[mirror_ubuntu-zesty-kernel.git] / kernel / memremap.c

/*
 * Copyright(c) 2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#include <linux/radix-tree.h>
#include <linux/memremap.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/pfn_t.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.h>

#ifndef ioremap_cache
/* temporary while we convert existing ioremap_cache users to memremap */
__weak void __iomem *ioremap_cache(resource_size_t offset, unsigned long size)
{
	return ioremap(offset, size);
}
#endif

static void *try_ram_remap(resource_size_t offset, size_t size)
{
	struct page *page = pfn_to_page(offset >> PAGE_SHIFT);

	/* In the simple case just return the existing linear address */
	if (!PageHighMem(page))
		return __va(offset);
	return NULL; /* fallback to ioremap_cache */
}

/**
 * memremap() - remap an iomem_resource as cacheable memory
 * @offset: iomem resource start address
 * @size: size of remap
 * @flags: either MEMREMAP_WB or MEMREMAP_WT
 *
 * memremap() is "ioremap" for cases where it is known that the resource
 * being mapped does not have i/o side effects and the __iomem
 * annotation is not applicable.
 *
 * MEMREMAP_WB - matches the default mapping for "System RAM" on
 * the architecture.  This is usually a read-allocate write-back cache.
 * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
 * memremap() will bypass establishing a new mapping and instead return
 * a pointer into the direct map.
 *
 * MEMREMAP_WT - establish a mapping whereby writes either bypass the
 * cache or are written through to memory and never exist in a
 * cache-dirty state with respect to program visibility.  Attempts to
 * map "System RAM" with this mapping type will fail.
 */
void *memremap(resource_size_t offset, size_t size, unsigned long flags)
{
	int is_ram = region_intersects(offset, size, "System RAM");
	void *addr = NULL;

	if (is_ram == REGION_MIXED) {
		WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
				&offset, (unsigned long) size);
		return NULL;
	}

	/* Try all mapping types requested until one returns non-NULL */
	if (flags & MEMREMAP_WB) {
		flags &= ~MEMREMAP_WB;
		/*
		 * MEMREMAP_WB is special in that it can be satisifed
		 * from the direct map.  Some archs depend on the
		 * capability of memremap() to autodetect cases where
		 * the requested range is potentially in "System RAM"
		 */
		if (is_ram == REGION_INTERSECTS)
			addr = try_ram_remap(offset, size);
		if (!addr)
			addr = ioremap_cache(offset, size);
	}

	/*
	 * If we don't have a mapping yet and more request flags are
	 * pending then we will be attempting to establish a new virtual
	 * address mapping.  Enforce that this mapping is not aliasing
	 * "System RAM"
	 */
	if (!addr && is_ram == REGION_INTERSECTS && flags) {
		WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
				&offset, (unsigned long) size);
		return NULL;
	}

	if (!addr && (flags & MEMREMAP_WT)) {
		flags &= ~MEMREMAP_WT;
		addr = ioremap_wt(offset, size);
	}

	return addr;
}
EXPORT_SYMBOL(memremap);

void memunmap(void *addr)
{
	if (is_vmalloc_addr(addr))
		iounmap((void __iomem *) addr);
}
EXPORT_SYMBOL(memunmap);

static void devm_memremap_release(struct device *dev, void *res)
{
	memunmap(*(void **)res);
}

static int devm_memremap_match(struct device *dev, void *res, void *match_data)
{
	return *(void **)res == match_data;
}

void *devm_memremap(struct device *dev, resource_size_t offset,
		size_t size, unsigned long flags)
{
	void **ptr, *addr;

	ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
			dev_to_node(dev));
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	addr = memremap(offset, size, flags);
	if (addr) {
		*ptr = addr;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
		return ERR_PTR(-ENXIO);
	}

	return addr;
}
EXPORT_SYMBOL(devm_memremap);

void devm_memunmap(struct device *dev, void *addr)
{
	WARN_ON(devres_release(dev, devm_memremap_release,
				devm_memremap_match, addr));
}
EXPORT_SYMBOL(devm_memunmap);

pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
{
	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
}
EXPORT_SYMBOL(phys_to_pfn_t);

#ifdef CONFIG_ZONE_DEVICE
static DEFINE_MUTEX(pgmap_lock);
static RADIX_TREE(pgmap_radix, GFP_KERNEL);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)

struct page_map {
	struct resource res;
	struct percpu_ref *ref;
	struct dev_pagemap pgmap;
	struct vmem_altmap altmap;
};

void get_zone_device_page(struct page *page)
{
	percpu_ref_get(page->pgmap->ref);
}
EXPORT_SYMBOL(get_zone_device_page);

void put_zone_device_page(struct page *page)
{
	put_dev_pagemap(page->pgmap);
}
EXPORT_SYMBOL(put_zone_device_page);

static void pgmap_radix_release(struct resource *res)
{
	resource_size_t key, align_start, align_size, align_end;

	align_start = res->start & ~(SECTION_SIZE - 1);
	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	align_end = align_start + align_size - 1;

	mutex_lock(&pgmap_lock);
	for (key = res->start; key <= res->end; key += SECTION_SIZE)
		radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
	mutex_unlock(&pgmap_lock);
}

static unsigned long pfn_first(struct page_map *page_map)
{
	struct dev_pagemap *pgmap = &page_map->pgmap;
	const struct resource *res = &page_map->res;
	struct vmem_altmap *altmap = pgmap->altmap;
	unsigned long pfn;

	pfn = res->start >> PAGE_SHIFT;
	if (altmap)
		pfn += vmem_altmap_offset(altmap);
	return pfn;
}

static unsigned long pfn_end(struct page_map *page_map)
{
	const struct resource *res = &page_map->res;

	return (res->start + resource_size(res)) >> PAGE_SHIFT;
}

#define for_each_device_pfn(pfn, map) \
	for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)

static void devm_memremap_pages_release(struct device *dev, void *data)
{
	struct page_map *page_map = data;
	struct resource *res = &page_map->res;
	resource_size_t align_start, align_size;
	struct dev_pagemap *pgmap = &page_map->pgmap;

	if (percpu_ref_tryget_live(pgmap->ref)) {
		dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
		percpu_ref_put(pgmap->ref);
	}

	/* pages are dead and unused, undo the arch mapping */
	align_start = res->start & ~(SECTION_SIZE - 1);
	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	arch_remove_memory(align_start, align_size);
	pgmap_radix_release(res);
	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
			"%s: failed to free all reserved pages\n", __func__);
}

/* assumes rcu_read_lock() held at entry */
struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
{
	struct page_map *page_map;

	WARN_ON_ONCE(!rcu_read_lock_held());

	page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
	return page_map ? &page_map->pgmap : NULL;
}

/**
 * devm_memremap_pages - remap and provide memmap backing for the given resource
 * @dev: hosting device for @res
 * @res: "host memory" address range
 * @ref: a live per-cpu reference count
 * @altmap: optional descriptor for allocating the memmap from @res
 *
 * Notes:
 * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
 *    (or devm release event).
 *
 * 2/ @res is expected to be a host memory range that could feasibly be
 *    treated as a "System RAM" range, i.e. not a device mmio range, but
 *    this is not enforced.
 */
void *devm_memremap_pages(struct device *dev, struct resource *res,
		struct percpu_ref *ref, struct vmem_altmap *altmap)
{
	int is_ram = region_intersects(res->start, resource_size(res),
			"System RAM");
	resource_size_t key, align_start, align_size, align_end;
	struct dev_pagemap *pgmap;
	struct page_map *page_map;
	unsigned long pfn;
	int error, nid;

	if (is_ram == REGION_MIXED) {
		WARN_ONCE(1, "%s attempted on mixed region %pr\n",
				__func__, res);
		return ERR_PTR(-ENXIO);
	}

	if (is_ram == REGION_INTERSECTS)
		return __va(res->start);

	if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
		dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
				__func__);
		return ERR_PTR(-ENXIO);
	}

	if (!ref)
		return ERR_PTR(-EINVAL);

	page_map = devres_alloc_node(devm_memremap_pages_release,
			sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
	if (!page_map)
		return ERR_PTR(-ENOMEM);
	pgmap = &page_map->pgmap;

	memcpy(&page_map->res, res, sizeof(*res));

	pgmap->dev = dev;
	if (altmap) {
		memcpy(&page_map->altmap, altmap, sizeof(*altmap));
		pgmap->altmap = &page_map->altmap;
	}
	pgmap->ref = ref;
	pgmap->res = &page_map->res;

	mutex_lock(&pgmap_lock);
	error = 0;
	align_start = res->start & ~(SECTION_SIZE - 1);
	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	align_end = align_start + align_size - 1;
	for (key = align_start; key <= align_end; key += SECTION_SIZE) {
		struct dev_pagemap *dup;

		rcu_read_lock();
		dup = find_dev_pagemap(key);
		rcu_read_unlock();
		if (dup) {
			dev_err(dev, "%s: %pr collides with mapping for %s\n",
					__func__, res, dev_name(dup->dev));
			error = -EBUSY;
			break;
		}
		error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
				page_map);
		if (error) {
			dev_err(dev, "%s: failed: %d\n", __func__, error);
			break;
		}
	}
	mutex_unlock(&pgmap_lock);
	if (error)
		goto err_radix;

	nid = dev_to_node(dev);
	if (nid < 0)
		nid = numa_mem_id();

	error = arch_add_memory(nid, align_start, align_size, true);
	if (error)
		goto err_add_memory;

	for_each_device_pfn(pfn, page_map) {
		struct page *page = pfn_to_page(pfn);

		/* ZONE_DEVICE pages must never appear on a slab lru */
		list_force_poison(&page->lru);
		page->pgmap = pgmap;
	}
	devres_add(dev, page_map);
	return __va(res->start);

 err_add_memory:
 err_radix:
	pgmap_radix_release(res);
	devres_free(page_map);
	return ERR_PTR(error);
}
EXPORT_SYMBOL(devm_memremap_pages);

unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
{
	/* number of pfns from base where pfn_to_page() is valid */
	return altmap->reserve + altmap->free;
}

void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
{
	altmap->alloc -= nr_pfns;
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
{
	/*
	 * 'memmap_start' is the virtual address for the first "struct
	 * page" in this range of the vmemmap array.  In the case of
	 * CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
	 * pointer arithmetic, so we can perform this to_vmem_altmap()
	 * conversion without concern for the initialization state of
	 * the struct page fields.
	 */
	struct page *page = (struct page *) memmap_start;
	struct dev_pagemap *pgmap;

	/*
	 * Uncoditionally retrieve a dev_pagemap associated with the
	 * given physical address, this is only for use in the
	 * arch_{add|remove}_memory() for setting up and tearing down
	 * the memmap.
	 */
	rcu_read_lock();
	pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
	rcu_read_unlock();

	return pgmap ? pgmap->altmap : NULL;
}
#endif /* CONFIG_SPARSEMEM_VMEMMAP */
#endif /* CONFIG_ZONE_DEVICE */
Commit	Line	Data
92281dee DW	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	*/
9476df7d DW	13	#include <linux/radix-tree.h>
9476df7d DW	14	#include <linux/memremap.h>
7d3dcf26	15	#include <linux/device.h>
92281dee	16	#include <linux/types.h>
34c0fd54	17	#include <linux/pfn_t.h>
92281dee DW	18	#include <linux/io.h>
92281dee DW	19	#include <linux/mm.h>
41e94a85	20	#include <linux/memory_hotplug.h>
92281dee DW	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
182475b7 DW	30	static void *try_ram_remap(resource_size_t offset, size_t size)
	31	{
	32	struct page *page = pfn_to_page(offset >> PAGE_SHIFT);
	33
	34	/* In the simple case just return the existing linear address */
	35	if (!PageHighMem(page))
	36	return __va(offset);
	37	return NULL; /* fallback to ioremap_cache */
	38	}
	39
92281dee DW	40	/**
	41	* memremap() - remap an iomem_resource as cacheable memory
	42	* @offset: iomem resource start address
	43	* @size: size of remap
	44	* @flags: either MEMREMAP_WB or MEMREMAP_WT
	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.
	49	*
	50	* MEMREMAP_WB - matches the default mapping for "System RAM" on
	51	* the architecture. This is usually a read-allocate write-back cache.
	52	* Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
	53	* memremap() will bypass establishing a new mapping and instead return
	54	* a pointer into the direct map.
	55	*
	56	* MEMREMAP_WT - establish a mapping whereby writes either bypass the
	57	* cache or are written through to memory and never exist in a
	58	* cache-dirty state with respect to program visibility. Attempts to
	59	* map "System RAM" with this mapping type will fail.
	60	*/
	61	void *memremap(resource_size_t offset, size_t size, unsigned long flags)
	62	{
	63	int is_ram = region_intersects(offset, size, "System RAM");
	64	void *addr = NULL;
	65
	66	if (is_ram == REGION_MIXED) {
	67	WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
	68	&offset, (unsigned long) size);
	69	return NULL;
	70	}
	71
	72	/* Try all mapping types requested until one returns non-NULL */
	73	if (flags & MEMREMAP_WB) {
	74	flags &= ~MEMREMAP_WB;
	75	/*
	76	* MEMREMAP_WB is special in that it can be satisifed
	77	* from the direct map. Some archs depend on the
	78	* capability of memremap() to autodetect cases where
	79	* the requested range is potentially in "System RAM"
	80	*/
	81	if (is_ram == REGION_INTERSECTS)
182475b7 DW	82	addr = try_ram_remap(offset, size);
182475b7 DW	83	if (!addr)
92281dee DW	84	addr = ioremap_cache(offset, size);
	85	}
	86
	87	/*
	88	* If we don't have a mapping yet and more request flags are
	89	* pending then we will be attempting to establish a new virtual
	90	* address mapping. Enforce that this mapping is not aliasing
	91	* "System RAM"
	92	*/
	93	if (!addr && is_ram == REGION_INTERSECTS && flags) {
	94	WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
	95	&offset, (unsigned long) size);
	96	return NULL;
	97	}
	98
	99	if (!addr && (flags & MEMREMAP_WT)) {
	100	flags &= ~MEMREMAP_WT;
	101	addr = ioremap_wt(offset, size);
	102	}
	103
	104	return addr;
	105	}
	106	EXPORT_SYMBOL(memremap);
	107
	108	void memunmap(void *addr)
	109	{
	110	if (is_vmalloc_addr(addr))
	111	iounmap((void __iomem *) addr);
	112	}
	113	EXPORT_SYMBOL(memunmap);
7d3dcf26 CH	114
	115	static void devm_memremap_release(struct device dev, void res)
	116	{
9273a8bb	117	memunmap((void *)res);
7d3dcf26 CH	118	}
	119
	120	static int devm_memremap_match(struct device dev, void res, void *match_data)
	121	{
	122	return (void *)res == match_data;
	123	}
	124
	125	void devm_memremap(struct device dev, resource_size_t offset,
	126	size_t size, unsigned long flags)
	127	{
	128	void *ptr, addr;
	129
538ea4aa DW	130	ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
538ea4aa DW	131	dev_to_node(dev));
7d3dcf26	132	if (!ptr)
b36f4761	133	return ERR_PTR(-ENOMEM);
7d3dcf26 CH	134
	135	addr = memremap(offset, size, flags);
	136	if (addr) {
	137	*ptr = addr;
	138	devres_add(dev, ptr);
93f834df	139	} else {
7d3dcf26	140	devres_free(ptr);
93f834df TK	141	return ERR_PTR(-ENXIO);
93f834df TK	142	}
7d3dcf26 CH	143
	144	return addr;
	145	}
	146	EXPORT_SYMBOL(devm_memremap);
	147
	148	void devm_memunmap(struct device dev, void addr)
	149	{
d741314f DW	150	WARN_ON(devres_release(dev, devm_memremap_release,
d741314f DW	151	devm_memremap_match, addr));
7d3dcf26 CH	152	}
7d3dcf26 CH	153	EXPORT_SYMBOL(devm_memunmap);
41e94a85	154
db78c222	155	pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
34c0fd54 DW	156	{
	157	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
	158	}
	159	EXPORT_SYMBOL(phys_to_pfn_t);
	160
41e94a85	161	#ifdef CONFIG_ZONE_DEVICE
9476df7d DW	162	static DEFINE_MUTEX(pgmap_lock);
	163	static RADIX_TREE(pgmap_radix, GFP_KERNEL);
	164	#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
	165	#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
	166
41e94a85 CH	167	struct page_map {
41e94a85 CH	168	struct resource res;
9476df7d DW	169	struct percpu_ref *ref;
9476df7d DW	170	struct dev_pagemap pgmap;
4b94ffdc	171	struct vmem_altmap altmap;
41e94a85 CH	172	};
41e94a85 CH	173
3565fce3 DW	174	void get_zone_device_page(struct page *page)
	175	{
	176	percpu_ref_get(page->pgmap->ref);
	177	}
	178	EXPORT_SYMBOL(get_zone_device_page);
	179
	180	void put_zone_device_page(struct page *page)
	181	{
	182	put_dev_pagemap(page->pgmap);
	183	}
	184	EXPORT_SYMBOL(put_zone_device_page);
	185
9476df7d DW	186	static void pgmap_radix_release(struct resource *res)
9476df7d DW	187	{
eb7d78c9 DW	188	resource_size_t key, align_start, align_size, align_end;
	189
	190	align_start = res->start & ~(SECTION_SIZE - 1);
	191	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	192	align_end = align_start + align_size - 1;
9476df7d DW	193
	194	mutex_lock(&pgmap_lock);
	195	for (key = res->start; key <= res->end; key += SECTION_SIZE)
	196	radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
	197	mutex_unlock(&pgmap_lock);
	198	}
	199
5c2c2587 DW	200	static unsigned long pfn_first(struct page_map *page_map)
	201	{
	202	struct dev_pagemap *pgmap = &page_map->pgmap;
	203	const struct resource *res = &page_map->res;
	204	struct vmem_altmap *altmap = pgmap->altmap;
	205	unsigned long pfn;
	206
	207	pfn = res->start >> PAGE_SHIFT;
	208	if (altmap)
	209	pfn += vmem_altmap_offset(altmap);
	210	return pfn;
	211	}
	212
	213	static unsigned long pfn_end(struct page_map *page_map)
	214	{
	215	const struct resource *res = &page_map->res;
	216
	217	return (res->start + resource_size(res)) >> PAGE_SHIFT;
	218	}
	219
	220	#define for_each_device_pfn(pfn, map) \
	221	for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
	222
9476df7d	223	static void devm_memremap_pages_release(struct device dev, void data)
41e94a85	224	{
9476df7d DW	225	struct page_map *page_map = data;
	226	struct resource *res = &page_map->res;
	227	resource_size_t align_start, align_size;
4b94ffdc	228	struct dev_pagemap *pgmap = &page_map->pgmap;
9476df7d	229
5c2c2587 DW	230	if (percpu_ref_tryget_live(pgmap->ref)) {
	231	dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
	232	percpu_ref_put(pgmap->ref);
	233	}
	234
41e94a85	235	/* pages are dead and unused, undo the arch mapping */
9476df7d DW	236	align_start = res->start & ~(SECTION_SIZE - 1);
	237	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	238	arch_remove_memory(align_start, align_size);
eb7d78c9	239	pgmap_radix_release(res);
4b94ffdc DW	240	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
4b94ffdc DW	241	"%s: failed to free all reserved pages\n", __func__);
9476df7d DW	242	}
	243
	244	/* assumes rcu_read_lock() held at entry */
	245	struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
	246	{
	247	struct page_map *page_map;
	248
	249	WARN_ON_ONCE(!rcu_read_lock_held());
	250
	251	page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
	252	return page_map ? &page_map->pgmap : NULL;
41e94a85 CH	253	}
41e94a85 CH	254
4b94ffdc DW	255	/**
	256	* devm_memremap_pages - remap and provide memmap backing for the given resource
	257	* @dev: hosting device for @res
	258	* @res: "host memory" address range
5c2c2587	259	* @ref: a live per-cpu reference count
4b94ffdc DW	260	* @altmap: optional descriptor for allocating the memmap from @res
4b94ffdc DW	261	*
5c2c2587 DW	262	* Notes:
	263	* 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
	264	* (or devm release event).
	265	*
	266	* 2/ @res is expected to be a host memory range that could feasibly be
	267	* treated as a "System RAM" range, i.e. not a device mmio range, but
	268	* this is not enforced.
4b94ffdc DW	269	*/
4b94ffdc DW	270	void devm_memremap_pages(struct device dev, struct resource *res,
