From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Linu Cherian <linu.cherian@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kasan-dev@googlegroups.com
Subject: [RFC V1 07/16] arm64/mm: Convert READ_ONCE() as p4dp_get() while accessing P4D
Date: Tue, 24 Feb 2026 10:41:44 +0530 [thread overview]
Message-ID: <20260224051153.3150613-8-anshuman.khandual@arm.com> (raw)
In-Reply-To: <20260224051153.3150613-1-anshuman.khandual@arm.com>
Convert all READ_ONCE() based P4D accesses as p4dp_get() instead which will
support both D64 and D128 translation regime going forward.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@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
Cc: kasan-dev@googlegroups.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/include/asm/pgtable.h | 13 +++----------
arch/arm64/mm/fault.c | 2 +-
arch/arm64/mm/fixmap.c | 2 +-
arch/arm64/mm/hugetlbpage.c | 2 +-
arch/arm64/mm/kasan_init.c | 4 ++--
arch/arm64/mm/mmu.c | 29 +++++++++++++++++++++++------
arch/arm64/mm/pageattr.c | 2 +-
arch/arm64/mm/trans_pgd.c | 4 ++--
8 files changed, 34 insertions(+), 24 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 93d06b5de34b..24ea4e04e9a1 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1003,12 +1003,7 @@ static inline pud_t *p4d_pgtable(p4d_t p4d)
return (pud_t *)__va(p4d_page_paddr(p4d));
}
-static inline phys_addr_t pud_offset_phys(p4d_t *p4dp, unsigned long addr)
-{
- BUG_ON(!pgtable_l4_enabled());
-
- return p4d_page_paddr(READ_ONCE(*p4dp)) + pud_index(addr) * sizeof(pud_t);
-}
+phys_addr_t pud_offset_phys(p4d_t *p4dp, unsigned long addr);
static inline
pud_t *pud_offset_lockless(p4d_t *p4dp, p4d_t p4d, unsigned long addr)
@@ -1019,10 +1014,8 @@ pud_t *pud_offset_lockless(p4d_t *p4dp, p4d_t p4d, unsigned long addr)
}
#define pud_offset_lockless pud_offset_lockless
-static inline pud_t *pud_offset(p4d_t *p4dp, unsigned long addr)
-{
- return pud_offset_lockless(p4dp, READ_ONCE(*p4dp), addr);
-}
+pud_t *pud_offset(p4d_t *p4dp, unsigned long addr);
+
#define pud_offset pud_offset
static inline pud_t *pud_set_fixmap(unsigned long addr)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 64836bc14798..f41f4c628d22 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -165,7 +165,7 @@ static void show_pte(unsigned long addr)
break;
p4dp = p4d_offset(pgdp, addr);
- p4d = READ_ONCE(*p4dp);
+ p4d = p4dp_get(p4dp);
pr_cont(", p4d=%016llx", p4d_val(p4d));
if (p4d_none(p4d) || p4d_bad(p4d))
break;
diff --git a/arch/arm64/mm/fixmap.c b/arch/arm64/mm/fixmap.c
index dd58af6561e0..4c2f71929777 100644
--- a/arch/arm64/mm/fixmap.c
+++ b/arch/arm64/mm/fixmap.c
@@ -74,7 +74,7 @@ static void __init early_fixmap_init_pmd(pud_t *pudp, unsigned long addr,
static void __init early_fixmap_init_pud(p4d_t *p4dp, unsigned long addr,
unsigned long end)
{
- p4d_t p4d = READ_ONCE(*p4dp);
+ p4d_t p4d = p4dp_get(p4dp);
pud_t *pudp;
if (CONFIG_PGTABLE_LEVELS > 3 && !p4d_none(p4d) &&
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index b229c05bfbb6..15241307baec 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -288,7 +288,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
return NULL;
p4dp = p4d_offset(pgdp, addr);
- if (!p4d_present(READ_ONCE(*p4dp)))
+ if (!p4d_present(p4dp_get(p4dp)))
return NULL;
pudp = pud_offset(p4dp, addr);
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 19492ef5940a..e50c40162bce 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -89,7 +89,7 @@ static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
bool early)
{
- if (p4d_none(READ_ONCE(*p4dp))) {
+ if (p4d_none(p4dp_get(p4dp))) {
phys_addr_t pud_phys = early ?
