arc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by using bit 5, which is yet unused. The only important parts seems to be to not use _PAGE_PRESENT (bit 9). Link: https://lkml.kernel.org/r/20230113171026.582290-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Vineet Gupta <vgupta@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -26,6 +26,9 @@
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#define _PAGE_GLOBAL (1 << 8) /* ASID agnostic (H) */
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#define _PAGE_PRESENT (1 << 9) /* PTE/TLB Valid (H) */
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/* We borrow bit 5 to store the exclusive marker in swap PTEs. */
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#define _PAGE_SWP_EXCLUSIVE _PAGE_DIRTY
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#ifdef CONFIG_ARC_MMU_V4
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#define _PAGE_HW_SZ (1 << 10) /* Normal/super (H) */
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#else
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@ -106,9 +109,18 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
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void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
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pte_t *ptep);
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/* Encode swap {type,off} tuple into PTE
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* We reserve 13 bits for 5-bit @type, keeping bits 12-5 zero, ensuring that
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* PAGE_PRESENT is zero in a PTE holding swap "identifier"
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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 PTEs:
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*
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* 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
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* 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
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* <-------------- offset -------------> <--- zero --> E < type ->
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*
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* E is the exclusive marker that is not stored in swap entries.
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* The zero'ed bits include _PAGE_PRESENT.
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*/
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#define __swp_entry(type, off) ((swp_entry_t) \
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{ ((type) & 0x1f) | ((off) << 13) })
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@ -120,6 +132,15 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
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#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
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#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
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static inline int pte_swp_exclusive(pte_t pte)
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{
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return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
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}
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PTE_BIT_FUNC(swp_mkexclusive, |= (_PAGE_SWP_EXCLUSIVE));
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PTE_BIT_FUNC(swp_clear_exclusive, &= ~(_PAGE_SWP_EXCLUSIVE));
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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#include <asm/hugepage.h>
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#endif
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