// SPDX-License-Identifier: GPL-2.0-only /* * DMA Pool allocator * * Copyright 2001 David Brownell * Copyright 2007 Intel Corporation * Author: Matthew Wilcox <willy@linux.intel.com> * * This allocator returns small blocks of a given size which are DMA-able by * the given device. It uses the dma_alloc_coherent page allocator to get * new pages, then splits them up into blocks of the required size. * Many older drivers still have their own code to do this. * * The current design of this allocator is fairly simple. The pool is * represented by the 'struct dma_pool' which keeps a doubly-linked list of * allocated pages. Each page in the page_list is split into blocks of at * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked * list of free blocks within the page. Used blocks aren't tracked, but we * keep a count of how many are currently allocated from each page. */ #include <linux/device.h> #include <linux/dma-mapping.h> #include <linux/dmapool.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/export.h> #include <linux/mutex.h> #include <linux/poison.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/stat.h> #include <linux/spinlock.h> #include <linux/string.h> #include <linux/types.h> #include <linux/wait.h> #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON) #define DMAPOOL_DEBUG 1 #endif struct dma_pool { /* the pool */ struct list_head page_list; spinlock_t lock; size_t size; struct device *dev; size_t allocation; size_t boundary; char name[32]; struct list_head pools; }; struct dma_page { /* cacheable header for 'allocation' bytes */ struct list_head page_list; void *vaddr; dma_addr_t dma; unsigned int in_use; unsigned int offset; }; static DEFINE_MUTEX(pools_lock); static DEFINE_MUTEX(pools_reg_lock); static ssize_t show_pools(struct device *dev, struct device_attribute *attr, char *buf) { unsigned temp; unsigned size; char *next; struct dma_page *page; struct dma_pool *pool; next = buf; size = PAGE_SIZE; temp = scnprintf(next, size, "poolinfo - 0.1\n"); size -= temp; next += temp; mutex_lock(&pools_lock); list_for_each_entry(pool, &dev->dma_pools, pools) { unsigned pages = 0; unsigned blocks = 0; spin_lock_irq(&pool->lock); list_for_each_entry(page, &pool->page_list, page_list) { pages++; blocks += page->in_use; } spin_unlock_irq(&pool->lock); /* per-pool info, no real statistics yet */ temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n", pool->name, blocks, pages * (pool->allocation / pool->size), pool->size, pages); size -= temp; next += temp; } mutex_unlock(&pools_lock); return PAGE_SIZE - size; } static DEVICE_ATTR(pools, 0444, show_pools, NULL); /** * dma_pool_create - Creates a pool of consistent memory blocks, for dma. * @name: name of pool, for diagnostics * @dev: device that will be doing the DMA * @size: size of the blocks in this pool. * @align: alignment requirement for blocks; must be a power of two * @boundary: returned blocks won't cross this power of two boundary * Context: not in_interrupt() * * Given one of these pools, dma_pool_alloc() * may be used to allocate memory. Such memory will all have "consistent" * DMA mappings, accessible by the device and its driver without using * cache flushing primitives. The actual size of blocks allocated may be * larger than requested because of alignment. * * If @boundary is nonzero, objects returned from dma_pool_alloc() won't * cross that size boundary. This is useful for devices which have * addressing restrictions on individual DMA transfers, such as not crossing * boundaries of 4KBytes. * * Return: a dma allocation pool with the requested characteristics, or * %NULL if one can't be created. */ struct dma_pool *dma_pool_create(const char *name, struct device *dev, size_t size, size_t align, size_t boundary) { struct dma_pool *retval; size_t allocation; bool empty = false; if (align == 0) align = 1; else if (align & (align - 1)) return NULL; if (size == 0) return NULL; else if (size < 4) size = 4; if ((size % align) != 0) size = ALIGN(size, align); allocation = max_t(size_t, size, PAGE_SIZE); if (!boundary) boundary = allocation; else if ((boundary < size) || (boundary & (boundary - 1))) return NULL; retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev)); if (!retval) return retval; strlcpy(retval->name, name, sizeof(retval->name)); retval->dev = dev; INIT_LIST_HEAD(&retval->page_list); spin_lock_init(&retval->lock); retval->size = size; retval->boundary = boundary; retval->allocation = allocation; INIT_LIST_HEAD(&retval->pools); /* * pools_lock ensures that the ->dma_pools list does not get corrupted. * pools_reg_lock ensures that there is not a race between * dma_pool_create() and dma_pool_destroy() or within dma_pool_create() * when the first invocation of dma_pool_create() failed on * device_create_file() and the second assumes that it has been done (I * know it is a short window). */ mutex_lock(&pools_reg_lock); mutex_lock(&pools_lock); if (list_empty(&dev->dma_pools)) empty = true; list_add(&retval->pools, &dev->dma_pools); mutex_unlock(&pools_lock); if (empty) { int err; err = device_create_file(dev, &dev_attr_pools); if (err) { mutex_lock(&pools_lock); list_del(&retval->pools); mutex_unlock(&pools_lock); mutex_unlock(&pools_reg_lock); kfree(retval); return NULL; } } mutex_unlock(&pools_reg_lock); return retval; } EXPORT_SYMBOL(dma_pool_create); static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) { unsigned int offset = 0; unsigned int next_boundary = pool->boundary; do { unsigned int next = offset + pool->size; if (unlikely((next + pool->size) >= next_boundary)) { next = next_boundary; next_boundary += pool->boundary; } *(int *)(page->vaddr + offset) = next; offset = next; } while (offset < pool->allocation); } static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) { struct dma_page *page; page = kmalloc(sizeof(*page), mem_flags); if (!page) return NULL; page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation, &page->dma, mem_flags); if (page->vaddr) { #ifdef DMAPOOL_DEBUG memset(page->vaddr, POOL_POISON_FREED, pool->allocation); #endif pool_initialise_page(pool, page); page->in_use = 0; page->offset = 0; } else { kfree(page); page = NULL; } return page; } static inline bool is_page_busy(struct dma_page *page) { return page->in_use != 0; } static void pool_free_page(struct dma_pool *pool, struct dma_page *page) { dma_addr_t dma = page->dma; #ifdef DMAPOOL_DEBUG memset(page->vaddr, POOL_POISON_FREED, pool->allocation); #endif dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma); list_del(&page->page_list); kfree(page); } /** * dma_pool_destroy - destroys a pool of dma memory blocks. * @pool: dma pool that will be destroyed * Context: !in_interrupt() * * Caller guarantees that no more memory from the pool is in use, * and that nothing will try to use the pool after this call. */ void dma_pool_destroy(struct dma_pool *pool) { bool empty = false; if (unlikely(!pool)) return; mutex_lock(&pools_reg_lock); mutex_lock(&pools_lock); list_del(&pool->pools); if (pool->dev && list_empty(&pool->dev->dma_pools)) empty = true; mutex_unlock(&pools_lock); if (empty) device_remove_file(pool->dev, &dev_attr_pools); mutex_unlock(&pools_reg_lock); while (!list_empty(&pool->page_list)) { struct dma_page *page; page = list_entry(pool->page_list.next, struct dma_page, page_list); if (is_page_busy(page)) { if (pool->dev) dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n", pool->name, page->vaddr); else pr_err("dma_pool_destroy %s, %p busy\n", pool->name, page->vaddr); /* leak the still-in-use consistent memory */ list_del(&page->page_list); kfree(page); } else pool_free_page(pool, page); } kfree(pool); } EXPORT_SYMBOL(dma_pool_destroy); /** * dma_pool_alloc - get a block of consistent memory * @pool: dma pool that will produce the block * @mem_flags: GFP_* bitmask * @handle: pointer to dma address of block * * Return: the kernel virtual address of a currently unused block, * and reports its dma address through the handle. * If such a memory block can't be allocated, %NULL is returned. */ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle) { unsigned long flags; struct dma_page *page; size_t offset; void *retval; might_sleep_if(gfpflags_allow_blocking(mem_flags)); spin_lock_irqsave(&pool->lock, flags); list_for_each_entry(page, &pool->page_list, page_list) { if (page->offset < pool->allocation) goto ready; } /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ spin_unlock_irqrestore(&pool->lock, flags); page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO)); if (!page) return NULL; spin_lock_irqsave(&pool->lock, flags); list_add(&page->page_list, &pool->page_list); ready: page->in_use++; offset = page->offset; page->offset = *(int *)(page->vaddr + offset); retval = offset + page->vaddr; *handle = offset + page->dma; #ifdef DMAPOOL_DEBUG { int i; u8 *data = retval; /* page->offset is stored in first 4 bytes */ for (i = sizeof(page->offset); i < pool->size; i++) { if (data[i] == POOL_POISON_FREED) continue; if (pool->dev) dev_err(pool->dev, "dma_pool_alloc %s, %p (corrupted)\n", pool->name, retval); else pr_err("dma_pool_alloc %s, %p (corrupted)\n", pool->name, retval); /* * Dump the first 4 bytes even if they are not * POOL_POISON_FREED */ print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1, data, pool->size, 1); break; } } if (!