Linaro-mm-sig

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[PATCHv15 0/8] Contiguous Memory Allocator

by Marek Szyprowski

Hello again, This is yet another round of Contiguous Memory Allocator patches. Now I implemented all the ideas that has been discussed during Linaro Sprint meeting. This version provides a solution for complete integration of CMA to DMA mapping subsystem on ARM architecture. The issue caused by double dma pages mapping and possible aliasing in coherent memory mapping has been finally resolved, both for GFP_ATOMIC case (allocations comes from coherent memory pool) and non-GFP_ATOMIC case (allocations comes from CMA managed areas). For coherent, nommu, ARMv4 and ARMv5 systems the current DMA-mapping implementation has been kept. For ARMv6+ systems, CMA has been enabled and a special pool of coherent memory for atomic allocations has been created. The size of this pool defaults to CONSISTEN_DMA_SIZE/8, but can be changed with coherent_pool kernel parameter (if really required). All atomic allocations are served from this pool. I've did a little simplification here, because there is no separate pool for writecombine memory - such requests are also served from coherent pool. I don't think that such simplification is a problem here - I found no driver that use dma_alloc_writecombine with GFP_ATOMIC flags. All non-atomic allocation are served from CMA area. Kernel mapping is updated to reflect required memory attributes changes. This is possible because during early boot, all CMA area are remapped with 4KiB pages in kernel low-memory. This version have been tested on Samsung S5PC110 based Goni machine and Exynos4 UniversalC210 board with various V4L2 multimedia drivers. Coherent atomic allocations has been tested by manually enabling the dma bounce for the s3c-sdhci device. All patches are prepared for Linux Kernel v3.1-rc2. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. TODO (optional): - implement support for contiguous memory areas placed in HIGHMEM zone Best regards -- Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v14: <http://www.spinics.net/lists/linux-media/msg36536.html> v13: (internal, intentionally not released) v12: <http://www.spinics.net/lists/linux-media/msg35674.html> v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v15: 1. fixed calculation of the total memory after activating CMA area (was broken from v12) 2. more code cleanup in drivers/base/dma-contiguous.c 3. added address limit for default CMA area 4. rewrote ARM DMA integration: - removed "ARM: DMA: steal memory for DMA coherent mappings" patch - kept current DMA mapping implementation for coherent, nommu and ARMv4/ARMv5 systems - enabled CMA for all ARMv6+ systems - added separate, small pool for coherent atomic allocations, defaults to CONSISTENT_DMA_SIZE/8, but can be changed with kernel parameter coherent_pool=[size] v14: 1. Merged with "ARM: DMA: steal memory for DMA coherent mappings" patch, added support for GFP_ATOMIC allocations. 2. Added checks for NULL device pointer v13: (internal, intentionally not released) v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Code "stolen" from Kamezawa. The first patch just moves code around and the second provide function for "allocates" already freed memory. mm: alloc_contig_range() added This is what Kamezawa asked: a function that tries to migrate all pages from given range and then use alloc_contig_freed_pages() (defined by the previous commit) to allocate those pages. mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added Introduction of the new migratetype and support for it in CMA. MIGRATE_CMA works similar to ZONE_MOVABLE expect almost any memory range can be marked as one. mm: cma: Contiguous Memory Allocator added The code CMA code. Manages CMA contexts and performs memory allocations. ARM: integrate CMA with dma-mapping subsystem Main client of CMA frame work. CMA serves as a alloc_pages() replacement. ARM: S5PV210: example of CMA private area for FIMC device on Goni board Example of platform/board specific code that creates cma context and assigns it to particular device. Patch summary: KAMEZAWA Hiroyuki (2): mm: move some functions from memory_hotplug.c to page_isolation.c mm: alloc_contig_freed_pages() added Marek Szyprowski (3): drivers: add Contiguous Memory Allocator ARM: integrate CMA with DMA-mapping subsystem ARM: S5PV210: example of CMA private area for FIMC device on Goni board Michal Nazarewicz (3): mm: alloc_contig_range() added mm: MIGRATE_CMA migration type added mm: MIGRATE_CMA isolation functions added arch/Kconfig | 3 + arch/arm/Kconfig | 2 + arch/arm/include/asm/device.h | 3 + arch/arm/include/asm/dma-contiguous.h | 33 +++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/mach-s5pv210/mach-goni.c | 4 + arch/arm/mm/dma-mapping.c | 362 +++++++++++++++++++++++++------ arch/arm/mm/init.c | 8 + arch/arm/mm/mm.h | 3 + arch/arm/mm/mmu.c | 29 ++- drivers/base/Kconfig | 79 +++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 386 +++++++++++++++++++++++++++++++++ include/linux/dma-contiguous.h | 102 +++++++++ include/linux/mmzone.h | 41 +++- include/linux/page-isolation.h | 51 ++++- mm/Kconfig | 8 +- mm/compaction.c | 10 + mm/memory_hotplug.c | 111 ---------- mm/page_alloc.c | 287 ++++++++++++++++++++++-- mm/page_isolation.c | 129 +++++++++++- 21 files changed, 1417 insertions(+), 236 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH v4] DRM: add DRM Driver for Samsung SoC EXYNOS4210.

