The patch titled
Subject: powerpc: mm: implement *_user_accessible_page() for ptes
has been added to the -mm mm-unstable 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-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Rohan McLure <rmclure@xxxxxxxxxxxxx>
Subject: powerpc: mm: implement *_user_accessible_page() for ptes
Date: Wed, 12 Feb 2025 03:14:02 +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@xxxxxxxxxxxxx: rebase and fix commit message]
Link: https://lkml.kernel.org/r/20250211161404.850215-10-ajd@xxxxxxxxxxxxx
Signed-off-by: Rohan McLure <rmclure@xxxxxxxxxxxxx>
Signed-off-by: Andrew Donnellan <ajd@xxxxxxxxxxxxx>
Reviewed-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Sweet Tea Dorminy <sweettea-kernel@xxxxxxxxxx>
Cc: <x86@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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
@@ -540,6 +540,11 @@ 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.
@@ -1431,5 +1436,17 @@ static inline bool is_pte_rw_upgrade(uns
return false;
}
+#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);
+}
+
+#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);
+}
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */
--- 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
@@ -224,6 +224,14 @@ static inline int pud_pfn(pud_t pud)
}
#endif
+#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 /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_PGTABLE_H */
_
Patches currently in -mm which might be from rmclure@xxxxxxxxxxxxx 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_pte_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-add-pud_pfn-stub.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
