kernel/memremap.c

   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
  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
  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)
  82                         addr = try_ram_remap(offset, size);
  83                 if (!addr)
  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);
 114
 115 static void devm_memremap_release(struct device *dev, void *res)
 116 {
 117         memunmap(res);
 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
 130         ptr = devres_alloc_node(devm_memremap_release, sizeof(*ptr), GFP_KERNEL,
 131                         dev_to_node(dev));
 132         if (!ptr)
 133                 return ERR_PTR(-ENOMEM);
 134
 135         addr = memremap(offset, size, flags);
 136         if (addr) {
 137                 *ptr = addr;
 138                 devres_add(dev, ptr);
 139         } else
 140                 devres_free(ptr);
 141
 142         return addr;
 143 }
 144 EXPORT_SYMBOL(devm_memremap);
 145
 146 void devm_memunmap(struct device *dev, void *addr)
 147 {
 148         WARN_ON(devres_release(dev, devm_memremap_release,
 149                                 devm_memremap_match, addr));
 150 }
 151 EXPORT_SYMBOL(devm_memunmap);
 152
 153 pfn_t phys_to_pfn_t(phys_addr_t addr, unsigned long flags)
 154 {
 155         return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
 156 }
 157 EXPORT_SYMBOL(phys_to_pfn_t);
 158
 159 #ifdef CONFIG_ZONE_DEVICE
 160 static DEFINE_MUTEX(pgmap_lock);
 161 static RADIX_TREE(pgmap_radix, GFP_KERNEL);
 162 #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
 163 #define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
 164
 165 struct page_map {
 166         struct resource res;
 167         struct percpu_ref *ref;
 168         struct dev_pagemap pgmap;
 169         struct vmem_altmap altmap;
 170 };
 171
 172 void get_zone_device_page(struct page *page)
 173 {
 174         percpu_ref_get(page->pgmap->ref);
 175 }
 176 EXPORT_SYMBOL(get_zone_device_page);
 177
 178 void put_zone_device_page(struct page *page)
 179 {
 180         put_dev_pagemap(page->pgmap);
 181 }
 182 EXPORT_SYMBOL(put_zone_device_page);
 183
 184 static void pgmap_radix_release(struct resource *res)
 185 {
 186         resource_size_t key, align_start, align_size, align_end;
 187
 188         align_start = res->start & ~(SECTION_SIZE - 1);
 189         align_size = ALIGN(resource_size(res), SECTION_SIZE);
 190         align_end = align_start + align_size - 1;
 191
 192         mutex_lock(&pgmap_lock);
 193         for (key = res->start; key <= res->end; key += SECTION_SIZE)
 194                 radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
 195         mutex_unlock(&pgmap_lock);
 196 }
 197
 198 static unsigned long pfn_first(struct page_map *page_map)
 199 {
 200         struct dev_pagemap *pgmap = &page_map->pgmap;
 201         const struct resource *res = &page_map->res;
 202         struct vmem_altmap *altmap = pgmap->altmap;
 203         unsigned long pfn;
 204
 205         pfn = res->start >> PAGE_SHIFT;
 206         if (altmap)
 207                 pfn += vmem_altmap_offset(altmap);
 208         return pfn;
 209 }
 210
 211 static unsigned long pfn_end(struct page_map *page_map)
 212 {
 213         const struct resource *res = &page_map->res;
 214
 215         return (res->start + resource_size(res)) >> PAGE_SHIFT;
 216 }
 217
 218 #define for_each_device_pfn(pfn, map) \
 219         for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
 220
 221 static void devm_memremap_pages_release(struct device *dev, void *data)
 222 {
 223         struct page_map *page_map = data;
 224         struct resource *res = &page_map->res;
 225         resource_size_t align_start, align_size;
 226         struct dev_pagemap *pgmap = &page_map->pgmap;
 227
 228         if (percpu_ref_tryget_live(pgmap->ref)) {
 229                 dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
 230                 percpu_ref_put(pgmap->ref);
 231         }
 232
 233         /* pages are dead and unused, undo the arch mapping */
 234         align_start = res->start & ~(SECTION_SIZE - 1);
 235         align_size = ALIGN(resource_size(res), SECTION_SIZE);
 236         arch_remove_memory(align_start, align_size);
 237         pgmap_radix_release(res);
 238         dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
 239                         "%s: failed to free all reserved pages\n", __func__);
 240 }
 241
 242 /* assumes rcu_read_lock() held at entry */
 243 struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 244 {
 245         struct page_map *page_map;
 246
 247         WARN_ON_ONCE(!rcu_read_lock_held());
 248
 249         page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
 250         return page_map ? &page_map->pgmap : NULL;
 251 }
 252
 253 /**
 254  * devm_memremap_pages - remap and provide memmap backing for the given resource
 255  * @dev: hosting device for @res
 256  * @res: "host memory" address range
 257  * @ref: a live per-cpu reference count
 258  * @altmap: optional descriptor for allocating the memmap from @res
 259  *
 260  * Notes:
 261  * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
 262  *    (or devm release event).
