mm: always define pxx_pgprot()

There're:

- 8 archs (arc, arm64, include, mips, powerpc, s390, sh, x86) that
support pte_pgprot().

- 2 archs (x86, sparc) that support pmd_pgprot().

- 1 arch (x86) that support pud_pgprot().

Always define them to be used in generic code, and then we don't need to
fiddle with "#ifdef"s when doing so.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Peter Xu <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Alex Williamson <[e-mail]>
Cc: Aneesh Kumar K.V <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Gavin Shan <[e-mail]>
Cc: Gerald Schaefer <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Niklas Schnelle <[e-mail]>
Cc: Paolo Bonzini <[e-mail]>
Cc: Ryan Roberts <[e-mail]>
Cc: Sean Christopherson <[e-mail]>
Cc: Sven Schnelle <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Zi Yan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/arm64/include/asm/pgtable.h

···
 /*
  * Select all bits except the pfn
  */
+#define pte_pgprot pte_pgprot
 static inline pgprot_t pte_pgprot(pte_t pte)
 {
 	unsigned long pfn = pte_pfn(pte);

arch/powerpc/include/asm/pgtable.h

···
 /*
  * Select all bits except the pfn
  */
+#define pte_pgprot pte_pgprot
 static inline pgprot_t pte_pgprot(pte_t pte)
 {
 	unsigned long pte_flags;

arch/s390/include/asm/pgtable.h

···
  * young/old accounting is not supported, i.e _PAGE_PROTECT and _PAGE_INVALID
  * must not be set.
  */
+#define pte_pgprot pte_pgprot
 static inline pgprot_t pte_pgprot(pte_t pte)
 {
 	unsigned long pte_flags = pte_val(pte) & _PAGE_CHG_MASK;

arch/sparc/include/asm/pgtable_64.h

···
 	return __pmd(pte_val(pte));
 }
 
+#define pmd_pgprot pmd_pgprot
 static inline pgprot_t pmd_pgprot(pmd_t entry)
 {
 	unsigned long val = pmd_val(entry);

include/linux/pgtable.h

···
 #define MAX_PTRS_PER_P4D PTRS_PER_P4D
 #endif
 
+#ifndef pte_pgprot
+#define pte_pgprot(x) ((pgprot_t) {0})
+#endif
+
+#ifndef pmd_pgprot
+#define pmd_pgprot(x) ((pgprot_t) {0})
+#endif
+
+#ifndef pud_pgprot
+#define pud_pgprot(x) ((pgprot_t) {0})
+#endif
+
 /* description of effects of mapping type and prot in current implementation.
  * this is due to the limited x86 page protection hardware.  The expected
  * behavior is in parens: