/************************************************************************** * * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA. * All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sub license, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice (including the * next paragraph) shall be included in all copies or substantial portions * of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE * USE OR OTHER DEALINGS IN THE SOFTWARE. * * **************************************************************************/ /* * Generic simple memory manager implementation. Intended to be used as a base * class implementation for more advanced memory managers. * * Note that the algorithm used is quite simple and there might be substantial * performance gains if a smarter free list is implemented. Currently it is just an * unordered stack of free regions. This could easily be improved if an RB-tree * is used instead. At least if we expect heavy fragmentation. * * Aligned allocations can also see improvement. * * Authors: * Thomas Hellström <thomas-at-tungstengraphics-dot-com> */ #include <drm/drmP.h> #include <drm/drm_mm.h> #include <linux/slab.h> #include <linux/seq_file.h> #include <linux/export.h> /** * DOC: Overview * * drm_mm provides a simple range allocator. The drivers are free to use the * resource allocator from the linux core if it suits them, the upside of drm_mm * is that it's in the DRM core. Which means that it's easier to extend for * some of the crazier special purpose needs of gpus. * * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node. * Drivers are free to embed either of them into their own suitable * datastructures. drm_mm itself will not do any allocations of its own, so if * drivers choose not to embed nodes they need to still allocate them * themselves. * * The range allocator also supports reservation of preallocated blocks. This is * useful for taking over initial mode setting configurations from the firmware, * where an object needs to be created which exactly matches the firmware's * scanout target. As long as the range is still free it can be inserted anytime * after the allocator is initialized, which helps with avoiding looped * depencies in the driver load sequence. * * drm_mm maintains a stack of most recently freed holes, which of all * simplistic datastructures seems to be a fairly decent approach to clustering * allocations and avoiding too much fragmentation. This means free space * searches are O(num_holes). Given that all the fancy features drm_mm supports * something better would be fairly complex and since gfx thrashing is a fairly * steep cliff not a real concern. Removing a node again is O(1). * * drm_mm supports a few features: Alignment and range restrictions can be * supplied. Further more every &drm_mm_node has a color value (which is just an * opaqua unsigned long) which in conjunction with a driver callback can be used * to implement sophisticated placement restrictions. The i915 DRM driver uses * this to implement guard pages between incompatible caching domains in the * graphics TT. * * Two behaviors are supported for searching and allocating: bottom-up and top-down. * The default is bottom-up. Top-down allocation can be used if the memory area * has different restrictions, or just to reduce fragmentation. * * Finally iteration helpers to walk all nodes and all holes are provided as are * some basic allocator dumpers for debugging. */ static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color, enum drm_mm_search_flags flags); static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color, u64 start, u64 end, enum drm_mm_search_flags flags); static void drm_mm_insert_helper(struct drm_mm_node *hole_node, struct drm_mm_node *node, u64 size, unsigned alignment, unsigned long color, enum drm_mm_allocator_flags flags) { struct drm_mm *mm = hole_node->mm; u64 hole_start = drm_mm_hole_node_start(hole_node); u64 hole_end = drm_mm_hole_node_end(hole_node); u64 adj_start = hole_start; u64 adj_end = hole_end; BUG_ON(node->allocated); if (mm->color_adjust) mm->color_adjust(hole_node, color, &adj_start, &adj_end); if (flags & DRM_MM_CREATE_TOP) adj_start = adj_end - size; if (alignment) { u64 tmp = adj_start; unsigned rem; rem = do_div(tmp, alignment); if (rem) { if (flags & DRM_MM_CREATE_TOP) adj_start -= rem; else adj_start += alignment - rem; } } BUG_ON(adj_start < hole_start); BUG_ON(adj_end > hole_end); if (adj_start == hole_start) { hole_node->hole_follows = 0; list_del(&hole_node->hole_stack); } node->start = adj_start; node->size = size; node->mm = mm; node->color = color; node->allocated = 1; INIT_LIST_HEAD(&node->hole_stack); list_add(&node->node_list, &hole_node->node_list); BUG_ON(node->start + node->size > adj_end); node->hole_follows = 0; if (__drm_mm_hole_node_start(node) < hole_end) { list_add(&node->hole_stack, &mm->hole_stack); node->hole_follows = 1; } } /** * drm_mm_reserve_node - insert an pre-initialized node * @mm: drm_mm allocator to insert @node into * @node: drm_mm_node to insert * * This functions inserts an already set-up drm_mm_node into the allocator, * meaning that start, size and color must be set by the caller. This is useful * to initialize the allocator with preallocated objects which must be set-up * before the range allocator can be set-up, e.g. when taking over a firmware * framebuffer. * * Returns: * 0 on success, -ENOSPC if there's no hole where @node is. */ int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) { struct drm_mm_node *hole; u64 end = node->start + node->size; u64 hole_start; u64 hole_end; BUG_ON(node == NULL); /* Find the relevant hole to add our node to */ drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { if (hole_start > node->start || hole_end < end) continue; node->mm = mm; node->allocated = 1; INIT_LIST_HEAD(&node->hole_stack); list_add(&node->node_list, &hole->node_list); if (node->start == hole_start) { hole->hole_follows = 0; list_del_init(&hole->hole_stack); } node->hole_follows = 0; if (end != hole_end) { list_add(&node->hole_stack, &mm->hole_stack); node->hole_follows = 1; } return 0; } return -ENOSPC; } EXPORT_SYMBOL(drm_mm_reserve_node); /** * drm_mm_insert_node_generic - search for space and insert @node * @mm: drm_mm to allocate from * @node: preallocate node to insert * @size: size of the allocation * @alignment: alignment of the allocation * @color: opaque tag value to use for this node * @sflags: flags to fine-tune the allocation search * @aflags: flags to fine-tune the allocation behavior * * The preallocated node must be cleared to 0. * * Returns: * 0 on success, -ENOSPC if there's no suitable hole. */ int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node, u64 size, unsigned alignment, unsigned long color, enum drm_mm_search_flags sflags, enum drm_mm_allocator_flags aflags) { struct drm_mm_node *hole_node; hole_node = drm_mm_search_free_generic(mm, size, alignment, color, sflags); if (!hole_node) return -ENOSPC; drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags); return 0; } EXPORT_SYMBOL(drm_mm_insert_node_generic); static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node, struct drm_mm_node *node, u64 size, unsigned alignment, unsigned long color, u64 start, u64 end, enum drm_mm_allocator_flags flags) { struct drm_mm *mm = hole_node->mm; u64 hole_start = drm_mm_hole_node_start(hole_node); u64 hole_end = drm_mm_hole_node_end(hole_node); u64 adj_start = hole_start; u64 adj_end = hole_end; BUG_ON(!hole_node->hole_follows || node->allocated); if (adj_start < start) adj_start = start; if (adj_end > end) adj_end = end; if (flags & DRM_MM_CREATE_TOP) adj_start = adj_end - size; if (mm->color_adjust) mm->color_adjust(hole_node, color, &adj_start, &adj_end); if (alignment) { u64 tmp = adj_start; unsigned rem; rem = do_div(tmp, alignment); if (rem) { if (flags & DRM_MM_CREATE_TOP) adj_start -= rem; else adj_start += alignment - rem; } } if (adj_start == hole_start) { hole_node->hole_follows = 0; list_del(&hole_node->hole_stack); } node->start = adj_start; node->size = size; node->mm = mm; node->color = color; node->allocated = 1; INIT_LIST_HEAD(&node->hole_stack); list_add(&node->node_list, &hole_node->node_list); BUG_ON(node->start < start); BUG_ON(node->start < adj_start); BUG_ON(node->start + node->size > adj_end); BUG_ON(node->start + node->size > end); node->hole_follows = 0; if (__drm_mm_hole_node_start(node) < hole_end) { list_add(&node->hole_stack, &mm->hole_stack); node->hole_follows = 1; } } /** * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node * @mm: drm_mm to allocate from * @node: preallocate node to insert * @size: size of the allocation * @alignment: alignment of the allocation * @color: opaque tag value to use for this node * @start: start of the allowed range for this node * @end: end of the allowed range for this node * @sflags: flags to fine-tune the allocation search * @aflags: flags to fine-tune the allocation behavior * * The preallocated node must be cleared to 0. * * Returns: * 0 on success, -ENOSPC if there's no suitable hole. */ int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node, u64 