arm64/mm: Check PXD_TYPE_TABLE in [p4d|pgd]_bad()

JIRA: https://issues.redhat.com/browse/RHEL-101059

commit 4fa8a9c
Author: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Fri, 21 Feb 2025 10:12:24 +0530

    Check page table entries against PXD_TYPE_TABLE on PXD_TYPE_MASK mask bits
    in [p4d|pgd]_bad() while determining a table entry instead of just checking
    only for PXD_TABLE_BIT.

    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/20250221044227.1145393-6-anshuman.khandual@arm.com
    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Signed-off-by: Mark Salter <msalter@redhat.com>

Author: mosalter

arch/arm64/include/asm/pgtable.h

@@ -918,7 +918,9 @@ static inline bool mm_pud_folded(const struct mm_struct *mm)
 	pr_err("%s:%d: bad pud %016llx.\n", __FILE__, __LINE__, pud_val(e))
 
 #define p4d_none(p4d)		(pgtable_l4_enabled() && !p4d_val(p4d))
-#define p4d_bad(p4d)		(pgtable_l4_enabled() && !(p4d_val(p4d) & P4D_TABLE_BIT))
+#define p4d_bad(p4d)		(pgtable_l4_enabled() && \
+				((p4d_val(p4d) & P4D_TYPE_MASK) != \
+				 P4D_TYPE_TABLE))
 #define p4d_present(p4d)	(!p4d_none(p4d))
 
 static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
@@ -1045,7 +1047,9 @@ static inline bool mm_p4d_folded(const struct mm_struct *mm)
 	pr_err("%s:%d: bad p4d %016llx.\n", __FILE__, __LINE__, p4d_val(e))
 
 #define pgd_none(pgd)		(pgtable_l5_enabled() && !pgd_val(pgd))
-#define pgd_bad(pgd)		(pgtable_l5_enabled() && !(pgd_val(pgd) & PGD_TABLE_BIT))
+#define pgd_bad(pgd)		(pgtable_l5_enabled() && \
+				((pgd_val(pgd) & PGD_TYPE_MASK) != \
+				 PGD_TYPE_TABLE))
 #define pgd_present(pgd)	(!pgd_none(pgd))
 
 static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)