5c2c2587	271	struct percpu_ref ref, struct vmem_altmap altmap)
41e94a85 CH	272	{
	273	int is_ram = region_intersects(res->start, resource_size(res),
	274	"System RAM");
eb7d78c9	275	resource_size_t key, align_start, align_size, align_end;
4b94ffdc	276	struct dev_pagemap *pgmap;
41e94a85	277	struct page_map *page_map;
5c2c2587	278	unsigned long pfn;
41e94a85 CH	279	int error, nid;
	280
	281	if (is_ram == REGION_MIXED) {
	282	WARN_ONCE(1, "%s attempted on mixed region %pr\n",
	283	__func__, res);
	284	return ERR_PTR(-ENXIO);
	285	}
	286
	287	if (is_ram == REGION_INTERSECTS)
	288	return __va(res->start);
	289
4b94ffdc DW	290	if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
	291	dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
	292	__func__);
	293	return ERR_PTR(-ENXIO);
	294	}
	295
5c2c2587 DW	296	if (!ref)
	297	return ERR_PTR(-EINVAL);
	298
538ea4aa DW	299	page_map = devres_alloc_node(devm_memremap_pages_release,
538ea4aa DW	300	sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
41e94a85 CH	301	if (!page_map)
41e94a85 CH	302	return ERR_PTR(-ENOMEM);
4b94ffdc	303	pgmap = &page_map->pgmap;
41e94a85 CH	304
	305	memcpy(&page_map->res, res, sizeof(*res));
	306
4b94ffdc DW	307	pgmap->dev = dev;
	308	if (altmap) {
	309	memcpy(&page_map->altmap, altmap, sizeof(*altmap));
	310	pgmap->altmap = &page_map->altmap;
	311	}
5c2c2587	312	pgmap->ref = ref;
4b94ffdc DW	313	pgmap->res = &page_map->res;
4b94ffdc DW	314
9476df7d DW	315	mutex_lock(&pgmap_lock);
9476df7d DW	316	error = 0;
eb7d78c9 DW	317	align_start = res->start & ~(SECTION_SIZE - 1);
	318	align_size = ALIGN(resource_size(res), SECTION_SIZE);
	319	align_end = align_start + align_size - 1;
	320	for (key = align_start; key <= align_end; key += SECTION_SIZE) {
9476df7d DW	321	struct dev_pagemap *dup;
	322
	323	rcu_read_lock();
	324	dup = find_dev_pagemap(key);
	325	rcu_read_unlock();
	326	if (dup) {
	327	dev_err(dev, "%s: %pr collides with mapping for %s\n",
	328	__func__, res, dev_name(dup->dev));
	329	error = -EBUSY;
	330	break;
	331	}
	332	error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
	333	page_map);
	334	if (error) {
	335	dev_err(dev, "%s: failed: %d\n", __func__, error);
	336	break;
	337	}
	338	}
	339	mutex_unlock(&pgmap_lock);
	340	if (error)
	341	goto err_radix;
	342
41e94a85 CH	343	nid = dev_to_node(dev);
41e94a85 CH	344	if (nid < 0)
7eff93b7	345	nid = numa_mem_id();
41e94a85	346
9476df7d DW	347	error = arch_add_memory(nid, align_start, align_size, true);
	348	if (error)
	349	goto err_add_memory;
41e94a85	350
5c2c2587 DW	351	for_each_device_pfn(pfn, page_map) {
	352	struct page *page = pfn_to_page(pfn);
	353
	354	/* ZONE_DEVICE pages must never appear on a slab lru */
	355	list_force_poison(&page->lru);
	356	page->pgmap = pgmap;
	357	}
41e94a85 CH	358	devres_add(dev, page_map);
41e94a85 CH	359	return __va(res->start);
9476df7d DW	360
	361	err_add_memory:
	362	err_radix:
	363	pgmap_radix_release(res);
	364	devres_free(page_map);
	365	return ERR_PTR(error);
41e94a85 CH	366	}
41e94a85 CH	367	EXPORT_SYMBOL(devm_memremap_pages);
4b94ffdc DW	368
	369	unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
	370	{
	371	/* number of pfns from base where pfn_to_page() is valid */
	372	return altmap->reserve + altmap->free;
	373	}
	374
	375	void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
	376	{
	377	altmap->alloc -= nr_pfns;
	378	}
	379
	380	#ifdef CONFIG_SPARSEMEM_VMEMMAP
	381	struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
	382	{
	383	/*
	384	* 'memmap_start' is the virtual address for the first "struct
	385	* page" in this range of the vmemmap array. In the case of
	386	* CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
	387	* pointer arithmetic, so we can perform this to_vmem_altmap()
	388	* conversion without concern for the initialization state of
	389	* the struct page fields.
	390	*/
	391	struct page page = (struct page ) memmap_start;
	392	struct dev_pagemap *pgmap;
	393
	394	/*
	395	* Uncoditionally retrieve a dev_pagemap associated with the
	396	* given physical address, this is only for use in the
	397	* arch_{add\|remove}_memory() for setting up and tearing down
	398	* the memmap.
	399	*/
	400	rcu_read_lock();
	401	pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
	402	rcu_read_unlock();
	403
	404	return pgmap ? pgmap->altmap : NULL;
	405	}
	406	#endif /* CONFIG_SPARSEMEM_VMEMMAP */
41e94a85	407	#endif /* CONFIG_ZONE_DEVICE */