size, unsigned alignment, unsigned long color, u64 start, u64 end, enum drm_mm_search_flags sflags, enum drm_mm_allocator_flags aflags) { struct drm_mm_node *hole_node; hole_node = drm_mm_search_free_in_range_generic(mm, size, alignment, color, start, end, sflags); if (!hole_node) return -ENOSPC; drm_mm_insert_helper_range(hole_node, node, size, alignment, color, start, end, aflags); return 0; } EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic); /** * drm_mm_remove_node - Remove a memory node from the allocator. * @node: drm_mm_node to remove * * This just removes a node from its drm_mm allocator. The node does not need to * be cleared again before it can be re-inserted into this or any other drm_mm * allocator. It is a bug to call this function on a un-allocated node. */ void drm_mm_remove_node(struct drm_mm_node *node) { struct drm_mm *mm = node->mm; struct drm_mm_node *prev_node; if (WARN_ON(!node->allocated)) return; BUG_ON(node->scanned_block || node->scanned_prev_free || node->scanned_next_free); prev_node = list_entry(node->node_list.prev, struct drm_mm_node, node_list); if (node->hole_follows) { BUG_ON(__drm_mm_hole_node_start(node) == __drm_mm_hole_node_end(node)); list_del(&node->hole_stack); } else BUG_ON(__drm_mm_hole_node_start(node) != __drm_mm_hole_node_end(node)); if (!prev_node->hole_follows) { prev_node->hole_follows = 1; list_add(&prev_node->hole_stack, &mm->hole_stack); } else list_move(&prev_node->hole_stack, &mm->hole_stack); list_del(&node->node_list); node->allocated = 0; } EXPORT_SYMBOL(drm_mm_remove_node); static int check_free_hole(u64 start, u64 end, u64 size, unsigned alignment) { if (end - start < size) return 0; if (alignment) { u64 tmp = start; unsigned rem; rem = do_div(tmp, alignment); if (rem) start += alignment - rem; } return end >= start + size; } static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color, enum drm_mm_search_flags flags) { struct drm_mm_node *entry; struct drm_mm_node *best; u64 adj_start; u64 adj_end; u64 best_size; BUG_ON(mm->scanned_blocks); best = NULL; best_size = ~0UL; __drm_mm_for_each_hole(entry, mm, adj_start, adj_end, flags & DRM_MM_SEARCH_BELOW) { u64 hole_size = adj_end - adj_start; if (mm->color_adjust) { mm->color_adjust(entry, color, &adj_start, &adj_end); if (adj_end <= adj_start) continue; } if (!check_free_hole(adj_start, adj_end, size, alignment)) continue; if (!(flags & DRM_MM_SEARCH_BEST)) return entry; if (hole_size < best_size) { best = entry; best_size = hole_size; } } return best; } static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color, u64 start, u64 end, enum drm_mm_search_flags flags) { struct drm_mm_node *entry; struct drm_mm_node *best; u64 adj_start; u64 adj_end; u64 best_size; BUG_ON(mm->scanned_blocks); best = NULL; best_size = ~0UL; __drm_mm_for_each_hole(entry, mm, adj_start, adj_end, flags & DRM_MM_SEARCH_BELOW) { u64 hole_size = adj_end - adj_start; if (adj_start < start) adj_start = start; if (adj_end > end) adj_end = end; if (mm->color_adjust) { mm->color_adjust(entry, color, &adj_start, &adj_end); if (adj_end <= adj_start) continue; } if (!check_free_hole(adj_start, adj_end, size, alignment)) continue; if (!(flags & DRM_MM_SEARCH_BEST)) return entry; if (hole_size < best_size) { best = entry; best_size = hole_size; } } return best; } /** * drm_mm_replace_node - move an allocation from @old to @new * @old: drm_mm_node to remove from the allocator * @new: drm_mm_node which should inherit @old's allocation * * This is useful for when drivers embed the drm_mm_node structure and hence * can't move allocations by reassigning pointers. It's a combination of remove * and insert with the guarantee that the allocation start will match. */ void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new) { list_replace(&old->node_list, &new->node_list); list_replace(&old->hole_stack, &new->hole_stack); new->hole_follows = old->hole_follows; new->mm = old->mm; new->start = old->start; new->size = old->size; new->color = old->color; old->allocated = 0; new->allocated = 1; } EXPORT_SYMBOL(drm_mm_replace_node); /** * DOC: lru scan roaster * * Very often GPUs need to have continuous allocations for a given object. When * evicting objects to make space for a new one it is therefore not most * efficient when we simply start to select all objects from the tail of an LRU * until there's a suitable hole: Especially for big objects or nodes that * otherwise have special allocation constraints there's a good chance we evict * lots of (smaller) objects unecessarily. * * The DRM range allocator