arm64/include/asm/pgalloc.h         | 1 -
 arch/csky/include/asm/pgalloc.h          | 2 --
 arch/hexagon/include/asm/pgtable.h       | 1 -
 arch/ia64/include/asm/pgalloc.h          | 1 -
 arch/m68k/include/asm/mcf_pgalloc.h      | 2 --
 arch/m68k/include/asm/motorola_pgalloc.h | 1 -
 arch/m68k/include/asm/pgtable.h          | 9 +++++++++
 arch/m68k/include/asm/sun3_pgalloc.h     | 1 -
 arch/microblaze/include/asm/pgalloc.h    | 2 --
 arch/mips/include/asm/pgalloc.h          | 1 -
 arch/nds32/include/asm/pgalloc.h         | 5 -----
 arch/nios2/include/asm/pgalloc.h         | 1 -
 arch/openrisc/include/asm/pgalloc.h      | 2 --
 arch/parisc/include/asm/pgalloc.h        | 1 -
 arch/powerpc/include/asm/pgalloc.h       | 5 -----
 arch/powerpc/include/asm/pgtable.h       | 6 ++++++
 arch/riscv/include/asm/pgalloc.h         | 2 --
 arch/s390/include/asm/pgalloc.h          | 3 ---
 arch/s390/include/asm/pgtable.h          | 3 +++
 arch/sh/include/asm/pgalloc.h            | 1 -
 arch/sparc/include/asm/pgalloc_32.h      | 1 -
 arch/sparc/include/asm/pgalloc_64.h      | 1 -
 arch/sparc/include/asm/pgtable_32.h      | 2 ++
 arch/sparc/include/asm/pgtable_64.h      | 2 ++
 arch/um/include/asm/pgalloc.h            | 1 -
 arch/x86/include/asm/pgalloc.h           | 2 --
 arch/xtensa/include/asm/pgalloc.h        | 2 --
 include/linux/pgtable.h                  | 9 +++++++++
 32 files changed, 33 insertions(+), 43 deletions(-)

diff --git a/arch/alpha/include/asm/pgalloc.h b/arch/alpha/include/asm/pgalloc.h
index 9c6a24fe493d..68be7adbfe58 100644
--- a/arch/alpha/include/asm/pgalloc.h
+++ b/arch/alpha/include/asm/pgalloc.h
@@ -18,7 +18,6 @@ pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t pte)
 {
 	pmd_set(pmd, (pte_t *)(page_to_pa(pte) + PAGE_OFFSET));
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 static inline void
 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
diff --git a/arch/arc/include/asm/pgalloc.h b/arch/arc/include/asm/pgalloc.h
index 6147db925248..a32ca3104ced 100644
--- a/arch/arc/include/asm/pgalloc.h
+++ b/arch/arc/include/asm/pgalloc.h
@@ -129,6 +129,4 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t ptep)
 
 #define __pte_free_tlb(tlb, pte, addr)  pte_free((tlb)->mm, pte)
 
-#define pmd_pgtable(pmd)	((pgtable_t) pmd_page_vaddr(pmd))
-
 #endif /* _ASM_ARC_PGALLOC_H */
diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h
index 577682e8cc7f..320cc0ae8a08 100644
--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -350,6 +350,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 
 #define kern_addr_valid(addr)	(1)
 
+#define pmd_pgtable(pmd)       ((pgtable_t) pmd_page_vaddr(pmd))
+
 /*
  * remap a physical page `pfn' of size `size' with page protection `prot'
  * into virtual address `from'
diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index fdee1f04f4f3..a17f01235c29 100644
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -143,7 +143,6 @@ pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep)
 
 	__pmd_populate(pmdp, page_to_phys(ptep), prot);
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 #endif /* CONFIG_MMU */
 
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 31fbab3d6f99..8433a2058eb1 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -86,6 +86,5 @@ pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep)
 	VM_BUG_ON(mm == &init_mm);
 	__pmd_populate(pmdp, page_to_phys(ptep), PMD_TYPE_TABLE | PMD_TABLE_PXN);
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 #endif
diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
index cd211aabbefd..bbbd0698b397 100644
--- a/arch/csky/include/asm/pgalloc.h
+++ b/arch/csky/include/asm/pgalloc.h
@@ -22,8 +22,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 	set_pmd(pmd, __pmd(__pa(page_address(pte))));
 }
 
