1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/errno.h>
6 #include <linux/slab.h>
7 #include <linux/vmalloc.h>
8 #include <linux/pagemap.h>
9 #include <linux/sched.h>
12 * get_vaddr_frames() - map virtual addresses to pfns
13 * @start: starting user address
14 * @nr_frames: number of pages / pfns from start to map
15 * @gup_flags: flags modifying lookup behaviour
16 * @vec: structure which receives pages / pfns of the addresses mapped.
17 * It should have space for at least nr_frames entries.
19 * This function maps virtual addresses from @start and fills @vec structure
20 * with page frame numbers or page pointers to corresponding pages (choice
21 * depends on the type of the vma underlying the virtual address). If @start
22 * belongs to a normal vma, the function grabs reference to each of the pages
23 * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
24 * touch page structures and the caller must make sure pfns aren't reused for
25 * anything else while he is using them.
27 * The function returns number of pages mapped which may be less than
28 * @nr_frames. In particular we stop mapping if there are more vmas of
29 * different type underlying the specified range of virtual addresses.
30 * When the function isn't able to map a single page, it returns error.
32 * This function takes care of grabbing mmap_sem as necessary.
34 int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
35 unsigned int gup_flags, struct frame_vector *vec)
37 struct mm_struct *mm = current->mm;
38 struct vm_area_struct *vma;
45 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
46 nr_frames = vec->nr_allocated;
48 down_read(&mm->mmap_sem);
50 vma = find_vma_intersection(mm, start, start + 1);
57 * While get_vaddr_frames() could be used for transient (kernel
58 * controlled lifetime) pinning of memory pages all current
59 * users establish long term (userspace controlled lifetime)
60 * page pinning. Treat get_vaddr_frames() like
61 * get_user_pages_longterm() and disallow it for filesystem-dax
64 if (vma_is_fsdax(vma)) {
69 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
72 ret = get_user_pages_locked(start, nr_frames,
73 gup_flags, (struct page **)(vec->ptrs), &locked);
78 /* This used to (racily) return non-refcounted pfns. Let people know */
79 WARN_ONCE(1, "get_vaddr_frames() cannot follow VM_IO mapping");
84 up_read(&mm->mmap_sem);
91 EXPORT_SYMBOL(get_vaddr_frames);
94 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
96 * @vec: frame vector to put
98 * Drop references to pages if get_vaddr_frames() acquired them. We also
99 * invalidate the frame vector so that it is prepared for the next call into
100 * get_vaddr_frames().
102 void put_vaddr_frames(struct frame_vector *vec)
109 pages = frame_vector_pages(vec);
111 * frame_vector_pages() might needed to do a conversion when
112 * get_vaddr_frames() got pages but vec was later converted to pfns.
113 * But it shouldn't really fail to convert pfns back...
115 if (WARN_ON(IS_ERR(pages)))
117 for (i = 0; i < vec->nr_frames; i++)
119 vec->got_ref = false;
123 EXPORT_SYMBOL(put_vaddr_frames);
126 * frame_vector_to_pages - convert frame vector to contain page pointers
127 * @vec: frame vector to convert
129 * Convert @vec to contain array of page pointers. If the conversion is
130 * successful, return 0. Otherwise return an error. Note that we do not grab
131 * page references for the page structures.
133 int frame_vector_to_pages(struct frame_vector *vec)
141 nums = frame_vector_pfns(vec);
142 for (i = 0; i < vec->nr_frames; i++)
143 if (!pfn_valid(nums[i]))
145 pages = (struct page **)nums;
146 for (i = 0; i < vec->nr_frames; i++)
147 pages[i] = pfn_to_page(nums[i]);
148 vec->is_pfns = false;
151 EXPORT_SYMBOL(frame_vector_to_pages);
154 * frame_vector_to_pfns - convert frame vector to contain pfns
155 * @vec: frame vector to convert
157 * Convert @vec to contain array of pfns.
159 void frame_vector_to_pfns(struct frame_vector *vec)
167 pages = (struct page **)(vec->ptrs);
168 nums = (unsigned long *)pages;
169 for (i = 0; i < vec->nr_frames; i++)
170 nums[i] = page_to_pfn(pages[i]);
173 EXPORT_SYMBOL(frame_vector_to_pfns);
176 * frame_vector_create() - allocate & initialize structure for pinned pfns
177 * @nr_frames: number of pfns slots we should reserve
179 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
182 struct frame_vector *frame_vector_create(unsigned int nr_frames)
184 struct frame_vector *vec;
185 int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
187 if (WARN_ON_ONCE(nr_frames == 0))
190 * This is absurdly high. It's here just to avoid strange effects when
191 * arithmetics overflows.
193 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
196 * Avoid higher order allocations, use vmalloc instead. It should
199 vec = kvmalloc(size, GFP_KERNEL);
202 vec->nr_allocated = nr_frames;
206 EXPORT_SYMBOL(frame_vector_create);
209 * frame_vector_destroy() - free memory allocated to carry frame vector
210 * @vec: Frame vector to free
212 * Free structure allocated by frame_vector_create() to carry frames.
214 void frame_vector_destroy(struct frame_vector *vec)
216 /* Make sure put_vaddr_frames() got called properly... */
217 VM_BUG_ON(vec->nr_frames > 0);
220 EXPORT_SYMBOL(frame_vector_destroy);