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1// SPDX-License-Identifier: GPL-2.02#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#include <media/frame_vector.h>12 13/**14 * get_vaddr_frames() - map virtual addresses to pfns15 * @start: starting user address16 * @nr_frames: number of pages / pfns from start to map17 * @write: the mapped address has write permission18 * @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 structure22 * with page frame numbers or page pointers to corresponding pages (choice23 * depends on the type of the vma underlying the virtual address). If @start24 * belongs to a normal vma, the function grabs reference to each of the pages25 * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't26 * touch page structures and the caller must make sure pfns aren't reused for27 * anything else while he is using them.28 *29 * The function returns number of pages mapped which may be less than30 * @nr_frames. In particular we stop mapping if there are more vmas of31 * 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 * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used35 * to be able to do that, but that could (racily) return non-refcounted36 * pfns.37 *38 * This function takes care of grabbing mmap_lock as necessary.39 */40int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write,41 struct frame_vector *vec)42{43 int ret;44 unsigned int gup_flags = FOLL_LONGTERM;45 46 if (nr_frames == 0)47 return 0;48 49 if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))50 nr_frames = vec->nr_allocated;51 52 start = untagged_addr(start);53 54 if (write)55 gup_flags |= FOLL_WRITE;56 57 ret = pin_user_pages_fast(start, nr_frames, gup_flags,58 (struct page **)(vec->ptrs));59 vec->got_ref = true;60 vec->is_pfns = false;61 vec->nr_frames = ret;62 63 if (likely(ret > 0))64 return ret;65 66 vec->nr_frames = 0;67 return ret ? ret : -EFAULT;68}69EXPORT_SYMBOL(get_vaddr_frames);70 71/**72 * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired73 * them74 * @vec: frame vector to put75 *76 * Drop references to pages if get_vaddr_frames() acquired them. We also77 * invalidate the frame vector so that it is prepared for the next call into78 * get_vaddr_frames().79 */80void put_vaddr_frames(struct frame_vector *vec)81{82 struct page **pages;83 84 if (!vec->got_ref)85 goto out;86 pages = frame_vector_pages(vec);87 /*88 * frame_vector_pages() might needed to do a conversion when89 * get_vaddr_frames() got pages but vec was later converted to pfns.90 * But it shouldn't really fail to convert pfns back...91 */92 if (WARN_ON(IS_ERR(pages)))93 goto out;94 95 unpin_user_pages(pages, vec->nr_frames);96 vec->got_ref = false;97out:98 vec->nr_frames = 0;99}100EXPORT_SYMBOL(put_vaddr_frames);101 102/**103 * frame_vector_to_pages - convert frame vector to contain page pointers104 * @vec: frame vector to convert105 *106 * Convert @vec to contain array of page pointers. If the conversion is107 * successful, return 0. Otherwise return an error. Note that we do not grab108 * page references for the page structures.109 */110int frame_vector_to_pages(struct frame_vector *vec)111{112 int i;113 unsigned long *nums;114 struct page **pages;115 116 if (!vec->is_pfns)117 return 0;118 nums = frame_vector_pfns(vec);119 for (i = 0; i < vec->nr_frames; i++)120 if (!pfn_valid(nums[i]))121 return -EINVAL;122 pages = (struct page **)nums;123 for (i = 0; i < vec->nr_frames; i++)124 pages[i] = pfn_to_page(nums[i]);125 vec->is_pfns = false;126 return 0;127}128EXPORT_SYMBOL(frame_vector_to_pages);129 130/**131 * frame_vector_to_pfns - convert frame vector to contain pfns132 * @vec: frame vector to convert133 *134 * Convert @vec to contain array of pfns.135 */136void frame_vector_to_pfns(struct frame_vector *vec)137{138 int i;139 unsigned long *nums;140 struct page **pages;141 142 if (vec->is_pfns)143 return;144 pages = (struct page **)(vec->ptrs);145 nums = (unsigned long *)pages;146 for (i = 0; i < vec->nr_frames; i++)147 nums[i] = page_to_pfn(pages[i]);148 vec->is_pfns = true;149}150EXPORT_SYMBOL(frame_vector_to_pfns);151 152/**153 * frame_vector_create() - allocate & initialize structure for pinned pfns154 * @nr_frames: number of pfns slots we should reserve155 *156 * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns157 * pfns.158 */159struct frame_vector *frame_vector_create(unsigned int nr_frames)160{161 struct frame_vector *vec;162 int size = struct_size(vec, ptrs, nr_frames);163 164 if (WARN_ON_ONCE(nr_frames == 0))165 return NULL;166 /*167 * This is absurdly high. It's here just to avoid strange effects when168 * arithmetics overflows.169 */170 if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))171 return NULL;172 /*173 * Avoid higher order allocations, use vmalloc instead. It should174 * be rare anyway.175 */176 vec = kvmalloc(size, GFP_KERNEL);177 if (!vec)178 return NULL;179 vec->nr_allocated = nr_frames;180 vec->nr_frames = 0;181 return vec;182}183EXPORT_SYMBOL(frame_vector_create);184 185/**186 * frame_vector_destroy() - free memory allocated to carry frame vector187 * @vec: Frame vector to free188 *189 * Free structure allocated by frame_vector_create() to carry frames.190 */191void frame_vector_destroy(struct frame_vector *vec)192{193 /* Make sure put_vaddr_frames() got called properly... */194 VM_BUG_ON(vec->nr_frames > 0);195 kvfree(vec);196}197EXPORT_SYMBOL(frame_vector_destroy);198