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The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
179 lines
5.0 KiB
C
179 lines
5.0 KiB
C
/**************************************************************************
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*
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* Copyright (c) 2006-2007 Tungsten Graphics, Inc., Cedar Park, TX., USA
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
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* USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/*
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* Authors: Thomas Hellström <thomas-at-tungstengraphics-dot-com>
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*/
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#include <linux/export.h>
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#include <linux/highmem.h>
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#include <drm/drm_cache.h>
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#if defined(CONFIG_X86)
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#include <asm/smp.h>
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/*
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* clflushopt is an unordered instruction which needs fencing with mfence or
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* sfence to avoid ordering issues. For drm_clflush_page this fencing happens
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* in the caller.
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*/
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static void
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drm_clflush_page(struct page *page)
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{
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uint8_t *page_virtual;
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unsigned int i;
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const int size = boot_cpu_data.x86_clflush_size;
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if (unlikely(page == NULL))
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return;
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page_virtual = kmap_atomic(page);
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for (i = 0; i < PAGE_SIZE; i += size)
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clflushopt(page_virtual + i);
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kunmap_atomic(page_virtual);
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}
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static void drm_cache_flush_clflush(struct page *pages[],
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unsigned long num_pages)
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{
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unsigned long i;
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mb(); /*Full memory barrier used before so that CLFLUSH is ordered*/
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for (i = 0; i < num_pages; i++)
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drm_clflush_page(*pages++);
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mb(); /*Also used after CLFLUSH so that all cache is flushed*/
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}
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#endif
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/**
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* drm_clflush_pages - Flush dcache lines of a set of pages.
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* @pages: List of pages to be flushed.
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* @num_pages: Number of pages in the array.
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*
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* Flush every data cache line entry that points to an address belonging
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* to a page in the array.
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*/
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void
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drm_clflush_pages(struct page *pages[], unsigned long num_pages)
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{
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#if defined(CONFIG_X86)
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if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
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drm_cache_flush_clflush(pages, num_pages);
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return;
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}
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if (wbinvd_on_all_cpus())
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pr_err("Timed out waiting for cache flush\n");
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#elif defined(__powerpc__)
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unsigned long i;
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for (i = 0; i < num_pages; i++) {
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struct page *page = pages[i];
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void *page_virtual;
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if (unlikely(page == NULL))
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continue;
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page_virtual = kmap_atomic(page);
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flush_dcache_range((unsigned long)page_virtual,
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(unsigned long)page_virtual + PAGE_SIZE);
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kunmap_atomic(page_virtual);
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}
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#else
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pr_err("Architecture has no drm_cache.c support\n");
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WARN_ON_ONCE(1);
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#endif
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}
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EXPORT_SYMBOL(drm_clflush_pages);
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/**
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* drm_clflush_sg - Flush dcache lines pointing to a scather-gather.
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* @st: struct sg_table.
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*
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* Flush every data cache line entry that points to an address in the
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* sg.
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*/
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void
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drm_clflush_sg(struct sg_table *st)
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{
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#if defined(CONFIG_X86)
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if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
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struct sg_page_iter sg_iter;
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mb(); /*CLFLUSH is ordered only by using memory barriers*/
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for_each_sgtable_page(st, &sg_iter, 0)
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drm_clflush_page(sg_page_iter_page(&sg_iter));
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mb(); /*Make sure that all cache line entry is flushed*/
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return;
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}
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if (wbinvd_on_all_cpus())
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pr_err("Timed out waiting for cache flush\n");
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#else
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pr_err("Architecture has no drm_cache.c support\n");
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WARN_ON_ONCE(1);
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#endif
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}
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EXPORT_SYMBOL(drm_clflush_sg);
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/**
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* drm_clflush_virt_range - Flush dcache lines of a region
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* @addr: Initial kernel memory address.
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* @length: Region size.
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*
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* Flush every data cache line entry that points to an address in the
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* region requested.
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*/
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void
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drm_clflush_virt_range(void *addr, unsigned long length)
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{
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#if defined(CONFIG_X86)
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if (static_cpu_has(X86_FEATURE_CLFLUSH)) {
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const int size = boot_cpu_data.x86_clflush_size;
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void *end = addr + length;
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addr = (void *)(((unsigned long)addr) & -size);
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mb(); /*CLFLUSH is only ordered with a full memory barrier*/
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for (; addr < end; addr += size)
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clflushopt(addr);
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clflushopt(end - 1); /* force serialisation */
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mb(); /*Ensure that evry data cache line entry is flushed*/
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return;
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}
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if (wbinvd_on_all_cpus())
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pr_err("Timed out waiting for cache flush\n");
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#else
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pr_err("Architecture has no drm_cache.c support\n");
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WARN_ON_ONCE(1);
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#endif
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}
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EXPORT_SYMBOL(drm_clflush_virt_range);
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