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1#include <linux/kernel.h>
2#include <linux/errno.h>
3#include <linux/err.h>
4#include <linux/mm.h>
5#include <linux/slab.h>
6#include <linux/vmalloc.h>
7#include <linux/pagemap.h>
8#include <linux/sched.h>
9
10/**
11 * get_vaddr_frames() - map virtual addresses to pfns
12 * @start: starting user address
13 * @nr_frames: number of pages / pfns from start to map
14 * @write: whether pages will be written to by the caller
15 * @force: whether to force write access even if user mapping is
16 * readonly. See description of the same argument of
17 get_user_pages().
18 * @vec: structure which receives pages / pfns of the addresses mapped.
19 * It should have space for at least nr_frames entries.
20 *
21 * This function maps virtual addresses from @start and fills @vec structure
22 * with page frame numbers or page pointers to corresponding pages (choice
23 * depends on the type of the vma underlying the virtual address). If @start
24 * belongs to a normal vma, the function grabs reference to each of the pages
25 * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
26 * touch page structures and the caller must make sure pfns aren't reused for
27 * anything else while he is using them.
28 *
29 * The function returns number of pages mapped which may be less than
30 * @nr_frames. In particular we stop mapping if there are more vmas of
31 * different type underlying the specified range of virtual addresses.
32 * When the function isn't able to map a single page, it returns error.
33 *
34 * This function takes care of grabbing mmap_sem as necessary.
35 */
36int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
37 bool write, bool force, struct frame_vector *vec)
38{
39 struct mm_struct *mm = current->mm;
40 struct vm_area_struct *vma;
41 int ret = 0;
42 int err;
43 int locked;
44
45 if (nr_frames == 0)
46 return 0;
47
48 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
49 nr_frames = vec->nr_allocated;
50
51 down_read(&mm->mmap_sem);
52 locked = 1;
53 vma = find_vma_intersection(mm, start, start + 1);
54 if (!vma) {
55 ret = -EFAULT;
56 goto out;
57 }
58 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
59 vec->got_ref = true;
60 vec->is_pfns = false;
61 ret = get_user_pages_locked(start, nr_frames,
62 write, force, (struct page **)(vec->ptrs), &locked);
63 goto out;
64 }
65
66 vec->got_ref = false;
67 vec->is_pfns = true;
68 do {
69 unsigned long *nums = frame_vector_pfns(vec);
70
71 while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
72 err = follow_pfn(vma, start, &nums[ret]);
73 if (err) {
74 if (ret == 0)
75 ret = err;
76 goto out;
77 }
78 start += PAGE_SIZE;
79 ret++;
80 }
81 /*
82 * We stop if we have enough pages or if VMA doesn't completely
83 * cover the tail page.
84 */
85 if (ret >= nr_frames || start < vma->vm_end)
86 break;
87 vma = find_vma_intersection(mm, start, start + 1);
88 } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
89out:
90 if (locked)
91 up_read(&mm->mmap_sem);
92 if (!ret)
93 ret = -EFAULT;
94 if (ret > 0)
95 vec->nr_frames = ret;
96 return ret;
97}
98EXPORT_SYMBOL(get_vaddr_frames);
99
100/**
101 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
102 * them
103 * @vec: frame vector to put
104 *
105 * Drop references to pages if get_vaddr_frames() acquired them. We also
106 * invalidate the frame vector so that it is prepared for the next call into
107 * get_vaddr_frames().
108 */
109void put_vaddr_frames(struct frame_vector *vec)
110{
111 int i;
112 struct page **pages;
113
114 if (!vec->got_ref)
115 goto out;
116 pages = frame_vector_pages(vec);
117 /*
118 * frame_vector_pages() might needed to do a conversion when
119 * get_vaddr_frames() got pages but vec was later converted to pfns.
120 * But it shouldn't really fail to convert pfns back...
121 */
122 if (WARN_ON(IS_ERR(pages)))
123 goto out;
124 for (i = 0; i < vec->nr_frames; i++)
125 put_page(pages[i]);
126 vec->got_ref = false;
127out:
128 vec->nr_frames = 0;
129}
130EXPORT_SYMBOL(put_vaddr_frames);
131
132/**
133 * frame_vector_to_pages - convert frame vector to contain page pointers
134 * @vec: frame vector to convert
135 *
136 * Convert @vec to contain array of page pointers. If the conversion is
137 * successful, return 0. Otherwise return an error. Note that we do not grab
138 * page references for the page structures.
