+ powerpc-mm-implement-_user_accessible_page-for-ptes.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: powerpc/mm: Implement *_user_accessible_page() for ptes
has been added to the -mm mm-new branch.  Its filename is
     powerpc-mm-implement-_user_accessible_page-for-ptes.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerpc-mm-implement-_user_accessible_page-for-ptes.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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------------------------------------------------------
From: Rohan McLure <rmclure@linux.ibm.com>
Subject: powerpc/mm: Implement *_user_accessible_page() for ptes
Date: Fri, 19 Dec 2025 04:09:42 +1100

Page table checking depends on architectures providing an implementation
of p{te,md,ud}_user_accessible_page.  With refactorisations made on
powerpc/mm, the pte_access_permitted() and similar methods verify whether
a userland page is accessible with the required permissions.

Since page table checking is the only user of
p{te,md,ud}_user_accessible_page(), implement these for all platforms,
using some of the same preliminary checks taken by pte_access_permitted()
on that platform.

Since commit 8e9bd41e4ce1 ("powerpc/nohash: Replace pte_user() by
pte_read()") pte_user() is no longer required to be present on all
platforms as it may be equivalent to or implied by pte_read().  Hence
implementations of pte_user_accessible_page() are specialised.

[ajd@linux.ibm.com: rebase and clean up]
Link: https://lkml.kernel.org/r/20251219-pgtable_check_v18rebase-v18-10-755bc151a50b@linux.ibm.com
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Guo Weikang <guoweikang.kernel@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Cc: Thomas Huth <thuth@redhat.com>
Cc: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/powerpc/include/asm/book3s/32/pgtable.h |    5 +++++
 arch/powerpc/include/asm/book3s/64/pgtable.h |   17 +++++++++++++++++
 arch/powerpc/include/asm/nohash/pgtable.h    |    5 +++++
 arch/powerpc/include/asm/pgtable.h           |    8 ++++++++
 4 files changed, 35 insertions(+)

--- a/arch/powerpc/include/asm/book3s/32/pgtable.h~powerpc-mm-implement-_user_accessible_page-for-ptes
+++ a/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -437,6 +437,11 @@ static inline bool pte_access_permitted(
 	return true;
 }
 
+static inline bool pte_user_accessible_page(pte_t pte, unsigned long addr)
+{
+	return pte_present(pte) && !is_kernel_addr(addr);
+}
+
 /* Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
  *
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h~powerpc-mm-implement-_user_accessible_page-for-ptes
+++ a/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -539,6 +539,11 @@ static inline bool pte_access_permitted(
 	return arch_pte_access_permitted(pte_val(pte), write, 0);
 }
 
+static inline bool pte_user_accessible_page(pte_t pte, unsigned long addr)
+{
+	return pte_present(pte) && pte_user(pte);
+}
+
 /*
  * Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
@@ -909,6 +914,12 @@ static inline bool pud_access_permitted(
 	return pte_access_permitted(pud_pte(pud), write);
 }
 
+#define pud_user_accessible_page pud_user_accessible_page
+static inline bool pud_user_accessible_page(pud_t pud, unsigned long addr)
+{
+	return pud_leaf(pud) && pte_user_accessible_page(pud_pte(pud), addr);
+}
+
 #define __p4d_raw(x)	((p4d_t) { __pgd_raw(x) })
 static inline __be64 p4d_raw(p4d_t x)
 {
@@ -1074,6 +1085,12 @@ static inline bool pmd_access_permitted(
 	return pte_access_permitted(pmd_pte(pmd), write);
 }
 
+#define pmd_user_accessible_page pmd_user_accessible_page
+static inline bool pmd_user_accessible_page(pmd_t pmd, unsigned long addr)
+{
+	return pmd_leaf(pmd) && pte_user_accessible_page(pmd_pte(pmd), addr);
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
 extern pud_t pfn_pud(unsigned long pfn, pgprot_t pgprot);
--- a/arch/powerpc/include/asm/nohash/pgtable.h~powerpc-mm-implement-_user_accessible_page-for-ptes
+++ a/arch/powerpc/include/asm/nohash/pgtable.h
@@ -243,6 +243,11 @@ static inline bool pte_access_permitted(
 	return true;
 }
 
+static inline bool pte_user_accessible_page(pte_t pte, unsigned long addr)
+{
+	return pte_present(pte) && !is_kernel_addr(addr);
+}
+
 /* Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
  *
--- a/arch/powerpc/include/asm/pgtable.h~powerpc-mm-implement-_user_accessible_page-for-ptes
+++ a/arch/powerpc/include/asm/pgtable.h
@@ -202,6 +202,14 @@ static inline bool arch_supports_memmap_
 
 #endif /* CONFIG_PPC64 */
 
+#ifndef pmd_user_accessible_page
+#define pmd_user_accessible_page(pmd, addr)	false
+#endif
+
+#ifndef pud_user_accessible_page
+#define pud_user_accessible_page(pud, addr)	false
+#endif
+
 #endif /* __ASSEMBLER__ */
 
 #endif /* _ASM_POWERPC_PGTABLE_H */
_

Patches currently in -mm which might be from rmclure@linux.ibm.com are

mm-page_table_check-reinstate-address-parameter-in-page_table_check_pud_set.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pmd_set.patch
mm-page_table_check-provide-addr-parameter-to-page_table_check_ptes_set.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pud_clear.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pmd_clear.patch
mm-page_table_check-reinstate-address-parameter-in-page_table_check_pte_clear.patch
mm-provide-address-parameter-to-ptemdud_user_accessible_page.patch
powerpc-mm-implement-_user_accessible_page-for-ptes.patch
powerpc-mm-use-set_pte_at_unchecked-for-internal-usages.patch
powerpc-mm-support-page-table-check.patch