by Rob Clark

On Wed, Sep 14, 2011 at 2:57 AM, Thomas Hellstrom <thomas(a)shipmail.org> wrote: >>>>>>>>> >>>>>>>>> +static struct drm_ioctl_desc samsung_ioctls[] = { >>>>>>>>> + DRM_IOCTL_DEF_DRV(SAMSUNG_GEM_CREATE, >>>>>>>>> samsung_drm_gem_create_ioctl, >>>>>>>>> + DRM_UNLOCKED | DRM_AUTH), >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> Hi! >>>>>>>> >>>>>>>> With reference my previous security comment. >>>>>>>> >>>>>>>> Let's say you have a compromised video player running as a DRM >>>>>>>> client, that >>>>>>>> tries to repeatedly allocate huge GEM buffers... >>>>>>>> >>>>>>>> What will happen when all DMA memory is exhausted? Will this cause >>>>>>>> other >>>>>>>> device drivers to see an OOM, or only DRM? >>>>>>>> >>>>>>>> The old DRI model basically allowed any authorized DRI client to >>>>>>>> exhaust >>>>>>>> video ram or AGP memory, but never system memory. Newer DRI drivers >>>>>>>> typically only allow DRI masters to do that. >>>>>>>> as >>>>>>>> >>>>>>>> I don't think an authorized DRI client should be able to easily >>>>>>>> >>>>> >>>>> exhaust >>>>> >>>>>>>> >>>>>>>> resources (DMA memory) used by other device drivers causing them to >>>>>>>> fail. >>>>>>>> >>>>>>> >>>>>>> I'm not entirely sure what else can be done, other than have a >>>>>>> threshold on max MB allocatable of buffer memory.. >>>>>>> >>>>>> >>>>>> Yes, I think that's what needs to be done, and that threshold should >>>>>> be low enough to keep other device drivers running in the worst >>>>>> allocation case. >>>>>> >>>>>> >>>>>>> >>>>>>> In the samsung driver case, he is only allocating scanout memory >>>>>>> >>> >>> from >>> >>>>>>> >>>>>>> CMA, so the limit will be the CMA region size.. beyond that you >>>>>>> >>> >>> can't >>> >>>>>>> >>>>>>> get physically contiguous memory. So I think this driver is safe. >>>>>>> >>>>>> >>>>>> It's not really what well-behaved user-space drivers do that should >>>>>> >>> >>> be >>> >>>>>> >>>>>> a concern, but what compromized application *might* do that is a >>>>>> >>>> >>>> concern. >>>> >>>>> >>>>> Hmm. I might have missed your point here. If the buffer allocation >>>>> >>> >>> ioctl >>> >>>>> >>>>> only allows allocating CMA memory, then I agree the driver fits the old >>>>> DRI security model, as long as no other devices on the platform will >>>>> ever use CMA. >>>>> >>>>> But in that case, there really should be a way for the driver to say >>>>> "Hey, all CMA memory on this system is mine", in the same way >>>>> traditional video drivers can claim the VRAM PCI resource. >>>>> >>>>> >>>> >>>> CMA could reserve memory region for a specific driver so DRM Client >>>> >>> >>> could >>> >>>> >>>> request memory allocation from only the region. >>>> >>>> >>>>> >>>>> This is to avoid the possibility that future drivers that need CMA will >>>>> be vulnerable to DOS-attacks from ill-behaved DRI clients. >>>>> >>>>> >>>> >>>> Thomas, if any application has root authority for ill-purpose then isn't >>>> >>> >>> it >>> >>>> >>>> possible to be vulnerable to DOS-attacks? I think DRM_AUTH means root >>>> authority. I know DRM Framework gives any root application DRM_AUTH >>>> authority for compatibility. >>>> >>> >>> DRM_AUTH just means that the client has authenticated w/ X11 (meaning >>> that it has permission to connect to x server).. >>> >>> >> >> Yes, I understood so. but see drm_open_helper() of drm_fops.c file please. >> in this function, you can see a line below. >> /* for compatibility root is always authenticated */ >> priv->authenticated = capable(CAP_SYS_ADMIN) >> >> I think the code above says that any application with root permission is >> authenticated. >> >> > > Yes, that is true. A root client may be assumed to have AUTH permissions, > but the inverse does not hold, meaning that an AUTH client may *not* be > assumed to have root permissions. I think there is a ROOT_ONLY ioctl flag > for that. > > The problem I'm seeing compared to other drivers is the following: > > Imagine for example that you have a disc driver that allocates temporary > memory out of the same DMA pool as the DRM driver. > > Now you have a video player that is a DRM client. It contains a security > flaw and is compromized by somebody trying to play a specially crafted video > stream. The video player starts to allocate gem buffers until it receives an > -ENOMEM. Then it stops allocating and does nothing. > > Now the system tries an important disc access (paging for example). This > fails, because the video player has exhausted all DMA memory and the disc > driver fails to allocate. > > The system is dead. > > The point is: > > If there is a chance that other drivers will use the same DMA/CMA pool as > the DRM driver, DRM must leave enough DMA/CMA memory for those drivers to > work. ah, ok, I get your point > The difference compared to other drm drivers: > > There are other drm drivers that work the same way, with a static allocator. > For example "via" and "sis". But those drivers completely claim the > resources they are using. Nobody else is expected to use VRAM / AGP. > > In the Samsung case, it's not clear to me whether the DMA/CMA pool *can* be > shared with other devices. > If it is, IMHO you must implement an allocation limit in DRM, if not, the > driver should probably be safe. It is possible to create a device private CMA pool.. although OTOH it might be desirable to let some other drivers (like v4l2) use buffers from the same pool.. I'm not entirely sure what will happen w/ dma_alloc_coherent, etc, if the global CMA pool is exhausted. Marek? I guess you know what would happen? BR, -R > Thanks, > Thomas

