[PATCH v3 0/7] dma-buf: Performance improvements for system heap & a system-uncached implementation
Hey All, So this is another revision of my patch series to performance optimizations to the dma-buf system heap.
Unfortunately, in working these up, I realized the heap-helpers infrastructure we tried to add to miniimize code duplication is not as generic as we intended. For some heaps it makes sense to deal with page lists, for other heaps it makes more sense to track things with sgtables.
So this series reworks the system heap to use sgtables, and then consolidates the pagelist method from the heap-helpers into the CMA heap. After which the heap-helpers logic is removed (as it is unused). I'd still like to find a better way to avoid some of the logic duplication in implementing the entire dma_buf_ops handlers per heap. But unfortunately that code is tied somewhat to how the buffer's memory is tracked.
After this, the series introduces an optimization that Ørjan Eide implemented for ION that avoids calling sync on attachments that don't have a mapping.
Next, an optimization to use larger order pages for the system heap. This change brings us closer to the current performance of the ION code.
Unfortunately, after submitting the last round, I realized that part of the reason the page-pooling patch I had included was providing such great performance numbers, was because the network page-pool implementation doesn't zero pages that it pulls from the cache. This is very inappropriate for buffers we pass to userland and was what gave it an unfair advantage (almost constant time performance) relative to ION's allocation performance numbers. I added some patches to zero the buffers manually similar to how ION does it, but I found this resulted in basically no performance improvement from the standard page allocator. Thus I've dropped that patch in this series for now.
Unfortunately this means we still have a performance delta from the ION system heap as measured by my microbenchmark, and this delta comes from ION system_heap's use of deferred freeing of pages. So less work is done in the measured interval of the microbenchmark. I'll be looking at adding similar code eventually but I don't want to hold the rest of the patches up on this, as it is still a good improvement over the current code.
I've updated the chart I shared earlier with current numbers (including with the unsubmitted net pagepool implementation, and with a different unsubmitted pagepool implementation borrowed from ION) here: https://docs.google.com/spreadsheets/d/1-1C8ZQpmkl_0DISkI6z4xelE08MlNAN7oEu3...
I did add to this series a reworked version of my uncached system heap implementation I was submitting a few weeks back. Since it duplicated a lot of the now reworked system heap code, I realized it would be much simpler to add the functionality to the system_heap implementaiton itself.
While not improving the core allocation performance, the uncached heap allocations do result in *much* improved performance on HiKey960 as it avoids a lot of flushing and invalidating buffers that the cpu doesn't touch often.
Feedback on these would be great!
thanks -john
New in v3: * Dropped page-pool patches as after correcting the code to zero buffers, they provided no net performance gain. * Added system-uncached implementation ontop of reworked system-heap. * Use the new sgtable mapping functions, in the system and cma code as Suggested-by: Daniel Mentz danielmentz@google.com * Cleanup: Use page_size() rather then open-coding it
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org
John Stultz (7): dma-buf: system_heap: Rework system heap to use sgtables instead of pagelists dma-buf: heaps: Move heap-helper logic into the cma_heap implementation dma-buf: heaps: Remove heap-helpers code dma-buf: heaps: Skip sync if not mapped dma-buf: system_heap: Allocate higher order pages if available dma-buf: dma-heap: Keep track of the heap device struct dma-buf: system_heap: Add a system-uncached heap re-using the system heap
drivers/dma-buf/dma-heap.c | 33 +- drivers/dma-buf/heaps/Makefile | 1 - drivers/dma-buf/heaps/cma_heap.c | 327 +++++++++++++++--- drivers/dma-buf/heaps/heap-helpers.c | 271 --------------- drivers/dma-buf/heaps/heap-helpers.h | 53 --- drivers/dma-buf/heaps/system_heap.c | 480 ++++++++++++++++++++++++--- include/linux/dma-heap.h | 9 + 7 files changed, 741 insertions(+), 433 deletions(-) delete mode 100644 drivers/dma-buf/heaps/heap-helpers.c delete mode 100644 drivers/dma-buf/heaps/heap-helpers.h
In preparation for some patches to optmize the system heap code, rework the dmabuf exporter to utilize sgtables rather then pageslists for tracking the associated pages.
This will allow for large order page allocations, as well as more efficient page pooling.
In doing so, the system heap stops using the heap-helpers logic which sadly is not quite as generic as I was hoping it to be, so this patch adds heap specific implementations of the dma_buf_ops function handlers.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- v2: * Fix locking issue and an unused return value Reported-by: kernel test robot lkp@intel.com Julia Lawall julia.lawall@lip6.fr * Make system_heap_buf_ops static Reported-by: kernel test robot lkp@intel.com v3: * Use the new sgtable mapping functions, as Suggested-by: Daniel Mentz danielmentz@google.com --- drivers/dma-buf/heaps/system_heap.c | 344 ++++++++++++++++++++++++---- 1 file changed, 298 insertions(+), 46 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 0bf688e3c023..00ed107b3b76 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -3,7 +3,11 @@ * DMABUF System heap exporter * * Copyright (C) 2011 Google, Inc. - * Copyright (C) 2019 Linaro Ltd. + * Copyright (C) 2019, 2020 Linaro Ltd. + * + * Portions based off of Andrew Davis' SRAM heap: + * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis afd@ti.com */
#include <linux/dma-buf.h> @@ -15,72 +19,321 @@ #include <linux/module.h> #include <linux/scatterlist.h> #include <linux/slab.h> -#include <linux/sched/signal.h> -#include <asm/page.h> - -#include "heap-helpers.h" +#include <linux/vmalloc.h>
struct dma_heap *sys_heap;
-static void system_heap_free(struct heap_helper_buffer *buffer) +struct system_heap_buffer { + struct dma_heap *heap; + struct list_head attachments; + struct mutex lock; + unsigned long len; + struct sg_table sg_table; + int vmap_cnt; + void *vaddr; +}; + +struct dma_heap_attachment { + struct device *dev; + struct sg_table *table; + struct list_head list; +}; + +static struct sg_table *dup_sg_table(struct sg_table *table) { - pgoff_t pg; + struct sg_table *new_table; + int ret, i; + struct scatterlist *sg, *new_sg; + + new_table = kzalloc(sizeof(*new_table), GFP_KERNEL); + if (!new_table) + return ERR_PTR(-ENOMEM); + + ret = sg_alloc_table(new_table, table->orig_nents, GFP_KERNEL); + if (ret) { + kfree(new_table); + return ERR_PTR(-ENOMEM); + } + + new_sg = new_table->sgl; + for_each_sgtable_sg(table, sg, i) { + sg_set_page(new_sg, sg_page(sg), sg->length, sg->offset); + new_sg = sg_next(new_sg); + } + + return new_table; +} + +static int system_heap_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + struct sg_table *table; + + a = kzalloc(sizeof(*a), GFP_KERNEL); + if (!a) + return -ENOMEM; + + table = dup_sg_table(&buffer->sg_table); + if (IS_ERR(table)) { + kfree(a); + return -ENOMEM; + } + + a->table = table; + a->dev = attachment->dev; + INIT_LIST_HEAD(&a->list); + + attachment->priv = a; + + mutex_lock(&buffer->lock); + list_add(&a->list, &buffer->attachments); + mutex_unlock(&buffer->lock); + + return 0; +} + +static void system_heap_detatch(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a = attachment->priv; + + mutex_lock(&buffer->lock); + list_del(&a->list); + mutex_unlock(&buffer->lock); + + sg_free_table(a->table); + kfree(a->table); + kfree(a); +} + +static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attachment, + enum dma_data_direction direction) +{ + struct dma_heap_attachment *a = attachment->priv; + struct sg_table *table = a->table; + int ret; + + ret = dma_map_sgtable(attachment->dev, table, direction, 0); + if (ret) + return ERR_PTR(ret); + + return table; +} + +static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, + struct sg_table *table, + enum dma_data_direction direction) +{ + dma_unmap_sgtable(attachment->dev, table, direction, 0); +} + +static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, + enum dma_data_direction direction) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + + mutex_lock(&buffer->lock); + + if (buffer->vmap_cnt) + invalidate_kernel_vmap_range(buffer->vaddr, buffer->len); + + list_for_each_entry(a, &buffer->attachments, list) { + dma_sync_sgtable_for_cpu(a->dev, a->table, direction); + } + mutex_unlock(&buffer->lock); + + return 0; +}
- for (pg = 0; pg < buffer->pagecount; pg++) - __free_page(buffer->pages[pg]); - kfree(buffer->pages); +static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, + enum dma_data_direction direction) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + + mutex_lock(&buffer->lock); + + if (buffer->vmap_cnt) + flush_kernel_vmap_range(buffer->vaddr, buffer->len); + + list_for_each_entry(a, &buffer->attachments, list) { + dma_sync_sgtable_for_device(a->dev, a->table, direction); + } + mutex_unlock(&buffer->lock); + + return 0; +} + +static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct sg_table *table = &buffer->sg_table; + unsigned long addr = vma->vm_start; + struct sg_page_iter piter; + int ret; + + for_each_sgtable_page(table, &piter, vma->vm_pgoff) { + struct page *page = sg_page_iter_page(&piter); + + ret = remap_pfn_range(vma, addr, page_to_pfn(page), PAGE_SIZE, + vma->vm_page_prot); + if (ret) + return ret; + addr += PAGE_SIZE; + if (addr >= vma->vm_end) + return 0; + } + return 0; +} + +static void *system_heap_do_vmap(struct system_heap_buffer *buffer) +{ + struct sg_table *table = &buffer->sg_table; + int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE; + struct page **pages = vmalloc(sizeof(struct page *) * npages); + struct page **tmp = pages; + struct sg_page_iter piter; + void *vaddr; + + if (!pages) + return ERR_PTR(-ENOMEM); + + for_each_sgtable_page(table, &piter, 0) { + WARN_ON(tmp - pages >= npages); + *tmp++ = sg_page_iter_page(&piter); + } + + vaddr = vmap(pages, npages, VM_MAP, PAGE_KERNEL); + vfree(pages); + + if (!vaddr) + return ERR_PTR(-ENOMEM); + + return vaddr; +} + +static void *system_heap_vmap(struct dma_buf *dmabuf) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + void *vaddr; + + mutex_lock(&buffer->lock); + if (buffer->vmap_cnt) { + buffer->vmap_cnt++; + vaddr = buffer->vaddr; + goto out; + } + + vaddr = system_heap_do_vmap(buffer); + if (IS_ERR(vaddr)) + goto out; + + buffer->vaddr = vaddr; + buffer->vmap_cnt++; +out: + mutex_unlock(&buffer->lock); + + return vaddr; +} + +static void system_heap_vunmap(struct dma_buf *dmabuf, void *vaddr) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + + mutex_lock(&buffer->lock); + if (!--buffer->vmap_cnt) { + vunmap(buffer->vaddr); + buffer->vaddr = NULL; + } + mutex_unlock(&buffer->lock); +} + +static void system_heap_dma_buf_release(struct dma_buf *dmabuf) +{ + struct system_heap_buffer *buffer = dmabuf->priv; + struct sg_table *table; + struct scatterlist *sg; + int i; + + table = &buffer->sg_table; + for_each_sgtable_sg(table, sg, i) + __free_page(sg_page(sg)); + sg_free_table(table); kfree(buffer); }
+static const struct dma_buf_ops system_heap_buf_ops = { + .attach = system_heap_attach, + .detach = system_heap_detatch, + .map_dma_buf = system_heap_map_dma_buf, + .unmap_dma_buf = system_heap_unmap_dma_buf, + .begin_cpu_access = system_heap_dma_buf_begin_cpu_access, + .end_cpu_access = system_heap_dma_buf_end_cpu_access, + .mmap = system_heap_mmap, + .vmap = system_heap_vmap, + .vunmap = system_heap_vunmap, + .release = system_heap_dma_buf_release, +}; + static int system_heap_allocate(struct dma_heap *heap, unsigned long len, unsigned long fd_flags, unsigned long heap_flags) { - struct heap_helper_buffer *helper_buffer; + struct system_heap_buffer *buffer; + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); struct dma_buf *dmabuf; - int ret = -ENOMEM; + struct sg_table *table; + struct scatterlist *sg; + pgoff_t pagecount; pgoff_t pg; + int i, ret = -ENOMEM;
- helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL); - if (!helper_buffer) + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!buffer) return -ENOMEM;
- init_heap_helper_buffer(helper_buffer, system_heap_free); - helper_buffer->heap = heap; - helper_buffer->size = len; - - helper_buffer->pagecount = len / PAGE_SIZE; - helper_buffer->pages = kmalloc_array(helper_buffer->pagecount, - sizeof(*helper_buffer->pages), - GFP_KERNEL); - if (!helper_buffer->pages) { - ret = -ENOMEM; - goto err0; - } + INIT_LIST_HEAD(&buffer->attachments); + mutex_init(&buffer->lock); + buffer->heap = heap; + buffer->len = len;
- for (pg = 0; pg < helper_buffer->pagecount; pg++) { + table = &buffer->sg_table; + pagecount = len / PAGE_SIZE; + if (sg_alloc_table(table, pagecount, GFP_KERNEL)) + goto free_buffer; + + sg = table->sgl; + for (pg = 0; pg < pagecount; pg++) { + struct page *page; /* * Avoid trying to allocate memory if the process - * has been killed by by SIGKILL + * has been killed by SIGKILL */ if (fatal_signal_pending(current)) - goto err1; - - helper_buffer->pages[pg] = alloc_page(GFP_KERNEL | __GFP_ZERO); - if (!helper_buffer->pages[pg]) - goto err1; + goto free_pages; + page = alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + goto free_pages; + sg_set_page(sg, page, page_size(page), 0); + sg = sg_next(sg); }
/* create the dmabuf */ - dmabuf = heap_helper_export_dmabuf(helper_buffer, fd_flags); + exp_info.ops = &system_heap_buf_ops; + exp_info.size = buffer->len; + exp_info.flags = fd_flags; + exp_info.priv = buffer; + dmabuf = dma_buf_export(&exp_info); if (IS_ERR(dmabuf)) { ret = PTR_ERR(dmabuf); - goto err1; + goto free_pages; }
- helper_buffer->dmabuf = dmabuf; - ret = dma_buf_fd(dmabuf, fd_flags); if (ret < 0) { dma_buf_put(dmabuf); @@ -90,12 +343,12 @@ static int system_heap_allocate(struct dma_heap *heap,
return ret;
-err1: - while (pg > 0) - __free_page(helper_buffer->pages[--pg]); - kfree(helper_buffer->pages); -err0: - kfree(helper_buffer); +free_pages: + for_each_sgtable_sg(table, sg, i) + __free_page(sg_page(sg)); + sg_free_table(table); +free_buffer: + kfree(buffer);
return ret; } @@ -107,7 +360,6 @@ static const struct dma_heap_ops system_heap_ops = { static int system_heap_create(void) { struct dma_heap_export_info exp_info; - int ret = 0;
exp_info.name = "system"; exp_info.ops = &system_heap_ops; @@ -115,9 +367,9 @@ static int system_heap_create(void)
sys_heap = dma_heap_add(&exp_info); if (IS_ERR(sys_heap)) - ret = PTR_ERR(sys_heap); + return PTR_ERR(sys_heap);
- return ret; + return 0; } module_init(system_heap_create); MODULE_LICENSE("GPL v2");
Since the heap-helpers logic ended up not being as generic as hoped, move the heap-helpers dma_buf_ops implementations into the cma_heap directly.
This will allow us to remove the heap_helpers code in a following patch.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- v2: * Fix unused return value and locking issue Reported-by: kernel test robot lkp@intel.com Julia Lawall julia.lawall@inria.fr * Make cma_heap_buf_ops static suggested by kernel test robot lkp@intel.com * Fix uninitialized return in cma Reported-by: kernel test robot lkp@intel.com * Minor cleanups v3: * Use the new sgtable mapping functions, as Suggested-by: Daniel Mentz danielmentz@google.com --- drivers/dma-buf/heaps/cma_heap.c | 317 ++++++++++++++++++++++++++----- 1 file changed, 267 insertions(+), 50 deletions(-)
diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index 626cf7fd033a..366963b94c72 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -2,76 +2,291 @@ /* * DMABUF CMA heap exporter * - * Copyright (C) 2012, 2019 Linaro Ltd. + * Copyright (C) 2012, 2019, 2020 Linaro Ltd. * Author: benjamin.gaignard@linaro.org for ST-Ericsson. + * + * Also utilizing parts of Andrew Davis' SRAM heap: + * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis afd@ti.com */ - #include <linux/cma.h> -#include <linux/device.h> #include <linux/dma-buf.h> -#include <linux/dma-heap.h> #include <linux/dma-contiguous.h> +#include <linux/dma-heap.h> +#include <linux/dma-mapping.h> #include <linux/err.h> -#include <linux/errno.h> #include <linux/highmem.h> +#include <linux/io.h> +#include <linux/mm.h> #include <linux/module.h> -#include <linux/slab.h> #include <linux/scatterlist.h> -#include <linux/sched/signal.h> +#include <linux/slab.h>
-#include "heap-helpers.h"
struct cma_heap { struct dma_heap *heap; struct cma *cma; };
-static void cma_heap_free(struct heap_helper_buffer *buffer) +struct cma_heap_buffer { + struct cma_heap *heap; + struct list_head attachments; + struct mutex lock; + unsigned long len; + struct page *cma_pages; + struct page **pages; + pgoff_t pagecount; + int vmap_cnt; + void *vaddr; +}; + +struct dma_heap_attachment { + struct device *dev; + struct sg_table table; + struct list_head list; +}; + +static int cma_heap_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) { - struct cma_heap *cma_heap = dma_heap_get_drvdata(buffer->heap); - unsigned long nr_pages = buffer->pagecount; - struct page *cma_pages = buffer->priv_virt; + struct cma_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + int ret;
- /* free page list */ - kfree(buffer->pages); - /* release memory */ - cma_release(cma_heap->cma, cma_pages, nr_pages); + a = kzalloc(sizeof(*a), GFP_KERNEL); + if (!a) + return -ENOMEM; + + ret = sg_alloc_table_from_pages(&a->table, buffer->pages, + buffer->pagecount, 0, + buffer->pagecount << PAGE_SHIFT, + GFP_KERNEL); + if (ret) { + kfree(a); + return ret; + } + + a->dev = attachment->dev; + INIT_LIST_HEAD(&a->list); + + attachment->priv = a; + + mutex_lock(&buffer->lock); + list_add(&a->list, &buffer->attachments); + mutex_unlock(&buffer->lock); + + return 0; +} + +static void cma_heap_detatch(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a = attachment->priv; + + mutex_lock(&buffer->lock); + list_del(&a->list); + mutex_unlock(&buffer->lock); + + sg_free_table(&a->table); + kfree(a); +} + +static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachment, + enum dma_data_direction direction) +{ + struct dma_heap_attachment *a = attachment->priv; + struct sg_table *table = &a->table; + int ret; + + ret = dma_map_sgtable(attachment->dev, table, direction, 0); + if (ret) + return ERR_PTR(-ENOMEM); + return table; +} + +static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, + struct sg_table *table, + enum dma_data_direction direction) +{ + dma_unmap_sgtable(attachment->dev, table, direction, 0); +} + +static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, + enum dma_data_direction direction) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + + if (buffer->vmap_cnt) + invalidate_kernel_vmap_range(buffer->vaddr, buffer->len); + + mutex_lock(&buffer->lock); + list_for_each_entry(a, &buffer->attachments, list) { + dma_sync_sgtable_for_cpu(a->dev, &a->table, direction); + } + mutex_unlock(&buffer->lock); + + return 0; +} + +static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, + enum dma_data_direction direction) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + struct dma_heap_attachment *a; + + if (buffer->vmap_cnt) + flush_kernel_vmap_range(buffer->vaddr, buffer->len); + + mutex_lock(&buffer->lock); + list_for_each_entry(a, &buffer->attachments, list) { + dma_sync_sgtable_for_device(a->dev, &a->table, direction); + } + mutex_unlock(&buffer->lock); + + return 0; +} + +static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct cma_heap_buffer *buffer = vma->vm_private_data; + + if (vmf->pgoff > buffer->pagecount) + return VM_FAULT_SIGBUS; + + vmf->page = buffer->pages[vmf->pgoff]; + get_page(vmf->page); + + return 0; +} + +static const struct vm_operations_struct dma_heap_vm_ops = { + .fault = cma_heap_vm_fault, +}; + +static int cma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + + if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) + return -EINVAL; + + vma->vm_ops = &dma_heap_vm_ops; + vma->vm_private_data = buffer; + + return 0; +} + +static void *cma_heap_do_vmap(struct cma_heap_buffer *buffer) +{ + void *vaddr; + + vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL); + if (!vaddr) + return ERR_PTR(-ENOMEM); + + return vaddr; +} + +static void *cma_heap_vmap(struct dma_buf *dmabuf) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + void *vaddr; + + mutex_lock(&buffer->lock); + if (buffer->vmap_cnt) { + buffer->vmap_cnt++; + vaddr = buffer->vaddr; + goto out; + } + + vaddr = cma_heap_do_vmap(buffer); + if (IS_ERR(vaddr)) + goto out; + + buffer->vaddr = vaddr; + buffer->vmap_cnt++; +out: + mutex_unlock(&buffer->lock); + + return vaddr; +} + +static void cma_heap_vunmap(struct dma_buf *dmabuf, void *vaddr) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + + mutex_lock(&buffer->lock); + if (!--buffer->vmap_cnt) { + vunmap(buffer->vaddr); + buffer->vaddr = NULL; + } + mutex_unlock(&buffer->lock); +} + +static void cma_heap_dma_buf_release(struct dma_buf *dmabuf) +{ + struct cma_heap_buffer *buffer = dmabuf->priv; + struct cma_heap *cma_heap = buffer->heap; + + if (buffer->vmap_cnt > 0) { + WARN(1, "%s: buffer still mapped in the kernel\n", __func__); + vunmap(buffer->vaddr); + } + + cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount); kfree(buffer); }
-/* dmabuf heap CMA operations functions */ +static const struct dma_buf_ops cma_heap_buf_ops = { + .attach = cma_heap_attach, + .detach = cma_heap_detatch, + .map_dma_buf = cma_heap_map_dma_buf, + .unmap_dma_buf = cma_heap_unmap_dma_buf, + .begin_cpu_access = cma_heap_dma_buf_begin_cpu_access, + .end_cpu_access = cma_heap_dma_buf_end_cpu_access, + .mmap = cma_heap_mmap, + .vmap = cma_heap_vmap, + .vunmap = cma_heap_vunmap, + .release = cma_heap_dma_buf_release, +}; + static int cma_heap_allocate(struct dma_heap *heap, - unsigned long len, - unsigned long fd_flags, - unsigned long heap_flags) + unsigned long len, + unsigned long fd_flags, + unsigned long heap_flags) { struct cma_heap *cma_heap = dma_heap_get_drvdata(heap); - struct heap_helper_buffer *helper_buffer; - struct page *cma_pages; + struct cma_heap_buffer *buffer; + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); size_t size = PAGE_ALIGN(len); - unsigned long nr_pages = size >> PAGE_SHIFT; + pgoff_t pagecount = size >> PAGE_SHIFT; unsigned long align = get_order(size); + struct page *cma_pages; struct dma_buf *dmabuf; int ret = -ENOMEM; pgoff_t pg;
- if (align > CONFIG_CMA_ALIGNMENT) - align = CONFIG_CMA_ALIGNMENT; - - helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL); - if (!helper_buffer) + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!buffer) return -ENOMEM;
- init_heap_helper_buffer(helper_buffer, cma_heap_free); - helper_buffer->heap = heap; - helper_buffer->size = len; + INIT_LIST_HEAD(&buffer->attachments); + mutex_init(&buffer->lock); + buffer->len = size; + + if (align > CONFIG_CMA_ALIGNMENT) + align = CONFIG_CMA_ALIGNMENT;
- cma_pages = cma_alloc(cma_heap->cma, nr_pages, align, false); + cma_pages = cma_alloc(cma_heap->cma, pagecount, align, false); if (!cma_pages) - goto free_buf; + goto free_buffer;
+ /* Clear the cma pages */ if (PageHighMem(cma_pages)) { - unsigned long nr_clear_pages = nr_pages; + unsigned long nr_clear_pages = pagecount; struct page *page = cma_pages;
while (nr_clear_pages > 0) { @@ -85,7 +300,6 @@ static int cma_heap_allocate(struct dma_heap *heap, */ if (fatal_signal_pending(current)) goto free_cma; - page++; nr_clear_pages--; } @@ -93,28 +307,30 @@ static int cma_heap_allocate(struct dma_heap *heap, memset(page_address(cma_pages), 0, size); }
- helper_buffer->pagecount = nr_pages; - helper_buffer->pages = kmalloc_array(helper_buffer->pagecount, - sizeof(*helper_buffer->pages), - GFP_KERNEL); - if (!helper_buffer->pages) { + buffer->pages = kmalloc_array(pagecount, sizeof(*buffer->pages), GFP_KERNEL); + if (!buffer->pages) { ret = -ENOMEM; goto free_cma; }
- for (pg = 0; pg < helper_buffer->pagecount; pg++) - helper_buffer->pages[pg] = &cma_pages[pg]; + for (pg = 0; pg < pagecount; pg++) + buffer->pages[pg] = &cma_pages[pg]; + + buffer->cma_pages = cma_pages; + buffer->heap = cma_heap; + buffer->pagecount = pagecount;
/* create the dmabuf */ - dmabuf = heap_helper_export_dmabuf(helper_buffer, fd_flags); + exp_info.ops = &cma_heap_buf_ops; + exp_info.size = buffer->len; + exp_info.flags = fd_flags; + exp_info.priv = buffer; + dmabuf = dma_buf_export(&exp_info); if (IS_ERR(dmabuf)) { ret = PTR_ERR(dmabuf); goto free_pages; }
