mm/powerpc: redefine pXd_huge() with pXd_leaf()

PowerPC book3s 4K mostly has the same definition on both, except
pXd_huge() constantly returns 0 for hash MMUs. As Michael Ellerman
pointed out [1], it is safe to check _PAGE_PTE on hash MMUs, as the bit
will never be set so it will keep returning false.

As a reference, __p[mu]d_mkhuge() will trigger a BUG_ON trying to create
such huge mappings for 4K hash MMUs. Meanwhile, the major powerpc hugetlb
pgtable walker __find_linux_pte() already used pXd_leaf() to check leaf
hugetlb mappings.

The goal should be that we will have one API pXd_leaf() to detect all
kinds of huge mappings (hugepd is still special in this case, though).
AFAICT we need to use the pXd_leaf() impl (rather than pXd_huge()'s) to
make sure ie. THPs on hash MMU will also return true.

This helps to simplify a follow up patch to drop pXd_huge() treewide.

NOTE: *_leaf() definition need to be moved before the inclusion of
asm/book3s/64/pgtable-4k.h, which defines pXd_huge() with it.

[1] https://lore.kernel.org/r/[e-mail]

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Peter Xu <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: "Aneesh Kumar K.V" <[e-mail]>
Cc: "Naveen N. Rao" <[e-mail]>
Cc: Alistair Popple <[e-mail]>
Cc: Andreas Larsson <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Bjorn Andersson <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Dave Hansen <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: Konrad Dybcio <[e-mail]>
Cc: Krzysztof Kozlowski <[e-mail]>
Cc: Lucas Stach <[e-mail]>
Cc: Mark Salter <[e-mail]>
Cc: "Matthew Wilcox (Oracle)" <[e-mail]>
Cc: Mike Rapoport (IBM) <[e-mail]>
Cc: Muchun Song <[e-mail]>
Cc: Naoya Horiguchi <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Shawn Guo <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Will Deacon <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/powerpc/include/asm/book3s/64/pgtable-4k.h

···
 #ifdef CONFIG_HUGETLB_PAGE
 static inline int pmd_huge(pmd_t pmd)
 {
-	/*
-	 * leaf pte for huge page
-	 */
-	if (radix_enabled())
-		return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-	return 0;
+	return pmd_leaf(pmd);
 }
 
 static inline int pud_huge(pud_t pud)
 {
-	/*
-	 * leaf pte for huge page
-	 */
-	if (radix_enabled())
-		return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
-	return 0;
+	return pud_leaf(pud);
 }
 
 /*

arch/powerpc/include/asm/book3s/64/pgtable.h

···
 
 extern struct page *vmemmap;
 extern unsigned long pci_io_base;
+
+#define pmd_leaf pmd_leaf
+static inline bool pmd_leaf(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
+#define pud_leaf pud_leaf
+static inline bool pud_leaf(pud_t pud)
+{
+	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}
 #endif /* __ASSEMBLY__ */
 
 #include <asm/book3s/64/hash.h>
···
 		return true;
 
 	return false;
-}
-
-/*
- * Like pmd_huge(), but works regardless of config options
- */
-#define pmd_leaf pmd_leaf
-static inline bool pmd_leaf(pmd_t pmd)
-{
-	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
-#define pud_leaf pud_leaf
-static inline bool pud_leaf(pud_t pud)
-{
-	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
 }
 
 #endif /* __ASSEMBLY__ */