1/*
  2 * Copyright(c) 2015 Intel Corporation. All rights reserved.
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of version 2 of the GNU General Public License as
  6 * published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope that it will be useful, but
  9 * WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 11 * General Public License for more details.
 12 */
 13#include <linux/radix-tree.h>
 14#include <linux/memremap.h>
 15#include <linux/device.h>
 16#include <linux/types.h>
 17#include <linux/pfn_t.h>
 18#include <linux/io.h>
 19#include <linux/mm.h>
 20#include <linux/memory_hotplug.h>
 21
 22#ifndef ioremap_cache
 23/* temporary while we convert existing ioremap_cache users to memremap */
 24__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
 25{
 26	return ioremap(offset, size);
 27}
 28#endif
 29
 30static void *try_ram_remap(resource_size_t offset, size_t size)
 31{
 32	unsigned long pfn = PHYS_PFN(offset);
 33
 34	/* In the simple case just return the existing linear address */
 35	if (pfn_valid(pfn) && !PageHighMem(pfn_to_page(pfn)))
 36		return __va(offset);
 37	return NULL; /* fallback to ioremap_cache */
 38}
 39
 40/**
 41 * memremap() - remap an iomem_resource as cacheable memory
 42 * @offset: iomem resource start address
 43 * @size: size of remap
 44 * @flags: any of MEMREMAP_WB, MEMREMAP_WT and MEMREMAP_WC
 45 *
 46 * memremap() is "ioremap" for cases where it is known that the resource
 47 * being mapped does not have i/o side effects and the __iomem
 48 * annotation is not applicable. In the case of multiple flags, the different
 49 * mapping types will be attempted in the order listed below until one of
 50 * them succeeds.
 51 *
 52 * MEMREMAP_WB - matches the default mapping for System RAM on
 53 * the architecture.  This is usually a read-allocate write-back cache.
 54 * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
 55 * memremap() will bypass establishing a new mapping and instead return
 56 * a pointer into the direct map.
 57 *
 58 * MEMREMAP_WT - establish a mapping whereby writes either bypass the
 59 * cache or are written through to memory and never exist in a
 60 * cache-dirty state with respect to program visibility.  Attempts to
 61 * map System RAM with this mapping type will fail.
 62 *
 63 * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
 64 * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
 65 * uncached. Attempts to map System RAM with this mapping type will fail.
 66 */
 67void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 68{
 69	int is_ram = region_intersects(offset, size,
 70				       IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 71	void *addr = NULL;
 72
 73	if (!flags)
 74		return NULL;
 75
 76	if (is_ram == REGION_MIXED) {
 77		WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
 78				&offset, (unsigned long) size);
 79		return NULL;
 80	}
 81
 82	/* Try all mapping types requested until one returns non-NULL */
 83	if (flags & MEMREMAP_WB) {
 84		/*
 85		 * MEMREMAP_WB is special in that it can be satisifed
 86		 * from the direct map.  Some archs depend on the
 87		 * capability of memremap() to autodetect cases where
 88		 * the requested range is potentially in System RAM.
 89		 */
 90		if (is_ram == REGION_INTERSECTS)
 91			addr = try_ram_remap(offset, size);
 92		if (!addr)
 93			addr = ioremap_cache(offset, size);
 94	}
 95
 96	/*
 97	 * If we don't have a mapping yet and other request flags are
 98	 * present then we will be attempting to establish a new virtual
 99	 * address mapping.  Enforce that this mapping is not aliasing
100	 * System RAM.
101	 */
102	if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
103		WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
104				&offset, (unsigned long) size);
105		return NULL;
106	}
107
108	if (!addr && (flags & MEMREMAP_WT))
109		addr = ioremap_wt(offset, size);
110
111	if (!addr && (flags & MEMREMAP_WC))
112		addr = ioremap_wc(offset, size);
113
114	return addr;
115}
116EXPORT_SYMBOL(memremap);
117
118void memunmap(void *addr)
119{
120	if (is_vmalloc_addr(addr))
121		iounmap((void __iomem *) addr);
122}
123EXPORT_SYMBOL(memunmap);
124
125static void devm_memremap_release(struct device *dev, void *res)
126{
127	memunmap(*(void **)res);
128}
129
130static int devm_memremap_match(struct device *dev, void *res, void *match_data)
131{
132	return *(void **)res == match_data;
133}
134
135void *devm_memremap(struct device *dev, resource_size_t offset,
136		size_t size, unsigned long flags)
137{
138	void **ptr, *addr;
139
140	ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
141			dev_to_node(dev));
142	if (!ptr)
143		return ERR_PTR(-ENOMEM);
144
145	addr = memremap(offset, size, flags);
146	if (addr) {
147		*ptr = addr;
148		devres_add(dev, ptr);
149	} else {
150		devres_free(ptr);
151		return ERR_PTR(-ENXIO);
152	}
153
154	return addr;
155}
156EXPORT_SYMBOL(devm_memremap);
157
158void devm_memunmap(struct device *dev, void *addr)
159{
160	WARN_ON(devres_release(dev, devm_memremap_release,
161				devm_memremap_match, addr));
162}
163EXPORT_SYMBOL(devm_memunmap);
164
165pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
166{
167	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
168}
169EXPORT_SYMBOL(phys_to_pfn_t);
170
171#ifdef CONFIG_ZONE_DEVICE
172static DEFINE_MUTEX(pgmap_lock);
173static RADIX_TREE(pgmap_radix, GFP_KERNEL);
174#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
175#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
176
177struct page_map {
178	struct resource res;
179	struct percpu_ref *ref;
180	struct dev_pagemap pgmap;
181	struct vmem_altmap altmap;
182};
183
184void get_zone_device_page(struct page *page)
185{
186	percpu_ref_get(page->pgmap->ref);
187}
188EXPORT_SYMBOL(get_zone_device_page);
189
190void put_zone_device_page(struct page *page)
191{
192	put_dev_pagemap(page->pgmap);
193}
194EXPORT_SYMBOL(put_zone_device_page);
195
196static void pgmap_radix_release(struct resource *res)
197{
198	resource_size_t key, align_start, align_size, align_end;
199
200	align_start = res->start & ~(SECTION_SIZE - 1);
201	align_size = ALIGN(resource_size(res), SECTION_SIZE);
202	align_end = align_start + align_size - 1;
203
204	mutex_lock(&pgmap_lock);
205	for (key = res->start; key <= res->end; key += SECTION_SIZE)
206		radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
207	mutex_unlock(&pgmap_lock);
208}
209
210static unsigned long pfn_first(struct page_map *page_map)
211{
212	struct dev_pagemap *pgmap = &page_map->pgmap;
213	const struct resource *res = &page_map->res;
214	struct vmem_altmap *altmap = pgmap->altmap;
215	unsigned long pfn;
216
217	pfn = res->start >> PAGE_SHIFT;
218	if (altmap)
219		pfn += vmem_altmap_offset(altmap);
220	return pfn;
221}
222
223static unsigned long pfn_end(struct page_map *page_map)
224{
225	const struct resource *res = &page_map->res;
226
227	return (res->start + resource_size(res)) >> PAGE_SHIFT;
228}
229
230#define for_each_device_pfn(pfn, map) \
231	for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
232
233static void devm_memremap_pages_release(struct device *dev, void *data)
234{
235	struct page_map *page_map = data;
236	struct resource *res = &page_map->res;
237	resource_size_t align_start, align_size;
238	struct dev_pagemap *pgmap = &page_map->pgmap;
239
240	if (percpu_ref_tryget_live(pgmap->ref)) {
241		dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
242		percpu_ref_put(pgmap->ref);
243	}
244
245	/* pages are dead and unused, undo the arch mapping */
246	align_start = res->start & ~(SECTION_SIZE - 1);
247	align_size = ALIGN(resource_size(res), SECTION_SIZE);
248	arch_remove_memory(align_start, align_size);
249	pgmap_radix_release(res);
250	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
251			"%s: failed to free all reserved pages\n", __func__);
252}
253
254/* assumes rcu_read_lock() held at entry */
255struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
256{
257	struct page_map *page_map;
258
259	WARN_ON_ONCE(!rcu_read_lock_held());
260
261	page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
262	return page_map ? &page_map->pgmap : NULL;
263}
264
265/**
266 * devm_memremap_pages - remap and provide memmap backing for the given resource
267 * @dev: hosting device for @res
268 * @res: "host memory" address range
269 * @ref: a live per-cpu reference count
270 * @altmap: optional descriptor for allocating the memmap from @res
271 *
272 * Notes:
273 * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
274 *    (or devm release event).
275 *
276 * 2/ @res is expected to be a host memory range that could feasibly be
277 *    treated as a "System RAM" range, i.e. not a device mmio range, but
278 *    this is not enforced.