- helper_buffer->dmabuf = dmabuf; - helper_buffer->priv_virt = cma_pages; - ret = dma_buf_fd(dmabuf, fd_flags); if (ret < 0) { dma_buf_put(dmabuf); @@ -125,11 +341,12 @@ static int cma_heap_allocate(struct dma_heap *heap, return ret;
free_pages: - kfree(helper_buffer->pages); + kfree(buffer->pages); free_cma: - cma_release(cma_heap->cma, cma_pages, nr_pages); -free_buf: - kfree(helper_buffer); + cma_release(cma_heap->cma, cma_pages, pagecount); +free_buffer: + kfree(buffer); + return ret; }
The heap-helpers code was not as generic as initially hoped and it is now not being used, so remove it from the tree.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- drivers/dma-buf/heaps/Makefile | 1 - drivers/dma-buf/heaps/heap-helpers.c | 271 --------------------------- drivers/dma-buf/heaps/heap-helpers.h | 53 ------ 3 files changed, 325 deletions(-) delete mode 100644 drivers/dma-buf/heaps/heap-helpers.c delete mode 100644 drivers/dma-buf/heaps/heap-helpers.h
diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile index 6e54cdec3da0..974467791032 100644 --- a/drivers/dma-buf/heaps/Makefile +++ b/drivers/dma-buf/heaps/Makefile @@ -1,4 +1,3 @@ # SPDX-License-Identifier: GPL-2.0 -obj-y += heap-helpers.o obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c deleted file mode 100644 index 9f964ca3f59c..000000000000 --- a/drivers/dma-buf/heaps/heap-helpers.c +++ /dev/null @@ -1,271 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -#include <linux/device.h> -#include <linux/dma-buf.h> -#include <linux/err.h> -#include <linux/highmem.h> -#include <linux/idr.h> -#include <linux/list.h> -#include <linux/slab.h> -#include <linux/uaccess.h> -#include <linux/vmalloc.h> -#include <uapi/linux/dma-heap.h> - -#include "heap-helpers.h" - -void init_heap_helper_buffer(struct heap_helper_buffer *buffer, - void (*free)(struct heap_helper_buffer *)) -{ - buffer->priv_virt = NULL; - mutex_init(&buffer->lock); - buffer->vmap_cnt = 0; - buffer->vaddr = NULL; - buffer->pagecount = 0; - buffer->pages = NULL; - INIT_LIST_HEAD(&buffer->attachments); - buffer->free = free; -} - -struct dma_buf *heap_helper_export_dmabuf(struct heap_helper_buffer *buffer, - int fd_flags) -{ - DEFINE_DMA_BUF_EXPORT_INFO(exp_info); - - exp_info.ops = &heap_helper_ops; - exp_info.size = buffer->size; - exp_info.flags = fd_flags; - exp_info.priv = buffer; - - return dma_buf_export(&exp_info); -} - -static void *dma_heap_map_kernel(struct heap_helper_buffer *buffer) -{ - void *vaddr; - - vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL); - if (!vaddr) - return ERR_PTR(-ENOMEM); - - return vaddr; -} - -static void dma_heap_buffer_destroy(struct heap_helper_buffer *buffer) -{ - if (buffer->vmap_cnt > 0) { - WARN(1, "%s: buffer still mapped in the kernel\n", __func__); - vunmap(buffer->vaddr); - } - - buffer->free(buffer); -} - -static void *dma_heap_buffer_vmap_get(struct heap_helper_buffer *buffer) -{ - void *vaddr; - - if (buffer->vmap_cnt) { - buffer->vmap_cnt++; - return buffer->vaddr; - } - vaddr = dma_heap_map_kernel(buffer); - if (IS_ERR(vaddr)) - return vaddr; - buffer->vaddr = vaddr; - buffer->vmap_cnt++; - return vaddr; -} - -static void dma_heap_buffer_vmap_put(struct heap_helper_buffer *buffer) -{ - if (!--buffer->vmap_cnt) { - vunmap(buffer->vaddr); - buffer->vaddr = NULL; - } -} - -struct dma_heaps_attachment { - struct device *dev; - struct sg_table table; - struct list_head list; -}; - -static int dma_heap_attach(struct dma_buf *dmabuf, - struct dma_buf_attachment *attachment) -{ - struct dma_heaps_attachment *a; - struct heap_helper_buffer *buffer = dmabuf->priv; - int ret; - - a = kzalloc(sizeof(*a), GFP_KERNEL); - if (!a) - return -ENOMEM; - - ret = sg_alloc_table_from_pages(&a->table, buffer->pages, - buffer->pagecount, 0, - buffer->pagecount << PAGE_SHIFT, - GFP_KERNEL); - if (ret) { - kfree(a); - return ret; - } - - a->dev = attachment->dev; - INIT_LIST_HEAD(&a->list); - - attachment->priv = a; - - mutex_lock(&buffer->lock); - list_add(&a->list, &buffer->attachments); - mutex_unlock(&buffer->lock); - - return 0; -} - -static void dma_heap_detach(struct dma_buf *dmabuf, - struct dma_buf_attachment *attachment) -{ - struct dma_heaps_attachment *a = attachment->priv; - struct heap_helper_buffer *buffer = dmabuf->priv; - - mutex_lock(&buffer->lock); - list_del(&a->list); - mutex_unlock(&buffer->lock); - - sg_free_table(&a->table); - kfree(a); -} - -static -struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment, - enum dma_data_direction direction) -{ - struct dma_heaps_attachment *a = attachment->priv; - struct sg_table *table; - - table = &a->table; - - if (!dma_map_sg(attachment->dev, table->sgl, table->nents, - direction)) - table = ERR_PTR(-ENOMEM); - return table; -} - -static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, - struct sg_table *table, - enum dma_data_direction direction) -{ - dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction); -} - -static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf) -{ - struct vm_area_struct *vma = vmf->vma; - struct heap_helper_buffer *buffer = vma->vm_private_data; - - if (vmf->pgoff > buffer->pagecount) - return VM_FAULT_SIGBUS; - - vmf->page = buffer->pages[vmf->pgoff]; - get_page(vmf->page); - - return 0; -} - -static const struct vm_operations_struct dma_heap_vm_ops = { - .fault = dma_heap_vm_fault, -}; - -static int dma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - - if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) - return -EINVAL; - - vma->vm_ops = &dma_heap_vm_ops; - vma->vm_private_data = buffer; - - return 0; -} - -static void dma_heap_dma_buf_release(struct dma_buf *dmabuf) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - - dma_heap_buffer_destroy(buffer); -} - -static int dma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, - enum dma_data_direction direction) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - struct dma_heaps_attachment *a; - int ret = 0; - - mutex_lock(&buffer->lock); - - if (buffer->vmap_cnt) - invalidate_kernel_vmap_range(buffer->vaddr, buffer->size); - - list_for_each_entry(a, &buffer->attachments, list) { - dma_sync_sg_for_cpu(a->dev, a->table.sgl, a->table.nents, - direction); - } - mutex_unlock(&buffer->lock); - - return ret; -} - -static int dma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, - enum dma_data_direction direction) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - struct dma_heaps_attachment *a; - - mutex_lock(&buffer->lock); - - if (buffer->vmap_cnt) - flush_kernel_vmap_range(buffer->vaddr, buffer->size); - - list_for_each_entry(a, &buffer->attachments, list) { - dma_sync_sg_for_device(a->dev, a->table.sgl, a->table.nents, - direction); - } - mutex_unlock(&buffer->lock); - - return 0; -} - -static void *dma_heap_dma_buf_vmap(struct dma_buf *dmabuf) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - void *vaddr; - - mutex_lock(&buffer->lock); - vaddr = dma_heap_buffer_vmap_get(buffer); - mutex_unlock(&buffer->lock); - - return vaddr; -} - -static void dma_heap_dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) -{ - struct heap_helper_buffer *buffer = dmabuf->priv; - - mutex_lock(&buffer->lock); - dma_heap_buffer_vmap_put(buffer); - mutex_unlock(&buffer->lock); -} - -const struct dma_buf_ops heap_helper_ops = { - .map_dma_buf = dma_heap_map_dma_buf, - .unmap_dma_buf = dma_heap_unmap_dma_buf, - .mmap = dma_heap_mmap, - .release = dma_heap_dma_buf_release, - .attach = dma_heap_attach, - .detach = dma_heap_detach, - .begin_cpu_access = dma_heap_dma_buf_begin_cpu_access, - .end_cpu_access = dma_heap_dma_buf_end_cpu_access, - .vmap = dma_heap_dma_buf_vmap, - .vunmap = dma_heap_dma_buf_vunmap, -}; diff --git a/drivers/dma-buf/heaps/heap-helpers.h b/drivers/dma-buf/heaps/heap-helpers.h deleted file mode 100644 index 805d2df88024..000000000000 --- a/drivers/dma-buf/heaps/heap-helpers.h +++ /dev/null @@ -1,53 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * DMABUF Heaps helper code - * - * Copyright (C) 2011 Google, Inc. - * Copyright (C) 2019 Linaro Ltd. - */ - -#ifndef _HEAP_HELPERS_H -#define _HEAP_HELPERS_H - -#include <linux/dma-heap.h> -#include <linux/list.h> - -/** - * struct heap_helper_buffer - helper buffer metadata - * @heap: back pointer to the heap the buffer came from - * @dmabuf: backing dma-buf for this buffer - * @size: size of the buffer - * @priv_virt pointer to heap specific private value - * @lock mutext to protect the data in this structure - * @vmap_cnt count of vmap references on the buffer - * @vaddr vmap'ed virtual address - * @pagecount number of pages in the buffer - * @pages list of page pointers - * @attachments list of device attachments - * - * @free heap callback to free the buffer - */ -struct heap_helper_buffer { - struct dma_heap *heap; - struct dma_buf *dmabuf; - size_t size; - - void *priv_virt; - struct mutex lock; - int vmap_cnt; - void *vaddr; - pgoff_t pagecount; - struct page **pages; - struct list_head attachments; - - void (*free)(struct heap_helper_buffer *buffer); -}; - -void init_heap_helper_buffer(struct heap_helper_buffer *buffer, - void (*free)(struct heap_helper_buffer *)); - -struct dma_buf *heap_helper_export_dmabuf(struct heap_helper_buffer *buffer, - int fd_flags); - -extern const struct dma_buf_ops heap_helper_ops; -#endif /* _HEAP_HELPERS_H */
This patch is basically a port of Ørjan Eide's similar patch for ION https://lore.kernel.org/lkml/20200414134629.54567-1-orjan.eide@arm.com/
Only sync the sg-list of dma-buf heap attachment when the attachment is actually mapped on the device.
dma-bufs may be synced at any time. It can be reached from user space via DMA_BUF_IOCTL_SYNC, so there are no guarantees from callers on when syncs may be attempted, and dma_buf_end_cpu_access() and dma_buf_begin_cpu_access() may not be paired.
