linux-kernel - [PATCH v4 06/16] arm64/mm: pte_clear(): New layer to manage contig bit

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Message-Id: <20231218105100.172635-7-ryan.roberts@arm.com>
Date: Mon, 18 Dec 2023 10:50:50 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Ard Biesheuvel <ardb@...nel.org>,
	Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Matthew Wilcox <willy@...radead.org>,
	Yu Zhao <yuzhao@...gle.com>,
	Mark Rutland <mark.rutland@....com>,
	David Hildenbrand <david@...hat.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	John Hubbard <jhubbard@...dia.com>,
	Zi Yan <ziy@...dia.com>,
	Barry Song <21cnbao@...il.com>,
	Alistair Popple <apopple@...dia.com>,
	Yang Shi <shy828301@...il.com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v4 06/16] arm64/mm: pte_clear(): New layer to manage contig bit

Create a new layer for the in-table PTE manipulation APIs. For now, The
existing API is prefixed with double underscore to become the
arch-private API and the public API is just a simple wrapper that calls
the private API.

The public API implementation will subsequently be used to transparently
manipulate the contiguous bit where appropriate. But since there are
already some contig-aware users (e.g. hugetlb, kernel mapper), we must
first ensure those users use the private API directly so that the future
contig-bit manipulations in the public API do not interfere with those
existing uses.

Tested-by: John Hubbard <jhubbard@...dia.com>
Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 arch/arm64/include/asm/pgtable.h | 3 ++-
 arch/arm64/mm/fixmap.c           | 2 +-
 arch/arm64/mm/hugetlbpage.c      | 2 +-
 arch/arm64/mm/mmu.c              | 2 +-
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 323ec91add60..1464e990580a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -93,7 +93,7 @@ static inline pteval_t __phys_to_pte_val(phys_addr_t phys)
 	__pte(__phys_to_pte_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
 
 #define pte_none(pte)		(!pte_val(pte))
-#define pte_clear(mm, addr, ptep) \
+#define __pte_clear(mm, addr, ptep) \
 				__set_pte(ptep, __pte(0))
 #define pte_page(pte)		(pfn_to_page(pte_pfn(pte)))
 
@@ -1121,6 +1121,7 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
 
 #define set_pte					__set_pte
 #define set_ptes				__set_ptes
+#define pte_clear				__pte_clear
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm64/mm/fixmap.c b/arch/arm64/mm/fixmap.c
index 51cd4501816d..bfc02568805a 100644
--- a/arch/arm64/mm/fixmap.c
+++ b/arch/arm64/mm/fixmap.c
@@ -123,7 +123,7 @@ void __set_fixmap(enum fixed_addresses idx,
 	if (pgprot_val(flags)) {
 		__set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags));
 	} else {
-		pte_clear(&init_mm, addr, ptep);
+		__pte_clear(&init_mm, addr, ptep);
 		flush_tlb_kernel_range(addr, addr+PAGE_SIZE);
 	}
 }
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 741cb53672fd..510b2d4b89a9 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -400,7 +400,7 @@ void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 	ncontig = num_contig_ptes(sz, &pgsize);
 
 	for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
-		pte_clear(mm, addr, ptep);
+		__pte_clear(mm, addr, ptep);
 }
 
 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e884279b268e..080e9b50f595 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -859,7 +859,7 @@ static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,
 			continue;
 
 		WARN_ON(!pte_present(pte));
-		pte_clear(&init_mm, addr, ptep);
+		__pte_clear(&init_mm, addr, ptep);
 		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 		if (free_mapped)
 			free_hotplug_page_range(pte_page(pte),
-- 
2.25.1