dma-mapping: move all DMA mapping code to kernel/dma

Currently the code is split over various files with dma- prefixes in the
lib/ and drives/base directories, and the number of files keeps growing.
Move them into a single directory to keep the code together and remove
the file name prefixes.  To match the irq infrastructure this directory
is placed under the kernel/ directory.

Signed-off-by: Christoph Hellwig <hch@lst.de>

10 files changed, 4343 insertions, 0 deletions

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
new file mode 100644
index 000000000000..9bd54304446f
--- /dev/null
+++ b/kernel/dma/Kconfig
@@ -0,0 +1,50 @@
+
+config HAS_DMA
+	bool
+	depends on !NO_DMA
+	default y
+
+config NEED_SG_DMA_LENGTH
+	bool
+
+config NEED_DMA_MAP_STATE
+	bool
+
+config ARCH_DMA_ADDR_T_64BIT
+	def_bool 64BIT || PHYS_ADDR_T_64BIT
+
+config HAVE_GENERIC_DMA_COHERENT
+	bool
+
+config ARCH_HAS_SYNC_DMA_FOR_DEVICE
+	bool
+
+config ARCH_HAS_SYNC_DMA_FOR_CPU
+	bool
+	select NEED_DMA_MAP_STATE
+
+config DMA_DIRECT_OPS
+	bool
+	depends on HAS_DMA
+
+config DMA_NONCOHERENT_OPS
+	bool
+	depends on HAS_DMA
+	select DMA_DIRECT_OPS
+
+config DMA_NONCOHERENT_MMAP
+	bool
+	depends on DMA_NONCOHERENT_OPS
+
+config DMA_NONCOHERENT_CACHE_SYNC
+	bool
+	depends on DMA_NONCOHERENT_OPS
+
+config DMA_VIRT_OPS
+	bool
+	depends on HAS_DMA
+
+config SWIOTLB
+	bool
+	select DMA_DIRECT_OPS
+	select NEED_DMA_MAP_STATE
diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
new file mode 100644
index 000000000000..6de44e4eb454
--- /dev/null
+++ b/kernel/dma/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_HAS_DMA)			+= mapping.o
+obj-$(CONFIG_DMA_CMA)			+= contiguous.o
+obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += coherent.o
+obj-$(CONFIG_DMA_DIRECT_OPS)		+= direct.o
+obj-$(CONFIG_DMA_NONCOHERENT_OPS)	+= noncoherent.o
+obj-$(CONFIG_DMA_VIRT_OPS)		+= virt.o
+obj-$(CONFIG_DMA_API_DEBUG)		+= debug.o
+obj-$(CONFIG_SWIOTLB)			+= swiotlb.o
+
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
new file mode 100644
index 000000000000..597d40893862
--- /dev/null
+++ b/kernel/dma/coherent.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Coherent per-device memory handling.
+ * Borrowed from i386
+ */
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+
+struct dma_coherent_mem {
+	void		*virt_base;
+	dma_addr_t	device_base;
+	unsigned long	pfn_base;
+	int		size;
+	int		flags;
+	unsigned long	*bitmap;
+	spinlock_t	spinlock;
+	bool		use_dev_dma_pfn_offset;
+};
+
+static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
+
+static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
+{
+	if (dev && dev->dma_mem)
+		return dev->dma_mem;
+	return NULL;
+}
+
+static inline dma_addr_t dma_get_device_base(struct device *dev,
+					     struct dma_coherent_mem * mem)
+{
+	if (mem->use_dev_dma_pfn_offset)
+		return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
+	else
+		return mem->device_base;
+}
+
+static int dma_init_coherent_memory(
+	phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags,
+	struct dma_coherent_mem **mem)
+{
+	struct dma_coherent_mem *dma_mem = NULL;
+	void __iomem *mem_base = NULL;
+	int pages = size >> PAGE_SHIFT;
+	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
+	int ret;
+
+	if (!size) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
+	if (!mem_base) {
+		ret = -EINVAL;
+		goto out;
+	}
+	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
+	if (!dma_mem) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!dma_mem->bitmap) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dma_mem->virt_base = mem_base;
+	dma_mem->device_base = device_addr;
+	dma_mem->pfn_base = PFN_DOWN(phys_addr);
+	dma_mem->size = pages;
+	dma_mem->flags = flags;
+	spin_lock_init(&dma_mem->spinlock);
+
+	*mem = dma_mem;
+	return 0;
+
+out:
+	kfree(dma_mem);
+	if (mem_base)
+		memunmap(mem_base);
+	return ret;
+}
+
+static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
+{
+	if (!mem)
+		return;
+
+	memunmap(mem->virt_base);
+	kfree(mem->bitmap);
+	kfree(mem);
+}
+
+static int dma_assign_coherent_memory(struct device *dev,
+				      struct dma_coherent_mem *mem)
+{
+	if (!dev)
+		return -ENODEV;
+
+	if (dev->dma_mem)
+		return -EBUSY;
+
+	dev->dma_mem = mem;
+	return 0;
+}
+
+int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
+				dma_addr_t device_addr, size_t size, int flags)
+{
+	struct dma_coherent_mem *mem;
+	int ret;
+
+	ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags, &mem);
+	if (ret)
+		return ret;
+
+	ret = dma_assign_coherent_memory(dev, mem);
+	if (ret)
+		dma_release_coherent_memory(mem);
+	return ret;
+}
+EXPORT_SYMBOL(dma_declare_coherent_memory);
+
+void dma_release_declared_memory(struct device *dev)
+{
+	struct dma_coherent_mem *mem = dev->dma_mem;
+
+	if (!mem)
+		return;
+	dma_release_coherent_memory(mem);
+	dev->dma_mem = NULL;
+}
+EXPORT_SYMBOL(dma_release_declared_memory);
+
+void *dma_mark_declared_memory_occupied(struct device *dev,
+					dma_addr_t device_addr, size_t size)
+{
+	struct dma_coherent_mem *mem = dev->dma_mem;
+	unsigned long flags;
+	int pos, err;
+
+	size += device_addr & ~PAGE_MASK;
+
+	if (!mem)
+		return ERR_PTR(-EINVAL);
+
+	spin_lock_irqsave(&mem->spinlock, flags);
+	pos = PFN_DOWN(device_addr - dma_get_device_base(dev, mem));
+	err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
+	spin_unlock_irqrestore(&mem->spinlock, flags);
+
+	if (err != 0)
+		return ERR_PTR(err);
+	return mem->virt_base + (pos << PAGE_SHIFT);
+}
+EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
+
+static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem,
+		ssize_t size, dma_addr_t *dma_handle)
+{
+	int order = get_order(size);
+	unsigned long flags;
+	int pageno;
+	void *ret;
+
+	spin_lock_irqsave(&mem->spinlock, flags);
+
+	if (unlikely(size > (mem->size << PAGE_SHIFT)))
+		goto err;
+
+	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
+	if (unlikely(pageno < 0))
+		goto err;
+
+	/*
+	 * Memory was found in the coherent area.
+	 */
+	*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
+	ret = mem->virt_base + (pageno << PAGE_SHIFT);
+	spin_unlock_irqrestore(&mem->spinlock, flags);
+	memset(ret, 0, size);
+	return ret;
+err:
+	spin_unlock_irqrestore(&mem->spinlock, flags);
+	return NULL;
+}
+
+/**
+ * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
+ * @dev:	device from which we allocate memory
+ * @size:	size of requested memory area
+ * @dma_handle:	This will be filled with the correct dma handle
+ * @ret:	This pointer will be filled with the virtual address
+ *		to allocated area.
+ *
+ * This function should be only called from per-arch dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ *
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
+ */
+int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
+		dma_addr_t *dma_handle, void **ret)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	if (!mem)
+		return 0;
+
+	*ret = __dma_alloc_from_coherent(mem, size, dma_handle);
+	if (*ret)
+		return 1;
+
+	/*
+	 * In the case where the allocation can not be satisfied from the
+	 * per-device area, try to fall back to generic memory if the
+	 * constraints allow it.
+	 */
+	return mem->flags & DMA_MEMORY_EXCLUSIVE;
+}
+EXPORT_SYMBOL(dma_alloc_from_dev_coherent);
+
+void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle)
+{
+	if (!dma_coherent_default_memory)
+		return NULL;
+
+	return __dma_alloc_from_coherent(dma_coherent_default_memory, size,
+			dma_handle);
+}
+
+static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
+				       int order, void *vaddr)
+{
+	if (mem && vaddr >= mem->virt_base && vaddr <
+		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
+		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+		unsigned long flags;
+
+		spin_lock_irqsave(&mem->spinlock, flags);
+		bitmap_release_region(mem->bitmap, page, order);
+		spin_unlock_irqrestore(&mem->spinlock, flags);
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * dma_release_from_dev_coherent() - free memory to device coherent memory pool
+ * @dev:	device from which the memory was allocated
+ * @order:	the order of pages allocated
+ * @vaddr:	virtual address of allocated pages
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ *
+ * Returns 1 if we correctly released the memory, or 0 if the caller should
+ * proceed with releasing memory from generic pools.
+ */
+int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	return __dma_release_from_coherent(mem, order, vaddr);
+}
+EXPORT_SYMBOL(dma_release_from_dev_coherent);
+
+int dma_release_from_global_coherent(int order, void *vaddr)
+{
+	if (!dma_coherent_default_memory)
+		return 0;
+
+	return __dma_release_from_coherent(dma_coherent_default_memory, order,
+			vaddr);
+}
+
+static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
+		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
+{
+	if (mem && vaddr >= mem->virt_base && vaddr + size <=
+		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
+		unsigned long off = vma->vm_pgoff;
+		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+		int user_count = vma_pages(vma);
+		int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+		*ret = -ENXIO;
+		if (off < count && user_count <= count - off) {
+			unsigned long pfn = mem->pfn_base + start + off;
+			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
+					       user_count << PAGE_SHIFT,
+					       vma->vm_page_prot);
+		}
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
+ * @dev:	device from which the memory was allocated
+ * @vma:	vm_area for the userspace memory
+ * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
+ * @size:	size of the memory buffer allocated
+ * @ret:	result from remap_pfn_range()
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, maps that memory to the provided vma.
+ *
+ * Returns 1 if @vaddr belongs to the device coherent pool and the caller
+ * should return @ret, or 0 if they should proceed with mapping memory from
+ * generic areas.
+ */
+int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
+			   void *vaddr, size_t size, int *ret)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
+}
+EXPORT_SYMBOL(dma_mmap_from_dev_coherent);
+
+int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
+				   size_t size, int *ret)
+{
+	if (!dma_coherent_default_memory)
+		return 0;
+
+	return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
+					vaddr, size, ret);
+}
+
+/*
+ * Support for reserved memory regions defined in device tree
+ */
+#ifdef CONFIG_OF_RESERVED_MEM
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+
+static struct reserved_mem *dma_reserved_default_memory __initdata;
+
+static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
+{
+	struct dma_coherent_mem *mem = rmem->priv;
+	int ret;
+
