[RFC V1 01/16] mm: Abstract printing of pxd_val()

Anshuman Khandual
2026-02-24T05:12:41Z

Ahead of adding support for D128 pgtables, refactor places that print
PTE values to use the new __PRIpte format specifier and __PRIpte_args()
macro to prepare the argument(s). When using D128 pgtables in future,
we can simply redefine __PRIpte and __PTIpte_args().

Besides there is also an assumption about pxd_val() being always capped
at 'unsigned long long' size but that will not work for D128 pgtables.
Just increase its size to u128 if the compiler supports via a separate
data type pxdval_t which also defaults to existing 'unsigned long long'.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
include/linux/pgtable.h | 5 +++++
mm/memory.c | 29 +++++++++++++++++++----------
2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index a50df42a893f..da17139a1279 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -17,6 +17,11 @@
#include <asm-generic/pgtable_uffd.h>
#include <linux/page_table_check.h>

+#ifndef __PRIpte
+#define __PRIpte "016llx"
+#define __PRIpte_args(val) ((u64)val)
+#endif
+
#if 5 - defined(__PAGETABLE_P4D_FOLDED) - defined(__PAGETABLE_PUD_FOLDED) - \
defined(__PAGETABLE_PMD_FOLDED) != CONFIG_PGTABLE_LEVELS
#error CONFIG_PGTABLE_LEVELS is not consistent with __PAGETABLE_{P4D,PUD,PMD}_FOLDED
diff --git a/mm/memory.c b/mm/memory.c
index 07778814b4a8..cfc3077fc52f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -532,9 +532,15 @@ static bool is_bad_page_map_ratelimited(void)
return false;
}

+#ifdef __SIZEOF_INT128__
+ typedef u128 pxdval_t;
+#else
+ typedef unsigned long long pxdval_t;
+#endif
+
static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long addr)
{
- unsigned long long pgdv, p4dv, pudv, pmdv;
+ pxdval_t pgdv, p4dv, pudv, pmdv;
p4d_t p4d, *p4dp;
pud_t pud, *pudp;
pmd_t pmd, *pmdp;
@@ -548,7 +554,7 @@ static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long add
pgdv = pgd_val(*pgdp);

if (!pgd_present(*pgdp) || pgd_leaf(*pgdp)) {
- pr_alert("pgd:%08llx\n", pgdv);
+ pr_alert("pgd:%" __PRIpte "\n", __PRIpte_args(pgdv));
return;
}

@@ -557,7 +563,8 @@ static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long add
p4dv = p4d_val(p4d);

if (!p4d_present(p4d) || p4d_leaf(p4d)) {
- pr_alert("pgd:%08llx p4d:%08llx\n", pgdv, p4dv);
+ pr_alert("pgd:%" __PRIpte "p4d:%" __PRIpte "\n",
+ __PRIpte_args(pgdv), __PRIpte_args(p4dv));
return;
}

@@ -566,7 +573,8 @@ static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long add
pudv = pud_val(pud);

if (!pud_present(pud) || pud_leaf(pud)) {
- pr_alert("pgd:%08llx p4d:%08llx pud:%08llx\n", pgdv, p4dv, pudv);
+ pr_alert("pgd:%" __PRIpte "p4d:%" __PRIpte "pud:%" __PRIpte "\n",
+ __PRIpte_args(pgdv), __PRIpte_args(p4dv), __PRIpte_args(pudv));
return;
}

@@ -580,8 +588,9 @@ static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long add
* doing another map would be bad. print_bad_page_map() should
* already take care of printing the PTE.
*/
- pr_alert("pgd:%08llx p4d:%08llx pud:%08llx pmd:%08llx\n", pgdv,
- p4dv, pudv, pmdv);
+ pr_alert("pgd:%" __PRIpte "p4d:%" __PRIpte "pud:%" __PRIpte "pmd:%" __PRIpte "\n",
+ __PRIpte_args(pgdv), __PRIpte_args(p4dv),
+ __PRIpte_args(pudv), __PRIpte_args(pmdv));
}

/*
@@ -597,7 +606,7 @@ static void __print_bad_page_map_pgtable(struct mm_struct *mm, unsigned long add
* page table lock.
*/
static void print_bad_page_map(struct vm_area_struct *vma,
- unsigned long addr, unsigned long long entry, struct page *page,
+ unsigned long addr, pxdval_t entry, struct page *page,
enum pgtable_level level)
{
struct address_space *mapping;
@@ -609,8 +618,8 @@ static void print_bad_page_map(struct vm_area_struct *vma,
mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
index = linear_page_index(vma, addr);

- pr_alert("BUG: Bad page map in process %s %s:%08llx", current->comm,
- pgtable_level_to_str(level), entry);
+ pr_alert("BUG: Bad page map in process %s %s:%" __PRIpte, current->comm,
+ pgtable_level_to_str(level), __PRIpte_args(entry));
__print_bad_page_map_pgtable(vma->vm_mm, addr);
if (page)
dump_page(page, "bad page map");
@@ -695,7 +704,7 @@ static void print_bad_page_map(struct vm_area_struct *vma,
*/
static inline struct page *__vm_normal_page(struct vm_area_struct *vma,
unsigned long addr, unsigned long pfn, bool special,
- unsigned long long entry, enum pgtable_level level)
+ pxdval_t entry, enum pgtable_level level)
{
if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
if (unlikely(special)) {
--
2.43.0