Since the sg_list's dma_address isn't set up until the buffer is used on the device, and dma_map_sg() is called on it, the dma_address will be NULL if sync is attempted on the dma-buf before it's mapped on a device.
Before v5.0 (commit 55897af63091 ("dma-direct: merge swiotlb_dma_ops into the dma_direct code")) this was a problem as the dma-api (at least the swiotlb_dma_ops on arm64) would use the potentially invalid dma_address. How that failed depended on how the device handled physical address 0. If 0 was a valid address to physical ram, that page would get flushed a lot, while the actual pages in the buffer would not get synced correctly. While if 0 is an invalid physical address it may cause a fault and trigger a crash.
In v5.0 this was incidentally fixed by commit 55897af63091 ("dma-direct: merge swiotlb_dma_ops into the dma_direct code"), as this moved the dma-api to use the page pointer in the sg_list, and (for Ion buffers at least) this will always be valid if the sg_list exists at all.
But, this issue is re-introduced in v5.3 with commit 449fa54d6815 ("dma-direct: correct the physical addr in dma_direct_sync_sg_for_cpu/device") moves the dma-api back to the old behaviour and picks the dma_address that may be invalid.
dma-buf core doesn't ensure that the buffer is mapped on the device, and thus have a valid sg_list, before calling the exporter's begin_cpu_access.
Logic and commit message originally by: Ørjan Eide orjan.eide@arm.com
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- drivers/dma-buf/heaps/cma_heap.c | 10 ++++++++++ drivers/dma-buf/heaps/system_heap.c | 10 ++++++++++ 2 files changed, 20 insertions(+)
diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index 366963b94c72..fece9d7739ae 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -44,6 +44,7 @@ struct dma_heap_attachment { struct device *dev; struct sg_table table; struct list_head list; + bool mapped; };
static int cma_heap_attach(struct dma_buf *dmabuf, @@ -68,6 +69,7 @@ static int cma_heap_attach(struct dma_buf *dmabuf,
a->dev = attachment->dev; INIT_LIST_HEAD(&a->list); + a->mapped = false;
attachment->priv = a;
@@ -102,6 +104,7 @@ static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachme ret = dma_map_sgtable(attachment->dev, table, direction, 0); if (ret) return ERR_PTR(-ENOMEM); + a->mapped = true; return table; }
@@ -109,6 +112,9 @@ static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table, enum dma_data_direction direction) { + struct dma_heap_attachment *a = attachment->priv; + + a->mapped = false; dma_unmap_sgtable(attachment->dev, table, direction, 0); }
@@ -123,6 +129,8 @@ static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
mutex_lock(&buffer->lock); list_for_each_entry(a, &buffer->attachments, list) { + if (!a->mapped) + continue; dma_sync_sgtable_for_cpu(a->dev, &a->table, direction); } mutex_unlock(&buffer->lock); @@ -141,6 +149,8 @@ static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
mutex_lock(&buffer->lock); list_for_each_entry(a, &buffer->attachments, list) { + if (!a->mapped) + continue; dma_sync_sgtable_for_device(a->dev, &a->table, direction); } mutex_unlock(&buffer->lock); diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 00ed107b3b76..ef8d47e5a7ff 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -37,6 +37,7 @@ struct dma_heap_attachment { struct device *dev; struct sg_table *table; struct list_head list; + bool mapped; };
static struct sg_table *dup_sg_table(struct sg_table *table) @@ -84,6 +85,7 @@ static int system_heap_attach(struct dma_buf *dmabuf, a->table = table; a->dev = attachment->dev; INIT_LIST_HEAD(&a->list); + a->mapped = false;
attachment->priv = a;
@@ -120,6 +122,7 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac if (ret) return ERR_PTR(ret);
+ a->mapped = true; return table; }
@@ -127,6 +130,9 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table, enum dma_data_direction direction) { + struct dma_heap_attachment *a = attachment->priv; + + a->mapped = false; dma_unmap_sgtable(attachment->dev, table, direction, 0); }
@@ -142,6 +148,8 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
list_for_each_entry(a, &buffer->attachments, list) { + if (!a->mapped) + continue; dma_sync_sgtable_for_cpu(a->dev, a->table, direction); } mutex_unlock(&buffer->lock); @@ -161,6 +169,8 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, flush_kernel_vmap_range(buffer->vaddr, buffer->len);
list_for_each_entry(a, &buffer->attachments, list) { + if (!a->mapped) + continue; dma_sync_sgtable_for_device(a->dev, a->table, direction); } mutex_unlock(&buffer->lock);
While the system heap can return non-contiguous pages, try to allocate larger order pages if possible.
This will allow slight performance gains and make implementing page pooling easier.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- v3: * Use page_size() rather then opencoding it --- drivers/dma-buf/heaps/system_heap.c | 83 ++++++++++++++++++++++------- 1 file changed, 65 insertions(+), 18 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index ef8d47e5a7ff..2b8d4b6abacb 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -40,6 +40,14 @@ struct dma_heap_attachment { bool mapped; };
+#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \ + | __GFP_NORETRY) & ~__GFP_RECLAIM) \ + | __GFP_COMP) +#define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO | __GFP_COMP) +static gfp_t order_flags[] = {HIGH_ORDER_GFP, LOW_ORDER_GFP, LOW_ORDER_GFP}; +static const unsigned int orders[] = {8, 4, 0}; +#define NUM_ORDERS ARRAY_SIZE(orders) + static struct sg_table *dup_sg_table(struct sg_table *table) { struct sg_table *new_table; @@ -270,8 +278,11 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) int i;
table = &buffer->sg_table; - for_each_sgtable_sg(table, sg, i) - __free_page(sg_page(sg)); + for_each_sg(table->sgl, sg, table->nents, i) { + struct page *page = sg_page(sg); + + __free_pages(page, compound_order(page)); + } sg_free_table(table); kfree(buffer); } @@ -289,6 +300,26 @@ static const struct dma_buf_ops system_heap_buf_ops = { .release = system_heap_dma_buf_release, };
+static struct page *alloc_largest_available(unsigned long size, + unsigned int max_order) +{ + struct page *page; + int i; + + for (i = 0; i < NUM_ORDERS; i++) { + if (size < (PAGE_SIZE << orders[i])) + continue; + if (max_order < orders[i]) + continue; + + page = alloc_pages(order_flags[i], orders[i]); + if (!page) + continue; + return page; + } + return NULL; +} + static int system_heap_allocate(struct dma_heap *heap, unsigned long len, unsigned long fd_flags, @@ -296,11 +327,13 @@ static int system_heap_allocate(struct dma_heap *heap, { struct system_heap_buffer *buffer; DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + unsigned long size_remaining = len; + unsigned int max_order = orders[0]; struct dma_buf *dmabuf; struct sg_table *table; struct scatterlist *sg; - pgoff_t pagecount; - pgoff_t pg; + struct list_head pages; + struct page *page, *tmp_page; int i, ret = -ENOMEM;
buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); @@ -312,25 +345,35 @@ static int system_heap_allocate(struct dma_heap *heap, buffer->heap = heap; buffer->len = len;
- table = &buffer->sg_table; - pagecount = len / PAGE_SIZE; - if (sg_alloc_table(table, pagecount, GFP_KERNEL)) - goto free_buffer; - - sg = table->sgl; - for (pg = 0; pg < pagecount; pg++) { - struct page *page; + INIT_LIST_HEAD(&pages); + i = 0; + while (size_remaining > 0) { /* * Avoid trying to allocate memory if the process * has been killed by SIGKILL */ if (fatal_signal_pending(current)) - goto free_pages; - page = alloc_page(GFP_KERNEL | __GFP_ZERO); + goto free_buffer; + + page = alloc_largest_available(size_remaining, max_order); if (!page) - goto free_pages; + goto free_buffer; + + list_add_tail(&page->lru, &pages); + size_remaining -= page_size(page); + max_order = compound_order(page); + i++; + } + + table = &buffer->sg_table; + if (sg_alloc_table(table, i, GFP_KERNEL)) + goto free_buffer; + + sg = table->sgl; + list_for_each_entry_safe(page, tmp_page, &pages, lru) { sg_set_page(sg, page, page_size(page), 0); sg = sg_next(sg); + list_del(&page->lru); }
/* create the dmabuf */ @@ -350,14 +393,18 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; } - return ret;
free_pages: - for_each_sgtable_sg(table, sg, i) - __free_page(sg_page(sg)); + for_each_sgtable_sg(table, sg, i) { + struct page *p = sg_page(sg); + + __free_pages(p, compound_order(p)); + } sg_free_table(table); free_buffer: + list_for_each_entry_safe(page, tmp_page, &pages, lru) + __free_pages(page, compound_order(page)); kfree(buffer);
return ret;
Keep track of the heap device struct.
