From patchwork Wed Dec 15 20:34:27 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?TWljaGHDheKAmiBOYXphcmV3aWN6?= X-Patchwork-Id: 414371 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id oBFKdT2m028292 for ; Wed, 15 Dec 2010 20:39:29 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754116Ab0LOUis (ORCPT ); Wed, 15 Dec 2010 15:38:48 -0500 Received: from mailout2.w1.samsung.com ([210.118.77.12]:10693 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753240Ab0LOUin (ORCPT ); Wed, 15 Dec 2010 15:38:43 -0500 Received: from spt2.w1.samsung.com (mailout2.w1.samsung.com [210.118.77.12]) by mailout2.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTP id <0LDH00MUULCDE3@mailout2.w1.samsung.com>; Wed, 15 Dec 2010 20:38:38 +0000 (GMT) Received: from linux.samsung.com ([106.116.38.10]) by spt2.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LDH00KXSLCCNU@spt2.w1.samsung.com>; Wed, 15 Dec 2010 20:38:37 +0000 (GMT) Received: from pikus.digital.local (unknown [106.116.48.169]) by linux.samsung.com (Postfix) with ESMTP id 3776A270056; Wed, 15 Dec 2010 21:38:13 +0100 (CET) Date: Wed, 15 Dec 2010 21:34:27 +0100 From: Michal Nazarewicz Subject: [PATCHv8 07/12] mm: cma: Contiguous Memory Allocator added In-reply-to: To: Michal Nazarewicz Cc: Andrew Morton , Ankita Garg , Daniel Walker , Johan MOSSBERG , KAMEZAWA Hiroyuki , Marek Szyprowski , Mel Gorman , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org Message-id: MIME-version: 1.0 X-Mailer: git-send-email 1.7.2.3 Content-type: TEXT/PLAIN Content-transfer-encoding: 7BIT References: Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]); Wed, 15 Dec 2010 20:39:29 +0000 (UTC) diff --git a/include/linux/cma.h b/include/linux/cma.h new file mode 100644 index 0000000..e9575fd --- /dev/null +++ b/include/linux/cma.h @@ -0,0 +1,219 @@ +#ifndef __LINUX_CMA_H +#define __LINUX_CMA_H + +/* + * Contiguous Memory Allocator + * Copyright (c) 2010 by Samsung Electronics. + * Written by Michal Nazarewicz (m.nazarewicz@samsung.com) + */ + +/* + * Contiguous Memory Allocator + * + * The Contiguous Memory Allocator (CMA) makes it possible for + * device drivers to allocate big contiguous chunks of memory after + * the system has booted. + * + * It requires some machine- and/or platform-specific initialisation + * code which prepares memory ranges to be used with CMA and later, + * device drivers can allocate memory from those ranges. + * + * Why is it needed? + * + * Various devices on embedded systems have no scatter-getter and/or + * IO map support and require contiguous blocks of memory to + * operate. They include devices such as cameras, hardware video + * coders, etc. + * + * Such devices often require big memory buffers (a full HD frame + * is, for instance, more then 2 mega pixels large, i.e. more than 6 + * MB of memory), which makes mechanisms such as kmalloc() or + * alloc_page() ineffective. + * + * At the same time, a solution where a big memory region is + * reserved for a device is suboptimal since often more memory is + * reserved then strictly required and, moreover, the memory is + * inaccessible to page system even if device drivers don't use it. + * + * CMA tries to solve this issue by operating on memory regions + * where only movable pages can be allocated from. This way, kernel + * can use the memory for pagecache and when device driver requests + * it, allocated pages can be migrated. + * + * Driver usage + * + * For device driver to use CMA it needs to have a pointer to a CMA + * context represented by a struct cma (which is an opaque data + * type). + * + * Once such pointer is obtained, device driver may allocate + * contiguous memory chunk using the following function: + * + * cm_alloc() + * + * This function returns a pointer to struct cm (another opaque data + * type) which represent a contiguous memory chunk. This pointer + * may be used with the following functions: + * + * cm_free() -- frees allocated contiguous memory + * cm_pin() -- pins memory + * cm_unpin() -- unpins memory + * cm_vmap() -- maps memory in kernel space + * cm_vunmap() -- unmaps memory from kernel space + * + * See the respective functions for more information. + * + * Platform/machine integration + * + * For device drivers to be able to use CMA platform or machine + * initialisation code must create a CMA context and pass it to + * device drivers. The latter may be done by a