supports this use-case through the scanning * interfaces. First a scan operation needs to be initialized with * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds * objects to the roaster (probably by walking an LRU list, but this can be * freely implemented) until a suitable hole is found or there's no further * evitable object. * * The the driver must walk through all objects again in exactly the reverse * order to restore the allocator state. Note that while the allocator is used * in the scan mode no other operation is allowed. * * Finally the driver evicts all objects selected in the scan. Adding and * removing an object is O(1), and since freeing a node is also O(1) the overall * complexity is O(scanned_objects). So like the free stack which needs to be * walked before a scan operation even begins this is linear in the number of * objects. It doesn't seem to hurt badly. */ /** * drm_mm_init_scan - initialize lru scanning * @mm: drm_mm to scan * @size: size of the allocation * @alignment: alignment of the allocation * @color: opaque tag value to use for the allocation * * This simply sets up the scanning routines with the parameters for the desired * hole. Note that there's no need to specify allocation flags, since they only * change the place a node is allocated from within a suitable hole. * * Warning: * As long as the scan list is non-empty, no other operations than * adding/removing nodes to/from the scan list are allowed. */ void drm_mm_init_scan(struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color) { mm->scan_color = color; mm->scan_alignment = alignment; mm->scan_size = size; mm->scanned_blocks = 0; mm->scan_hit_start = 0; mm->scan_hit_end = 0; mm->scan_check_range = 0; mm->prev_scanned_node = NULL; } EXPORT_SYMBOL(drm_mm_init_scan); /** * drm_mm_init_scan - initialize range-restricted lru scanning * @mm: drm_mm to scan * @size: size of the allocation * @alignment: alignment of the allocation * @color: opaque tag value to use for the allocation * @start: start of the allowed range for the allocation * @end: end of the allowed range for the allocation * * This simply sets up the scanning routines with the parameters for the desired * hole. Note that there's no need to specify allocation flags, since they only * change the place a node is allocated from within a suitable hole. * * Warning: * As long as the scan list is non-empty, no other operations than * adding/removing nodes to/from the scan list are allowed. */ void drm_mm_init_scan_with_range(struct drm_mm *mm, u64 size, unsigned alignment, unsigned long color, u64 start, u64 end) { mm->scan_color = color; mm->scan_alignment = alignment; mm->scan_size = size; mm->scanned_blocks = 0; mm->scan_hit_start = 0; mm->scan_hit_end = 0; mm->scan_start = start; mm->scan_end = end; mm->scan_check_range = 1; mm->prev_scanned_node = NULL; } EXPORT_SYMBOL(drm_mm_init_scan_with_range); /** * drm_mm_scan_add_block - add a node to the scan list * @node: drm_mm_node to add * * Add a node to the scan list that might be freed to make space for the desired * hole. * * Returns: * True if a hole has been found, false otherwise. */ bool drm_mm_scan_add_block(struct drm_mm_node *node) { struct drm_mm *mm = node->mm; struct drm_mm_node *prev_node; u64 hole_start, hole_end; u64 adj_start, adj_end; mm->scanned_blocks++; BUG_ON(node->scanned_block); node->scanned_block = 1; prev_node = list_entry(node->node_list.prev, struct drm_mm_node, node_list); node->scanned_preceeds_hole = prev_node->hole_follows; prev_node->hole_follows = 1; list_del(&node->node_list); node->node_list.prev = &prev_node->node_list; node->node_list.next = &mm->prev_scanned_node->node_list; mm->prev_scanned_node = node; adj_start = hole_start = drm_mm_hole_node_start(prev_node); adj_end = hole_end = drm_mm_hole_node_end(prev_node); if (mm->scan_check_range) { if (adj_start < mm->scan_start) adj_start = mm->scan_start; if (adj_end > mm->scan_end) adj_end = mm->scan_end; } if (mm->color_adjust) mm->color_adjust(prev_node, mm->scan_color, &adj_start, &adj_end); if (check_free_hole(adj_start, adj_end, mm->scan_size, mm->scan_alignment)) { mm->scan_hit_start = hole_start; mm->scan_hit_end = hole_end; return true; } return false; } EXPORT_SYMBOL(drm_mm_scan_add_block); /** * drm_mm_scan_remove_block - remove a node from the scan list * @node: drm_mm_node to remove * * Nodes _must_ be removed in the exact same order from the scan list as they * have been added, otherwise the internal state of the memory manager will be * corrupted. * * When the scan list is empty, the