// SPDX-License-Identifier: GPL-2.0#include <linux/kernel.h>#include <linux/errno.h>#include <linux/err.h>#include <linux/mm.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <linux/pagemap.h>#include <linux/sched.h> /** * get_vaddr_frames() - map virtual addresses to pfns * @start:	starting user address * @nr_frames:	number of pages / pfns from start to map * @gup_flags:	flags modifying lookup behaviour * @vec:	structure which receives pages / pfns of the addresses mapped. *		It should have space for at least nr_frames entries. * * This function maps virtual addresses from @start and fills @vec structure * with page frame numbers or page pointers to corresponding pages (choice * depends on the type of the vma underlying the virtual address). If @start * belongs to a normal vma, the function grabs reference to each of the pages * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't * touch page structures and the caller must make sure pfns aren't reused for * anything else while he is using them. * * The function returns number of pages mapped which may be less than * @nr_frames. In particular we stop mapping if there are more vmas of * different type underlying the specified range of virtual addresses. * When the function isn't able to map a single page, it returns error. * * This function takes care of grabbing mmap_lock as necessary. */int get_vaddr_frames(unsigned long start, unsigned int nr_frames,		     unsigned int gup_flags, struct frame_vector *vec){	struct mm_struct *mm = current->mm;	struct vm_area_struct *vma;	int ret = 0;	int err;	int locked; 	if (nr_frames == 0)		return 0; 	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))		nr_frames = vec->nr_allocated; 	start = untagged_addr(start); 	mmap_read_lock(mm);	locked = 1;	vma = find_vma_intersection(mm, start, start + 1);	if (!vma) {		ret = -EFAULT;		goto out;	} 	/*	 * While get_vaddr_frames() could be used for transient (kernel	 * controlled lifetime) pinning of memory pages all current	 * users establish long term (userspace controlled lifetime)	 * page pinning. Treat get_vaddr_frames() like	 * get_user_pages_longterm() and disallow it for filesystem-dax	 * mappings.	 */	if (vma_is_fsdax(vma)) {		ret = -EOPNOTSUPP;		goto out;	} 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {		vec->got_ref = true;		vec->is_pfns = false;		ret = pin_user_pages_locked(start, nr_frames,			gup_flags, (struct page **)(vec->ptrs), &locked);		goto out;	} 	vec->got_ref = false;	vec->is_pfns = true;	do {		unsigned long *nums = frame_vector_pfns(vec); 		while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {			err = follow_pfn(vma, start, &nums[ret]);			if (err) {				if (ret == 0)					ret = err;				goto out;			}			start += PAGE_SIZE;			ret++;		}		/*		 * We stop if we have enough pages or if VMA doesn't completely		 * cover the tail page.		 */		if (ret >= nr_frames || start < vma->vm_end)			break;		vma = find_vma_intersection(mm, start, start + 1);	} while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));out:	if (locked)		mmap_read_unlock(mm);	if (!ret)		ret = -EFAULT;	if (ret > 0)		vec->nr_frames = ret;	return ret;}EXPORT_SYMBOL(get_vaddr_frames); /** * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired *			them * @vec:	frame vector to put * * Drop references to pages if get_vaddr_frames() acquired them. We also * invalidate the frame vector so that it is prepared for the next call into * get_vaddr_frames(). */void put_vaddr_frames(struct frame_vector *vec){	struct page **pages; 	if (!vec->got_ref)		goto out;	pages = frame_vector_pages(vec);	/*	 * frame_vector_pages() might needed to do a conversion when	 * get_vaddr_frames() got pages but vec was later converted to pfns.	 * But it shouldn't really fail to convert pfns back...	 */	if (WARN_ON(IS_ERR(pages)))		goto out; 	unpin_user_pages(pages, vec->nr_frames);	vec->got_ref = false;out:	vec->nr_frames = 0;}EXPORT_SYMBOL(put_vaddr_frames); /** * frame_vector_to_pages - convert frame vector to contain page pointers * @vec:	frame vector to convert * * Convert @vec to contain array of page pointers.  If the conversion is * successful, return 0. Otherwise return an error. Note that we do not grab * page references for the page structures. */int frame_vector_to_pages(struct frame_vector *vec){	int i;	unsigned long *nums;	struct page **pages; 	if (!vec->is_pfns)		return 0;	nums = frame_vector_pfns(vec);	for (i = 0; i < vec->nr_frames; i++)		if (!pfn_valid(nums[i]))			return -EINVAL;	pages = (struct page **)nums;	for (i = 0; i < vec->nr_frames; i++)		pages[i] = pfn_to_page(nums[i]);	vec->is_pfns = false;	return 0;}EXPORT_SYMBOL(frame_vector_to_pages); /** * frame_vector_to_pfns - convert frame vector to contain pfns * @vec:	frame vector to convert * * Convert @vec to contain array of pfns. */void frame_vector_to_pfns(struct frame_vector *vec){	int i;	unsigned long *nums;	struct page **pages; 	if (vec->is_pfns)		return;	pages = (struct page **)(vec->ptrs);	nums = (unsigned long *)pages;	for (i = 0; i < vec->nr_frames; i++)		nums[i] = page_to_pfn(pages[i]);	vec->is_pfns = true;}EXPORT_SYMBOL(frame_vector_to_pfns); /** * frame_vector_create() - allocate & initialize structure for pinned pfns * @nr_frames:	number of pfns slots we should reserve * * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns * pfns. */struct frame_vector *frame_vector_create(unsigned int nr_frames){	struct frame_vector *vec;	int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames; 	if (WARN_ON_ONCE(nr_frames == 0))		return NULL;	/*	 * This is absurdly high. It's here just to avoid strange effects when	 * arithmetics overflows.	 */	if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))		return NULL;	/*	 * Avoid higher order allocations, use vmalloc instead. It should	 * be rare anyway.	 */	vec = kvmalloc(size, GFP_KERNEL);	if (!vec)		return NULL;	vec->nr_allocated = nr_frames;	vec->nr_frames = 0;	return vec;}EXPORT_SYMBOL(frame_vector_create); /** * frame_vector_destroy() - free memory allocated to carry frame vector * @vec:	Frame vector to free * * Free structure allocated by frame_vector_create() to carry frames. */void frame_vector_destroy(struct frame_vector *vec){	/* Make sure put_vaddr_frames() got called properly... */	VM_BUG_ON(vec->nr_frames > 0);	kvfree(vec);}EXPORT_SYMBOL(frame_vector_destroy);