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Krishna Reddy

Hi, The following change fixes a bug, which causes releasing incorrect iova space, in the original patch of this mail thread. It fixes compilation error either. diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 82d5134..8c16ed7 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -900,10 +900,8 @@ static int __iommu_remove_mapping(struct device *dev, dma_addr_t iova, size_t si unsigned int count = size >> PAGE_SHIFT; int i; - for (i=0; i<count; i++) { - iommu_unmap(mapping->domain, iova, 0); - iova += PAGE_SIZE; - } + for (i=0; i<count; i++) + iommu_unmap(mapping->domain, iova + i * PAGE_SIZE, 0); __free_iova(mapping, iova, size); return 0; } @@ -1073,7 +1071,7 @@ int arm_iommu_map_sg(struct device *dev, struct scatterlist *sg, int nents, size += sg->length; } __map_sg_chunk(dev, start, size, &dma->dma_address, dir); - d->dma_address += offset; + dma->dma_address += offset; return count; -nvpublic

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Krishna Reddy

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Krishna Reddy

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Krishna Reddy

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping

by Krishna Reddy

Hi, The following change fixes a bug, which causes releasing incorrect iova space, in this patch. It fixes compilation error either. diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 82d5134..8c16ed7 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -900,10 +900,8 @@ static int __iommu_remove_mapping(struct device *dev, dma_addr_t iova, size_t si unsigned int count = size >> PAGE_SHIFT; int i; - for (i=0; i<count; i++) { - iommu_unmap(mapping->domain, iova, 0); - iova += PAGE_SIZE; - } + for (i=0; i<count; i++) + iommu_unmap(mapping->domain, iova + i * PAGE_SIZE, 0); __free_iova(mapping, iova, size); return 0; } @@ -1073,7 +1071,7 @@ int arm_iommu_map_sg(struct device *dev, struct scatterlist *sg, int nents, size += sg->length; } __map_sg_chunk(dev, start, size, &dma->dma_address, dir); - d->dma_address += offset; + dma->dma_address += offset; return count; -KR ----------------------------------------------------------------------------------- This email message is for the sole use of the intended recipient(s) and may contain confidential information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. -----------------------------------------------------------------------------------

