linux-kernel - [PATCH v1 5/7] s390/pgtable: support __HAVE_ARCH_PTE_SWP

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Message-Id: <20220315141837.137118-6-david@redhat.com>
Date:   Tue, 15 Mar 2022 15:18:35 +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>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Yang Shi <shy828301@...il.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Nadav Amit <namit@...are.com>, Rik van Riel <riel@...riel.com>,
        Roman Gushchin <guro@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Donald Dutile <ddutile@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Oleg Nesterov <oleg@...hat.com>, Jan Kara <jack@...e.cz>,
        Liang Zhang <zhangliang5@...wei.com>,
        Pedro Gomes <pedrodemargomes@...il.com>,
        Oded Gabbay <oded.gabbay@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, linux-mm@...ck.org,
        x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        David Hildenbrand <david@...hat.com>
Subject: [PATCH v1 5/7] s390/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

Let's steal one bit from the offset. While at it, document the meaning
of bit 62 for swap ptes.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/s390/include/asm/pgtable.h | 37 ++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 008a6c856fa4..c182212a2b44 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -181,6 +181,8 @@ static inline int is_module_addr(void *addr)
 #define _PAGE_SOFT_DIRTY 0x000
 #endif
 
+#define _PAGE_SWP_EXCLUSIVE _PAGE_LARGE	/* SW pte exclusive swap bit */
+
 /* Set of bits not changed in pte_modify */
 #define _PAGE_CHG_MASK		(PAGE_MASK | _PAGE_SPECIAL | _PAGE_DIRTY | \
 				 _PAGE_YOUNG | _PAGE_SOFT_DIRTY)
@@ -796,6 +798,24 @@ static inline int pmd_protnone(pmd_t pmd)
 }
 #endif
 
+#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
+static inline pte_t pte_swp_mkexclusive(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_SWP_EXCLUSIVE;
+	return pte;
+}
+
+static inline int pte_swp_exclusive(pte_t pte)
+{
+	return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+	pte_val(pte) &= ~_PAGE_SWP_EXCLUSIVE;
+	return pte;
+}
+
 static inline int pte_soft_dirty(pte_t pte)
 {
 	return pte_val(pte) & _PAGE_SOFT_DIRTY;
@@ -1675,16 +1695,19 @@ static inline int has_transparent_hugepage(void)
  * information in the lowcore.
  * Bits 54 and 63 are used to indicate the page type.
  * A swap pte is indicated by bit pattern (pte & 0x201) == 0x200
- * This leaves the bits 0-51 and bits 56-62 to store type and offset.
- * We use the 5 bits from 57-61 for the type and the 52 bits from 0-51
+ * This leaves the bits 0-50 and bits 56-61 to store type and offset.
+ * We use the 5 bits from 57-61 for the type and the 51 bits from 0-50
  * for the offset.
- * |			  offset			|01100|type |00|
- * |0000000000111111111122222222223333333333444444444455|55555|55566|66|
- * |0123456789012345678901234567890123456789012345678901|23456|78901|23|
+ * |			  offset		       |E|01100|type |S0|
+ * |000000000011111111112222222222333333333344444444445|5|55555|55566|66|
+ * |012345678901234567890123456789012345678901234567890|1|23456|78901|23|
+ *
+ * S (bit 62) is used for softdirty tracking.
+ * E (bit 51) is used to remember PG_anon_exclusive.
  */
 
-#define __SWP_OFFSET_MASK	((1UL << 52) - 1)
-#define __SWP_OFFSET_SHIFT	12
+#define __SWP_OFFSET_MASK	((1UL << 51) - 1)
+#define __SWP_OFFSET_SHIFT	13
 #define __SWP_TYPE_MASK		((1UL << 5) - 1)
 #define __SWP_TYPE_SHIFT	2
 
-- 
2.35.1