* [PATCH 1/2] arm64/mm: Move __check_safe_pte_update()
2026-09-01 6:54 [PATCH 0/2] arm64/mm: Standardize printing for pgtable entries Anshuman Khandual
@ 2026-09-01 6:54 ` Anshuman Khandual
2026-09-01 6:54 ` [PATCH 2/2] arm64/mm: Standardize printing for pgtable entries Anshuman Khandual
1 sibling, 0 replies; 3+ messages in thread
From: Anshuman Khandual @ 2026-09-01 6:54 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Anshuman Khandual, David Hildenbrand, Mike Rapoport,
Andrew Morton, Lorenzo Stoakes, Catalin Marinas, Will Deacon,
linux-kernel, linux-mm
The page table entry print helpers and related macros which are defined in
<linux/pgtable.h> will not be accessible in platform <asm/pgtable.h> which
is basically caused by cycling dependency.
Move __check_safe_pte_update() inside arch/arm64/mm/mmu.c as a preparation
for subsequent usage of the afore mentioned generic MM helpers.
This does not cause any functional change.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Should __check_safe_pte_update() be wrapped in #ifdef CONFIG_DEBUG_VM
along with dropping off current IS_ENABLED() test. That would ensure
the function never gets called when CONFIG_DEBUG_VM is disabled. That
will preserve current behaviour as the inline function gets dropped
when CONFIG_DEBUG_VM remains disabled.
arch/arm64/include/asm/pgtable.h | 47 +-------------------------------
arch/arm64/mm/mmu.c | 45 ++++++++++++++++++++++++++++++
2 files changed, 46 insertions(+), 46 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e89ec5f4787b..61fbfab3e06e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -387,52 +387,7 @@ static inline pte_t __ptep_get(pte_t *ptep)
extern void __sync_icache_dcache(pte_t pteval);
bool pgattr_change_is_safe(pteval_t old, pteval_t new);
-/*
- * PTE bits configuration in the presence of hardware Dirty Bit Management
- * (PTE_WRITE == PTE_DBM):
- *
- * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw)
- * 0 0 | 1 0 0
- * 0 1 | 1 1 0
- * 1 0 | 1 0 1
- * 1 1 | 0 1 x
- *
- * When hardware DBM is not present, the software PTE_DIRTY bit is updated via
- * the page fault mechanism. Checking the dirty status of a pte becomes:
- *
- * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY)
- */
-
-static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep,
- pte_t pte)
-{
- pte_t old_pte;
-
- if (!IS_ENABLED(CONFIG_DEBUG_VM))
- return;
-
- old_pte = __ptep_get(ptep);
-
- if (!pte_valid(old_pte) || !pte_valid(pte))
- return;
- if (mm != current->active_mm && atomic_read(&mm->mm_users) <= 1)
- return;
-
- /*
- * Check for potential race with hardware updates of the pte
- * (__ptep_set_access_flags safely changes valid ptes without going
- * through an invalid entry).
- */
- VM_WARN_ONCE(!pte_young(pte),
- "%s: racy access flag clearing: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
- VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte),
- "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
- VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)),
- "%s: unsafe attribute change: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
-}
+void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte);
static inline void __sync_cache_and_tags(pte_t pte, unsigned int nr_pages)
{
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 79d90226fd5d..e9c66d26bc0a 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -2392,4 +2392,49 @@ int arch_set_user_pkey_access(int pkey, unsigned long init_val)
return 0;
}
+
+/*
+ * PTE bits configuration in the presence of hardware Dirty Bit Management
+ * (PTE_WRITE == PTE_DBM):
+ *
+ * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw)
+ * 0 0 | 1 0 0
+ * 0 1 | 1 1 0
+ * 1 0 | 1 0 1
+ * 1 1 | 0 1 x
+ *
+ * When hardware DBM is not present, the software PTE_DIRTY bit is updated via
+ * the page fault mechanism. Checking the dirty status of a pte becomes:
+ *
+ * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY)
+ */
+void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte)
+{
+ pte_t old_pte;
+
+ if (!IS_ENABLED(CONFIG_DEBUG_VM))
+ return;
+
+ old_pte = __ptep_get(ptep);
+
+ if (!pte_valid(old_pte) || !pte_valid(pte))
+ return;
+ if (mm != current->active_mm && atomic_read(&mm->mm_users) <= 1)
+ return;
+
+ /*
+ * Check for potential race with hardware updates of the pte
+ * (__ptep_set_access_flags safely changes valid ptes without going
+ * through an invalid entry).