+	if (!mem) {
+		ret = dma_init_coherent_memory(rmem->base, rmem->base,
+					       rmem->size,
+					       DMA_MEMORY_EXCLUSIVE, &mem);
+		if (ret) {
+			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
+				&rmem->base, (unsigned long)rmem->size / SZ_1M);
+			return ret;
+		}
+	}
+	mem->use_dev_dma_pfn_offset = true;
+	rmem->priv = mem;
+	dma_assign_coherent_memory(dev, mem);
+	return 0;
+}
+
+static void rmem_dma_device_release(struct reserved_mem *rmem,
+				    struct device *dev)
+{
+	if (dev)
+		dev->dma_mem = NULL;
+}
+
+static const struct reserved_mem_ops rmem_dma_ops = {
+	.device_init	= rmem_dma_device_init,
+	.device_release	= rmem_dma_device_release,
+};
+
+static int __init rmem_dma_setup(struct reserved_mem *rmem)
+{
+	unsigned long node = rmem->fdt_node;
+
+	if (of_get_flat_dt_prop(node, "reusable", NULL))
+		return -EINVAL;
+
+#ifdef CONFIG_ARM
+	if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
+		pr_err("Reserved memory: regions without no-map are not yet supported\n");
+		return -EINVAL;
+	}
+
+	if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
+		WARN(dma_reserved_default_memory,
+		     "Reserved memory: region for default DMA coherent area is redefined\n");
+		dma_reserved_default_memory = rmem;
+	}
+#endif
+
+	rmem->ops = &rmem_dma_ops;
+	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
+		&rmem->base, (unsigned long)rmem->size / SZ_1M);
+	return 0;
+}
+
+static int __init dma_init_reserved_memory(void)
+{
+	const struct reserved_mem_ops *ops;
+	int ret;
+
+	if (!dma_reserved_default_memory)
+		return -ENOMEM;
+
+	ops = dma_reserved_default_memory->ops;
+
+	/*
+	 * We rely on rmem_dma_device_init() does not propagate error of
+	 * dma_assign_coherent_memory() for "NULL" device.
+	 */
+	ret = ops->device_init(dma_reserved_default_memory, NULL);
+
+	if (!ret) {
+		dma_coherent_default_memory = dma_reserved_default_memory->priv;
+		pr_info("DMA: default coherent area is set\n");
+	}
+
+	return ret;
+}
+
+core_initcall(dma_init_reserved_memory);
+
+RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
+#endif
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
new file mode 100644
index 000000000000..d987dcd1bd56
--- /dev/null
+++ b/kernel/dma/contiguous.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Contiguous Memory Allocator for DMA mapping framework
+ * Copyright (c) 2010-2011 by Samsung Electronics.
+ * Written by:
+ *	Marek Szyprowski <m.szyprowski@samsung.com>
+ *	Michal Nazarewicz <mina86@mina86.com>
+ */
+
+#define pr_fmt(fmt) "cma: " fmt
+
+#ifdef CONFIG_CMA_DEBUG
+#ifndef DEBUG
+#  define DEBUG
+#endif
+#endif
+
+#include <asm/page.h>
+#include <asm/dma-contiguous.h>
+
+#include <linux/memblock.h>
+#include <linux/err.h>
+#include <linux/sizes.h>
+#include <linux/dma-contiguous.h>
+#include <linux/cma.h>
+
+#ifdef CONFIG_CMA_SIZE_MBYTES
+#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
+#else
+#define CMA_SIZE_MBYTES 0
+#endif
+
+struct cma *dma_contiguous_default_area;
+
+/*
+ * Default global CMA area size can be defined in kernel's .config.
+ * This is useful mainly for distro maintainers to create a kernel
+ * that works correctly for most supported systems.
+ * The size can be set in bytes or as a percentage of the total memory
+ * in the system.
+ *
+ * Users, who want to set the size of global CMA area for their system
+ * should use cma= kernel parameter.
+ */
+static const phys_addr_t size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M;
+static phys_addr_t size_cmdline = -1;
+static phys_addr_t base_cmdline;
+static phys_addr_t limit_cmdline;
+
+static int __init early_cma(char *p)
+{
+	pr_debug("%s(%s)\n", __func__, p);
+	size_cmdline = memparse(p, &p);
+	if (*p != '@')
+		return 0;
+	base_cmdline = memparse(p + 1, &p);
+	if (*p != '-') {
+		limit_cmdline = base_cmdline + size_cmdline;
+		return 0;
+	}
+	limit_cmdline = memparse(p + 1, &p);
+
+	return 0;
+}
+early_param("cma", early_cma);
+
+#ifdef CONFIG_CMA_SIZE_PERCENTAGE
+
+static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
+{
+	struct memblock_region *reg;
+	unsigned long total_pages = 0;
+
+	/*
+	 * We cannot use memblock_phys_mem_size() here, because
+	 * memblock_analyze() has not been called yet.
