Subject: [PATCH RFC 07/13] mm/arm: Redefine pmd_huge() with pmd_leaf()

From: [email-masked]
Date: Wed, 6 Mar 2024 18:41:41 +0800

From: Peter Xu <[email-masked]>

Most of the archs already define these two APIs the same way.  ARM is more
complicated in two aspects:

  - For pXd_huge() it's always checking against !PXD_TABLE_BIT, while for
    pXd_leaf() it's always checking against PXD_TYPE_SECT.

  - SECT/TABLE bits are defined differently on 2-level v.s. 3-level ARM
    pgtables, which makes the whole thing even harder to follow.

Luckily, the second complexity should be hidden by the pmd_leaf()
implementation against 2-level v.s. 3-level headers.  Invoke pmd_leaf()
directly for pmd_huge(), to remove the first part of complexity.  This
prepares to drop pXd_huge() API globally.

When at it, drop the obsolete comments - it's outdated.

Cc: Russell King <[email-masked]>
Cc: Shawn Guo <[email-masked]>
Cc: Krzysztof Kozlowski <[email-masked]>
Cc: Bjorn Andersson <[email-masked]>
Cc: Arnd Bergmann <[email-masked]>
Cc: Konrad Dybcio <[email-masked]>
Cc: Fabio Estevam <[email-masked]>
Cc: [email-masked]
Signed-off-by: Peter Xu <[email-masked]>
---
 arch/arm/mm/hugetlbpage.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/arm/mm/hugetlbpage.c b/arch/arm/mm/hugetlbpage.c
index dd7a0277c5c0..c2fa643f6bb5 100644
--- a/arch/arm/mm/hugetlbpage.c
+++ b/arch/arm/mm/hugetlbpage.c
@@ -18,11 +18,6 @@
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
 
-/*
- * On ARM, huge pages are backed by pmd's rather than pte's, so we do a lot
- * of type casting from pmd_t * to pte_t *.
- */
-
 int pud_huge(pud_t pud)
 {
 	return 0;
@@ -30,5 +25,5 @@ int pud_huge(pud_t pud)
 
 int pmd_huge(pmd_t pmd)
 {
-	return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
+	return pmd_leaf(pmd);
 }
-- 
2.44.0