selected memory nodes can be freed. An * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then * return the just freed block (because its at the top of the free_stack list). * * Returns: * True if this block should be evicted, false otherwise. Will always * return false when no hole has been found. */ bool drm_mm_scan_remove_block(struct drm_mm_node *node) { struct drm_mm *mm = node->mm; struct drm_mm_node *prev_node; mm->scanned_blocks--; BUG_ON(!node->scanned_block); node->scanned_block = 0; prev_node = list_entry(node->node_list.prev, struct drm_mm_node, node_list); prev_node->hole_follows = node->scanned_preceeds_hole; list_add(&node->node_list, &prev_node->node_list); return (drm_mm_hole_node_end(node) > mm->scan_hit_start && node->start < mm->scan_hit_end); } EXPORT_SYMBOL(drm_mm_scan_remove_block); /** * drm_mm_clean - checks whether an allocator is clean * @mm: drm_mm allocator to check * * Returns: * True if the allocator is completely free, false if there's still a node * allocated in it. */ bool drm_mm_clean(struct drm_mm * mm) { struct list_head *head = &mm->head_node.node_list; return (head->next->next == head); } EXPORT_SYMBOL(drm_mm_clean); /** * drm_mm_init - initialize a drm-mm allocator * @mm: the drm_mm structure to initialize * @start: start of the range managed by @mm * @size: end of the range managed by @mm * * Note that @mm must be cleared to 0 before calling this function. */ void drm_mm_init(struct drm_mm * mm, u64 start, u64 size) { INIT_LIST_HEAD(&mm->hole_stack); mm->scanned_blocks = 0; /* Clever trick to avoid a special case in the free hole tracking. */ INIT_LIST_HEAD(&mm->head_node.node_list); INIT_LIST_HEAD(&mm->head_node.hole_stack); mm->head_node.hole_follows = 1; mm->head_node.scanned_block = 0; mm->head_node.scanned_prev_free = 0; mm->head_node.scanned_next_free = 0; mm->head_node.mm = mm; mm->head_node.start = start + size; mm->head_node.size = start - mm->head_node.start; list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack); mm->color_adjust = NULL; } EXPORT_SYMBOL(drm_mm_init); /** * drm_mm_takedown - clean up a drm_mm allocator * @mm: drm_mm allocator to clean up * * Note that it is a bug to call this function on an allocator which is not * clean. */ void drm_mm_takedown(struct drm_mm * mm) { WARN(!list_empty(&mm->head_node.node_list), "Memory manager not clean during takedown.\n"); } EXPORT_SYMBOL(drm_mm_takedown); static u64 drm_mm_debug_hole(struct drm_mm_node *entry, const char *prefix) { u64 hole_start, hole_end, hole_size; if (entry->hole_follows) { hole_start = drm_mm_hole_node_start(entry); hole_end = drm_mm_hole_node_end(entry); hole_size = hole_end - hole_start; pr_debug("%s %#llx-%#llx: %llu: free\n", prefix, hole_start, hole_end, hole_size); return hole_size; } return 0; } /** * drm_mm_debug_table - dump allocator state to dmesg * @mm: drm_mm allocator to dump * @prefix: prefix to use for dumping to dmesg */ void drm_mm_debug_table(struct drm_mm *mm, const char *prefix) { struct drm_mm_node *entry; u64 total_used = 0, total_free = 0, total = 0; total_free += drm_mm_debug_hole(&mm->head_node, prefix); drm_mm_for_each_node(entry, mm) { pr_debug("%s %#llx-%#llx: %llu: used\n", prefix, entry->start, entry->start + entry->size, entry->size); total_used += entry->size; total_free += drm_mm_debug_hole(entry, prefix); } total = total_free + total_used; pr_debug("%s total: %llu, used %llu free %llu\n", prefix, total, total_used, total_free); } EXPORT_SYMBOL(drm_mm_debug_table); #if defined(CONFIG_DEBUG_FS) static u64 drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry) { u64 hole_start, hole_end, hole_size; if (entry->hole_follows) { hole_start = drm_mm_hole_node_start(entry); hole_end = drm_mm_hole_node_end(entry); hole_size = hole_end - hole_start; seq_printf(m, "%#llx-%#llx: %llu: free\n", hole_start, hole_end, hole_size); return hole_size; } return 0; } /** * drm_mm_dump_table - dump allocator state to a seq_file * @m: seq_file to dump to * @mm: drm_mm allocator to dump */ int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm) { struct drm_mm_node *entry; u64 total_used = 0, total_free = 0, total = 0; total_free += drm_mm_dump_hole(m, &mm->head_node); drm_mm_for_each_node(entry, mm) { seq_printf(m, "%#016llx-%#016llx: %llu: used\n", entry->start, entry->start + entry->size, entry->size); total_used += entry->size; total_free += drm_mm_dump_hole(m, entry); } total = total_free + total_used; seq_printf(m, "total: %llu, used %llu free %llu\n", total, total_used, total_free); return 0; } EXPORT_SYMBOL(drm_mm_dump_table); #endif