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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/frame_vector.c
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
;
46 if (WARN_ON_ONCE(nr_frames
> vec
->nr_allocated
))
47 nr_frames
= vec
->nr_allocated
;
49 down_read(&mm
->mmap_sem
);
51 vma
= find_vma_intersection(mm
, start
, start
+ 1);
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
65 if (vma_is_fsdax(vma
))
68 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
))) {
71 ret
= get_user_pages_locked(start
, nr_frames
,
72 gup_flags
, (struct page
**)(vec
->ptrs
), &locked
);
79 unsigned long *nums
= frame_vector_pfns(vec
);
81 while (ret
< nr_frames
&& start
+ PAGE_SIZE
<= vma
->vm_end
) {
82 err
= follow_pfn(vma
, start
, &nums
[ret
]);
92 * We stop if we have enough pages or if VMA doesn't completely
93 * cover the tail page.
95 if (ret
>= nr_frames
|| start
< vma
->vm_end
)
97 vma
= find_vma_intersection(mm
, start
, start
+ 1);
98 } while (vma
&& vma
->vm_flags
& (VM_IO
| VM_PFNMAP
));
101 up_read(&mm
->mmap_sem
);
105 vec
->nr_frames
= ret
;
108 EXPORT_SYMBOL(get_vaddr_frames
);
111 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
113 * @vec: frame vector to put
115 * Drop references to pages if get_vaddr_frames() acquired them. We also
116 * invalidate the frame vector so that it is prepared for the next call into
117 * get_vaddr_frames().
119 void put_vaddr_frames(struct frame_vector
*vec
)
126 pages
= frame_vector_pages(vec
);
128 * frame_vector_pages() might needed to do a conversion when
129 * get_vaddr_frames() got pages but vec was later converted to pfns.
130 * But it shouldn't really fail to convert pfns back...
132 if (WARN_ON(IS_ERR(pages
)))
134 for (i
= 0; i
< vec
->nr_frames
; i
++)
136 vec
->got_ref
= false;
140 EXPORT_SYMBOL(put_vaddr_frames
);
143 * frame_vector_to_pages - convert frame vector to contain page pointers
144 * @vec: frame vector to convert
146 * Convert @vec to contain array of page pointers. If the conversion is
147 * successful, return 0. Otherwise return an error. Note that we do not grab
148 * page references for the page structures.
150 int frame_vector_to_pages(struct frame_vector
*vec
)
158 nums
= frame_vector_pfns(vec
);
159 for (i
= 0; i
< vec
->nr_frames
; i
++)
160 if (!pfn_valid(nums
[i
]))
162 pages
= (struct page
**)nums
;
163 for (i
= 0; i
< vec
->nr_frames
; i
++)
164 pages
[i
] = pfn_to_page(nums
[i
]);
165 vec
->is_pfns
= false;
168 EXPORT_SYMBOL(frame_vector_to_pages
);
171 * frame_vector_to_pfns - convert frame vector to contain pfns
172 * @vec: frame vector to convert
174 * Convert @vec to contain array of pfns.
176 void frame_vector_to_pfns(struct frame_vector
*vec
)
184 pages
= (struct page
**)(vec
->ptrs
);
185 nums
= (unsigned long *)pages
;
186 for (i
= 0; i
< vec
->nr_frames
; i
++)
187 nums
[i
] = page_to_pfn(pages
[i
]);
190 EXPORT_SYMBOL(frame_vector_to_pfns
);
193 * frame_vector_create() - allocate & initialize structure for pinned pfns
194 * @nr_frames: number of pfns slots we should reserve
196 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
199 struct frame_vector
*frame_vector_create(unsigned int nr_frames
)
201 struct frame_vector
*vec
;
202 int size
= sizeof(struct frame_vector
) + sizeof(void *) * nr_frames
;
204 if (WARN_ON_ONCE(nr_frames
== 0))
207 * This is absurdly high. It's here just to avoid strange effects when
208 * arithmetics overflows.
210 if (WARN_ON_ONCE(nr_frames
> INT_MAX
/ sizeof(void *) / 2))
213 * Avoid higher order allocations, use vmalloc instead. It should
216 vec
= kvmalloc(size
, GFP_KERNEL
);
219 vec
->nr_allocated
= nr_frames
;
223 EXPORT_SYMBOL(frame_vector_create
);
226 * frame_vector_destroy() - free memory allocated to carry frame vector
227 * @vec: Frame vector to free
229 * Free structure allocated by frame_vector_create() to carry frames.
231 void frame_vector_destroy(struct frame_vector
*vec
)
233 /* Make sure put_vaddr_frames() got called properly... */
234 VM_BUG_ON(vec
->nr_frames
> 0);
237 EXPORT_SYMBOL(frame_vector_destroy
);