14 years, 5 months

[RFC] dma-shared-buf: Add buffer sharing framework

by Sumit Semwal

This RFC is aimed at introducing the buffer sharing framework for review. Since almost all the discussion about buffer sharing objects happened on linaro-mm-sig list, I am sending it first for review within the list, and will share it with other lists after first-set of review comments from here. -- This is the first step in defining a buffer sharing framework. A new buffer object is added, with hooks to allow for easy sharing of this buffer object across devices. The idea was first mooted at the Linaro memory management mini-summit in Budapest in May 2011, as part of multiple things needed for a 'unified memory management framework'. It took a more concrete shape at Linaro memory-management mini-summit in Cambridge, Aug 2011. The framework allows: - a new buffer-object to be created, which associates a file pointer with each user-buffer and associated allocator-defined operations on that buffer. This operation is called the 'export' operation. - this exported buffer-object to be shared with the other entity by asking for its 'file-descriptor (fd)', and sharing the fd across. - a received fd to get the buffer object back, where it can be accessed using the associated allocator-defined operations. - the exporter and importer to share the scatterlist using get_ and put_ operations. Some file operations are provided as wrappers over the allocator-defined operations, which allows usage of fops(eg mmap) on the associated 'fd'. This is based on design suggestions from many people at both the mini-summits, most notably from Arnd Bergmann <arnd(a)arndb.de>, and Rob Clark <rob(a)ti.com>. The implementation is inspired from proof-of-concept patch-set from Tomasz Stanislawski <t.stanislaws(a)samsung.com>, who demonstrated buffer sharing between two v4l2 devices. Signed-off-by: Sumit Semwal <sumit.semwal(a)ti.com> --- drivers/base/Kconfig | 10 +++ drivers/base/Makefile | 1 + drivers/base/dma-buf.c | 196 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 105 +++++++++++++++++++++++++ 4 files changed, 312 insertions(+), 0 deletions(-) create mode 100644 drivers/base/dma-buf.c create mode 100644 include/linux/dma-buf.h diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index d57e8d0..5398ce8 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -168,4 +168,14 @@ config SYS_HYPERVISOR bool default n +config DMA_SHARED_BUFFER + bool "Buffer framework to be shared between drivers" + default n + depends on ANON_INODES + help + This option enables the framework for buffer-sharing between + multiple drivers. A buffer is associated with a file using driver + APIs extension; the file's descriptor can then be passed on to other + driver. + endmenu diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 4c5701c..bd95732 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_DEVTMPFS) += devtmpfs.o obj-y += power/ obj-$(CONFIG_HAS_DMA) += dma-mapping.o obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o +obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf.o obj-$(CONFIG_ISA) += isa.o obj-$(CONFIG_FW_LOADER) += firmware_class.o obj-$(CONFIG_NUMA) += node.o diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c new file mode 100644 index 0000000..e35b385 --- /dev/null +++ b/drivers/base/dma-buf.c @@ -0,0 +1,196 @@ +/* + * Framework for buffer objects that can be shared across devices/subsystems. + * + * Copyright(C) 2011 Texas Instruments Inc. All rights reserved. + * Author: Sumit Semwal <sumit.semwal(a)ti.com> + * + * Many thanks to linaro-mm-sig list, and specially + * Arnd Bergmann <arnd(a)arndb.de> and Rob Clark <rob(a)ti.com> + * for their support in creation and refining of this idea. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/dma-buf.h> +#include <linux/anon_inodes.h> + +static int is_dma_buf_file(struct file *); + +/* file operation wrappers for dma buf ops */ +static ssize_t dma_buf_read(struct file *file, char __user *buf, size_t size, + loff_t *offset) +{ + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) + return -EINVAL; + + dmabuf = file->private_data; + return dmabuf->ops->read(dmabuf, buf, size); +} + +static ssize_t dma_buf_write(struct file *file, char __user *buf, size_t size, + loff_t *offset) +{ + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) + return -EINVAL; + + dmabuf = file->private_data; + return dmabuf->ops->write(dmabuf, buf, size); +} + +static int dma_buf_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) + return -EINVAL; + + dmabuf = file->private_data; + return dmabuf->ops->mmap(dmabuf, vma); +} + +static int dma_buf_release(struct inode *inode, struct file *file) +{ + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) + return -EINVAL; + + dmabuf = file->private_data; + + dmabuf->ops->release(dmabuf); + kfree(dmabuf); + return 0; +} + +static const struct file_operations dma_buf_fops = { + .mmap = dma_buf_mmap, + .read = dma_buf_read, + .write = dma_buf_write, + .release = dma_buf_release, +}; + +/* + * is_dma_buf_file - Check if struct file* is associated with dma_buf + */ +static inline int is_dma_buf_file(struct file *file) +{ + return file->f_op == &dma_buf_fops; +} + +/** + * dma_buf_export - Creates a new dma_buf, and associates an anon file + * with this buffer,so it can be exported. + * Also 'attach' the allocator specific data and ops to the buffer. + * + * @priv: Attach private data of allocator to this buffer + * @ops: Attach allocator-defined dma buf ops to the new buffer. + * + * Returns, on success, a newly created dma_buf object, which wraps the + * supplied private data and operations for dma_buf_ops. On failure to + * allocate the dma_buf object, it can return NULL. + * + */ +struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops) +{ + struct dma_buf *dmabuf; + struct file *file; + + BUG_ON(!priv || !ops); + + dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL); + if (dmabuf == NULL) + return dmabuf; + + dmabuf->priv = priv; + dmabuf->ops = ops; + + file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, 0); + + dmabuf->file = file; + file->private_data = dmabuf; + + return dmabuf; +} +EXPORT_SYMBOL(dma_buf_export); + +/** + * dma_buf_fd - returns a file descriptor for the given dma_buf + * @dmabuf: [in] pointer to dma_buf for which fd is required. + * + * On success, returns an associated 'fd'. Else, returns error. + */ +int dma_buf_fd(struct dma_buf *dmabuf) +{ + int error, fd; + + if (!dmabuf->file) + return -EINVAL; + + error = get_unused_fd_flags(0); + if (error < 0) + return error; + fd = error; + + fd_install(fd, dmabuf->file); + + return fd; +} +EXPORT_SYMBOL(dma_buf_fd); + +/** + * dma_buf_get - returns the dma_buf structure related to an fd + * @fd: [in] fd associated with the dma_buf to be returned + * + * On success, returns the dma_buf structure associated with an fd; uses + * file's refcounting done by fget to increase refcount. returns ERR_PTR + * otherwise. + */ +struct dma_buf *dma_buf_get(int fd) +{ + struct file *file; + + file = fget(fd); + + if (!file) + return ERR_PTR(-EBADF); + + if (!is_dma_buf_file(file)) { + fput(file); + return ERR_PTR(-EINVAL); + } + + return file->private_data; +} +EXPORT_SYMBOL(dma_buf_get); + +/** + * dma_buf_put - decreases refcount of the buffer + * @dmabuf: [in] buffer to reduce refcount of + * + * Uses file's refcounting done implicitly by fput() + */ +void dma_buf_put(struct dma_buf *dmabuf) +{ + BUG_ON(!dmabuf->file); + + fput(dmabuf->file); + + return; +} +EXPORT_SYMBOL(dma_buf_put); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h new file mode 100644 index 0000000..c22896a --- /dev/null +++ b/include/linux/dma-buf.h @@ -0,0 +1,105 @@ +/* + * Header file for dma buffer sharing framework. + * + * Copyright(C) 2011 Texas Instruments Inc. All rights reserved. + * Author: Sumit Semwal <sumit.semwal(a)ti.com> + * + * Many thanks to linaro-mm-sig list, and specially + * Arnd Bergmann <arnd(a)arndb.de> and Rob Clark <rob(a)ti.com> + * for their support in creation and refining of this idea. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef __DMA_BUF_H__ +#define __DMA_BUF_H__ + +#include <linux/file.h> +#include <linux/err.h> +#include <linux/device.h> +#include <linux/scatterlist.h> + +struct dma_buf; + +/** + * struct dma_buf_ops - operations possible on struct dmabuf + * @get_scatterlist: returns list of scatter pages allocated, increases + * usecount of the buffer + * @put_scatterlist: decreases usecount of buffer, might deallocate scatter + * pages + * @mmap: map this buffer + * @read: read from this buffer + * @write: write to this buffer + * @release: release this buffer; to be called after the last dma_buf_put + * @sync_sg_for_cpu: sync the sg list for cpu + * @sync_sg_for_device: synch the sg list for device + */ +struct dma_buf_ops { + /* allow buffer to not be pinned when DMA is not happening */ + struct scatterlist * (*get_scatterlist)(struct dma_buf *); + void (*put_scatterlist)(struct dma_buf *, struct scatterlist *); + + /* allow allocator to mmap/read/write to take care of cache attrib */ + int (*mmap)(struct dma_buf *, struct vm_area_struct *); + ssize_t (*read)(struct dma_buf *, void *, size_t); + ssize_t (*write)(struct dma_buf *, void *, size_t); + /* after final dma_buf_put() */ + void (*release)(struct dma_buf *); + + /* allow allocator to take care of cache ops */ + void (*sync_sg_for_cpu) (struct dma_buf *, struct device *); + void (*sync_sg_for_device)(struct dma_buf *, struct device *); +}; + +/** + * struct dma_buf - shared buffer object + * @file: file pointer used for sharing buffers across, and for refcounting. + * @ops: dma_buf_ops associated with this buffer object + * @priv: user specific private data + */ +struct dma_buf { + struct file *file; + struct dma_buf_ops *ops; + void *priv; +}; + +#ifdef CONFIG_DMA_SHARED_BUFFER + +struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops); +int dma_buf_fd(struct dma_buf *dmabuf); +struct dma_buf *dma_buf_get(int fd); +void dma_buf_put(struct dma_buf *dmabuf); + +#else +static inline struct dma_buf *dma_buf_export(void *priv, + struct dma_buf_ops *ops) +{ + return ERR_PTR(-ENODEV); +} + +static inline int dma_buf_fd(struct dma_buf *dmabuf) +{ + return -ENODEV; +} + +static inline struct dma_buf *dma_buf_get(int fd) +{ + return ERR_PTR(-ENODEV); +} + +static inline void dma_buf_put(struct dma_buf *dmabuf) +{ + return; +} +#endif /* CONFIG_DMA_SHARED_BUFFER */ + +#endif /* __DMA_BUF_H__ */ -- 1.7.4.1

