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#include "i915_mm.h"
 31
 32struct remap_pfn {
 33	struct mm_struct *mm;
 34	unsigned long pfn;
 35	pgprot_t prot;
 36
 37	struct sgt_iter sgt;
 38	resource_size_t iobase;
 39};
 40
 41#define use_dma(io) ((io) != -1)
 42
 43static inline unsigned long sgt_pfn(const struct remap_pfn *r)
 44{
 45	if (use_dma(r->iobase))
 46		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
 47	else
 48		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
 49}
 50
 51static int remap_sg(pte_t *pte, unsigned long addr, void *data)
 52{
 53	struct remap_pfn *r = data;
 54
 55	if (GEM_WARN_ON(!r->sgt.sgp))
 56		return -EINVAL;
 57
 58	/* Special PTE are not associated with any struct page */
 59	set_pte_at(r->mm, addr, pte,
 60		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
 61	r->pfn++; /* track insertions in case we need to unwind later */
 62
 63	r->sgt.curr += PAGE_SIZE;
 64	if (r->sgt.curr >= r->sgt.max)
 65		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
 66
 67	return 0;
 68}
 69
 70#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
 71
 72#if IS_ENABLED(CONFIG_X86)
 73static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
 74{
 75	struct remap_pfn *r = data;
 76
 77	/* Special PTE are not associated with any struct page */
 78	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
 79	r->pfn++;
 80
 81	return 0;
 82}
 83
 84/**
 85 * remap_io_mapping - remap an IO mapping to userspace
 86 * @vma: user vma to map to
 87 * @addr: target user address to start at
 88 * @pfn: physical address of kernel memory
 89 * @size: size of map area
 90 * @iomap: the source io_mapping
 91 *
 92 *  Note: this is only safe if the mm semaphore is held when called.
 93 */
 94int remap_io_mapping(struct vm_area_struct *vma,
 95		     unsigned long addr, unsigned long pfn, unsigned long size,
 96		     struct io_mapping *iomap)
 97{
 98	struct remap_pfn r;
 99	int err;
100
101	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
102
103	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
104	r.mm = vma->vm_mm;
105	r.pfn = pfn;
106	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
107			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
108
109	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
110	if (unlikely(err)) {
111		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
112		return err;
113	}
114
115	return 0;
116}
117#endif
118
119/**
120 * remap_io_sg - remap an IO mapping to userspace
121 * @vma: user vma to map to
122 * @addr: target user address to start at
123 * @size: size of map area
124 * @sgl: Start sg entry
125 * @offset: offset from the start of the page
126 * @iobase: Use stored dma address offset by this address or pfn if -1
127 *
128 *  Note: this is only safe if the mm semaphore is held when called.
129 */
130int remap_io_sg(struct vm_area_struct *vma,
131		unsigned long addr, unsigned long size,
132		struct scatterlist *sgl, unsigned long offset,
133		resource_size_t iobase)
134{
135	struct remap_pfn r = {
136		.mm = vma->vm_mm,
137		.prot = vma->vm_page_prot,
138		.sgt = __sgt_iter(sgl, use_dma(iobase)),
139		.iobase = iobase,
140	};
141	int err;
142
143	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
144	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
145
146	while (offset >= sg_dma_len(r.sgt.sgp) >> PAGE_SHIFT) {
147		offset -= sg_dma_len(r.sgt.sgp) >> PAGE_SHIFT;
148		r.sgt = __sgt_iter(__sg_next(r.sgt.sgp), use_dma(iobase));
149		if (!r.sgt.sgp)
150			return -EINVAL;
151	}
152	r.sgt.curr = offset << PAGE_SHIFT;
153
154	if (!use_dma(iobase))
155		flush_cache_range(vma, addr, size);
156
157	err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
158	if (unlikely(err)) {
159		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
160		return err;
161	}
162
163	return 0;
164}