diff options
| author | David Hildenbrand <david@redhat.com> | 2023-01-13 18:10:05 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-03 07:33:06 +0100 |
| commit | 41e0d49104dbff888ef6446ea46842fde66c0a76 (patch) | |
| tree | 80f4e075cc2fa864733031c9d47d124e03de5dba /arch/csky/abiv1 | |
| parent | arm/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE (diff) | |
| download | linux-41e0d49104dbff888ef6446ea46842fde66c0a76.tar.xz linux-41e0d49104dbff888ef6446ea46842fde66c0a76.zip | |
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/abiv1')
| -rw-r--r-- | arch/csky/abiv1/inc/abi/pgtable-bits.h | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/arch/csky/abiv1/inc/abi/pgtable-bits.h b/arch/csky/abiv1/inc/abi/pgtable-bits.h index 752c8b3f9194..ae7a2f76dd42 100644 --- a/arch/csky/abiv1/inc/abi/pgtable-bits.h +++ b/arch/csky/abiv1/inc/abi/pgtable-bits.h @@ -10,6 +10,9 @@ #define _PAGE_ACCESSED (1<<3) #define _PAGE_MODIFIED (1<<4) +/* We borrow bit 9 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE (1<<9) + /* implemented in hardware */ #define _PAGE_GLOBAL (1<<6) #define _PAGE_VALID (1<<7) @@ -26,7 +29,8 @@ #define _PAGE_PROT_NONE _PAGE_READ /* - * 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_PRESENT (zero) @@ -35,15 +39,16 @@ * bit 6: _PAGE_GLOBAL (zero) * bit 7: _PAGE_VALID (zero) * bit 8: swap type[4] - * bit 9 - 31: swap offset + * bit 9: exclusive marker + * bit 10 - 31: swap offset */ #define __swp_type(x) ((((x).val >> 2) & 0xf) | \ (((x).val >> 4) & 0x10)) -#define __swp_offset(x) ((x).val >> 9) +#define __swp_offset(x) ((x).val >> 10) #define __swp_entry(type, offset) ((swp_entry_t) { \ ((type & 0xf) << 2) | \ ((type & 0x10) << 4) | \ - ((offset) << 9)}) + ((offset) << 10)}) #define HAVE_ARCH_UNMAPPED_AREA |