arm64/mm: Redefine CONT_{PTE, PMD}_SHIFT

Currently, the value of CONT_{PTE, PMD}_SHIFT is off from standard
{PAGE, PMD}_SHIFT. In turn, we have to consider adding {PAGE, PMD}_SHIFT
when using CONT_{PTE, PMD}_SHIFT in the function hugetlbpage_init().
It's a bit confusing.

This redefines CONT_{PTE, PMD}_SHIFT with {PAGE, PMD}_SHIFT included
so that the later values needn't be added when using the former ones
in function hugetlbpage_init(). Note that the values of CONT_{PTES, PMDS}
are unchanged.

Suggested-by: Will Deacon <[email protected]>
Signed-off-by: Gavin Shan <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Link: https://lkml.org/lkml/2020/5/6/190
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: Gavin Shan

arch/arm64/include/asm/pgtable-hwdef.h

@@ -82,20 +82,20 @@
  * Contiguous page definitions.
  */
 #ifdef CONFIG_ARM64_64K_PAGES
-#define CONT_PTE_SHIFT		5
-#define CONT_PMD_SHIFT		5
+#define CONT_PTE_SHIFT		(5 + PAGE_SHIFT)
+#define CONT_PMD_SHIFT		(5 + PMD_SHIFT)
 #elif defined(CONFIG_ARM64_16K_PAGES)
-#define CONT_PTE_SHIFT		7
-#define CONT_PMD_SHIFT		5
+#define CONT_PTE_SHIFT		(7 + PAGE_SHIFT)
+#define CONT_PMD_SHIFT		(5 + PMD_SHIFT)
 #else
-#define CONT_PTE_SHIFT		4
-#define CONT_PMD_SHIFT		4
+#define CONT_PTE_SHIFT		(4 + PAGE_SHIFT)
+#define CONT_PMD_SHIFT		(4 + PMD_SHIFT)
 #endif
 
-#define CONT_PTES		(1 << CONT_PTE_SHIFT)
+#define CONT_PTES		(1 << (CONT_PTE_SHIFT - PAGE_SHIFT))
 #define CONT_PTE_SIZE		(CONT_PTES * PAGE_SIZE)
 #define CONT_PTE_MASK		(~(CONT_PTE_SIZE - 1))
-#define CONT_PMDS		(1 << CONT_PMD_SHIFT)
+#define CONT_PMDS		(1 << (CONT_PMD_SHIFT - PMD_SHIFT))
 #define CONT_PMD_SIZE		(CONT_PMDS * PMD_SIZE)
 #define CONT_PMD_MASK		(~(CONT_PMD_SIZE - 1))
 /* the the numerical offset of the PTE within a range of CONT_PTES */

arch/arm64/mm/hugetlbpage.c

@@ -457,9 +457,9 @@ static int __init hugetlbpage_init(void)
 #ifdef CONFIG_ARM64_4K_PAGES
 	hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 #endif
-	hugetlb_add_hstate((CONT_PMD_SHIFT + PMD_SHIFT) - PAGE_SHIFT);
+	hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
 	hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
-	hugetlb_add_hstate((CONT_PTE_SHIFT + PAGE_SHIFT) - PAGE_SHIFT);
+	hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
 
 	return 0;
 }