+ */
+ VM_WARN_ONCE(!pte_young(pte),
+ "%s: racy access flag clearing: 0x%016llx -> 0x%016llx",
+ __func__, pte_val(old_pte), pte_val(pte));
+ VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte),
+ "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx",
+ __func__, pte_val(old_pte), pte_val(pte));
+ VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)),
+ "%s: unsafe attribute change: 0x%016llx -> 0x%016llx",
+ __func__, pte_val(old_pte), pte_val(pte));
+}
#endif
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] arm64/mm: Standardize printing for pgtable entries
2026-09-01 6:54 [PATCH 0/2] arm64/mm: Standardize printing for pgtable entries Anshuman Khandual
2026-09-01 6:54 ` [PATCH 1/2] arm64/mm: Move __check_safe_pte_update() Anshuman Khandual
@ 2026-09-01 6:54 ` Anshuman Khandual
1 sibling, 0 replies; 3+ messages in thread
From: Anshuman Khandual @ 2026-09-01 6:54 UTC (permalink / raw)
To: linux-arm-kernel
Cc: Anshuman Khandual, David Hildenbrand, Mike Rapoport,
Andrew Morton, Lorenzo Stoakes, Catalin Marinas, Will Deacon,
linux-kernel, linux-mm
Standardize printing for pgtable entries using recently introduced generic
helper ptval_bytes_to_hex_str() in core MM which automatically enables 128
bits entries when added later.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/mm/fault.c | 20 +++++++++++++++-----
arch/arm64/mm/mmu.c | 16 ++++++++++------
2 files changed, 25 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 0b52557652be..c75bab3c2f4b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -130,6 +130,11 @@ static inline unsigned long mm_to_pgd_phys(struct mm_struct *mm)
*/
static void show_pte(unsigned long addr)
{
+ char pgd_str[PTVAL_STR_MAX];
+ char p4d_str[PTVAL_STR_MAX];
+ char pud_str[PTVAL_STR_MAX];
+ char pmd_str[PTVAL_STR_MAX];
+ char pte_str[PTVAL_STR_MAX];
struct mm_struct *mm;
pgd_t *pgdp;
pgd_t pgd;
@@ -156,7 +161,8 @@ static void show_pte(unsigned long addr)
vabits_actual, mm_to_pgd_phys(mm));
pgdp = pgd_offset(mm, addr);
pgd = READ_ONCE(*pgdp);
- pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd));
+ ptval_to_str(pgd_str, pgd_val(pgd));
+ pr_alert("[%016lx] pgd=%s", addr, pgd_str);
do {
p4d_t *p4dp, p4d;
@@ -169,19 +175,22 @@ static void show_pte(unsigned long addr)
p4dp = p4d_offset(pgdp, addr);
p4d = READ_ONCE(*p4dp);
- pr_cont(", p4d=%016llx", p4d_val(p4d));
+ ptval_to_str(p4d_str, p4d_val(p4d));
+ pr_cont(", p4d=%s", p4d_str);
if (p4d_none(p4d) || p4d_bad(p4d))
break;
pudp = pud_offset(p4dp, addr);
pud = READ_ONCE(*pudp);
- pr_cont(", pud=%016llx", pud_val(pud));
+ ptval_to_str(pud_str, pud_val(pud));
+ pr_cont(", pud=%s", pud_str);
if (pud_none(pud) || pud_bad(pud))
break;
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
- pr_cont(", pmd=%016llx", pmd_val(pmd));
+ ptval_to_str(pmd_str, pmd_val(pmd));
+ pr_cont(", pmd=%s", pmd_str);
if (pmd_none(pmd) || pmd_bad(pmd))
break;
@@ -190,7 +199,8 @@ static void show_pte(unsigned long addr)
break;
pte = __ptep_get(ptep);
- pr_cont(", pte=%016llx", pte_val(pte));
+ ptval_to_str(pte_str, pte_val(pte));
+ pr_cont(", pte=%s", pte_str);
pte_unmap(ptep);
} while(0);
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e9c66d26bc0a..b5de4095d650 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -2410,6 +2410,8 @@ int arch_set_user_pkey_access(int pkey, unsigned long init_val)
*/
void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte)
{
+ char pte_str_old[PTVAL_STR_MAX];
+ char pte_str[PTVAL_STR_MAX];
pte_t old_pte;
if (!IS_ENABLED(CONFIG_DEBUG_VM))
@@ -2427,14 +2429,16 @@ void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, pte_t pte)
* (__ptep_set_access_flags safely changes valid ptes without going
* through an invalid entry).
*/
+ ptval_to_str(pte_str, pte_val(pte));
+ ptval_to_str(pte_str_old, pte_val(old_pte));
VM_WARN_ONCE(!pte_young(pte),
- "%s: racy access flag clearing: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
+ "%s: racy access flag clearing: %s -> %s",
+ __func__, pte_str_old, pte_str);
VM_WARN_ONCE(pte_write(old_pte) && !pte_dirty(pte),
- "%s: racy dirty state clearing: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
+ "%s: racy dirty state clearing: %s -> %s",
+ __func__, pte_str_old, pte_str);
VM_WARN_ONCE(!pgattr_change_is_safe(pte_val(old_pte), pte_val(pte)),
- "%s: unsafe attribute change: 0x%016llx -> 0x%016llx",
- __func__, pte_val(old_pte), pte_val(pte));
+ "%s: unsafe attribute change: %s -> %s",
+ __func__, pte_str_old, pte_str);
}
#endif
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread