1/*
  2 * Copyright © 2014 Intel Corporation
  3 *
  4 * Permission is hereby granted, free of charge, to any person obtaining a
  5 * copy of this software and associated documentation files (the "Software"),
  6 * to deal in the Software without restriction, including without limitation
  7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  8 * and/or sell copies of the Software, and to permit persons to whom the
  9 * Software is furnished to do so, subject to the following conditions:
 10 *
 11 * The above copyright notice and this permission notice (including the next
 12 * paragraph) shall be included in all copies or substantial portions of the
 13 * Software.
 14 *
 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 21 * IN THE SOFTWARE.
 22 *
 23 */
 24
 25#include <linux/mm.h>
 26#include <linux/io-mapping.h>
 27
 28
 29#include "i915_drv.h"
 30
 31struct remap_pfn {
 32	struct mm_struct *mm;
 33	unsigned long pfn;
 34	pgprot_t prot;
 35
 36	struct sgt_iter sgt;
 37	resource_size_t iobase;
 38};
 39
 40static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
 41{
 42	struct remap_pfn *r = data;
 43
 44	/* Special PTE are not associated with any struct page */
 45	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
 46	r->pfn++;
 47
 48	return 0;
 49}
 50
 51#define use_dma(io) ((io) != -1)
 52
 53static inline unsigned long sgt_pfn(const struct remap_pfn *r)
 54{
 55	if (use_dma(r->iobase))
 56		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
 57	else
 58		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
 59}
 60
 61static int remap_sg(pte_t *pte, unsigned long addr, void *data)
 62{
 63	struct remap_pfn *r = data;
 64
 65	if (GEM_WARN_ON(!r->sgt.pfn))
 66		return -EINVAL;
 67
 68	/* Special PTE are not associated with any struct page */
 69	set_pte_at(r->mm, addr, pte,
 70		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
 71	r->pfn++; /* track insertions in case we need to unwind later */
 72
 73	r->sgt.curr += PAGE_SIZE;
 74	if (r->sgt.curr >= r->sgt.max)
 75		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
 76
 77	return 0;
 78}
 79
 80/**
 81 * remap_io_mapping - remap an IO mapping to userspace
 82 * @vma: user vma to map to
 83 * @addr: target user address to start at
 84 * @pfn: physical address of kernel memory
 85 * @size: size of map area
 86 * @iomap: the source io_mapping
 87 *
 88 *  Note: this is only safe if the mm semaphore is held when called.
 89 */
 90int remap_io_mapping(struct vm_area_struct *vma,
 91		     unsigned long addr, unsigned long pfn, unsigned long size,
 92		     struct io_mapping *iomap)
 93{
 94	struct remap_pfn r;
 95	int err;
 96
 97#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
 98	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
 99
100	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
101	r.mm = vma->vm_mm;
102	r.pfn = pfn;
103	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
104			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
105
106	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
107	if (unlikely(err)) {
108		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
109		return err;
110	}
111
112	return 0;
113}
114
115/**
116 * remap_io_sg - remap an IO mapping to userspace
117 * @vma: user vma to map to
118 * @addr: target user address to start at
119 * @size: size of map area
120 * @sgl: Start sg entry
121 * @iobase: Use stored dma address offset by this address or pfn if -1
122 *
123 *  Note: this is only safe if the mm semaphore is held when called.
124 */
125int remap_io_sg(struct vm_area_struct *vma,
126		unsigned long addr, unsigned long size,
127		struct scatterlist *sgl, resource_size_t iobase)
128{
129	struct remap_pfn r = {
130		.mm = vma->vm_mm,
131		.prot = vma->vm_page_prot,
132		.sgt = __sgt_iter(sgl, use_dma(iobase)),
133		.iobase = iobase,
134	};
135	int err;
136
137	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
138	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
139
140	if (!use_dma(iobase))
141		flush_cache_range(vma, addr, size);
142
143	err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
144	if (unlikely(err)) {
145		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
146		return err;
147	}
148
149	return 0;
150}