From: Barry Song v-songbaohua@oppo.com
mainline inclusion from mainline-v6.9-rc1 commit ac96cc4d1ceda01d08deda1e45b9f1b55b0624d2 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I9CUEQ CVE: NA
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madvise, mprotect and some others might need folio_pte_batch to check if a range of PTEs are completely mapped to a large folio with contiguous physical addresses. Let's make it available in mm/internal.h.
While at it, add proper kernel doc and sanity-check more input parameters using two additional VM_WARN_ON_FOLIO().
[21cnbao@gmail.com: build fix] Link: https://lkml.kernel.org/r/CAGsJ_4wWzG-37D82vqP_zt+Fcbz+URVe5oXLBc4M5wbN8A_gp... [david@redhat.com: improve the doc for the exported func] Link: https://lkml.kernel.org/r/20240227104201.337988-1-21cnbao@gmail.com Signed-off-by: David Hildenbrand david@redhat.com Signed-off-by: Barry Song v-songbaohua@oppo.com Suggested-by: David Hildenbrand david@redhat.com Reviewed-by: Ryan Roberts ryan.roberts@arm.com Acked-by: David Hildenbrand david@redhat.com Cc: Lance Yang ioworker0@gmail.com Cc: Yin Fengwei fengwei.yin@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org (cherry picked from commit ac96cc4d1ceda01d08deda1e45b9f1b55b0624d2) Signed-off-by: Kefeng Wang wangkefeng.wang@huawei.com --- mm/internal.h | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++ mm/memory.c | 76 ----------------------------------------- 2 files changed, 93 insertions(+), 76 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h index ef68eddaa5d3..68c7d528b9db 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -83,6 +83,99 @@ static inline void *folio_raw_mapping(struct folio *folio) return (void *)(mapping & ~PAGE_MAPPING_FLAGS); }
+#ifdef CONFIG_MMU + +/* Flags for folio_pte_batch(). */ +typedef int __bitwise fpb_t; + +/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */ +#define FPB_IGNORE_DIRTY ((__force fpb_t)BIT(0)) + +/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */ +#define FPB_IGNORE_SOFT_DIRTY ((__force fpb_t)BIT(1)) + +static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) +{ + if (flags & FPB_IGNORE_DIRTY) + pte = pte_mkclean(pte); + if (likely(flags & FPB_IGNORE_SOFT_DIRTY)) + pte = pte_clear_soft_dirty(pte); + return pte_wrprotect(pte_mkold(pte)); +} + +/** + * folio_pte_batch - detect a PTE batch for a large folio + * @folio: The large folio to detect a PTE batch for. + * @addr: The user virtual address the first page is mapped at. + * @start_ptep: Page table pointer for the first entry. + * @pte: Page table entry for the first page. + * @max_nr: The maximum number of table entries to consider. + * @flags: Flags to modify the PTE batch semantics. + * @any_writable: Optional pointer to indicate whether any entry except the + * first one is writable. + * + * Detect a PTE batch: consecutive (present) PTEs that map consecutive + * pages of the same large folio. + * + * All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN, + * the accessed bit, writable bit, dirty bit (with FPB_IGNORE_DIRTY) and + * soft-dirty bit (with FPB_IGNORE_SOFT_DIRTY). + * + * start_ptep must map any page of the folio. max_nr must be at least one and + * must be limited by the caller so scanning cannot exceed a single page table. + * + * Return: the number of table entries in the batch. + */ +static inline int folio_pte_batch(struct folio *folio, unsigned long addr, + pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, + bool *any_writable) +{ + unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio); + const pte_t *end_ptep = start_ptep + max_nr; + pte_t expected_pte, *ptep; + bool writable; + int nr; + + if (any_writable) + *any_writable = false; + + VM_WARN_ON_FOLIO(!pte_present(pte), folio); + VM_WARN_ON_FOLIO(!folio_test_large(folio) || max_nr < 1, folio); + VM_WARN_ON_FOLIO(page_folio(pfn_to_page(pte_pfn(pte))) != folio, folio); + + nr = pte_batch_hint(start_ptep, pte); + expected_pte = __pte_batch_clear_ignored(pte_advance_pfn(pte, nr), flags); + ptep = start_ptep + nr; + + while (ptep < end_ptep) { + pte = ptep_get(ptep); + if (any_writable) + writable = !!pte_write(pte); + pte = __pte_batch_clear_ignored(pte, flags); + + if (!pte_same(pte, expected_pte)) + break; + + /* + * Stop immediately once we reached the end of the folio. In + * corner cases the next PFN might fall into a different + * folio. + */ + if (pte_pfn(pte) >= folio_end_pfn) + break; + + if (any_writable) + *any_writable |= writable; + + nr = pte_batch_hint(ptep, pte); + expected_pte = pte_advance_pfn(expected_pte, nr); + ptep += nr; + } + + return min(ptep - start_ptep, max_nr); +} +#endif /* CONFIG_MMU */ + void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio, int nr_throttled); static inline void acct_reclaim_writeback(struct folio *folio) diff --git a/mm/memory.c b/mm/memory.c index 0f463c803d4e..83f030d6818d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -958,82 +958,6 @@ static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma, set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr); }
-/* Flags for folio_pte_batch(). */ -typedef int __bitwise fpb_t; - -/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */ -#define FPB_IGNORE_DIRTY ((__force fpb_t)BIT(0)) - -/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */ -#define FPB_IGNORE_SOFT_DIRTY ((__force fpb_t)BIT(1)) - -static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) -{ - if (flags & FPB_IGNORE_DIRTY) - pte = pte_mkclean(pte); - if (likely(flags & FPB_IGNORE_SOFT_DIRTY)) - pte = pte_clear_soft_dirty(pte); - return pte_wrprotect(pte_mkold(pte)); -} - -/* - * Detect a PTE batch: consecutive (present) PTEs that map consecutive - * pages of the same folio. - * - * All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN, - * the accessed bit, writable bit, dirty bit (with FPB_IGNORE_DIRTY) and - * soft-dirty bit (with FPB_IGNORE_SOFT_DIRTY). - * - * If "any_writable" is set, it will indicate if any other PTE besides the - * first (given) PTE is writable. - */ -static inline int folio_pte_batch(struct folio *folio, unsigned long addr, - pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags, - bool *any_writable) -{ - unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio); - const pte_t *end_ptep = start_ptep + max_nr; - pte_t expected_pte, *ptep; - bool writable; - int nr; - - if (any_writable) - *any_writable = false; - - VM_WARN_ON_FOLIO(!pte_present(pte), folio); - - nr = pte_batch_hint(start_ptep, pte); - expected_pte = __pte_batch_clear_ignored(pte_advance_pfn(pte, nr), flags); - ptep = start_ptep + nr; - - while (ptep < end_ptep) { - pte = ptep_get(ptep); - if (any_writable) - writable = !!pte_write(pte); - pte = __pte_batch_clear_ignored(pte, flags); - - if (!pte_same(pte, expected_pte)) - break; - - /* - * Stop immediately once we reached the end of the folio. In - * corner cases the next PFN might fall into a different - * folio. - */ - if (pte_pfn(pte) >= folio_end_pfn) - break; - - if (any_writable) - *any_writable |= writable; - - nr = pte_batch_hint(ptep, pte); - expected_pte = pte_advance_pfn(expected_pte, nr); - ptep += nr; - } - - return min(ptep - start_ptep, max_nr); -} - /* * Copy one present PTE, trying to batch-process subsequent PTEs that map * consecutive pages of the same folio by copying them as well.