-#define pmd_pgtable(pmd) pmd_page(pmd)
-
 extern void pgd_init(unsigned long *p);
 
 static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
diff --git a/arch/hexagon/include/asm/pgtable.h b/arch/hexagon/include/asm/pgtable.h
index e4979508cddf..18cd6ea9ab23 100644
--- a/arch/hexagon/include/asm/pgtable.h
+++ b/arch/hexagon/include/asm/pgtable.h
@@ -239,7 +239,6 @@ static inline int pmd_bad(pmd_t pmd)
  * pmd_page - converts a PMD entry to a page pointer
  */
 #define pmd_page(pmd)  (pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 /**
  * pte_none - check if pte is mapped
diff --git a/arch/ia64/include/asm/pgalloc.h b/arch/ia64/include/asm/pgalloc.h
index 9601cfe83c94..0fb2b6291d58 100644
--- a/arch/ia64/include/asm/pgalloc.h
+++ b/arch/ia64/include/asm/pgalloc.h
@@ -52,7 +52,6 @@ pmd_populate(struct mm_struct *mm, pmd_t * pmd_entry, pgtable_t pte)
 {
 	pmd_val(*pmd_entry) = page_to_phys(pte);
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 static inline void
 pmd_populate_kernel(struct mm_struct *mm, pmd_t * pmd_entry, pte_t * pte)
diff --git a/arch/m68k/include/asm/mcf_pgalloc.h b/arch/m68k/include/asm/mcf_pgalloc.h
index bc1228e00518..5c2c0a864524 100644
--- a/arch/m68k/include/asm/mcf_pgalloc.h
+++ b/arch/m68k/include/asm/mcf_pgalloc.h
@@ -32,8 +32,6 @@ extern inline pmd_t *pmd_alloc_kernel(pgd_t *pgd, unsigned long address)
 
 #define pmd_populate_kernel pmd_populate
 
-#define pmd_pgtable(pmd) pfn_to_virt(pmd_val(pmd) >> PAGE_SHIFT)
-
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
 				  unsigned long address)
 {
diff --git a/arch/m68k/include/asm/motorola_pgalloc.h b/arch/m68k/include/asm/motorola_pgalloc.h
index b4fc3b4f6bb3..74a817d9387f 100644
--- a/arch/m68k/include/asm/motorola_pgalloc.h
+++ b/arch/m68k/include/asm/motorola_pgalloc.h
@@ -88,7 +88,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page
 {
 	pmd_set(pmd, page);
 }
-#define pmd_pgtable(pmd) ((pgtable_t)pmd_page_vaddr(pmd))
 
 static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 {
diff --git a/arch/m68k/include/asm/pgtable.h b/arch/m68k/include/asm/pgtable.h
index ad15d655a9bf..7be5e5e712b2 100644
--- a/arch/m68k/include/asm/pgtable.h
+++ b/arch/m68k/include/asm/pgtable.h
@@ -4,3 +4,12 @@
 #else
 #include <asm/pgtable_mm.h>
 #endif
+
+
+#if defined(CONFIG_COLDFIRE)
+#define pmd_pgtable(pmd) pfn_to_virt(pmd_val(pmd) >> PAGE_SHIFT)
+#elif defined(CONFIG_SUN3)
+#define pmd_pgtable(pmd) pmd_page(pmd)
+#else
+#define pmd_pgtable(pmd) ((pgtable_t)pmd_page_vaddr(pmd))
+#endif
diff --git a/arch/m68k/include/asm/sun3_pgalloc.h b/arch/m68k/include/asm/sun3_pgalloc.h
index 000f64869b91..198036aff519 100644
--- a/arch/m68k/include/asm/sun3_pgalloc.h
+++ b/arch/m68k/include/asm/sun3_pgalloc.h
@@ -32,7 +32,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page
 {
 	pmd_val(*pmd) = __pa((unsigned long)page_address(page));
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 /*
  * allocating and freeing a pmd is trivial: the 1-entry pmd is
diff --git a/arch/microblaze/include/asm/pgalloc.h b/arch/microblaze/include/asm/pgalloc.h
index d56b9f670ad1..6c33b05f730f 100644
--- a/arch/microblaze/include/asm/pgalloc.h
+++ b/arch/microblaze/include/asm/pgalloc.h
@@ -28,8 +28,6 @@ static inline pgd_t *get_pgd(void)
 
 #define pgd_alloc(mm)		get_pgd()
 
-#define pmd_pgtable(pmd)	pmd_page(pmd)
-
 extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm);
 
 #define __pte_free_tlb(tlb, pte, addr)	pte_free((tlb)->mm, (pte))
diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
index 8b18424b3120..dd53d0f79cb3 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -28,7 +28,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 {
 	set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 /*
  * Initialize a new pmd table with invalid pointers.
diff --git a/arch/nds32/include/asm/pgalloc.h b/arch/nds32/include/asm/pgalloc.h
index 85c117347c86..a08e1ebca70e 100644
--- a/arch/nds32/include/asm/pgalloc.h
+++ b/arch/nds32/include/asm/pgalloc.h
@@ -12,11 +12,6 @@
 #define __HAVE_ARCH_PTE_ALLOC_ONE
 #include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
 