global variable or + * a platform/machine specific function. For the former CMA + * provides the following functions: + * + * cma_reserve() + * cma_create() + * + * The cma_reserve() function must be called when memblock is still + * operational and reserving memory with it is still possible. On + * ARM platform the "reserve" machine callback is a perfect place to + * call it. + * + * The last function creates a CMA context on a range of previously + * initialised memory addresses. Because it uses kmalloc() it needs + * to be called after SLAB is initialised. + */ + +/***************************** Kernel level API *****************************/ + +#if defined __KERNEL__ && defined CONFIG_CMA + +/* CMA context */ +struct cma; +/* Contiguous Memory chunk */ +struct cm; + +/** + * cma_reserve() - reserves memory. + * @start: start address of the memory range in bytes hint; if unsure + * pass zero. + * @size: size of the memory to reserve in bytes. + * @alignment: desired alignment in bytes (must be power of two or zero). + * + * It will use memblock to allocate memory. @start and @size will be + * aligned to PAGE_SIZE. + * + * Returns reserved's area physical address or value that yields true + * when checked with IS_ERR_VALUE(). + */ +unsigned long cma_reserve(unsigned long start, unsigned long size, + unsigned long alignment); + +/** + * cma_create() - creates a CMA context. + * @start: start address of the context in bytes. + * @size: size of the context in bytes. + * @min_alignment: minimal desired alignment or zero. + * @private: whether to create private context. + * + * The range must be page aligned. Different contexts cannot overlap. + * + * Unless @private is true the memory range must lay in ZONE_MOVABLE. + * If @private is true no underlaying memory checking is done and + * during allocation no pages migration will be performed - it is + * assumed that the memory is reserved and only CMA manages it. + * + * @start and @size must be page and @min_alignment alignment. + * @min_alignment specifies the minimal alignment that user will be + * able to request through cm_alloc() function. In most cases one + * will probably pass zero as @min_alignment but if the CMA context + * will be used only for, say, 1 MiB blocks passing 1 << 20 as + * @min_alignment may increase performance and reduce memory usage + * slightly. + * + * Because this function uses kmalloc() it must be called after SLAB + * is initialised. This in particular means that it cannot be called + * just after cma_reserve() since the former needs to be run way + * earlier. + * + * Returns pointer to CMA context or a pointer-error on error. + */ +struct cma *cma_create(unsigned long start, unsigned long size, + unsigned long min_alignment, _Bool private); + +/** + * cma_destroy() - destroys CMA context. + * @cma: context to destroy. + */ +void cma_destroy(struct cma *cma); + +/** + * cm_alloc() - allocates contiguous memory. + * @cma: CMA context to use. + * @size: desired chunk size in bytes (must be non-zero). + * @alignent: desired minimal alignment in bytes (must be power of two + * or zero). + * + * Returns pointer to structure representing contiguous memory or + * a pointer-error on error. + */ +struct cm *cm_alloc(struct cma *cma, unsigned long size, + unsigned long alignment); + +/** + * cm_free() - frees contiguous memory. + * @cm: contiguous memory to free. + * + * The contiguous memory must be not be pinned (see cma_pin()) and + * must not be mapped to kernel space (cma_vmap()). + */ +void cm_free(struct cm *cm); + +/** + * cm_pin() - pins contiguous memory. + * @cm: contiguous memory to pin. + * + * Pinning is required to obtain contiguous memory's physical address. + * While memory is pinned the memory will remain valid it may change + * if memory is unpinned and then pinned again. This facility is + * provided so that memory defragmentation can be implemented inside + * CMA. + * + * Each call to cm_pin() must be accompanied by call to cm_unpin() and + * the calls may be nested. + * + * Returns chunk's physical address or a value that yields true when + * tested with IS_ERR_VALUE(). + */ +unsigned long cm_pin(struct cm *cm); + +/** + * cm_unpin() - unpins contiguous memory. + * @cm: contiguous memory to unpin. + * + * See cm_pin(). + */ +void cm_unpin(struct cm *cm); + +/** + * cm_vmap() - maps memory to kernel space (or returns existing