__pa_symbol(kasan_early_shadow_pud)
: kasan_alloc_zeroed_page(node);
@@ -162,7 +162,7 @@ static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
do {
next = p4d_addr_end(addr, end);
kasan_pud_populate(p4dp, addr, next, node, early);
- } while (p4dp++, addr = next, addr != end && p4d_none(READ_ONCE(*p4dp)));
+ } while (p4dp++, addr = next, addr != end && p4d_none(p4dp_get(p4dp)));
}
static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a80d06db4de6..16ae11b29f66 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -354,7 +354,7 @@ static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end,
{
int ret = 0;
unsigned long next;
- p4d_t p4d = READ_ONCE(*p4dp);
+ p4d_t p4d = p4dp_get(p4dp);
pud_t *pudp;
if (p4d_none(p4d)) {
@@ -443,7 +443,7 @@ static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end,
}
do {
- p4d_t old_p4d = READ_ONCE(*p4dp);
+ p4d_t old_p4d = p4dp_get(p4dp);
next = p4d_addr_end(addr, end);
@@ -453,7 +453,7 @@ static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end,
goto out;
BUG_ON(p4d_val(old_p4d) != 0 &&
- p4d_val(old_p4d) != READ_ONCE(p4d_val(*p4dp)));
+ p4d_val(old_p4d) != (p4d_val(p4dp_get(p4dp))));
phys += next - addr;
} while (p4dp++, addr = next, addr != end);
@@ -1541,7 +1541,7 @@ static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr,
do {
next = p4d_addr_end(addr, end);
p4dp = p4d_offset(pgdp, addr);
- p4d = READ_ONCE(*p4dp);
+ p4d = p4dp_get(p4dp);
if (p4d_none(p4d))
continue;
@@ -1703,7 +1703,7 @@ static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr,
do {
next = p4d_addr_end(addr, end);
p4dp = p4d_offset(pgdp, addr);
- p4d = READ_ONCE(*p4dp);
+ p4d = p4dp_get(p4dp);
if (p4d_none(p4d))
continue;
@@ -1724,7 +1724,7 @@ static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr,
*/
p4dp = p4d_offset(pgdp, 0UL);
for (i = 0; i < PTRS_PER_P4D; i++) {
- if (!p4d_none(READ_ONCE(p4dp[i])))
+ if (!p4d_none(p4dp_get(p4dp + i)))
return;
}
@@ -2258,4 +2258,21 @@ int pmdp_test_and_clear_young(struct vm_area_struct *vma,
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG */
+#if CONFIG_PGTABLE_LEVELS > 3
+phys_addr_t pud_offset_phys(p4d_t *p4dp, unsigned long addr)
+{
+ p4d_t p4d = p4dp_get(p4dp);
+
+ BUG_ON(!pgtable_l4_enabled());
+
+ return p4d_page_paddr(p4d) + pud_index(addr) * sizeof(pud_t);
+}
+
+pud_t *pud_offset(p4d_t *p4dp, unsigned long addr)
+{
+ p4d_t p4d = p4dp_get(p4dp);
+
+ return pud_offset_lockless(p4dp, p4d, addr);
+}
+#endif
#endif
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 581b461d4d15..b45190507e59 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -397,7 +397,7 @@ bool kernel_page_present(struct page *page)
return false;
p4dp = p4d_offset(pgdp, addr);
- if (p4d_none(READ_ONCE(*p4dp)))
+ if (p4d_none(p4dp_get(p4dp)))
return false;
pudp = pud_offset(p4dp, addr);
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
index 71f489d439ef..75f0a6a5a43a 100644
--- a/arch/arm64/mm/trans_pgd.c
+++ b/arch/arm64/mm/trans_pgd.c
@@ -126,7 +126,7 @@ static int copy_pud(struct trans_pgd_info *info, p4d_t *dst_p4dp,
unsigned long next;
unsigned long addr = start;
- if (p4d_none(READ_ONCE(*dst_p4dp))) {
+ if (p4d_none(p4dp_get(dst_p4dp))) {
dst_pudp = trans_alloc(info);
if (!dst_pudp)
return -ENOMEM;
@@ -173,7 +173,7 @@ static int copy_p4d(struct trans_pgd_info *info, pgd_t *dst_pgdp,
src_p4dp = p4d_offset(src_pgdp, start);
do {
next = p4d_addr_end(addr, end);
- if (p4d_none(READ_ONCE(*src_p4dp)))
+ if (p4d_none(p4dp_get(src_p4dp)))
continue;
if (copy_pud(info, dst_p4dp, src_p4dp, addr, next))
return -ENOMEM;
--
2.43.0
next prev parent reply other threads:[~2026-02-24 5:13 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-24 5:11 [RFC V1 00/16] arm64/mm: Enable 128 bit page table entries Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 01/16] mm: Abstract printing of pxd_val() Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 02/16] mm: Add read-write accessors for vm_page_prot Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 03/16] mm: Replace READ_ONCE() in pud_trans_unstable() Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 04/16] perf/events: Replace READ_ONCE() with standard pgtable accessors Anshuman Khandual
2026-02-24 8:48 ` Peter Zijlstra
2026-02-24 5:11 ` [RFC V1 05/16] arm64/mm: Convert READ_ONCE() as pmdp_get() while accessing PMD Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 06/16] arm64/mm: Convert READ_ONCE() as pudp_get() while accessing PUD Anshuman Khandual
2026-02-24 5:11 ` Anshuman Khandual [this message]
2026-02-24 5:11 ` [RFC V1 08/16] arm64/mm: Convert READ_ONCE() as pgdp_get() while accessing PGD Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 09/16] arm64/mm: Route all pgtable reads via ptdesc_get() Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 10/16] arm64/mm: Route all pgtable writes via ptdesc_set() Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 11/16] arm64/mm: Route all pgtable atomics to central helpers Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 12/16] arm64/mm: Abstract printing of pxd_val() Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 13/16] arm64/mm: Override read-write accessors for vm_page_prot Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 14/16] arm64/mm: Enable fixmap with 5 level page table Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 15/16] arm64/mm: Add macros __tlb_asid_level and __tlb_range Anshuman Khandual
2026-02-24 5:11 ` [RFC V1 16/16] arm64/mm: Add initial support for FEAT_D128 page tables Anshuman Khandual
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