summaryrefslogtreecommitdiff
path: root/arch/csky/abiv2
diff options
context:
space:
mode:
authorDavid Hildenbrand <david@redhat.com>2023-01-13 20:10:05 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-02-03 09:33:06 +0300
commit41e0d49104dbff888ef6446ea46842fde66c0a76 (patch)
tree80f4e075cc2fa864733031c9d47d124e03de5dba /arch/csky/abiv2
parent20aae9eff5acd8f50f72adca1176f9269a46b827 (diff)
downloadlinux-41e0d49104dbff888ef6446ea46842fde66c0a76.tar.xz
csky/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the offset. This reduces the maximum swap space per file to 16 GiB (was 32 GiB). We might actually be able to reuse one of the other software bits (_PAGE_READ / PAGE_WRITE) instead, because we only have to keep pte_present(), pte_none() and HW happy. For now, let's keep it simple because there might be something non-obvious. Link: https://lkml.kernel.org/r/20230113171026.582290-6-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Guo Ren <guoren@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/csky/abiv2')
-rw-r--r--arch/csky/abiv2/inc/abi/pgtable-bits.h19
1 files changed, 12 insertions, 7 deletions
diff --git a/arch/csky/abiv2/inc/abi/pgtable-bits.h b/arch/csky/abiv2/inc/abi/pgtable-bits.h
index 7e7f389f546f..526152bd2156 100644
--- a/arch/csky/abiv2/inc/abi/pgtable-bits.h
+++ b/arch/csky/abiv2/inc/abi/pgtable-bits.h
@@ -10,6 +10,9 @@
#define _PAGE_PRESENT (1<<10)
#define _PAGE_MODIFIED (1<<11)
+/* We borrow bit 7 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE (1<<7)
+
/* implemented in hardware */
#define _PAGE_GLOBAL (1<<0)
#define _PAGE_VALID (1<<1)
@@ -26,23 +29,25 @@
#define _PAGE_PROT_NONE _PAGE_WRITE
/*
- * Encode and decode a swap entry
+ * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
+ * are !pte_none() && !pte_present().
*
* Format of swap PTE:
* bit 0: _PAGE_GLOBAL (zero)
* bit 1: _PAGE_VALID (zero)
* bit 2 - 6: swap type
- * bit 7 - 8: swap offset[0 - 1]
+ * bit 7: exclusive marker
+ * bit 8: swap offset[0]
* bit 9: _PAGE_WRITE (zero)
* bit 10: _PAGE_PRESENT (zero)
- * bit 11 - 31: swap offset[2 - 22]
+ * bit 11 - 31: swap offset[1 - 21]
*/
#define __swp_type(x) (((x).val >> 2) & 0x1f)
-#define __swp_offset(x) ((((x).val >> 7) & 0x3) | \
- (((x).val >> 9) & 0x7ffffc))
+#define __swp_offset(x) ((((x).val >> 8) & 0x1) | \
+ (((x).val >> 10) & 0x3ffffe))
#define __swp_entry(type, offset) ((swp_entry_t) { \
((type & 0x1f) << 2) | \
- ((offset & 0x3) << 7) | \
- ((offset & 0x7ffffc) << 9)})
+ ((offset & 0x1) << 8) | \
+ ((offset & 0x3ffffe) << 10)})
#endif /* __ASM_CSKY_PGTABLE_BITS_H */