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>
11 #include <media/frame_vector.h>
14 * get_vaddr_frames() - map virtual addresses to pfns
15 * @start: starting user address
16 * @nr_frames: number of pages / pfns from start to map
17 * @vec: structure which receives pages / pfns of the addresses mapped.
18 * It should have space for at least nr_frames entries.
20 * This function maps virtual addresses from @start and fills @vec structure
21 * with page frame numbers or page pointers to corresponding pages (choice
22 * depends on the type of the vma underlying the virtual address). If @start
23 * belongs to a normal vma, the function grabs reference to each of the pages
24 * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
25 * touch page structures and the caller must make sure pfns aren't reused for
26 * anything else while he is using them.
28 * The function returns number of pages mapped which may be less than
29 * @nr_frames. In particular we stop mapping if there are more vmas of
30 * different type underlying the specified range of virtual addresses.
31 * When the function isn't able to map a single page, it returns error.
33 * This function takes care of grabbing mmap_lock as necessary.
35 int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
36 struct frame_vector *vec)
38 struct mm_struct *mm = current->mm;
39 struct vm_area_struct *vma;
46 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
47 nr_frames = vec->nr_allocated;
49 start = untagged_addr(start);
51 ret = pin_user_pages_fast(start, nr_frames,
52 FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
53 (struct page **)(vec->ptrs));
65 unsigned long *nums = frame_vector_pfns(vec);
67 vma = find_vma_intersection(mm, start, start + 1);
71 while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
72 err = follow_pfn(vma, start, &nums[ret]);
81 /* Bail out if VMA doesn't completely cover the tail page. */
82 if (start < vma->vm_end)
84 } while (ret < nr_frames);
94 EXPORT_SYMBOL(get_vaddr_frames);
97 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
99 * @vec: frame vector to put
101 * Drop references to pages if get_vaddr_frames() acquired them. We also
102 * invalidate the frame vector so that it is prepared for the next call into
103 * get_vaddr_frames().
105 void put_vaddr_frames(struct frame_vector *vec)
111 pages = frame_vector_pages(vec);
113 * frame_vector_pages() might needed to do a conversion when
114 * get_vaddr_frames() got pages but vec was later converted to pfns.
115 * But it shouldn't really fail to convert pfns back...
117 if (WARN_ON(IS_ERR(pages)))
120 unpin_user_pages(pages, vec->nr_frames);
121 vec->got_ref = false;
125 EXPORT_SYMBOL(put_vaddr_frames);
128 * frame_vector_to_pages - convert frame vector to contain page pointers
129 * @vec: frame vector to convert
131 * Convert @vec to contain array of page pointers. If the conversion is
132 * successful, return 0. Otherwise return an error. Note that we do not grab
133 * page references for the page structures.
135 int frame_vector_to_pages(struct frame_vector *vec)
143 nums = frame_vector_pfns(vec);
144 for (i = 0; i < vec->nr_frames; i++)
145 if (!pfn_valid(nums[i]))
147 pages = (struct page **)nums;
148 for (i = 0; i < vec->nr_frames; i++)
149 pages[i] = pfn_to_page(nums[i]);
150 vec->is_pfns = false;
153 EXPORT_SYMBOL(frame_vector_to_pages);
156 * frame_vector_to_pfns - convert frame vector to contain pfns
157 * @vec: frame vector to convert
159 * Convert @vec to contain array of pfns.
161 void frame_vector_to_pfns(struct frame_vector *vec)
169 pages = (struct page **)(vec->ptrs);
170 nums = (unsigned long *)pages;
171 for (i = 0; i < vec->nr_frames; i++)
172 nums[i] = page_to_pfn(pages[i]);
175 EXPORT_SYMBOL(frame_vector_to_pfns);
178 * frame_vector_create() - allocate & initialize structure for pinned pfns
179 * @nr_frames: number of pfns slots we should reserve
181 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
184 struct frame_vector *frame_vector_create(unsigned int nr_frames)
186 struct frame_vector *vec;
187 int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
189 if (WARN_ON_ONCE(nr_frames == 0))
192 * This is absurdly high. It's here just to avoid strange effects when
193 * arithmetics overflows.
195 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
198 * Avoid higher order allocations, use vmalloc instead. It should
201 vec = kvmalloc(size, GFP_KERNEL);
204 vec->nr_allocated = nr_frames;
208 EXPORT_SYMBOL(frame_vector_create);
211 * frame_vector_destroy() - free memory allocated to carry frame vector
212 * @vec: Frame vector to free
214 * Free structure allocated by frame_vector_create() to carry frames.
216 void frame_vector_destroy(struct frame_vector *vec)
218 /* Make sure put_vaddr_frames() got called properly... */
219 VM_BUG_ON(vec->nr_frames > 0);
222 EXPORT_SYMBOL(frame_vector_destroy);