arm64/mm: Re-organize arch_make_huge_pte()

Core HugeTLB defines a fallback definition for arch_make_huge_pte(), which
calls platform provided pte_mkhuge(). But if any platform already provides
an override for arch_make_huge_pte(), then it does not need to provide the
helper pte_mkhuge().

arm64 override for arch_make_huge_pte() calls pte_mkhuge() internally, thus
creating an impression, that both of these callbacks are being used in core
HugeTLB and hence required to be defined. This drops off pte_mkhuge() which
was never required to begin with as there could not be any section mappings
at the PTE level. Re-organize arch_make_huge_pte() based on requested page
size and create the entry for the applicable page table level as needed. It
also removes a redundancy of clearing PTE_TABLE_BIT bit followed by setting
both PTE_TABLE_BIT and PTE_VALID bits (via PTE_TYPE_MASK) in the pte, while
creating CONT_PTE_SIZE size entries.

Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20241029044529.2624785-1-anshuman.khandual@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: Anshuman Khandual

arch/arm64/include/asm/pgtable.h

@@ -438,11 +438,6 @@ static inline void __set_ptes(struct mm_struct *mm,
 	}
 }
 
-/*
- * Huge pte definitions.
- */
-#define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))
-
 /*
  * Hugetlb definitions.
  */

arch/arm64/mm/hugetlbpage.c

@@ -361,14 +361,25 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
 {
 	size_t pagesize = 1UL << shift;
 
-	entry = pte_mkhuge(entry);
-	if (pagesize == CONT_PTE_SIZE) {
-		entry = pte_mkcont(entry);
-	} else if (pagesize == CONT_PMD_SIZE) {
+	switch (pagesize) {
+#ifndef __PAGETABLE_PMD_FOLDED
+	case PUD_SIZE:
+		entry = pud_pte(pud_mkhuge(pte_pud(entry)));
+		break;
+#endif
+	case CONT_PMD_SIZE:
 		entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
-	} else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
+		fallthrough;
+	case PMD_SIZE:
+		entry = pmd_pte(pmd_mkhuge(pte_pmd(entry)));
+		break;
+	case CONT_PTE_SIZE:
+		entry = pte_mkcont(entry);
+		break;
+	default:
 		pr_warn("%s: unrecognized huge page size 0x%lx\n",
 			__func__, pagesize);
+		break;
 	}
 	return entry;
 }