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;
40 int ret_pin_user_pages_fast = 0;
47 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
48 nr_frames = vec->nr_allocated;
50 start = untagged_addr(start);
52 ret = pin_user_pages_fast(start, nr_frames,
53 FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
54 (struct page **)(vec->ptrs));
60 ret_pin_user_pages_fast = ret;
67 unsigned long *nums = frame_vector_pfns(vec);
69 vma = vma_lookup(mm, start);
73 while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
74 err = follow_pfn(vma, start, &nums[ret]);
78 // If follow_pfn() returns -EINVAL, then this
79 // is not an IO mapping or a raw PFN mapping.
80 // In that case, return the original error from
81 // pin_user_pages_fast(). Otherwise this
82 // function would return -EINVAL when
83 // pin_user_pages_fast() returned -ENOMEM,
84 // which makes debugging hard.
85 if (err == -EINVAL && ret_pin_user_pages_fast)
86 ret = ret_pin_user_pages_fast;
94 /* Bail out if VMA doesn't completely cover the tail page. */
95 if (start < vma->vm_end)
97 } while (ret < nr_frames);
104 vec->nr_frames = ret;
107 EXPORT_SYMBOL(get_vaddr_frames);
110 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
112 * @vec: frame vector to put
114 * Drop references to pages if get_vaddr_frames() acquired them. We also
115 * invalidate the frame vector so that it is prepared for the next call into
116 * get_vaddr_frames().
118 void put_vaddr_frames(struct frame_vector *vec)
124 pages = frame_vector_pages(vec);
126 * frame_vector_pages() might needed to do a conversion when
127 * get_vaddr_frames() got pages but vec was later converted to pfns.
128 * But it shouldn't really fail to convert pfns back...
130 if (WARN_ON(IS_ERR(pages)))
133 unpin_user_pages(pages, vec->nr_frames);
134 vec->got_ref = false;
138 EXPORT_SYMBOL(put_vaddr_frames);
141 * frame_vector_to_pages - convert frame vector to contain page pointers
142 * @vec: frame vector to convert
144 * Convert @vec to contain array of page pointers. If the conversion is
145 * successful, return 0. Otherwise return an error. Note that we do not grab
146 * page references for the page structures.
148 int frame_vector_to_pages(struct frame_vector *vec)
156 nums = frame_vector_pfns(vec);
157 for (i = 0; i < vec->nr_frames; i++)
158 if (!pfn_valid(nums[i]))
160 pages = (struct page **)nums;
161 for (i = 0; i < vec->nr_frames; i++)
162 pages[i] = pfn_to_page(nums[i]);
163 vec->is_pfns = false;
166 EXPORT_SYMBOL(frame_vector_to_pages);
169 * frame_vector_to_pfns - convert frame vector to contain pfns
170 * @vec: frame vector to convert
172 * Convert @vec to contain array of pfns.
174 void frame_vector_to_pfns(struct frame_vector *vec)
182 pages = (struct page **)(vec->ptrs);
183 nums = (unsigned long *)pages;
184 for (i = 0; i < vec->nr_frames; i++)
185 nums[i] = page_to_pfn(pages[i]);
188 EXPORT_SYMBOL(frame_vector_to_pfns);
191 * frame_vector_create() - allocate & initialize structure for pinned pfns
192 * @nr_frames: number of pfns slots we should reserve
194 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
197 struct frame_vector *frame_vector_create(unsigned int nr_frames)
199 struct frame_vector *vec;
200 int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
202 if (WARN_ON_ONCE(nr_frames == 0))
205 * This is absurdly high. It's here just to avoid strange effects when
206 * arithmetics overflows.
208 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
211 * Avoid higher order allocations, use vmalloc instead. It should
214 vec = kvmalloc(size, GFP_KERNEL);
217 vec->nr_allocated = nr_frames;
221 EXPORT_SYMBOL(frame_vector_create);
224 * frame_vector_destroy() - free memory allocated to carry frame vector
225 * @vec: Frame vector to free
227 * Free structure allocated by frame_vector_create() to carry frames.
229 void frame_vector_destroy(struct frame_vector *vec)
231 /* Make sure put_vaddr_frames() got called properly... */
232 VM_BUG_ON(vec->nr_frames > 0);
235 EXPORT_SYMBOL(frame_vector_destroy);