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| author | David Hildenbrand <david@redhat.com> | 2023-01-13 18:10:23 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-02 22:33:10 -0800 |
| commit | e2858d778e6832d8f58dc3b361f78bd9f03cd2dd (patch) | |
| tree | e970a5149921607af0121b6c251dfa9cef05eae0 | |
| parent | adf8e329ff56a873c789f797a69a330fb8c4ff9e (diff) | |
| download | lwn-e2858d778e6832d8f58dc3b361f78bd9f03cd2dd.tar.gz lwn-e2858d778e6832d8f58dc3b361f78bd9f03cd2dd.zip | |
um/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 10, which is yet
unused for swap PTEs.
The pte_mkuptodate() is a bit weird in __pte_to_swp_entry() for a swap PTE
... but it only messes with bit 1 and 2 and there is a comment in
set_pte(), so leave these bits alone.
While at it, mask the type in __swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-24-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | arch/um/include/asm/pgtable.h | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h index 4e3052f2671a..cedc5fd451ce 100644 --- a/arch/um/include/asm/pgtable.h +++ b/arch/um/include/asm/pgtable.h @@ -21,6 +21,9 @@ #define _PAGE_PROTNONE 0x010 /* if the user mapped it with PROT_NONE; pte_present gives true */ +/* We borrow bit 10 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE 0x400 + #ifdef CONFIG_3_LEVEL_PGTABLES #include <asm/pgtable-3level.h> #else @@ -288,16 +291,46 @@ extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr); #define update_mmu_cache(vma,address,ptep) do {} while (0) -/* Encode and de-code a swap entry */ +/* + * 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 1 0 + * + * E is the exclusive marker that is not stored in swap entries. + * _PAGE_NEWPAGE (bit 1) is always set to 1 in set_pte(). + */ #define __swp_type(x) (((x).val >> 5) & 0x1f) #define __swp_offset(x) ((x).val >> 11) #define __swp_entry(type, offset) \ - ((swp_entry_t) { ((type) << 5) | ((offset) << 11) }) + ((swp_entry_t) { (((type) & 0x1f) << 5) | ((offset) << 11) }) #define __pte_to_swp_entry(pte) \ ((swp_entry_t) { pte_val(pte_mkuptodate(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_get_bits(pte, _PAGE_SWP_EXCLUSIVE); +} + +static inline pte_t pte_swp_mkexclusive(pte_t pte) +{ + pte_set_bits(pte, _PAGE_SWP_EXCLUSIVE); + return pte; +} + +static inline pte_t pte_swp_clear_exclusive(pte_t pte) +{ + pte_clear_bits(pte, _PAGE_SWP_EXCLUSIVE); + return pte; +} + /* Clear a kernel PTE and flush it from the TLB */ #define kpte_clear_flush(ptep, vaddr) \ do { \ |