-/*
- * Since we have only two-level page tables, these are trivial
- */
-#define pmd_pgtable(pmd) pmd_page(pmd)
-
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
 extern void pgd_free(struct mm_struct *mm, pgd_t * pgd);
 
diff --git a/arch/nios2/include/asm/pgalloc.h b/arch/nios2/include/asm/pgalloc.h
index e6600d2a5ae0..3c4ae74d5798 100644
--- a/arch/nios2/include/asm/pgalloc.h
+++ b/arch/nios2/include/asm/pgalloc.h
@@ -25,7 +25,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 {
 	set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 /*
  * Initialize a new pmd table with invalid pointers.
diff --git a/arch/openrisc/include/asm/pgalloc.h b/arch/openrisc/include/asm/pgalloc.h
index 88820299ecc4..b7b2b8d16fad 100644
--- a/arch/openrisc/include/asm/pgalloc.h
+++ b/arch/openrisc/include/asm/pgalloc.h
@@ -72,6 +72,4 @@ do {					\
 	tlb_remove_page((tlb), (pte));	\
 } while (0)
 
-#define pmd_pgtable(pmd) pmd_page(pmd)
-
 #endif
diff --git a/arch/parisc/include/asm/pgalloc.h b/arch/parisc/include/asm/pgalloc.h
index dda557085311..6a7e98e71f1d 100644
--- a/arch/parisc/include/asm/pgalloc.h
+++ b/arch/parisc/include/asm/pgalloc.h
@@ -69,6 +69,5 @@ pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
 
 #define pmd_populate(mm, pmd, pte_page) \
 	pmd_populate_kernel(mm, pmd, page_address(pte_page))
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 #endif
diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h
index 6dd78a2dc03a..3360cad78ace 100644
--- a/arch/powerpc/include/asm/pgalloc.h
+++ b/arch/powerpc/include/asm/pgalloc.h
@@ -70,9 +70,4 @@ extern struct kmem_cache *pgtable_cache[];
 #include <asm/nohash/pgalloc.h>
 #endif
 
-static inline pgtable_t pmd_pgtable(pmd_t pmd)
-{
-	return (pgtable_t)pmd_page_vaddr(pmd);
-}
-
 #endif /* _ASM_POWERPC_PGALLOC_H */
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index c6a676714f04..5969743719bc 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -152,6 +152,12 @@ static inline bool p4d_is_leaf(p4d_t p4d)
 }
 #endif
 
+#define pmd_pgtable pmd_pgtable
+static inline pgtable_t pmd_pgtable(pmd_t pmd)
+{
+	return (pgtable_t)pmd_page_vaddr(pmd);
+}
+
 #ifdef CONFIG_PPC64
 #define is_ioremap_addr is_ioremap_addr
 static inline bool is_ioremap_addr(const void *x)
diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 23b1544e0ca5..0af6933a7100 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -38,8 +38,6 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
 
-#define pmd_pgtable(pmd)	pmd_page(pmd)
-
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 {
 	pgd_t *pgd;
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 6b187cd72251..f14a555eff74 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -134,9 +134,6 @@ static inline void pmd_populate(struct mm_struct *mm,
 
 #define pmd_populate_kernel(mm, pmd, pte) pmd_populate(mm, pmd, pte)
 
-#define pmd_pgtable(pmd) \
-	((pgtable_t)__va(pmd_val(pmd) & -sizeof(pte_t)*PTRS_PER_PTE))
-
 /*
  * page table entry allocation/free routines.
  */
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 7c66ae5d7e32..b9760abe0c98 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1730,4 +1730,7 @@ extern void s390_reset_cmma(struct mm_struct *mm);
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 
+#define pmd_pgtable(pmd) \
+	((pgtable_t)__va(pmd_val(pmd) & -sizeof(pte_t)*PTRS_PER_PTE))
+
 #endif /* _S390_PAGE_H */
diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h
index 0e6b0be25e33..a9e98233c4d4 100644
--- a/arch/sh/include/asm/pgalloc.h
+++ b/arch/sh/include/asm/pgalloc.h
@@ -30,7 +30,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 {
 	set_pmd(pmd, __pmd((unsigned long)page_address(pte)));
 }
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 #define __pte_free_tlb(tlb,pte,addr)			\
 do {							\
diff --git a/arch/sparc/include/asm/pgalloc_32.h b/arch/sparc/include/asm/pgalloc_32.h
index 9d353e6dc5a9..4f73e87b22a3 100644
--- a/arch/sparc/include/asm/pgalloc_32.h
+++ b/arch/sparc/include/asm/pgalloc_32.h
@@ -51,7 +51,6 @@ static inline void free_pmd_fast(pmd_t * pmd)
 #define __pmd_free_tlb(tlb, pmd, addr)	pmd_free((tlb)->mm, pmd)
 
