[PATCH mm-unstable v1 14/26] nios2/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	John Hubbard <jhubbard@nvidia.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Yang Shi <shy828301@gmail.com>, Vlastimil Babka <vbabka@suse.cz>,
	Nadav Amit <namit@vmware.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Peter Xu <peterx@redhat.com>,
	linux-mm@kvack.org, x86@kernel.org, linux-alpha@vger.kernel.org,
	linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
	linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
	loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org,
	linux-mips@vger.kernel.org, openrisc@lists.librecores.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
	linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
	linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
	David Hildenbrand <david@redhat.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Subject: [PATCH mm-unstable v1 14/26] nios2/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Date: Fri, 13 Jan 2023 18:10:14 +0100	[thread overview]
Message-ID: <20230113171026.582290-15-david@redhat.com> (raw)
In-Reply-To: <20230113171026.582290-1-david@redhat.com>

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using the yet-unused bit
31.

Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/nios2/include/asm/pgtable-bits.h |  3 +++
 arch/nios2/include/asm/pgtable.h      | 22 +++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/nios2/include/asm/pgtable-bits.h b/arch/nios2/include/asm/pgtable-bits.h
index bfddff383e89..724f9b08b1d1 100644
--- a/arch/nios2/include/asm/pgtable-bits.h
+++ b/arch/nios2/include/asm/pgtable-bits.h
@@ -31,4 +31,7 @@
 #define _PAGE_ACCESSED	(1<<26)	/* page referenced */
 #define _PAGE_DIRTY	(1<<27)	/* dirty page */
 
+/* We borrow bit 31 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE	(1<<31)
+
 #endif /* _ASM_NIOS2_PGTABLE_BITS_H */
diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
index d1e5c9eb4643..05999da01731 100644
--- a/arch/nios2/include/asm/pgtable.h
+++ b/arch/nios2/include/asm/pgtable.h
@@ -239,7 +239,9 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
  *
  *   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
- *   0 < type -> 0 0 0 0 0 0 <-------------- offset --------------->
+ *   E < type -> 0 0 0 0 0 0 <-------------- offset --------------->
+ *
+ *   E is the exclusive marker that is not stored in swap entries.
  *
  * Note that the offset field is always non-zero if the swap type is 0, thus
  * !pte_none() is always true.
@@ -251,6 +253,24 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 #define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 
+#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;
+}
+
 extern void __init paging_init(void);
 extern void __init mmu_init(void);
 
-- 
2.39.0

