hugetlb: introduce generic version of huge_ptep_get

ia64, mips, parisc, powerpc, sh, sparc, x86 architectures use the same
version of huge_ptep_get, so move this generic implementation into
asm-generic/hugetlb.h.

[arnd@arndb.de: fix ARM 3level page tables]
  Link: http://lkml.kernel.org/r/20181005161722.904274-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20180920060358.16606-12-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Tested-by: Helge Deller <deller@gmx.de>			[parisc]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Acked-by: Paul Burton <paul.burton@mips.com>		[MIPS]
Acked-by: Ingo Molnar <mingo@kernel.org>		[x86]
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm/include/asm/hugetlb-3level.h

@@ -29,6 +29,7 @@
  * ptes.
  * (The valid bit is automatically cleared by set_pte_at for PROT_NONE ptes).
  */
+#define __HAVE_ARCH_HUGE_PTEP_GET
 static inline pte_t huge_ptep_get(pte_t *ptep)
 {
 	pte_t retval = *ptep;

arch/arm/include/asm/hugetlb.h

@@ -23,9 +23,8 @@
 #define _ASM_ARM_HUGETLB_H
 
 #include <asm/page.h>
-#include <asm-generic/hugetlb.h>
-
 #include <asm/hugetlb-3level.h>
+#include <asm-generic/hugetlb.h>
 
 static inline int is_hugepage_only_range(struct mm_struct *mm,
 					 unsigned long addr, unsigned long len)

arch/arm64/include/asm/hugetlb.h

@@ -20,6 +20,7 @@
 
 #include <asm/page.h>
 
+#define __HAVE_ARCH_HUGE_PTEP_GET
 static inline pte_t huge_ptep_get(pte_t *ptep)
 {
 	return READ_ONCE(*ptep);

arch/ia64/include/asm/hugetlb.h

@@ -27,11 +27,6 @@ static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 {
 }
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

arch/mips/include/asm/hugetlb.h

@@ -82,11 +82,6 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 	return changed;
 }
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

arch/parisc/include/asm/hugetlb.h

@@ -48,11 +48,6 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 					     unsigned long addr, pte_t *ptep,
 					     pte_t pte, int dirty);
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

arch/powerpc/include/asm/hugetlb.h

@@ -139,11 +139,6 @@ extern int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 				      unsigned long addr, pte_t *ptep,
 				      pte_t pte, int dirty);
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

arch/sh/include/asm/hugetlb.h

@@ -32,11 +32,6 @@ static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 {
 }
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 	clear_bit(PG_dcache_clean, &page->flags);

arch/sparc/include/asm/hugetlb.h

@@ -53,11 +53,6 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 	return changed;
 }
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

arch/x86/include/asm/hugetlb.h

@@ -13,11 +13,6 @@ static inline int is_hugepage_only_range(struct mm_struct *mm,
 	return 0;
 }
 
-static inline pte_t huge_ptep_get(pte_t *ptep)
-{
-	return *ptep;
-}
-
 static inline void arch_clear_hugepage_flags(struct page *page)
 {
 }

include/asm-generic/hugetlb.h

@@ -119,4 +119,11 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 }
 #endif
 
+#ifndef __HAVE_ARCH_HUGE_PTEP_GET
+static inline pte_t huge_ptep_get(pte_t *ptep)
+{
+	return *ptep;
+}
+#endif
+
 #endif /* _ASM_GENERIC_HUGETLB_H */