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Message-Id: <20221206144730.163732-24-david@redhat.com>
Date: Tue, 6 Dec 2022 15:47:27 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
John Hubbard <jhubbard@...dia.com>,
Jason Gunthorpe <jgg@...dia.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Yang Shi <shy828301@...il.com>,
Vlastimil Babka <vbabka@...e.cz>,
Nadav Amit <namit@...are.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Peter Xu <peterx@...hat.com>, linux-mm@...ck.org,
x86@...nel.org, linux-alpha@...r.kernel.org,
linux-snps-arc@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
loongarch@...ts.linux.dev, linux-m68k@...ts.linux-m68k.org,
linux-mips@...r.kernel.org, openrisc@...ts.librecores.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org,
David Hildenbrand <david@...hat.com>,
Richard Weinberger <richard@....at>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Johannes Berg <johannes@...solutions.net>
Subject: [PATCH mm-unstable RFC 23/26] um/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 10, which is
yet unused for swap PTEs.
The pte_mkuptodate() is a bit weird in __pte_to_swp_entry() for a swap PTE
... but it only messes with bit 1 and 2 and there is a comment in
set_pte(), so leave these bits alone.
While at it, mask the type in __swp_entry().
Cc: Richard Weinberger <richard@....at>
Cc: Anton Ivanov <anton.ivanov@...bridgegreys.com>
Cc: Johannes Berg <johannes@...solutions.net>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
arch/um/include/asm/pgtable.h | 37 +++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index 4e3052f2671a..cedc5fd451ce 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -21,6 +21,9 @@
#define _PAGE_PROTNONE 0x010 /* if the user mapped it with PROT_NONE;
pte_present gives true */
+/* We borrow bit 10 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE 0x400
+
#ifdef CONFIG_3_LEVEL_PGTABLES
#include <asm/pgtable-3level.h>
#else
@@ -288,16 +291,46 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
#define update_mmu_cache(vma,address,ptep) do {} while (0)
-/* Encode and de-code a swap entry */
+/*
+ * 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 1 0
+ *
+ * E is the exclusive marker that is not stored in swap entries.
+ * _PAGE_NEWPAGE (bit 1) is always set to 1 in set_pte().
+ */
#define __swp_type(x) (((x).val >> 5) & 0x1f)
#define __swp_offset(x) ((x).val >> 11)
#define __swp_entry(type, offset) \
- ((swp_entry_t) { ((type) << 5) | ((offset) << 11) })
+ ((swp_entry_t) { (((type) & 0x1f) << 5) | ((offset) << 11) })
#define __pte_to_swp_entry(pte) \
((swp_entry_t) { pte_val(pte_mkuptodate(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_get_bits(pte, _PAGE_SWP_EXCLUSIVE);
+}
+
+static inline pte_t pte_swp_mkexclusive(pte_t pte)
+{
+ pte_set_bits(pte, _PAGE_SWP_EXCLUSIVE);
+ return pte;
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+ pte_clear_bits(pte, _PAGE_SWP_EXCLUSIVE);
+ return pte;
+}
+
/* Clear a kernel PTE and flush it from the TLB */
#define kpte_clear_flush(ptep, vaddr) \
do { \
--
2.38.1
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