139 */
140int frame_vector_to_pages(struct frame_vector *vec)
141{
142 int i;
143 unsigned long *nums;
144 struct page **pages;
145
146 if (!vec->is_pfns)
147 return 0;
148 nums = frame_vector_pfns(vec);
149 for (i = 0; i < vec->nr_frames; i++)
150 if (!pfn_valid(nums[i]))
151 return -EINVAL;
152 pages = (struct page **)nums;
153 for (i = 0; i < vec->nr_frames; i++)
154 pages[i] = pfn_to_page(nums[i]);
155 vec->is_pfns = false;
156 return 0;
157}
158EXPORT_SYMBOL(frame_vector_to_pages);
159
160/**
161 * frame_vector_to_pfns - convert frame vector to contain pfns
162 * @vec: frame vector to convert
163 *
164 * Convert @vec to contain array of pfns.
165 */
166void frame_vector_to_pfns(struct frame_vector *vec)
167{
168 int i;
169 unsigned long *nums;
170 struct page **pages;
171
172 if (vec->is_pfns)
173 return;
174 pages = (struct page **)(vec->ptrs);
175 nums = (unsigned long *)pages;
176 for (i = 0; i < vec->nr_frames; i++)
177 nums[i] = page_to_pfn(pages[i]);
178 vec->is_pfns = true;
179}
180EXPORT_SYMBOL(frame_vector_to_pfns);
181
182/**
183 * frame_vector_create() - allocate & initialize structure for pinned pfns
184 * @nr_frames: number of pfns slots we should reserve
185 *
186 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
187 * pfns.
188 */
189struct frame_vector *frame_vector_create(unsigned int nr_frames)
190{
191 struct frame_vector *vec;
192 int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
193
194 if (WARN_ON_ONCE(nr_frames == 0))
195 return NULL;
196 /*
197 * This is absurdly high. It's here just to avoid strange effects when
198 * arithmetics overflows.
199 */
200 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
201 return NULL;
202 /*
203 * Avoid higher order allocations, use vmalloc instead. It should
204 * be rare anyway.
205 */
206 if (size <= PAGE_SIZE)
207 vec = kmalloc(size, GFP_KERNEL);
208 else
209 vec = vmalloc(size);
210 if (!vec)
211 return NULL;
212 vec->nr_allocated = nr_frames;
213 vec->nr_frames = 0;
214 return vec;
215}
216EXPORT_SYMBOL(frame_vector_create);
217
218/**
219 * frame_vector_destroy() - free memory allocated to carry frame vector
220 * @vec: Frame vector to free
221 *
222 * Free structure allocated by frame_vector_create() to carry frames.
223 */
224void frame_vector_destroy(struct frame_vector *vec)
225{
226 /* Make sure put_vaddr_frames() got called properly... */
227 VM_BUG_ON(vec->nr_frames > 0);
228 kvfree(vec);
229}
230EXPORT_SYMBOL(frame_vector_destroy);
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/kernel.h>
3#include <linux/errno.h>
4#include <linux/err.h>
5#include <linux/mm.h>
6#include <linux/slab.h>
7#include <linux/vmalloc.h>
8#include <linux/pagemap.h>
9#include <linux/sched.h>
10
11/**
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.
18 *
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.
26 *
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.
31 *
32 * This function takes care of grabbing mmap_sem as necessary.
33 */
34int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
35 unsigned int gup_flags, struct frame_vector *vec)
36{
37 struct mm_struct *mm = current->mm;
38 struct vm_area_struct *vma;
39 int ret = 0;
40 int err;
41 int locked;
42
43 if (nr_frames == 0)
44 return 0;
45
46 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
47 nr_frames = vec->nr_allocated;
48
49 down_read(&mm->mmap_sem);
50 locked = 1;
51 vma = find_vma_intersection(mm, start, start + 1);
52 if (!vma) {
53 ret = -EFAULT;
54 goto out;
55 }
56
57 /*
58 * While get_vaddr_frames() could be used for transient (kernel
59 * controlled lifetime) pinning of memory pages all current
60 * users establish long term (userspace controlled lifetime)
61 * page pinning. Treat get_vaddr_frames() like
62 * get_user_pages_longterm() and disallow it for filesystem-dax
63 * mappings.
64 */
65 if (vma_is_fsdax(vma)) {
66 ret = -EOPNOTSUPP;
67 goto out;
68 }
69
70 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
71 vec->got_ref = true;
72 vec->is_pfns = false;
73 ret = get_user_pages_locked(start, nr_frames,
74 gup_flags, (struct page **)(vec->ptrs), &locked);
75 goto out;
76 }
77
78 vec->got_ref = false;
79 vec->is_pfns = true;
80 do {
81 unsigned long *nums = frame_vector_pfns(vec);
82
83 while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
84 err = follow_pfn(vma, start, &nums[ret]);
85 if (err) {
86 if (ret == 0)
87 ret = err;
88 goto out;
89 }
90 start += PAGE_SIZE;
91 ret++;
92 }
93 /*
94 * We stop if we have enough pages or if VMA doesn't completely
95 * cover the tail page.
