linux-kernel - [PATCH RFC 08/13] mm/arm64: Merge pXd_huge() and pXd

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Date: Wed,  6 Mar 2024 18:41:42 +0800
From: peterx@...hat.com
To: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc: linuxppc-dev@...ts.ozlabs.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>,
	Jason Gunthorpe <jgg@...dia.com>,
	peterx@...hat.com,
	Matthew Wilcox <willy@...radead.org>,
	Mike Rapoport <rppt@...nel.org>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	x86@...nel.org,
	sparclinux@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Mark Salter <msalter@...hat.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>
Subject: [PATCH RFC 08/13] mm/arm64: Merge pXd_huge() and pXd_leaf() definitions

From: Peter Xu <peterx@...hat.com>

Unlike most archs, aarch64 defines pXd_huge() and pXd_leaf() slightly
differently.  Redefine the pXd_huge() with pXd_leaf().

There used to be two traps for old aarch64 definitions over these APIs that
I found when reading the code around, they're:

 (1) 4797ec2dc83a ("arm64: fix pud_huge() for 2-level pagetables")
 (2) 23bc8f69f0ec ("arm64: mm: fix p?d_leaf()")

Define pXd_huge() with the current pXd_leaf() will make sure (2) isn't a
problem (on PROT_NONE checks). To make sure it also works for (1), we move
over the __PAGETABLE_PMD_FOLDED check to pud_leaf(), allowing it to
constantly returning "false" for 2-level pgtables, which looks even safer
to cover both now.

Cc: Muchun Song <muchun.song@...ux.dev>
Cc: Mark Salter <msalter@...hat.com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/arm64/include/asm/pgtable.h | 4 ++++
 arch/arm64/mm/hugetlbpage.c      | 8 ++------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 401087e8a43d..14d24c357c7a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -704,7 +704,11 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!pud_table(pud))
 #define pud_present(pud)	pte_present(pud_pte(pud))
+#ifndef __PAGETABLE_PMD_FOLDED
 #define pud_leaf(pud)		(pud_present(pud) && !pud_table(pud))
+#else
+#define pud_leaf(pud)		false
+#endif
 #define pud_valid(pud)		pte_valid(pud_pte(pud))
 #define pud_user(pud)		pte_user(pud_pte(pud))
 #define pud_user_exec(pud)	pte_user_exec(pud_pte(pud))
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 0f0e10bb0a95..1234bbaef5bf 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -81,16 +81,12 @@ bool arch_hugetlb_migration_supported(struct hstate *h)
 
 int pmd_huge(pmd_t pmd)
 {
-	return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
+	return pmd_leaf(pmd);
 }
 
 int pud_huge(pud_t pud)
 {
-#ifndef __PAGETABLE_PMD_FOLDED
-	return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
-#else
-	return 0;
-#endif
+	return pud_leaf(pud);
 }
 
 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
-- 
2.44.0