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41e0d49104
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>
55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_CSKY_PGTABLE_BITS_H
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#define __ASM_CSKY_PGTABLE_BITS_H
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/* implemented in software */
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#define _PAGE_PRESENT (1<<0)
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#define _PAGE_READ (1<<1)
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#define _PAGE_WRITE (1<<2)
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#define _PAGE_ACCESSED (1<<3)
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#define _PAGE_MODIFIED (1<<4)
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/* We borrow bit 9 to store the exclusive marker in swap PTEs. */
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#define _PAGE_SWP_EXCLUSIVE (1<<9)
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/* implemented in hardware */
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#define _PAGE_GLOBAL (1<<6)
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#define _PAGE_VALID (1<<7)
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#define _PAGE_DIRTY (1<<8)
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#define _PAGE_CACHE (3<<9)
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#define _PAGE_UNCACHE (2<<9)
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#define _PAGE_SO _PAGE_UNCACHE
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#define _CACHE_MASK (7<<9)
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#define _CACHE_CACHED _PAGE_CACHE
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#define _CACHE_UNCACHED _PAGE_UNCACHE
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#define _PAGE_PROT_NONE _PAGE_READ
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/*
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* Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
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* are !pte_none() && !pte_present().
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*
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* Format of swap PTE:
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* bit 0: _PAGE_PRESENT (zero)
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* bit 1: _PAGE_READ (zero)
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* bit 2 - 5: swap type[0 - 3]
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* bit 6: _PAGE_GLOBAL (zero)
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* bit 7: _PAGE_VALID (zero)
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* bit 8: swap type[4]
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* bit 9: exclusive marker
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* bit 10 - 31: swap offset
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*/
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#define __swp_type(x) ((((x).val >> 2) & 0xf) | \
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(((x).val >> 4) & 0x10))
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#define __swp_offset(x) ((x).val >> 10)
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#define __swp_entry(type, offset) ((swp_entry_t) { \
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((type & 0xf) << 2) | \
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((type & 0x10) << 4) | \
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((offset) << 10)})
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#define HAVE_ARCH_UNMAPPED_AREA
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#endif /* __ASM_CSKY_PGTABLE_BITS_H */
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