diff options
| author | David Hildenbrand <david@redhat.com> | 2023-01-13 18:10:15 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-02 22:33:08 -0800 |
| commit | 5ae3e74474f82613482ed67b0c234f61ac6ca2dd (patch) | |
| tree | 52957d626663b2e33e9ddda05c2d525cdfe71403 /arch/openrisc | |
| parent | 4d1d955f7c0cdbb7562d19049f859c74276fdfeb (diff) | |
| download | lwn-5ae3e74474f82613482ed67b0c234f61ac6ca2dd.tar.gz lwn-5ae3e74474f82613482ed67b0c234f61ac6ca2dd.zip | |
openrisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the
type. Generic MM currently only uses 5 bits for the type
(MAX_SWAPFILES_SHIFT), so the stolen bit is effectively unused.
While at it, mask the type in __swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-16-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/openrisc')
| -rw-r--r-- | arch/openrisc/include/asm/pgtable.h | 41 |
1 files changed, 36 insertions, 5 deletions
diff --git a/arch/openrisc/include/asm/pgtable.h b/arch/openrisc/include/asm/pgtable.h index 6477c17b3062..903b32d662ab 100644 --- a/arch/openrisc/include/asm/pgtable.h +++ b/arch/openrisc/include/asm/pgtable.h @@ -154,6 +154,9 @@ extern void paging_init(void); #define _KERNPG_TABLE \ (_PAGE_BASE | _PAGE_SRE | _PAGE_SWE | _PAGE_ACCESSED | _PAGE_DIRTY) +/* We borrow bit 11 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_U_SHARED + #define PAGE_NONE __pgprot(_PAGE_ALL) #define PAGE_READONLY __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE) #define PAGE_READONLY_X __pgprot(_PAGE_ALL | _PAGE_URE | _PAGE_SRE | _PAGE_EXEC) @@ -385,16 +388,44 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, /* __PHX__ FIXME, SWAP, this probably doesn't work */ -/* Encode and de-code a swap entry (must be !pte_none(e) && !pte_present(e)) */ -/* Since the PAGE_PRESENT bit is bit 4, we can use the bits above */ - -#define __swp_type(x) (((x).val >> 5) & 0x7f) +/* + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + * + * Format of swap PTEs: + * + * 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 + * <-------------- offset ---------------> E <- type --> 0 0 0 0 0 + * + * E is the exclusive marker that is not stored in swap entries. + * The zero'ed bits include _PAGE_PRESENT. + */ +#define __swp_type(x) (((x).val >> 5) & 0x3f) #define __swp_offset(x) ((x).val >> 12) #define __swp_entry(type, offset) \ - ((swp_entry_t) { ((type) << 5) | ((offset) << 12) }) + ((swp_entry_t) { (((type) & 0x3f) << 5) | ((offset) << 12) }) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) +#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; +} + typedef pte_t *pte_addr_t; #endif /* __ASSEMBLY__ */ |