This will be useful for special DMA allocations and actions.
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- drivers/dma-buf/dma-heap.c | 33 +++++++++++++++++++++++++-------- include/linux/dma-heap.h | 9 +++++++++ 2 files changed, 34 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index afd22c9dbdcf..72c746755d89 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -30,6 +30,7 @@ * @heap_devt heap device node * @list list head connecting to list of heaps * @heap_cdev heap char device + * @heap_dev heap device struct * * Represents a heap of memory from which buffers can be made. */ @@ -40,6 +41,7 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; + struct device *heap_dev; };
static LIST_HEAD(heap_list); @@ -190,10 +192,21 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) return heap->priv; }
+/** + * dma_heap_get_dev() - get device struct for the heap + * @heap: DMA-Heap to retrieve device struct from + * + * Returns: + * The device struct for the heap. + */ +struct device *dma_heap_get_dev(struct dma_heap *heap) +{ + return heap->heap_dev; +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; - struct device *dev_ret; unsigned int minor; int ret;
@@ -247,16 +260,20 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) goto err1; }
- dev_ret = device_create(dma_heap_class, - NULL, - heap->heap_devt, - NULL, - heap->name); - if (IS_ERR(dev_ret)) { + heap->heap_dev = device_create(dma_heap_class, + NULL, + heap->heap_devt, + NULL, + heap->name); + if (IS_ERR(heap->heap_dev)) { pr_err("dma_heap: Unable to create device\n"); - err_ret = ERR_CAST(dev_ret); + err_ret = ERR_CAST(heap->heap_dev); goto err2; } + + /* Make sure it doesn't disappear on us */ + heap->heap_dev = get_device(heap->heap_dev); + /* Add heap to the list */ mutex_lock(&heap_list_lock); list_add(&heap->list, &heap_list); diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 454e354d1ffb..82857e096910 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -50,6 +50,15 @@ struct dma_heap_export_info { */ void *dma_heap_get_drvdata(struct dma_heap *heap);
+/** + * dma_heap_get_dev() - get device struct for the heap + * @heap: DMA-Heap to retrieve device struct from + * + * Returns: + * The device struct for the heap. + */ +struct device *dma_heap_get_dev(struct dma_heap *heap); + /** * dma_heap_add - adds a heap to dmabuf heaps * @exp_info: information needed to register this heap
This adds a heap that allocates non-contiguous buffers that are marked as writecombined, so they are not cached by the CPU.
This is useful, as most graphics buffers are usually not touched by the CPU or only written into once by the CPU. So when mapping the buffer over and over between devices, we can skip the CPU syncing, which saves a lot of cache management overhead, greatly improving performance.
For folk using ION, there was a ION_FLAG_CACHED flag, which signaled if the returned buffer should be CPU cacheable or not. With DMA-BUF heaps, we do not yet have such a flag, and by default the current heaps (system and cma) produce CPU cachable buffers. So for folks transitioning from ION to DMA-BUF Heaps, this fills in some of that missing functionality.
There has been a suggestion to make this functionality a flag (DMAHEAP_FLAG_UNCACHED?) on the system heap, similar to how ION used the ION_FLAG_CACHED. But I want to make sure an _UNCACHED flag would truely be a generic attribute across all heaps. So far that has been unclear, so having it as a separate heap seemes better for now. (But I'm open to discussion on this point!)
This is a rework of earlier efforts to add a uncached system heap, done utilizing the exisitng system heap, adding just a bit of logic to handle the uncached case.
Feedback would be very welcome!
Many thanks to Liam Mark for his help to get this working.
Pending opensource users of this code include: * AOSP HiKey960 gralloc: - https://android-review.googlesource.com/c/device/linaro/hikey/+/1399519 - Visibly improves performance over the system heap * AOSP Codec2 (possibly, needs more review): - https://android-review.googlesource.com/c/platform/frameworks/av/+/1360640/1...
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org --- drivers/dma-buf/heaps/system_heap.c | 87 ++++++++++++++++++++++++++--- 1 file changed, 79 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 2b8d4b6abacb..952f1fd9dacf 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -22,6 +22,7 @@ #include <linux/vmalloc.h>
struct dma_heap *sys_heap; +struct dma_heap *sys_uncached_heap;
struct system_heap_buffer { struct dma_heap *heap; @@ -31,6 +32,8 @@ struct system_heap_buffer { struct sg_table sg_table; int vmap_cnt; void *vaddr; + + bool uncached; };
struct dma_heap_attachment { @@ -38,6 +41,8 @@ struct dma_heap_attachment { struct sg_table *table; struct list_head list; bool mapped; + + bool uncached; };
#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \ @@ -94,7 +99,7 @@ static int system_heap_attach(struct dma_buf *dmabuf, a->dev = attachment->dev; INIT_LIST_HEAD(&a->list); a->mapped = false; - + a->uncached = buffer->uncached; attachment->priv = a;
mutex_lock(&buffer->lock); @@ -124,9 +129,13 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac { struct dma_heap_attachment *a = attachment->priv; struct sg_table *table = a->table; + int attr = 0; int ret;
- ret = dma_map_sgtable(attachment->dev, table, direction, 0); + if (a->uncached) + attr = DMA_ATTR_SKIP_CPU_SYNC; + + ret = dma_map_sgtable(attachment->dev, table, direction, attr); if (ret) return ERR_PTR(ret);
@@ -139,9 +148,12 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction) { struct dma_heap_attachment *a = attachment->priv; + int attr = 0;
+ if (a->uncached) + attr = DMA_ATTR_SKIP_CPU_SYNC; a->mapped = false; - dma_unmap_sgtable(attachment->dev, table, direction, 0); + dma_unmap_sgtable(attachment->dev, table, direction, attr); }
static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, @@ -150,6 +162,9 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, struct system_heap_buffer *buffer = dmabuf->priv; struct dma_heap_attachment *a;
+ if (buffer->uncached) + return 0; + mutex_lock(&buffer->lock);
if (buffer->vmap_cnt) @@ -171,6 +186,9 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, struct system_heap_buffer *buffer = dmabuf->priv; struct dma_heap_attachment *a;
+ if (buffer->uncached) + return 0; + mutex_lock(&buffer->lock);
if (buffer->vmap_cnt) @@ -194,6 +212,9 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) struct sg_page_iter piter; int ret;
+ if (buffer->uncached) + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); + for_each_sgtable_page(table, &piter, vma->vm_pgoff) { struct page *page = sg_page_iter_page(&piter);
@@ -215,8 +236,12 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) struct page **pages = vmalloc(sizeof(struct page *) * npages); struct page **tmp = pages; struct sg_page_iter piter; + pgprot_t pgprot = PAGE_KERNEL; void *vaddr;
+ if (buffer->uncached) + pgprot = pgprot_writecombine(PAGE_KERNEL); + if (!pages) return ERR_PTR(-ENOMEM);
@@ -225,7 +250,7 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) *tmp++ = sg_page_iter_page(&piter); }
- vaddr = vmap(pages, npages, VM_MAP, PAGE_KERNEL); + vaddr = vmap(pages, npages, VM_MAP, pgprot); vfree(pages);
if (!vaddr) @@ -278,6 +303,10 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) int i;
table = &buffer->sg_table; + /* Unmap the uncached buffers from the heap device (pairs with the map on allocate) */ + if (buffer->uncached) + dma_unmap_sgtable(dma_heap_get_dev(buffer->heap), table, DMA_BIDIRECTIONAL, 0); + for_each_sg(table->sgl, sg, table->nents, i) { struct page *page = sg_page(sg);
@@ -320,10 +349,11 @@ static struct page *alloc_largest_available(unsigned long size, return NULL; }
-static int system_heap_allocate(struct dma_heap *heap, - unsigned long len, - unsigned long fd_flags, - unsigned long heap_flags) +static int system_heap_do_allocate(struct dma_heap *heap, + unsigned long len, + unsigned long fd_flags, + unsigned long heap_flags, + bool uncached) { struct system_heap_buffer *buffer; DEFINE_DMA_BUF_EXPORT_INFO(exp_info); @@ -344,6 +374,7 @@ static int system_heap_allocate(struct dma_heap *heap, mutex_init(&buffer->lock); buffer->heap = heap; buffer->len = len; + buffer->uncached = uncached;
INIT_LIST_HEAD(&pages); i = 0; @@ -393,6 +424,16 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; } + + /* + * For uncached buffers, we need to initially flush cpu cache, since + * the __GFP_ZERO on the allocation means the zeroing was done by the + * cpu and thus it is likely cached. Map (and implicitly flush) it out + * now so we don't get corruption later on. + */ + if (buffer->uncached) + dma_map_sgtable(dma_heap_get_dev(heap), table, DMA_BIDIRECTIONAL, 0); + return ret;
free_pages: @@ -410,10 +451,30 @@ static int system_heap_allocate(struct dma_heap *heap, return ret; }
+static int system_heap_allocate(struct dma_heap *heap, + unsigned long len, + unsigned long fd_flags, + unsigned long heap_flags) +{ + return system_heap_do_allocate(heap, len, fd_flags, heap_flags, false); +} + static const struct dma_heap_ops system_heap_ops = { .allocate = system_heap_allocate, };
+static int system_uncached_heap_allocate(struct dma_heap *heap, + unsigned long len, + unsigned long fd_flags, + unsigned long heap_flags) +{ + return system_heap_do_allocate(heap, len, fd_flags, heap_flags, true); +} + +static const struct dma_heap_ops system_uncached_heap_ops = { + .allocate = system_uncached_heap_allocate, +}; + static int system_heap_create(void) { struct dma_heap_export_info exp_info; @@ -426,6 +487,16 @@ static int system_heap_create(void) if (IS_ERR(sys_heap)) return PTR_ERR(sys_heap);
+ exp_info.name = "system-uncached"; + exp_info.ops = &system_uncached_heap_ops; + exp_info.priv = NULL; + + sys_uncached_heap = dma_heap_add(&exp_info); + if (IS_ERR(sys_uncached_heap)) + return PTR_ERR(sys_heap); + + dma_coerce_mask_and_coherent(dma_heap_get_dev(sys_uncached_heap), DMA_BIT_MASK(64)); + return 0; } module_init(system_heap_create);
On Sat, Oct 03, 2020 at 04:02:57AM +0000, John Stultz wrote:
This adds a heap that allocates non-contiguous buffers that are marked as writecombined, so they are not cached by the CPU.
This is useful, as most graphics buffers are usually not touched by the CPU or only written into once by the CPU. So when mapping the buffer over and over between devices, we can skip the CPU syncing, which saves a lot of cache management overhead, greatly improving performance.
For folk using ION, there was a ION_FLAG_CACHED flag, which signaled if the returned buffer should be CPU cacheable or not. With DMA-BUF heaps, we do not yet have such a flag, and by default the current heaps (system and cma) produce CPU cachable buffers. So for folks transitioning from ION to DMA-BUF Heaps, this fills in some of that missing functionality.
There has been a suggestion to make this functionality a flag (DMAHEAP_FLAG_UNCACHED?) on the system heap, similar to how ION used the ION_FLAG_CACHED. But I want to make sure an _UNCACHED flag would truely be a generic attribute across all heaps. So far that has been unclear, so having it as a separate heap seemes better for now. (But I'm open to discussion on this point!)
This is a rework of earlier efforts to add a uncached system heap, done utilizing the exisitng system heap, adding just a bit of logic to handle the uncached case.
Feedback would be very welcome!
Many thanks to Liam Mark for his help to get this working.
Pending opensource users of this code include:
- AOSP HiKey960 gralloc:
- https://android-review.googlesource.com/c/device/linaro/hikey/+/1399519
- Visibly improves performance over the system heap
- AOSP Codec2 (possibly, needs more review):
Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: �rjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz john.stultz@linaro.org
drivers/dma-buf/heaps/system_heap.c | 87 ++++++++++++++++++++++++++--- 1 file changed, 79 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 2b8d4b6abacb..952f1fd9dacf 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -22,6 +22,7 @@ #include <linux/vmalloc.h>
struct dma_heap *sys_heap; +struct dma_heap *sys_uncached_heap;
struct system_heap_buffer { struct dma_heap *heap; @@ -31,6 +32,8 @@ struct system_heap_buffer { struct sg_table sg_table; int vmap_cnt; void *vaddr;
- bool uncached;
};
struct dma_heap_attachment { @@ -38,6 +41,8 @@ struct dma_heap_attachment { struct sg_table *table; struct list_head list; bool mapped;
- bool uncached;
};
#define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \ @@ -94,7 +99,7 @@ static int system_heap_attach(struct dma_buf *dmabuf, a->dev = attachment->dev; INIT_LIST_HEAD(&a->list); a->mapped = false;
a->uncached = buffer->uncached; attachment->priv = a;
mutex_lock(&buffer->lock);
@@ -124,9 +129,13 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac { struct dma_heap_attachment *a = attachment->priv; struct sg_table *table = a->table;
- int attr = 0; int ret;
- ret = dma_map_sgtable(attachment->dev, table, direction, 0);
- if (a->uncached)
attr = DMA_ATTR_SKIP_CPU_SYNC;- ret = dma_map_sgtable(attachment->dev, table, direction, attr); if (ret) return ERR_PTR(ret);
@@ -139,9 +148,12 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction) { struct dma_heap_attachment *a = attachment->priv;
int attr = 0;
if (a->uncached)
attr = DMA_ATTR_SKIP_CPU_SYNC;a->mapped = false;
- dma_unmap_sgtable(attachment->dev, table, direction, 0);
- dma_unmap_sgtable(attachment->dev, table, direction, attr);
}
static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, @@ -150,6 +162,9 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, struct system_heap_buffer *buffer = dmabuf->priv; struct dma_heap_attachment *a;
if (buffer->uncached)
return 0;mutex_lock(&buffer->lock);
if (buffer->vmap_cnt)
@@ -171,6 +186,9 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, struct system_heap_buffer *buffer = dmabuf->priv; struct dma_heap_attachment *a;
if (buffer->uncached)
return 0;mutex_lock(&buffer->lock);
if (buffer->vmap_cnt)
@@ -194,6 +212,9 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) struct sg_page_iter piter; int ret;
- if (buffer->uncached)
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);- for_each_sgtable_page(table, &piter, vma->vm_pgoff) { struct page *page = sg_page_iter_page(&piter);
@@ -215,8 +236,12 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) struct page **pages = vmalloc(sizeof(struct page *) * npages); struct page **tmp = pages; struct sg_page_iter piter;
pgprot_t pgprot = PAGE_KERNEL; void *vaddr;
if (buffer->uncached)
pgprot = pgprot_writecombine(PAGE_KERNEL);
I think this should go after the 'if (!pages)' check. Best to get the allocation failure check as close to the allocation as possible IMO.
- if (!pages) return ERR_PTR(-ENOMEM);
@@ -225,7 +250,7 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) *tmp++ = sg_page_iter_page(&piter); }
- vaddr = vmap(pages, npages, VM_MAP, PAGE_KERNEL);
vaddr = vmap(pages, npages, VM_MAP, pgprot); vfree(pages);
if (!vaddr)
@@ -278,6 +303,10 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) int i;
table = &buffer->sg_table;
- /* Unmap the uncached buffers from the heap device (pairs with the map on allocate) */
- if (buffer->uncached)
dma_unmap_sgtable(dma_heap_get_dev(buffer->heap), table, DMA_BIDIRECTIONAL, 0);- for_each_sg(table->sgl, sg, table->nents, i) { struct page *page = sg_page(sg);
@@ -320,10 +349,11 @@ static struct page *alloc_largest_available(unsigned long size, return NULL; }
-static int system_heap_allocate(struct dma_heap *heap,
unsigned long len,unsigned long fd_flags,unsigned long heap_flags)+static int system_heap_do_allocate(struct dma_heap *heap,
unsigned long len,unsigned long fd_flags,unsigned long heap_flags,bool uncached){ struct system_heap_buffer *buffer; DEFINE_DMA_BUF_EXPORT_INFO(exp_info); @@ -344,6 +374,7 @@ static int system_heap_allocate(struct dma_heap *heap, mutex_init(&buffer->lock); buffer->heap = heap; buffer->len = len;
buffer->uncached = uncached;
INIT_LIST_HEAD(&pages); i = 0;
@@ -393,6 +424,16 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; }
- /*
* For uncached buffers, we need to initially flush cpu cache, since* the __GFP_ZERO on the allocation means the zeroing was done by the* cpu and thus it is likely cached. Map (and implicitly flush) it out* now so we don't get corruption later on.*/- if (buffer->uncached)
dma_map_sgtable(dma_heap_get_dev(heap), table, DMA_BIDIRECTIONAL, 0);
Do we have to keep this mapping around for the entire lifetime of the buffer?
Also, this problem (and solution) keeps lingering around. It really feels like there should be a better way to solve "clean the linear mapping all the way to DRAM", but I don't know what that should be.