(mem_flags & __GFP_ZERO)) memset(retval, POOL_POISON_ALLOCATED, pool->size); #endif spin_unlock_irqrestore(&pool->lock, flags); if (want_init_on_alloc(mem_flags)) memset(retval, 0, pool->size); return retval; } EXPORT_SYMBOL(dma_pool_alloc); static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) { struct dma_page *page; list_for_each_entry(page, &pool->page_list, page_list) { if (dma < page->dma) continue; if ((dma - page->dma) < pool->allocation) return page; } return NULL; } /** * dma_pool_free - put block back into dma pool * @pool: the dma pool holding the block * @vaddr: virtual address of block * @dma: dma address of block * * Caller promises neither device nor driver will again touch this block * unless it is first re-allocated. */ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) { struct dma_page *page; unsigned long flags; unsigned int offset; spin_lock_irqsave(&pool->lock, flags); page = pool_find_page(pool, dma); if (!page) { spin_unlock_irqrestore(&pool->lock, flags); if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n", pool->name, vaddr, (unsigned long)dma); else pr_err("dma_pool_free %s, %p/%lx (bad dma)\n", pool->name, vaddr, (unsigned long)dma); return; } offset = vaddr - page->vaddr; if (want_init_on_free()) memset(vaddr, 0, pool->size); #ifdef DMAPOOL_DEBUG if ((dma - page->dma) != offset) { spin_unlock_irqrestore(&pool->lock, flags); if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%pad\n", pool->name, vaddr, &dma); else pr_err("dma_pool_free %s, %p (bad vaddr)/%pad\n", pool->name, vaddr, &dma); return; } { unsigned int chain = page->offset; while (chain < pool->allocation) { if (chain != offset) { chain = *(int *)(page->vaddr + chain); continue; } spin_unlock_irqrestore(&pool->lock, flags); if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, dma %pad already free\n", pool->name, &dma); else pr_err("dma_pool_free %s, dma %pad already free\n", pool->name, &dma); return; } } memset(vaddr, POOL_POISON_FREED, pool->size); #endif page->in_use--; *(int *)vaddr = page->offset; page->offset = offset; /* * Resist a temptation to do * if (!is_page_busy(page)) pool_free_page(pool, page); * Better have a few empty pages hang around. */ spin_unlock_irqrestore(&pool->lock, flags); } EXPORT_SYMBOL(dma_pool_free); /* * Managed DMA pool */ static void dmam_pool_release(struct device *dev, void *res) { struct dma_pool *pool = *(struct dma_pool **)res; dma_pool_destroy(pool); } static int dmam_pool_match(struct device *dev, void *res, void *match_data) { return *(struct dma_pool **)res == match_data; } /** * dmam_pool_create - Managed dma_pool_create() * @name: name of pool, for diagnostics * @dev: device that will be doing the DMA * @size: size of the blocks in this pool. * @align: alignment requirement for blocks; must be a power of two * @allocation: returned blocks won't cross this boundary (or zero) * * Managed dma_pool_create(). DMA pool created with this function is * automatically destroyed on driver detach. * * Return: a managed dma allocation pool with the requested * characteristics, or %NULL if one can't be created. */ struct dma_pool *dmam_pool_create(const char *name, struct device *dev, size_t size, size_t align, size_t allocation) { struct dma_pool **ptr, *pool; ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return NULL; pool = *ptr = dma_pool_create(name, dev, size, align, allocation); if (pool) devres_add(dev, ptr); else devres_free(ptr); return pool; } EXPORT_SYMBOL(dmam_pool_create); /** * dmam_pool_destroy - Managed dma_pool_destroy() * @pool: dma pool that will be destroyed * * Managed dma_pool_destroy(). */ void dmam_pool_destroy(struct dma_pool *pool) { struct device *dev = pool->dev; WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool)); } EXPORT_SYMBOL(dmam_pool_destroy);