The patch titled
Subject: openrisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
has been added to the -mm mm-unstable branch. Its filename is
openrisc-mm-support-__have_arch_pte_swp_exclusive.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/openrisc-mm-support-__have_arch_pte_swp_exclusive.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: openrisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Date: Fri, 13 Jan 2023 18:10:15 +0100
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the
type. Generic MM currently only uses 5 bits for the type
(MAX_SWAPFILES_SHIFT), so the stolen bit is effectively unused.
While at it, mask the type in __swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-16-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Stefan Kristiansson <stefan.kristiansson@xxxxxxxxxxxxx>
Cc: Stafford Horne <shorne@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/openrisc/include/asm/pgtable.h~openrisc-mm-support-__have_arch_pte_swp_exclusive
+++ a/arch/openrisc/include/asm/pgtable.h
@@ -154,6 +154,9 @@ extern void paging_init(void);
#define _KERNPG_TABLE \
(_PAGE_BASE | _PAGE_SRE | _PAGE_SWE | _PAGE_ACCESSED | _PAGE_DIRTY)
+/* We borrow bit 11 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE _PAGE_U_SHARED
+
#define PAGE_NONE __pgprot(_PAGE_ALL)
#define PAGE_READONLY __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE)
#define PAGE_READONLY_X __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_EXEC)
@@ -385,16 +388,44 @@ static inline void update_mmu_cache(stru
/* __PHX__ FIXME, SWAP, this probably doesn't work */
-/* Encode and de-code a swap entry (must be !pte_none(e) && !pte_present(e)) */
-/* Since the PAGE_PRESENT bit is bit 4, we can use the bits above */
-
-#define __swp_type(x) (((x).val >> 5) & 0x7f)
+/*
+ * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
+ * are !pte_none() && !pte_present().
+ *
+ * Format of swap PTEs:
+ *
+ * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
+ * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
+ * <-------------- offset ---------------> E <- type --> 0 0 0 0 0
+ *
+ * E is the exclusive marker that is not stored in swap entries.
+ * The zero'ed bits include _PAGE_PRESENT.
+ */
+#define __swp_type(x) (((x).val >> 5) & 0x3f)
#define __swp_offset(x) ((x).val >> 12)
#define __swp_entry(type, offset) \
- ((swp_entry_t) { ((type) << 5) | ((offset) << 12) })
+ ((swp_entry_t) { (((type) & 0x3f) << 5) | ((offset) << 12) })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
+#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)
+{
+ pte_val(pte) |= _PAGE_SWP_EXCLUSIVE;
+ return pte;
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+ pte_val(pte) &= ~_PAGE_SWP_EXCLUSIVE;
+ return pte;
+}
+
typedef pte_t *pte_addr_t;
#endif /* __ASSEMBLY__ */
_
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
