1 /* 2 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA 3 * Copyright (c) 2012 David Airlie <airlied@linux.ie> 4 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 22 * OTHER DEALINGS IN THE SOFTWARE. 23 */ 24 25 #include <drm/drmP.h> 26 #include <drm/drm_mm.h> 27 #include <drm/drm_vma_manager.h> 28 #include <linux/mm.h> 29 #include <linux/module.h> 30 #include <linux/rbtree.h> 31 #include <linux/slab.h> 32 #include <linux/spinlock.h> 33 #include <linux/types.h> 34 35 /** 36 * DOC: vma offset manager 37 * 38 * The vma-manager is responsible to map arbitrary driver-dependent memory 39 * regions into the linear user address-space. It provides offsets to the 40 * caller which can then be used on the address_space of the drm-device. It 41 * takes care to not overlap regions, size them appropriately and to not 42 * confuse mm-core by inconsistent fake vm_pgoff fields. 43 * Drivers shouldn't use this for object placement in VMEM. This manager should 44 * only be used to manage mappings into linear user-space VMs. 45 * 46 * We use drm_mm as backend to manage object allocations. But it is highly 47 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to 48 * speed up offset lookups. 49 * 50 * You must not use multiple offset managers on a single address_space. 51 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will 52 * no longer be linear. Please use VM_NONLINEAR in that case and implement your 53 * own offset managers. 54 * 55 * This offset manager works on page-based addresses. That is, every argument 56 * and return code (with the exception of drm_vma_node_offset_addr()) is given 57 * in number of pages, not number of bytes. That means, object sizes and offsets 58 * must always be page-aligned (as usual). 59 * If you want to get a valid byte-based user-space address for a given offset, 60 * please see drm_vma_node_offset_addr(). 61 */ 62 63 /** 64 * drm_vma_offset_manager_init - Initialize new offset-manager 65 * @mgr: Manager object 66 * @page_offset: Offset of available memory area (page-based) 67 * @size: Size of available address space range (page-based) 68 * 69 * Initialize a new offset-manager. The offset and area size available for the 70 * manager are given as @page_offset and @size. Both are interpreted as 71 * page-numbers, not bytes. 72 * 73 * Adding/removing nodes from the manager is locked internally and protected 74 * against concurrent access. However, node allocation and destruction is left 75 * for the caller. While calling into the vma-manager, a given node must 76 * always be guaranteed to be referenced. 77 */ 78 void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr, 79 unsigned long page_offset, unsigned long size) 80 { 81 lockinit(&mgr->vm_lock, "drmvml", 0, LK_CANRECURSE); 82 mgr->vm_addr_space_rb = RB_ROOT; 83 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); 84 } 85 EXPORT_SYMBOL(drm_vma_offset_manager_init); 86 87 /** 88 * drm_vma_offset_manager_destroy() - Destroy offset manager 89 * @mgr: Manager object 90 * 91 * Destroy an object manager which was previously created via 92 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes 93 * before destroying the manager. Otherwise, drm_mm will refuse to free the 94 * requested resources. 95 * 96 * The manager must not be accessed after this function is called. 97 */ 98 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) 99 { 100 /* take the lock to protect against buggy drivers */ 101 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 102 drm_mm_takedown(&mgr->vm_addr_space_mm); 103 lockmgr(&mgr->vm_lock, LK_RELEASE); 104 } 105 EXPORT_SYMBOL(drm_vma_offset_manager_destroy); 106 107 /** 108 * drm_vma_offset_lookup() - Find node in offset space 109 * @mgr: Manager object 110 * @start: Start address for object (page-based) 111 * @pages: Size of object (page-based) 112 * 113 * Find a node given a start address and object size. This returns the _best_ 114 * match for the given node. That is, @start may point somewhere into a valid 115 * region and the given node will be returned, as long as the node spans the 116 * whole requested area (given the size in number of pages as @pages). 