mapping). + * @cm: contiguous memory to map. + * + * Each call to cm_vmap() must be accompanied with call to cm_vunmap() + * and the calls may be nested. + * + * Returns kernel virtual address or a pointer-error. + */ +void *cm_vmap(struct cm *cm); + +/** + * cm_vunmap() - unmpas memory from kernel space. + * @cm: contiguous memory to unmap. + * + * See cm_vmap(). + */ +void cm_vunmap(struct cm *cm); + +#endif + +#endif diff --git a/mm/Kconfig b/mm/Kconfig index b911ad3..2beab4d 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -331,3 +331,25 @@ config CLEANCACHE in a negligible performance hit. If unsure, say Y to enable cleancache + +config CMA + bool "Contiguous Memory Allocator" + select MIGRATION + select GENERIC_ALLOCATOR + help + This enables the Contiguous Memory Allocator which allows drivers + to allocate big physically-contiguous blocks of memory for use with + hardware components that do not support I/O map nor scatter-gather. + + For more information see . If unsure, say "n". + +config CMA_DEBUG + bool "CMA debug messages (DEVELOPEMENT)" + depends on CMA + help + Turns on debug messages in CMA. This produces KERN_DEBUG + messages for every CMA call as well as various messages while + processing calls such as cma_alloc(). This option does not + affect warning and error messages. + + This is mostly used during development. If unsure, say "n". diff --git a/mm/Makefile b/mm/Makefile index 0b08d1c..c6a84f1 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -43,3 +43,4 @@ obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o obj-$(CONFIG_CLEANCACHE) += cleancache.o +obj-$(CONFIG_CMA) += cma.o diff --git a/mm/cma.c b/mm/cma.c new file mode 100644 index 0000000..d82361b --- /dev/null +++ b/mm/cma.c @@ -0,0 +1,328 @@ +/* + * Contiguous Memory Allocator framework + * Copyright (c) 2010 by Samsung Electronics. + * Written by Michal Nazarewicz (m.nazarewicz@samsung.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License or (at your optional) any later version of the license. + */ + +/* + * See include/linux/cma.h for details. + */ + +#define pr_fmt(fmt) "cma: " fmt + +#ifdef CONFIG_CMA_DEBUG +# define DEBUG +#endif + +#include + +#ifndef CONFIG_NO_BOOTMEM +# include +#endif +#ifdef CONFIG_HAVE_MEMBLOCK +# include +#endif + +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "internal.h" + +/* XXX Revisit */ +#ifdef phys_to_pfn +/* nothing to do */ +#elif defined __phys_to_pfn +# define phys_to_pfn __phys_to_pfn +#else +# warning correct phys_to_pfn implementation needed +static unsigned long phys_to_pfn(phys_addr_t phys) +{ + return virt_to_pfn(phys_to_virt(phys)); +} +#endif + + +/************************* Initialise CMA *************************/ + +unsigned long cma_reserve(unsigned long start, unsigned long size, + unsigned long alignment) +{ + pr_debug("%s(%p+%p/%p)\n", __func__, (void *)start, (void *)size, + (void *)alignment); + + /* Sanity checks */ + if (!size || (alignment & (alignment - 1))) + return (unsigned long)-EINVAL; + + /* Sanitise input arguments */ + start = PAGE_ALIGN(start); + size = PAGE_ALIGN(size); + if (alignment < PAGE_SIZE) + alignment = PAGE_SIZE; + + /* Reserve memory */ + if (start) { + if (memblock_is_region_reserved(start, size) || + memblock_reserve(start, size) < 0) + return (unsigned long)-EBUSY; + } else { + /* + * Use __memblock_alloc_base() since + * memblock_alloc_base() panic()s. + */ + u64 addr = __memblock_alloc_base(size, alignment, 0); + if (!addr) { + return (unsigned long)-ENOMEM; + } else if (addr + size > ~(unsigned long)0) { + memblock_free(addr, size); + return (unsigned long)-EOVERFLOW; + } else { + start = addr; + } + } + + return start; +} + + +/************************** CMA context ***************************/ + +struct cma { + bool migrate; + struct gen_pool *pool; +}; + +static int __cma_check_range(unsigned long start, unsigned long size) +{ + unsigned long pfn, count; + struct page *page; + struct zone *zone; + + start = phys_to_pfn(start); + if (WARN_ON(!pfn_valid(start))) + return -EINVAL; + + if (WARN_ON(page_zonenum(pfn_to_page(start)) != ZONE_MOVABLE)) + return -EINVAL; + + /* First check if all pages are valid and in the same zone */ + zone = page_zone(pfn_to_page(start)); + count = size >> PAGE_SHIFT; + pfn = start; + while (++pfn, --count) { + if (WARN_ON(!pfn_valid(pfn)) || + WARN_ON(page_zone(pfn_to_page(pfn)) != zone)) + return -EINVAL; + } + + /* Now check migratetype of their pageblocks. */ + start = start & ~(pageblock_nr_pages - 1); + pfn = ALIGN(pfn, pageblock_nr_pages); + page = pfn_to_page(start); + count = (pfn - start) >> PAGE_SHIFT; + do { + if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_MOVABLE)) + return -EINVAL; + page += pageblock_nr_pages; + } while (--count); + + return 0; +} + +struct cma *cma_create(unsigned long start, unsigned long size, + unsigned long min_alignment, bool private) +{ + struct gen_pool *pool; + struct cma *cma; + int ret; + + pr_debug("%s(%p+%p)\n", __func__, (void *)start, (void *)size); + + if (!size) + return ERR_PTR(-EINVAL); + if (min_alignment & (min_alignment - 1)) + return ERR_PTR(-EINVAL); + if (min_alignment < PAGE_SIZE) + min_alignment = PAGE_SIZE; + if ((start | size) & (min_alignment - 1)) + return ERR_PTR(-EINVAL); + if (start + size < start) + return ERR_PTR(-EOVERFLOW); + + if (!private) { + ret = __cma_check_range(start, size); + if (ret < 0) + return ERR_PTR(ret); + } + + cma = kmalloc(sizeof *cma, GFP_KERNEL); + if (!cma) + return ERR_PTR(-ENOMEM); + + pool = gen_pool_create(ffs(min_alignment) - 1, -1); + if (!pool) { + ret = -ENOMEM; + goto error1; + } + + ret = gen_pool_add(pool, start, size, -1); + if (unlikely(ret)) + goto error2; + + cma->migrate = !private; + cma->pool = pool; + + pr_debug("%s: returning <%p>\n", __func__, (void *)cma); + return cma; + +error2: + gen_pool_destroy(pool); +error1: + kfree(cma); + return ERR_PTR(ret); +} + +void cma_destroy(struct cma *cma) +{ + pr_debug("%s(<%p>)\n", __func__, (void *)cma); + gen_pool_destroy((void *)cma); +} + + +/************************* Allocate and free *************************/ + +struct cm { + struct cma *cma; + unsigned long phys, size; + atomic_t pinned, mapped; +}; + +/* Protects cm_alloc(), cm_free() as well as gen_pools of each cm. */ +static DEFINE_MUTEX(cma_mutex); + +struct cm *cm_alloc(struct cma *cma, unsigned long size, + unsigned long alignment) +{ + unsigned long start; + int ret = -ENOMEM; + struct cm *cm; + + pr_debug("%s(<%p>, %p/%p)\n", __func__, (void *)cma, + (void *)size, (void *)alignment); + + if (!size || (alignment & (alignment - 1))) + return ERR_PTR(-EINVAL); + size = PAGE_ALIGN(size); + + cm = kmalloc(sizeof *cm, GFP_KERNEL); + if (!cm) + return ERR_PTR(-ENOMEM); + + mutex_lock(&cma_mutex); + + start = gen_pool_alloc_aligned(cma->pool, size, + alignment ? ffs(alignment) - 1 : 0); + if (!start) + goto error1; + + if (cma->migrate) { + unsigned long pfn = phys_to_pfn(start); + ret = alloc_contig_range(pfn, pfn + (size >> PAGE_SHIFT), 0); + if (ret) + goto error2; + } + + mutex_unlock(&cma_mutex); + + cm->cma = cma; + cm->phys = start; + cm->size = size; + atomic_set(&cm->pinned, 0); + atomic_set(&cm->mapped, 0); + + pr_debug("%s(): returning [%p]\n", __func__, (void *)cm); + return cm; + +error2: + gen_pool_free((void *)cma, start, size); +error1: + mutex_unlock(&cma_mutex); + kfree(cm); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(cm_alloc); + +void cm_free(struct cm *cm) +{ + pr_debug("%s([%p])\n", __func__, (void *)cm); + + if (WARN_ON(atomic_read(&cm->pinned) || atomic_read(&cm->mapped))) + return; + + mutex_lock(&cma_mutex); + + gen_pool_free(cm->cma->pool, cm->phys, cm->size); + if (cm->cma->migrate) + free_contig_pages(phys_to_page(cm->phys), + cm->size >> PAGE_SHIFT); + + mutex_unlock(&cma_mutex); + + kfree(cm); +} +EXPORT_SYMBOL_GPL(cm_free); + + +/************************* Mapping and addresses *************************/ + +/* + * Currently no-operations but keep reference counters for error + * checking. + */ + +unsigned long cm_pin(struct cm *cm) +{ + pr_debug("%s([%p])\n", __func__, (void *)cm); + atomic_inc(&cm->pinned); + return cm->phys; +} +EXPORT_SYMBOL_GPL(cm_pin); + +void cm_unpin(struct cm *cm) +{ + pr_debug("%s([%p])\n", __func__, (void *)cm); + WARN_ON(!atomic_add_unless(&cm->pinned, -1, 0)); +} +EXPORT_SYMBOL_GPL(cm_unpin); + +void *cm_vmap(struct cm *cm) +{ + pr_debug("%s([%p])\n", __func__, (void *)cm); + atomic_inc(&cm->mapped); + /* + * XXX We should probably do something more clever in the + * future. The memory might be highmem after all. + */ + return phys_to_virt(cm->phys); +} +EXPORT_SYMBOL_GPL(cm_vmap); + +void cm_vunmap(struct cm *cm) +{ + pr_debug("%s([%p])\n", __func__, (void *)cm); + WARN_ON(!atomic_add_unless(&cm->mapped, -1, 0)); +} +EXPORT_SYMBOL_GPL(cm_vunmap);