linux-4.4.1/__dma_clear_buffer()

参照元†

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説明†

パス: linux-4.4.1/arch/arm/mm/dma-mapping.c

FIXME: これは何？
- 説明

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引数†

struct page *page
- linux-4.4.1/page
size_t size

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返り値†

なし

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参考†

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実装†

static void __dma_clear_buffer(struct page *page, size_t size)
{
        /*
         * Ensure that the allocated pages are zeroed, and that any data
         * lurking in the kernel direct-mapped region is invalidated.
         */
        if (PageHighMem(page)) {

- linux-4.4.1/PageHighMem()

                phys_addr_t base = __pfn_to_phys(page_to_pfn(page));
                phys_addr_t end = base + size;

- linux-4.4.1/__pfn_to_phys()
- linux-4.4.1/page_to_pfn()

                while (size > 0) {
                        void *ptr = kmap_atomic(page);
                        memset(ptr, 0, PAGE_SIZE);
                        dmac_flush_range(ptr, ptr + PAGE_SIZE);
                        kunmap_atomic(ptr);

                        page++;
                        size -= PAGE_SIZE;
                }
                outer_flush_range(base, end);

- linux-4.4.1/outer_flush_range()

        } else {
                void *ptr = page_address(page);
                memset(ptr, 0, size);
                dmac_flush_range(ptr, ptr + size);
                outer_flush_range(__pa(ptr), __pa(ptr) + size);