- return ret;
free_pages: @@ -410,10 +451,30 @@ static int system_heap_allocate(struct dma_heap *heap, return ret; }
+static int system_heap_allocate(struct dma_heap *heap,
unsigned long len,unsigned long fd_flags,unsigned long heap_flags)+{
- return system_heap_do_allocate(heap, len, fd_flags, heap_flags, false);
+}
static const struct dma_heap_ops system_heap_ops = { .allocate = system_heap_allocate, };
+static int system_uncached_heap_allocate(struct dma_heap *heap,
unsigned long len,unsigned long fd_flags,unsigned long heap_flags)+{
- return system_heap_do_allocate(heap, len, fd_flags, heap_flags, true);
+}
+static const struct dma_heap_ops system_uncached_heap_ops = {
- .allocate = system_uncached_heap_allocate,
+};
static int system_heap_create(void) { struct dma_heap_export_info exp_info; @@ -426,6 +487,16 @@ static int system_heap_create(void) if (IS_ERR(sys_heap)) return PTR_ERR(sys_heap);
- exp_info.name = "system-uncached";
- exp_info.ops = &system_uncached_heap_ops;
- exp_info.priv = NULL;
- sys_uncached_heap = dma_heap_add(&exp_info);
- if (IS_ERR(sys_uncached_heap))
return PTR_ERR(sys_heap);
In principle, there's a race here between the heap getting registered to sysfs and the dma_mask getting updated.
I don't think it would cause a problem in practice, but with the API as it is, there's no way to avoid it - so I wonder if the dma_heap_get_dev() accessor isn't the right API design.
Cheers, -Brian
- dma_coerce_mask_and_coherent(dma_heap_get_dev(sys_uncached_heap), DMA_BIT_MASK(64));
- return 0;
} module_init(system_heap_create); -- 2.17.1
On Thu, Oct 8, 2020 at 4:51 AM Brian Starkey brian.starkey@arm.com wrote:
On Sat, Oct 03, 2020 at 04:02:57AM +0000, John Stultz wrote:
@@ -215,8 +236,12 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) struct page **pages = vmalloc(sizeof(struct page *) * npages); struct page **tmp = pages; struct sg_page_iter piter;
pgprot_t pgprot = PAGE_KERNEL; void *vaddr;if (buffer->uncached)pgprot = pgprot_writecombine(PAGE_KERNEL);I think this should go after the 'if (!pages)' check. Best to get the allocation failure check as close to the allocation as possible IMO.
Sounds good. Changed in my tree.
@@ -393,6 +424,16 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; }
/** For uncached buffers, we need to initially flush cpu cache, since* the __GFP_ZERO on the allocation means the zeroing was done by the* cpu and thus it is likely cached. Map (and implicitly flush) it out* now so we don't get corruption later on.*/if (buffer->uncached)dma_map_sgtable(dma_heap_get_dev(heap), table, DMA_BIDIRECTIONAL, 0);Do we have to keep this mapping around for the entire lifetime of the buffer?
Yea, I guess we can just map and unmap it right there. It will look a little absurd, but that sort of aligns with your next point.
Also, this problem (and solution) keeps lingering around. It really feels like there should be a better way to solve "clean the linear mapping all the way to DRAM", but I don't know what that should be.
Yea, something better here would be nice...
@@ -426,6 +487,16 @@ static int system_heap_create(void) if (IS_ERR(sys_heap)) return PTR_ERR(sys_heap);
exp_info.name = "system-uncached";exp_info.ops = &system_uncached_heap_ops;exp_info.priv = NULL;sys_uncached_heap = dma_heap_add(&exp_info);if (IS_ERR(sys_uncached_heap))return PTR_ERR(sys_heap);In principle, there's a race here between the heap getting registered to sysfs and the dma_mask getting updated.
I don't think it would cause a problem in practice, but with the API as it is, there's no way to avoid it - so I wonder if the dma_heap_get_dev() accessor isn't the right API design.
Hrm. I guess to address your concern we would need split dma_heap_add() into something like: dma_heap_create() dma_heap_add()
Which breaks the creation of the heap with the registering it to the subsystem, so some attributes can be tweaked inbetween?
I'll see about taking a stab at this, but I'll probably submit my updated series sooner with this un-addressed so I can get some further review.
thanks -john
On Fri, Oct 16, 2020 at 12:03 PM John Stultz john.stultz@linaro.org wrote:
On Thu, Oct 8, 2020 at 4:51 AM Brian Starkey brian.starkey@arm.com wrote:
On Sat, Oct 03, 2020 at 04:02:57AM +0000, John Stultz wrote:
@@ -426,6 +487,16 @@ static int system_heap_create(void) if (IS_ERR(sys_heap)) return PTR_ERR(sys_heap);
exp_info.name = "system-uncached";exp_info.ops = &system_uncached_heap_ops;exp_info.priv = NULL;sys_uncached_heap = dma_heap_add(&exp_info);if (IS_ERR(sys_uncached_heap))return PTR_ERR(sys_heap);In principle, there's a race here between the heap getting registered to sysfs and the dma_mask getting updated.
I don't think it would cause a problem in practice, but with the API as it is, there's no way to avoid it - so I wonder if the dma_heap_get_dev() accessor isn't the right API design.
Hrm. I guess to address your concern we would need split dma_heap_add() into something like: dma_heap_create() dma_heap_add()
Which breaks the creation of the heap with the registering it to the subsystem, so some attributes can be tweaked inbetween?
Looking at this some more, this approach isn't going to work. We create the device and then we call dma_coerce_mask_and_coherent() on it, but as soon as the device is created it seems possible for userland to directly access it. Again, though, as you mentioned this isn't terribly likely in practice.
The best thing I can think of for now is to have the uncached heap's allocate pointer initially point to a dummy function that returns EBUSY and then after we update the dma mask then we can set it to the real alloc. I'll go with that for now, but let me know if you have other suggestions.
thanks -john
On Fri, Oct 16, 2020 at 12:04 PM John Stultz john.stultz@linaro.org wrote:
On Thu, Oct 8, 2020 at 4:51 AM Brian Starkey brian.starkey@arm.com wrote:
On Sat, Oct 03, 2020 at 04:02:57AM +0000, John Stultz wrote:
@@ -393,6 +424,16 @@ static int system_heap_allocate(struct dma_heap *heap, /* just return, as put will call release and that will free */ return ret; }
/** For uncached buffers, we need to initially flush cpu cache, since* the __GFP_ZERO on the allocation means the zeroing was done by the* cpu and thus it is likely cached. Map (and implicitly flush) it out* now so we don't get corruption later on.*/if (buffer->uncached)dma_map_sgtable(dma_heap_get_dev(heap), table, DMA_BIDIRECTIONAL, 0);Do we have to keep this mapping around for the entire lifetime of the buffer?
Yea, I guess we can just map and unmap it right there. It will look a little absurd, but that sort of aligns with your next point.
Also, this problem (and solution) keeps lingering around. It really feels like there should be a better way to solve "clean the linear mapping all the way to DRAM", but I don't know what that should be.
Yea, something better here would be nice...
In ION, we had a little helper function named ion_buffer_prep_noncached that called arch_dma_prep_coherent() on all sg entries like so
for_each_sg(table->sgl, sg, table->orig_nents, i) arch_dma_prep_coherent(sg_page(sg), sg->length);
Would that help?
Hi John,
On Sat, Oct 03, 2020 at 04:02:50AM +0000, John Stultz wrote:
Hey All,
...
I did add to this series a reworked version of my uncached system heap implementation I was submitting a few weeks back. Since it duplicated a lot of the now reworked system heap code, I realized it would be much simpler to add the functionality to the system_heap implementaiton itself.
That looks like a neat approach to me. Referencing your previous thread, I like the separate heap (as you have done), rather than a generic "cached"/"noncached" flag on all heaps.
While not improving the core allocation performance, the uncached heap allocations do result in *much* improved performance on HiKey960 as it avoids a lot of flushing and invalidating buffers that the cpu doesn't touch often.
Feedback on these would be great!
Minor nit: s/detatch/detach/ on both heaps, but other than that you can add my r-b to patches 1-5.
As you've said, it does feel like there's some room for de-duplication, but that will be easier to work out once the implementations settle.
I've a couple of comments for the uncached heap, but I'm not confident I understand the implications of having the non-cached alias enough to say if it looks OK or not.
Cheers! -Brian
On Thu, Oct 8, 2020 at 4:36 AM Brian Starkey brian.starkey@arm.com wrote:
Hi John,
On Sat, Oct 03, 2020 at 04:02:50AM +0000, John Stultz wrote:
Hey All,
...
I did add to this series a reworked version of my uncached system heap implementation I was submitting a few weeks back. Since it duplicated a lot of the now reworked system heap code, I realized it would be much simpler to add the functionality to the system_heap implementaiton itself.
That looks like a neat approach to me. Referencing your previous thread, I like the separate heap (as you have done), rather than a generic "cached"/"noncached" flag on all heaps.
Sounds good! I really appreciate the feedback on this.
While not improving the core allocation performance, the uncached heap allocations do result in *much* improved performance on HiKey960 as it avoids a lot of flushing and invalidating buffers that the cpu doesn't touch often.
Feedback on these would be great!
Minor nit: s/detatch/detach/ on both heaps, but other than that you can add my r-b to patches 1-5.
Doh! Thanks for the spelling catch! Thanks again!
As you've said, it does feel like there's some room for de-duplication, but that will be easier to work out once the implementations settle.
I've a couple of comments for the uncached heap, but I'm not confident I understand the implications of having the non-cached alias enough to say if it looks OK or not.
Thanks so much! -john
dri-devel@lists.freedesktop.org
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Brian Starkey -
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John Stultz