The patch titled
Subject: powerpc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit book3s
has been added to the -mm mm-unstable branch. Its filename is
powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s.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: David Hildenbrand <david@xxxxxxxxxx>
Subject: powerpc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit book3s
Date: Fri, 13 Jan 2023 18:10:17 +0100
We already implemented support for 64bit book3s in commit bff9beaa2e80
("powerpc/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE for book3s")
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE also in 32bit by reusing yet
unused LSB 2 / MSB 29. There seems to be no real reason why that bit
cannot be used, and reusing it avoids having to steal one bit from the
swap offset.
While at it, mask the type in __swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-18-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h~powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s
+++ a/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -42,6 +42,9 @@
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)
+/* We borrow the _PAGE_USER bit to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE _PAGE_USER
+
/* And here we include common definitions */
#define _PAGE_KERNEL_RO 0
@@ -363,17 +366,42 @@ static inline void __ptep_set_access_fla
#define pmd_page(pmd) pfn_to_page(pmd_pfn(pmd))
/*
- * Encode and decode a swap entry.
- * Note that the bits we use in a PTE for representing a swap entry
- * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used).
- * -- paulus
+ * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
+ * are !pte_none() && !pte_present().
+ *
+ * Format of swap PTEs (32bit PTEs):
+ *
+ * 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * <----------------- offset --------------------> < type -> E H P
+ *
+ * E is the exclusive marker that is not stored in swap entries.
+ * _PAGE_PRESENT (P) and __PAGE_HASHPTE (H) must be 0.
+ *
+ * For 64bit PTEs, the offset is extended by 32bit.
*/
#define __swp_type(entry) ((entry).val & 0x1f)
#define __swp_offset(entry) ((entry).val >> 5)
-#define __swp_entry(type, offset) ((swp_entry_t) { (type) | ((offset) << 5) })
+#define __swp_entry(type, offset) ((swp_entry_t) { ((type) & 0x1f) | ((offset) << 5) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) >> 3 })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val << 3 })
+#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
+static inline int pte_swp_exclusive(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
+}
+
+static inline pte_t pte_swp_mkexclusive(pte_t pte)
+{
+ return __pte(pte_val(pte) | _PAGE_SWP_EXCLUSIVE);
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+ return __pte(pte_val(pte) & ~_PAGE_SWP_EXCLUSIVE);
+}
+
/* Generic accessors to PTE bits */
static inline int pte_write(pte_t pte) { return !!(pte_val(pte) & _PAGE_RW);}
static inline int pte_read(pte_t pte) { return 1; }
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range.patch
mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range-fix.patch
mm-mprotect-drop-pgprot_t-parameter-from-change_protection.patch
mm-mprotect-drop-pgprot_t-parameter-from-change_protection-fix.patch
selftests-vm-cow-add-cow-tests-for-collapsing-of-pte-mapped-anon-thp.patch
mm-nommu-factor-out-check-for-nommu-shared-mappings-into-is_nommu_shared_mapping.patch
mm-nommu-dont-use-vm_mayshare-for-map_private-mappings.patch
drivers-misc-open-dice-dont-touch-vm_mayshare.patch
selftests-mm-define-madv_pageout-to-fix-compilation-issues.patch
mm-debug_vm_pgtable-more-pte_swp_exclusive-sanity-checks.patch
alpha-mm-support-__have_arch_pte_swp_exclusive.patch
arc-mm-support-__have_arch_pte_swp_exclusive.patch
arm-mm-support-__have_arch_pte_swp_exclusive.patch
csky-mm-support-__have_arch_pte_swp_exclusive.patch
hexagon-mm-support-__have_arch_pte_swp_exclusive.patch
ia64-mm-support-__have_arch_pte_swp_exclusive.patch
loongarch-mm-support-__have_arch_pte_swp_exclusive.patch
m68k-mm-remove-dummy-__swp-definitions-for-nommu.patch
m68k-mm-support-__have_arch_pte_swp_exclusive.patch
microblaze-mm-support-__have_arch_pte_swp_exclusive.patch
mips-mm-support-__have_arch_pte_swp_exclusive.patch
nios2-mm-refactor-swap-pte-layout.patch
nios2-mm-support-__have_arch_pte_swp_exclusive.patch
openrisc-mm-support-__have_arch_pte_swp_exclusive.patch
parisc-mm-support-__have_arch_pte_swp_exclusive.patch
powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s.patch
powerpc-nohash-mm-support-__have_arch_pte_swp_exclusive.patch
riscv-mm-support-__have_arch_pte_swp_exclusive.patch
sh-mm-support-__have_arch_pte_swp_exclusive.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-32bit.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-64bit.patch
um-mm-support-__have_arch_pte_swp_exclusive.patch
x86-mm-support-__have_arch_pte_swp_exclusive-also-on-32bit.patch
xtensa-mm-support-__have_arch_pte_swp_exclusive.patch
mm-remove-__have_arch_pte_swp_exclusive.patch
