From f59c0924d61aa2a2bb85936a593140f327112787 Mon Sep 17 00:00:00 2001
From: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Date: Thu, 13 Nov 2025 15:28:02 +0800
Subject: mm: userfaultfd: add pgtable_supports_uffd_wp()

Some platforms can customize the PTE/PMD entry uffd-wp bit making it
unavailable even if the architecture provides the resource.  This patch
adds a macro API pgtable_supports_uffd_wp() that allows architectures to
define their specific implementations to check if the uffd-wp bit is
available on which device the kernel is running.

Also this patch is removing "ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP" and
"ifdef CONFIG_PTE_MARKER_UFFD_WP" in favor of pgtable_supports_uffd_wp()
and uffd_supports_wp_marker() checks respectively that default to
IS_ENABLED(CONFIG_HAVE_ARCH_USERFAULTFD_WP) and
"IS_ENABLED(CONFIG_HAVE_ARCH_USERFAULTFD_WP) &&
IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP)" if not overridden by the
architecture, no change in behavior is expected.

Link: https://lkml.kernel.org/r/20251113072806.795029-3-zhangchunyan@iscas.ac.cn
Signed-off-by: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Conor Dooley <conor.dooley@microchip.com>
Cc: Conor Dooley <conor@kernel.org>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/mm_inline.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'include/linux/mm_inline.h')

diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index b58f34c4fe92..fa2d6ba811b5 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -553,7 +553,6 @@ static inline pte_marker copy_pte_marker(
 
 	return dstm;
 }
-#endif
 
 /*
  * If this pte is wr-protected by uffd-wp in any form, arm the special pte to
@@ -571,9 +570,11 @@ static inline bool
 pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr,
 			      pte_t *pte, pte_t pteval)
 {
-#ifdef CONFIG_PTE_MARKER_UFFD_WP
 	bool arm_uffd_pte = false;
 
+	if (!uffd_supports_wp_marker())
+		return false;
+
 	/* The current status of the pte should be "cleared" before calling */
 	WARN_ON_ONCE(!pte_none(ptep_get(pte)));
 
@@ -602,7 +603,7 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr,
 			   make_pte_marker(PTE_MARKER_UFFD_WP));
 		return true;
 	}
-#endif
+
 	return false;
 }
 
@@ -616,6 +617,7 @@ static inline bool vma_has_recency(const struct vm_area_struct *vma)
 
 	return true;
 }
+#endif
 
 /**
  * num_pages_contiguous() - determine the number of contiguous pages
-- 
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