279 */
280void *devm_memremap_pages(struct device *dev, struct resource *res,
281		struct percpu_ref *ref, struct vmem_altmap *altmap)
282{
283	resource_size_t key, align_start, align_size, align_end;
284	struct dev_pagemap *pgmap;
285	struct page_map *page_map;
286	int error, nid, is_ram;
287	unsigned long pfn;
288
289	align_start = res->start & ~(SECTION_SIZE - 1);
290	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
291		- align_start;
292	is_ram = region_intersects(align_start, align_size,
293		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
294
295	if (is_ram == REGION_MIXED) {
296		WARN_ONCE(1, "%s attempted on mixed region %pr\n",
297				__func__, res);
298		return ERR_PTR(-ENXIO);
299	}
300
301	if (is_ram == REGION_INTERSECTS)
302		return __va(res->start);
303
304	if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
305		dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
306				__func__);
307		return ERR_PTR(-ENXIO);
308	}
309
310	if (!ref)
311		return ERR_PTR(-EINVAL);
312
313	page_map = devres_alloc_node(devm_memremap_pages_release,
314			sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
315	if (!page_map)
316		return ERR_PTR(-ENOMEM);
317	pgmap = &page_map->pgmap;
318
319	memcpy(&page_map->res, res, sizeof(*res));
320
321	pgmap->dev = dev;
322	if (altmap) {
323		memcpy(&page_map->altmap, altmap, sizeof(*altmap));
324		pgmap->altmap = &page_map->altmap;
325	}
326	pgmap->ref = ref;
327	pgmap->res = &page_map->res;
328
329	mutex_lock(&pgmap_lock);
330	error = 0;
331	align_end = align_start + align_size - 1;
332	for (key = align_start; key <= align_end; key += SECTION_SIZE) {
333		struct dev_pagemap *dup;
334
335		rcu_read_lock();
336		dup = find_dev_pagemap(key);
337		rcu_read_unlock();
338		if (dup) {
339			dev_err(dev, "%s: %pr collides with mapping for %s\n",
340					__func__, res, dev_name(dup->dev));
341			error = -EBUSY;
342			break;
343		}
344		error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
345				page_map);
346		if (error) {
347			dev_err(dev, "%s: failed: %d\n", __func__, error);
348			break;
349		}
350	}
351	mutex_unlock(&pgmap_lock);
352	if (error)
353		goto err_radix;
354
355	nid = dev_to_node(dev);
356	if (nid < 0)
357		nid = numa_mem_id();
358
359	error = arch_add_memory(nid, align_start, align_size, true);
360	if (error)
361		goto err_add_memory;
362
363	for_each_device_pfn(pfn, page_map) {
364		struct page *page = pfn_to_page(pfn);
365
366		/*
367		 * ZONE_DEVICE pages union ->lru with a ->pgmap back
368		 * pointer.  It is a bug if a ZONE_DEVICE page is ever
369		 * freed or placed on a driver-private list.  Seed the
370		 * storage with LIST_POISON* values.
371		 */
372		list_del(&page->lru);
373		page->pgmap = pgmap;
374	}
375	devres_add(dev, page_map);
376	return __va(res->start);
377
378 err_add_memory:
379 err_radix:
380	pgmap_radix_release(res);
381	devres_free(page_map);
382	return ERR_PTR(error);
383}
384EXPORT_SYMBOL(devm_memremap_pages);
385
386unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
387{
388	/* number of pfns from base where pfn_to_page() is valid */
389	return altmap->reserve + altmap->free;
390}
391
392void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
393{
394	altmap->alloc -= nr_pfns;
395}
396
397#ifdef CONFIG_SPARSEMEM_VMEMMAP
398struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
399{
400	/*
401	 * 'memmap_start' is the virtual address for the first "struct
402	 * page" in this range of the vmemmap array.  In the case of
403	 * CONFIG_SPARSEMEM_VMEMMAP a page_to_pfn conversion is simple
404	 * pointer arithmetic, so we can perform this to_vmem_altmap()
405	 * conversion without concern for the initialization state of
406	 * the struct page fields.
407	 */
408	struct page *page = (struct page *) memmap_start;
409	struct dev_pagemap *pgmap;
410
411	/*
412	 * Unconditionally retrieve a dev_pagemap associated with the
413	 * given physical address, this is only for use in the
414	 * arch_{add|remove}_memory() for setting up and tearing down
415	 * the memmap.
416	 */
417	rcu_read_lock();
418	pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
419	rcu_read_unlock();
420
421	return pgmap ? pgmap->altmap : NULL;
422}
423#endif /* CONFIG_SPARSEMEM_VMEMMAP */
424#endif /* CONFIG_ZONE_DEVICE */