14 years, 5 months

Memory Management Documentation effort

by Benjamin Gaignard

Hello, I'm writing documentation about CMA ( https://wiki.linaro.org/OfficeofCTO/MemoryManagement?action=AttachFile&do=v… ) and DMA_Buf ( https://wiki.linaro.org/OfficeofCTO/MemoryManagement?action=AttachFile&do=v… ) The goal is to explain outside the Linaro community how CMA and DMA_Buf works. I have tried to summarize my understanding in few slides and now I need you to review and comment this first draft. Additionnal info about who is doing what and when it will be delivered are welcome. Regards, Benjamin -- Benjamin Gaignard Multimedia Working Group Linaro.org <http://www.linaro.org/>* **│ *Open source software for ARM SoCs ** Follow *Linaro: *Facebook <http://www.facebook.com/pages/Linaro> | Twitter<http://twitter.com/#!/linaroorg> | Blog <http://www.linaro.org/linaro-blog/>

14 years, 5 months

Re: [Linaro-mm-sig] [PATCH 8/8] ARM: S5PV210: example of CMA private area for FIMC device on Goni board

by Aguirre, Sergio

Hi Marek/Kyungmin, On Fri, Aug 19, 2011 at 04:27:44PM +0200, Marek Szyprowski wrote: > This patch is an example how device private CMA area can be activated. > It creates one CMA region and assigns it to the first s5p-fimc device on > Samsung Goni S5PC110 board. > > Signed-off-by: Marek Szyprowski <m.szyprowski(a)samsung.com> > Signed-off-by: Kyungmin Park <kyungmin.park(a)samsung.com> > --- > arch/arm/mach-s5pv210/mach-goni.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > diff --git a/arch/arm/mach-s5pv210/mach-goni.c b/arch/arm/mach-s5pv210/mach-goni.c > index 14578f5..f766c45 100644 > --- a/arch/arm/mach-s5pv210/mach-goni.c > +++ b/arch/arm/mach-s5pv210/mach-goni.c > @@ -26,6 +26,7 @@ > #include <linux/input.h> > #include <linux/gpio.h> > #include <linux/interrupt.h> > +#include <linux/dma-contiguous.h> > > #include <asm/mach/arch.h> > #include <asm/mach/map.h> > @@ -857,6 +858,9 @@ static void __init goni_map_io(void) > static void __init goni_reserve(void) > { > s5p_mfc_reserve_mem(0x43000000, 8 << 20, 0x51000000, 8 << 20); > + > + /* Create private 16MiB contiguous memory area for s5p-fimc.0 device */ > + dma_declare_contiguous(&s5p_device_fimc0.dev, 16*SZ_1M, 0); This is broken, since according to patch #0006, dma_declare_contiguous requires a 4th param (limit) which you're not providing here. Regards, Sergio > } > > static void __init goni_machine_init(void) > -- > 1.7.1.569.g6f426

14 years, 6 months

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