96 */
97 if (ret >= nr_frames || start < vma->vm_end)
98 break;
99 vma = find_vma_intersection(mm, start, start + 1);
100 } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
101out:
102 if (locked)
103 up_read(&mm->mmap_sem);
104 if (!ret)
105 ret = -EFAULT;
106 if (ret > 0)
107 vec->nr_frames = ret;
108 return ret;
109}
110EXPORT_SYMBOL(get_vaddr_frames);
111
112/**
113 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
114 * them
115 * @vec: frame vector to put
116 *
117 * Drop references to pages if get_vaddr_frames() acquired them. We also
118 * invalidate the frame vector so that it is prepared for the next call into
119 * get_vaddr_frames().
120 */
121void put_vaddr_frames(struct frame_vector *vec)
122{
123 int i;
124 struct page **pages;
125
126 if (!vec->got_ref)
127 goto out;
128 pages = frame_vector_pages(vec);
129 /*
130 * frame_vector_pages() might needed to do a conversion when
131 * get_vaddr_frames() got pages but vec was later converted to pfns.
132 * But it shouldn't really fail to convert pfns back...
133 */
134 if (WARN_ON(IS_ERR(pages)))
135 goto out;
136 for (i = 0; i < vec->nr_frames; i++)
137 put_page(pages[i]);
138 vec->got_ref = false;
139out:
140 vec->nr_frames = 0;
141}
142EXPORT_SYMBOL(put_vaddr_frames);
143
144/**
145 * frame_vector_to_pages - convert frame vector to contain page pointers
146 * @vec: frame vector to convert
147 *
148 * Convert @vec to contain array of page pointers. If the conversion is
149 * successful, return 0. Otherwise return an error. Note that we do not grab
150 * page references for the page structures.
151 */
152int frame_vector_to_pages(struct frame_vector *vec)
153{
154 int i;
155 unsigned long *nums;
156 struct page **pages;
157
158 if (!vec->is_pfns)
159 return 0;
160 nums = frame_vector_pfns(vec);
161 for (i = 0; i < vec->nr_frames; i++)
162 if (!pfn_valid(nums[i]))
163 return -EINVAL;
164 pages = (struct page **)nums;
165 for (i = 0; i < vec->nr_frames; i++)
166 pages[i] = pfn_to_page(nums[i]);
167 vec->is_pfns = false;
168 return 0;
169}
170EXPORT_SYMBOL(frame_vector_to_pages);
171
172/**
173 * frame_vector_to_pfns - convert frame vector to contain pfns
174 * @vec: frame vector to convert
175 *
176 * Convert @vec to contain array of pfns.
177 */
178void frame_vector_to_pfns(struct frame_vector *vec)
179{
180 int i;
181 unsigned long *nums;
182 struct page **pages;
183
184 if (vec->is_pfns)
185 return;
186 pages = (struct page **)(vec->ptrs);
187 nums = (unsigned long *)pages;
188 for (i = 0; i < vec->nr_frames; i++)
189 nums[i] = page_to_pfn(pages[i]);
190 vec->is_pfns = true;
191}
192EXPORT_SYMBOL(frame_vector_to_pfns);
193
194/**
195 * frame_vector_create() - allocate & initialize structure for pinned pfns
196 * @nr_frames: number of pfns slots we should reserve
197 *
198 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
199 * pfns.
200 */
201struct frame_vector *frame_vector_create(unsigned int nr_frames)
202{
203 struct frame_vector *vec;
204 int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
205
206 if (WARN_ON_ONCE(nr_frames == 0))
207 return NULL;
208 /*
209 * This is absurdly high. It's here just to avoid strange effects when
210 * arithmetics overflows.
211 */
212 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
213 return NULL;
214 /*
215 * Avoid higher order allocations, use vmalloc instead. It should
216 * be rare anyway.
217 */
218 vec = kvmalloc(size, GFP_KERNEL);
219 if (!vec)
220 return NULL;
221 vec->nr_allocated = nr_frames;
222 vec->nr_frames = 0;
223 return vec;
224}
225EXPORT_SYMBOL(frame_vector_create);
226
227/**
228 * frame_vector_destroy() - free memory allocated to carry frame vector
229 * @vec: Frame vector to free
230 *
231 * Free structure allocated by frame_vector_create() to carry frames.
232 */
233void frame_vector_destroy(struct frame_vector *vec)
234{
235 /* Make sure put_vaddr_frames() got called properly... */
236 VM_BUG_ON(vec->nr_frames > 0);
237 kvfree(vec);
238}
239EXPORT_SYMBOL(frame_vector_destroy);