 #define pmd_populate(mm, pmd, pte)	pmd_set(pmd, pte)
-#define pmd_pgtable(pmd)		(pgtable_t)__pmd_page(pmd)
 
 void pmd_set(pmd_t *pmdp, pte_t *ptep);
 #define pmd_populate_kernel		pmd_populate
diff --git a/arch/sparc/include/asm/pgalloc_64.h b/arch/sparc/include/asm/pgalloc_64.h
index a8dafc550985..7b5561d17ab1 100644
--- a/arch/sparc/include/asm/pgalloc_64.h
+++ b/arch/sparc/include/asm/pgalloc_64.h
@@ -67,7 +67,6 @@ void pte_free(struct mm_struct *mm, pgtable_t ptepage);
 
 #define pmd_populate_kernel(MM, PMD, PTE)	pmd_set(MM, PMD, PTE)
 #define pmd_populate(MM, PMD, PTE)		pmd_set(MM, PMD, PTE)
-#define pmd_pgtable(PMD)			((pte_t *)pmd_page_vaddr(PMD))
 
 void pgtable_free(void *table, bool is_page);
 
diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
index 0888bda245f5..ebaf374b55ab 100644
--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -432,4 +432,6 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 /* We provide our own get_unmapped_area to cope with VA holes for userland */
 #define HAVE_ARCH_UNMAPPED_AREA
 
+#define pmd_pgtable(pmd)	((pgtable_t)__pmd_page(pmd))
+
 #endif /* !(_SPARC_PGTABLE_H) */
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index a400e0f23046..e0ee48ec3903 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1117,6 +1117,8 @@ extern unsigned long cmdline_memory_size;
 
 asmlinkage void do_sparc64_fault(struct pt_regs *regs);
 
+#define pmd_pgtable(PMD)	((pte_t *)pmd_page_vaddr(PMD))
+
 #ifdef CONFIG_HUGETLB_PAGE
 
 #define pud_leaf_size pud_leaf_size
diff --git a/arch/um/include/asm/pgalloc.h b/arch/um/include/asm/pgalloc.h
index 2bbf28cf3aa9..8ec7cd46dd96 100644
--- a/arch/um/include/asm/pgalloc.h
+++ b/arch/um/include/asm/pgalloc.h
@@ -19,7 +19,6 @@
 	set_pmd(pmd, __pmd(_PAGE_TABLE +			\
 		((unsigned long long)page_to_pfn(pte) <<	\
 			(unsigned long long) PAGE_SHIFT)))
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 /*
  * Allocate and free page tables.
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index 62ad61d6fefc..c7ec5bb88334 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -84,8 +84,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 	set_pmd(pmd, __pmd(((pteval_t)pfn << PAGE_SHIFT) | _PAGE_TABLE));
 }
 
-#define pmd_pgtable(pmd) pmd_page(pmd)
-
 #if CONFIG_PGTABLE_LEVELS > 2
 extern void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd);
 
diff --git a/arch/xtensa/include/asm/pgalloc.h b/arch/xtensa/include/asm/pgalloc.h
index d3a22da4d2c9..eeb2de3a89e5 100644
--- a/arch/xtensa/include/asm/pgalloc.h
+++ b/arch/xtensa/include/asm/pgalloc.h
@@ -25,7 +25,6 @@
 	(pmd_val(*(pmdp)) = ((unsigned long)ptep))
 #define pmd_populate(mm, pmdp, page)					     \
 	(pmd_val(*(pmdp)) = ((unsigned long)page_to_virt(page)))
-#define pmd_pgtable(pmd) pmd_page(pmd)
 
 static inline pgd_t*
 pgd_alloc(struct mm_struct *mm)
@@ -63,7 +62,6 @@ static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
 	return page;
 }
 
-#define pmd_pgtable(pmd) pmd_page(pmd)
 #endif /* CONFIG_MMU */
 
 #endif /* _XTENSA_PGALLOC_H */
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 9e6f71265f72..5fa6d69759ef 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -37,6 +37,15 @@
 #define FIRST_USER_ADDRESS	0UL
 #endif
 
+/*
+ * This defines the generic helper for accessing PMD page
+ * table page. Although platforms can still override this
+ * via their respective <asm/pgtable.h>.
+ */
+#ifndef pmd_pgtable
+#define pmd_pgtable(pmd) pmd_page(pmd)
+#endif
+
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
  *
-- 
2.20.1


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