// SPDX-License-Identifier: GPL-2.0 #include <linux/pagewalk.h> #include <linux/hugetlb.h> #include <linux/bitops.h> #include <linux/mmu_notifier.h> #include <linux/mm_inline.h> #include <asm/cacheflush.h> #include <asm/tlbflush.h> /** * struct wp_walk - Private struct for pagetable walk callbacks * @range: Range for mmu notifiers * @tlbflush_start: Address of first modified pte * @tlbflush_end: Address of last modified pte + 1 * @total: Total number of modified ptes */ struct wp_walk { … }; /** * wp_pte - Write-protect a pte * @pte: Pointer to the pte * @addr: The start of protecting virtual address * @end: The end of protecting virtual address * @walk: pagetable walk callback argument * * The function write-protects a pte and records the range in * virtual address space of touched ptes for efficient range TLB flushes. */ static int wp_pte(pte_t *pte, unsigned long addr, unsigned long end, struct mm_walk *walk) { … } /** * struct clean_walk - Private struct for the clean_record_pte function. * @base: struct wp_walk we derive from * @bitmap_pgoff: Address_space Page offset of the first bit in @bitmap * @bitmap: Bitmap with one bit for each page offset in the address_space range * covered. * @start: Address_space page offset of first modified pte relative * to @bitmap_pgoff * @end: Address_space page offset of last modified pte relative * to @bitmap_pgoff */ struct clean_walk { … }; #define to_clean_walk(_wpwalk) … /** * clean_record_pte - Clean a pte and record its address space offset in a * bitmap * @pte: Pointer to the pte * @addr: The start of virtual address to be clean * @end: The end of virtual address to be clean * @walk: pagetable walk callback argument * * The function cleans a pte and records the range in * virtual address space of touched ptes for efficient TLB flushes. * It also records dirty ptes in a bitmap representing page offsets * in the address_space, as well as the first and last of the bits * touched. */ static int clean_record_pte(pte_t *pte, unsigned long addr, unsigned long end, struct mm_walk *walk) { … } /* * wp_clean_pmd_entry - The pagewalk pmd callback. * * Dirty-tracking should take place on the PTE level, so * WARN() if encountering a dirty huge pmd. * Furthermore, never split huge pmds, since that currently * causes dirty info loss. The pagefault handler should do * that if needed. */ static int wp_clean_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { … } /* * wp_clean_pud_entry - The pagewalk pud callback. * * Dirty-tracking should take place on the PTE level, so * WARN() if encountering a dirty huge puds. * Furthermore, never split huge puds, since that currently * causes dirty info loss. The pagefault handler should do * that if needed. */ static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end, struct mm_walk *walk) { … } /* * wp_clean_pre_vma - The pagewalk pre_vma callback. * * The pre_vma callback performs the cache flush, stages the tlb flush * and calls the necessary mmu notifiers. */ static int wp_clean_pre_vma(unsigned long start, unsigned long end, struct mm_walk *walk) { … } /* * wp_clean_post_vma - The pagewalk post_vma callback. * * The post_vma callback performs the tlb flush and calls necessary mmu * notifiers. */ static void wp_clean_post_vma(struct mm_walk *walk) { … } /* * wp_clean_test_walk - The pagewalk test_walk callback. * * Won't perform dirty-tracking on COW, read-only or HUGETLB vmas. */ static int wp_clean_test_walk(unsigned long start, unsigned long end, struct mm_walk *walk) { … } static const struct mm_walk_ops clean_walk_ops = …; static const struct mm_walk_ops wp_walk_ops = …; /** * wp_shared_mapping_range - Write-protect all ptes in an address space range * @mapping: The address_space we want to write protect * @first_index: The first page offset in the range * @nr: Number of incremental page offsets to cover * * Note: This function currently skips transhuge page-table entries, since * it's intended for dirty-tracking on the PTE level. It will warn on * encountering transhuge write-enabled entries, though, and can easily be * extended to handle them as well. * * Return: The number of ptes actually write-protected. Note that * already write-protected ptes are not counted. */ unsigned long wp_shared_mapping_range(struct address_space *mapping, pgoff_t first_index, pgoff_t nr) { … } EXPORT_SYMBOL_GPL(…); /** * clean_record_shared_mapping_range - Clean and record all ptes in an * address space range * @mapping: The address_space we want to clean * @first_index: The first page offset in the range * @nr: Number of incremental page offsets to cover * @bitmap_pgoff: The page offset of the first bit in @bitmap * @bitmap: Pointer to a bitmap of at least @nr bits. The bitmap needs to * cover the whole range @first_index..@first_index + @nr. * @start: Pointer to number of the first set bit in @bitmap. * is modified as new bits are set by the function. * @end: Pointer to the number of the last set bit in @bitmap. * none set. The value is modified as new bits are set by the function. * * When this function returns there is no guarantee that a CPU has * not already dirtied new ptes. However it will not clean any ptes not * reported in the bitmap. The guarantees are as follows: * * * All ptes dirty when the function starts executing will end up recorded * in the bitmap. * * All ptes dirtied after that will either remain dirty, be recorded in the * bitmap or both. * * If a caller needs to make sure all dirty ptes are picked up and none * additional are added, it first needs to write-protect the address-space * range and make sure new writers are blocked in page_mkwrite() or * pfn_mkwrite(). And then after a TLB flush following the write-protection * pick up all dirty bits. * * This function currently skips transhuge page-table entries, since * it's intended for dirty-tracking on the PTE level. It will warn on * encountering transhuge dirty entries, though, and can easily be extended * to handle them as well. * * Return: The number of dirty ptes actually cleaned. */ unsigned long clean_record_shared_mapping_range(struct address_space *mapping, pgoff_t first_index, pgoff_t nr, pgoff_t bitmap_pgoff, unsigned long *bitmap, pgoff_t *start, pgoff_t *end) { … } EXPORT_SYMBOL_GPL(…);
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