117 * 118 * RETURNS: 119 * Returns NULL if no suitable node can be found. Otherwise, the best match 120 * is returned. It's the caller's responsibility to make sure the node doesn't 121 * get destroyed before the caller can access it. 122 */ 123 struct drm_vma_offset_node *drm_vma_offset_lookup(struct drm_vma_offset_manager *mgr, 124 unsigned long start, 125 unsigned long pages) 126 { 127 struct drm_vma_offset_node *node; 128 129 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 130 node = drm_vma_offset_lookup_locked(mgr, start, pages); 131 lockmgr(&mgr->vm_lock, LK_RELEASE); 132 133 return node; 134 } 135 EXPORT_SYMBOL(drm_vma_offset_lookup); 136 137 /** 138 * drm_vma_offset_lookup_locked() - Find node in offset space 139 * @mgr: Manager object 140 * @start: Start address for object (page-based) 141 * @pages: Size of object (page-based) 142 * 143 * Same as drm_vma_offset_lookup() but requires the caller to lock offset lookup 144 * manually. See drm_vma_offset_lock_lookup() for an example. 145 * 146 * RETURNS: 147 * Returns NULL if no suitable node can be found. Otherwise, the best match 148 * is returned. 149 */ 150 struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, 151 unsigned long start, 152 unsigned long pages) 153 { 154 struct drm_vma_offset_node *node, *best; 155 struct rb_node *iter; 156 unsigned long offset; 157 158 iter = mgr->vm_addr_space_rb.rb_node; 159 best = NULL; 160 161 while (likely(iter)) { 162 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); 163 offset = node->vm_node.start; 164 if (start >= offset) { 165 iter = iter->rb_right; 166 best = node; 167 if (start == offset) 168 break; 169 } else { 170 iter = iter->rb_left; 171 } 172 } 173 174 /* verify that the node spans the requested area */ 175 if (best) { 176 offset = best->vm_node.start + best->vm_node.size; 177 if (offset < start + pages) 178 best = NULL; 179 } 180 181 return best; 182 } 183 EXPORT_SYMBOL(drm_vma_offset_lookup_locked); 184 185 /* internal helper to link @node into the rb-tree */ 186 static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, 187 struct drm_vma_offset_node *node) 188 { 189 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; 190 struct rb_node *parent = NULL; 191 struct drm_vma_offset_node *iter_node; 192 193 while (likely(*iter)) { 194 parent = *iter; 195 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); 196 197 if (node->vm_node.start < iter_node->vm_node.start) 198 iter = &(*iter)->rb_left; 199 else if (node->vm_node.start > iter_node->vm_node.start) 200 iter = &(*iter)->rb_right; 201 else 202 BUG(); 203 } 204 205 rb_link_node(&node->vm_rb, parent, iter); 206 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); 207 } 208 209 /** 210 * drm_vma_offset_add() - Add offset node to manager 211 * @mgr: Manager object 212 * @node: Node to be added 213 * @pages: Allocation size visible to user-space (in number of pages) 214 * 215 * Add a node to the offset-manager. If the node was already added, this does 216 * nothing and return 0. @pages is the size of the object given in number of 217 * pages. 218 * After this call succeeds, you can access the offset of the node until it 219 * is removed again. 220 * 221 * If this call fails, it is safe to retry the operation or call 222 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that 223 * case. 224 * 225 * @pages is not required to be the same size as the underlying memory object 226 * that you want to map. It only limits the size that user-space can map into 227 * their address space. 228 * 229 * RETURNS: 230 * 0 on success, negative error code on failure. 231 */ 232 int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, 233 struct drm_vma_offset_node *node, unsigned long pages) 234 { 235 int ret; 236 237 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 238 239 if (drm_mm_node_allocated(&node->vm_node)) { 240 ret = 0; 241 goto out_unlock; 242 } 243 244 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, 245 pages, 0, DRM_MM_SEARCH_DEFAULT); 246 if (ret) 247 goto out_unlock; 248 249 _drm_vma_offset_add_rb(mgr, node); 250 251 out_unlock: 252 lockmgr(&mgr->vm_lock, LK_RELEASE); 253 return ret; 254 } 255 EXPORT_SYMBOL(drm_vma_offset_add); 256 257 /** 258 * drm_vma_offset_remove() - Remove offset node from manager 259 * @mgr: Manager object 260 * @node: Node to be removed 261 * 262 * Remove a node from the offset manager. If the node wasn't added before, this 263 * does nothing. After this call returns, the offset and size will be 0 until a 264 * new offset is allocated via drm_vma_offset_add() again. Helper functions like 265 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no 266 * offset is allocated. 267 */ 268 void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, 269 struct drm_vma_offset_node *node) 270 { 271 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 272 273 if (drm_mm_node_allocated(&node->vm_node)) { 274 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); 275 drm_mm_remove_node(&node->vm_node); 276 memset(&node->vm_node, 0, sizeof(node->vm_node)); 277 } 278 279 lockmgr(&mgr->vm_lock, LK_RELEASE); 280 } 281 EXPORT_SYMBOL(drm_vma_offset_remove); 282