 263  *
 264  * 2/ @res is expected to be a host memory range that could feasibly be
 265  *    treated as a "System RAM" range, i.e. not a device mmio range, but
 266  *    this is not enforced.
 267  */
 268 void *devm_memremap_pages(struct device *dev, struct resource *res,
 269                 struct percpu_ref *ref, struct vmem_altmap *altmap)
 270 {
 271         int is_ram = region_intersects(res->start, resource_size(res),
 272                         "System RAM");
 273         resource_size_t key, align_start, align_size, align_end;
 274         struct dev_pagemap *pgmap;
 275         struct page_map *page_map;
 276         unsigned long pfn;
 277         int error, nid;
 278
 279         if (is_ram == REGION_MIXED) {
 280                 WARN_ONCE(1, "%s attempted on mixed region %pr\n",
 281                                 __func__, res);
 282                 return ERR_PTR(-ENXIO);
 283         }
 284
 285         if (is_ram == REGION_INTERSECTS)
 286                 return __va(res->start);
 287
 288         if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
 289                 dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
 290                                 __func__);
 291                 return ERR_PTR(-ENXIO);
 292         }
 293
 294         if (!ref)
 295                 return ERR_PTR(-EINVAL);
 296
 297         page_map = devres_alloc_node(devm_memremap_pages_release,
 298                         sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
 299         if (!page_map)
 300                 return ERR_PTR(-ENOMEM);
 301         pgmap = &page_map->pgmap;
 302
 303         memcpy(&page_map->res, res, sizeof(*res));
 304
 305         pgmap->dev = dev;
 306         if (altmap) {
 307                 memcpy(&page_map->altmap, altmap, sizeof(*altmap));
 308                 pgmap->altmap = &page_map->altmap;
 309         }
 310         pgmap->ref = ref;
 311         pgmap->res = &page_map->res;
 312
 313         mutex_lock(&pgmap_lock);
 314         error = 0;
 315         align_start = res->start & ~(SECTION_SIZE - 1);
 316         align_size = ALIGN(resource_size(res), SECTION_SIZE);
 317         align_end = align_start + align_size - 1;
 318         for (key = align_start; key <= align_end; key += SECTION_SIZE) {
 319                 struct dev_pagemap *dup;
 320
 321                 rcu_read_lock();
 322                 dup = find_dev_pagemap(key);
 323                 rcu_read_unlock();
 324                 if (dup) {
 325                         dev_err(dev, "%s: %pr collides with mapping for %s\n",
 326                                         __func__, res, dev_name(dup->dev));
 327                         error = -EBUSY;
 328                         break;
 329                 }
 330                 error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
 331                                 page_map);
 332                 if (error) {
 333                         dev_err(dev, "%s: failed: %d\n", __func__, error);
 334                         break;
 335                 }
 336         }
 337         mutex_unlock(&pgmap_lock);
 338         if (error)
 339                 goto err_radix;
 340
 341         nid = dev_to_node(dev);
 342         if (nid < 0)
 343                 nid = numa_mem_id();
 344
 345         error = arch_add_memory(nid, align_start, align_size, true);
 346         if (error)
 347                 goto err_add_memory;
 348
 349         for_each_device_pfn(pfn, page_map) {
 350                 struct page *page = pfn_to_page(pfn);
 351
 352                 /* ZONE_DEVICE pages must never appear on a slab lru */
 353                 list_force_poison(&page->lru);
 354                 page->pgmap = pgmap;
 355         }
 356         devres_add(dev, page_map);
 357         return __va(res->start);
 358
 359  err_add_memory:
 360  err_radix:
 361         pgmap_radix_release(res);
 362         devres_free(page_map);
 363         return ERR_PTR(error);
 364 }
 365 EXPORT_SYMBOL(devm_memremap_pages);
 366
 367 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 368 {
 369         /* number of pfns from base where pfn_to_page() is valid */
 370         return altmap->reserve + altmap->free;
 371 }
 372
 373 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
 374 {
 375         altmap->alloc -= nr_pfns;
 376 }
 377
 378 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 379 struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
 380 {
 381         /*
 382          * 'memmap_start' is the virtual address for the first "struct
 383          * page" in this range of the vmemmap array.  In the case of
 384          * CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
 385          * pointer arithmetic, so we can perform this to_vmem_altmap()
 386          * conversion without concern for the initialization state of
 387          * the struct page fields.
 388          */
 389         struct page *page = (struct page *) memmap_start;
 390         struct dev_pagemap *pgmap;
 391
 392         /*
 393          * Uncoditionally retrieve a dev_pagemap associated with the
 394          * given physical address, this is only for use in the
 395          * arch_{add|remove}_memory() for setting up and tearing down
 396          * the memmap.
 397          */
 398         rcu_read_lock();
 399         pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
 400         rcu_read_unlock();
 401
 402         return pgmap ? pgmap->altmap : NULL;
 403 }
 404 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 405 #endif /* CONFIG_ZONE_DEVICE */