powerpc: mm: implement *_user_accessible_page() for ptes

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 fix commit message]
Link: https://lkml.kernel.org/r/20250813062614.51759-12-ajd@linux.ibm.com
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nicholas Miehlbradt <nicholas@linux.ibm.com>
Cc: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 92d21c6faf1e57665f7078b8ca3f2c267e1ce9d4..b225967f85ea14871560ffbc75131f1376ddc0c4 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -437,6 +437,11 @@ static inline bool pte_access_permitted(pte_t pte, bool write)
        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.
  *

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index c19800365315997ffbe5d00819d6573196e9124f..48f3a41317dd75d3cc1e287df507603af99a7373 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -539,6 +539,11 @@ static inline bool pte_access_permitted(pte_t pte, bool write)
        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.
@@ -1381,5 +1386,17 @@ static inline bool is_pte_rw_upgrade(unsigned long old_val, unsigned long new_va
        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_ */

diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 7d6b9e5b286ef93f49823ee15c5ff93e10b7f159..a8bc4f24beb154929e58a8cb1f90e611f77c7790 100644 (file)
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -243,6 +243,11 @@ static inline bool pte_access_permitted(pte_t pte, bool write)
        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.
  *

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 0f73a9ade0ed4edb9026bd1775cc35fb29545481..d0938e9c33fb4d97f0908840f11d7421c84b9739 100644 (file)
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -223,6 +223,14 @@ 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 */