diff options
Diffstat (limited to 'include/linux/pagewalk.h')
| -rw-r--r-- | include/linux/pagewalk.h | 76 |
1 files changed, 73 insertions, 3 deletions
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 27cd1e59ccf7..9700a29f8afb 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -25,12 +25,15 @@ enum page_walk_lock { * this handler is required to be able to handle * pmd_trans_huge() pmds. They may simply choose to * split_huge_page() instead of handling it explicitly. - * @pte_entry: if set, called for each PTE (lowest-level) entry, - * including empty ones + * @pte_entry: if set, called for each PTE (lowest-level) entry + * including empty ones, except if @install_pte is set. + * If @install_pte is set, @pte_entry is called only for + * existing PTEs. * @pte_hole: if set, called for each hole at all levels, * depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD. * Any folded depths (where PTRS_PER_P?D is equal to 1) - * are skipped. + * are skipped. If @install_pte is specified, this will + * not trigger for any populated ranges. * @hugetlb_entry: if set, called for each hugetlb entry. This hook * function is called with the vma lock held, in order to * protect against a concurrent freeing of the pte_t* or @@ -51,6 +54,13 @@ enum page_walk_lock { * @pre_vma: if set, called before starting walk on a non-null vma. * @post_vma: if set, called after a walk on a non-null vma, provided * that @pre_vma and the vma walk succeeded. + * @install_pte: if set, missing page table entries are installed and + * thus all levels are always walked in the specified + * range. This callback is then invoked at the PTE level + * (having split any THP pages prior), providing the PTE to + * install. If allocations fail, the walk is aborted. This + * operation is only available for userland memory. Not + * usable for hugetlb ranges. * * p?d_entry callbacks are called even if those levels are folded on a * particular architecture/configuration. @@ -76,6 +86,8 @@ struct mm_walk_ops { int (*pre_vma)(unsigned long start, unsigned long end, struct mm_walk *walk); void (*post_vma)(struct mm_walk *walk); + int (*install_pte)(unsigned long addr, unsigned long next, + pte_t *ptep, struct mm_walk *walk); enum page_walk_lock walk_lock; }; @@ -130,4 +142,62 @@ int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, pgoff_t nr, const struct mm_walk_ops *ops, void *private); +typedef int __bitwise folio_walk_flags_t; + +/* + * Walk migration entries as well. Careful: a large folio might get split + * concurrently. + */ +#define FW_MIGRATION ((__force folio_walk_flags_t)BIT(0)) + +/* Walk shared zeropages (small + huge) as well. */ +#define FW_ZEROPAGE ((__force folio_walk_flags_t)BIT(1)) + +enum folio_walk_level { + FW_LEVEL_PTE, + FW_LEVEL_PMD, + FW_LEVEL_PUD, +}; + +/** + * struct folio_walk - folio_walk_start() / folio_walk_end() data + * @page: exact folio page referenced (if applicable) + * @level: page table level identifying the entry type + * @pte: pointer to the page table entry (FW_LEVEL_PTE). + * @pmd: pointer to the page table entry (FW_LEVEL_PMD). + * @pud: pointer to the page table entry (FW_LEVEL_PUD). + * @ptl: pointer to the page table lock. + * + * (see folio_walk_start() documentation for more details) + */ +struct folio_walk { + /* public */ + struct page *page; + enum folio_walk_level level; + union { + pte_t *ptep; + pud_t *pudp; + pmd_t *pmdp; + }; + union { + pte_t pte; + pud_t pud; + pmd_t pmd; + }; + /* private */ + struct vm_area_struct *vma; + spinlock_t *ptl; +}; + +struct folio *folio_walk_start(struct folio_walk *fw, + struct vm_area_struct *vma, unsigned long addr, + folio_walk_flags_t flags); + +#define folio_walk_end(__fw, __vma) do { \ + spin_unlock((__fw)->ptl); \ + if (likely((__fw)->level == FW_LEVEL_PTE)) \ + pte_unmap((__fw)->ptep); \ + vma_pgtable_walk_end(__vma); \ +} while (0) + #endif /* _LINUX_PAGEWALK_H */ |