+	 */
+	for_each_memblock(memory, reg)
+		total_pages += memblock_region_memory_end_pfn(reg) -
+			       memblock_region_memory_base_pfn(reg);
+
+	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
+}
+
+#else
+
+static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
+{
+	return 0;
+}
+
+#endif
+
+/**
+ * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
+ * @limit: End address of the reserved memory (optional, 0 for any).
+ *
+ * This function reserves memory from early allocator. It should be
+ * called by arch specific code once the early allocator (memblock or bootmem)
+ * has been activated and all other subsystems have already allocated/reserved
+ * memory.
+ */
+void __init dma_contiguous_reserve(phys_addr_t limit)
+{
+	phys_addr_t selected_size = 0;
+	phys_addr_t selected_base = 0;
+	phys_addr_t selected_limit = limit;
+	bool fixed = false;
+
+	pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
+
+	if (size_cmdline != -1) {
+		selected_size = size_cmdline;
+		selected_base = base_cmdline;
+		selected_limit = min_not_zero(limit_cmdline, limit);
+		if (base_cmdline + size_cmdline == limit_cmdline)
+			fixed = true;
+	} else {
+#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
+		selected_size = size_bytes;
+#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
+		selected_size = cma_early_percent_memory();
+#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
+		selected_size = min(size_bytes, cma_early_percent_memory());
+#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
+		selected_size = max(size_bytes, cma_early_percent_memory());
+#endif
+	}
+
+	if (selected_size && !dma_contiguous_default_area) {
+		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
+			 (unsigned long)selected_size / SZ_1M);
+
+		dma_contiguous_reserve_area(selected_size, selected_base,
+					    selected_limit,
+					    &dma_contiguous_default_area,
+					    fixed);
+	}
+}
+
+/**
+ * dma_contiguous_reserve_area() - reserve custom contiguous area
+ * @size: Size of the reserved area (in bytes),
+ * @base: Base address of the reserved area optional, use 0 for any
+ * @limit: End address of the reserved memory (optional, 0 for any).
+ * @res_cma: Pointer to store the created cma region.
+ * @fixed: hint about where to place the reserved area
+ *
+ * This function reserves memory from early allocator. It should be
+ * called by arch specific code once the early allocator (memblock or bootmem)
+ * has been activated and all other subsystems have already allocated/reserved
+ * memory. This function allows to create custom reserved areas for specific
+ * devices.
+ *
+ * If @fixed is true, reserve contiguous area at exactly @base.  If false,
+ * reserve in range from @base to @limit.
+ */
+int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
+				       phys_addr_t limit, struct cma **res_cma,
+				       bool fixed)
+{
+	int ret;
+
+	ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed,
+					"reserved", res_cma);
+	if (ret)
+		return ret;
+
+	/* Architecture specific contiguous memory fixup. */
+	dma_contiguous_early_fixup(cma_get_base(*res_cma),
+				cma_get_size(*res_cma));
+
+	return 0;
+}
+
+/**
+ * dma_alloc_from_contiguous() - allocate pages from contiguous area
+ * @dev:   Pointer to device for which the allocation is performed.
+ * @count: Requested number of pages.
+ * @align: Requested alignment of pages (in PAGE_SIZE order).
+ * @gfp_mask: GFP flags to use for this allocation.
+ *
+ * This function allocates memory buffer for specified device. It uses
+ * device specific contiguous memory area if available or the default
+ * global one. Requires architecture specific dev_get_cma_area() helper
+ * function.
+ */
+struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
+				       unsigned int align, gfp_t gfp_mask)
+{
+	if (align > CONFIG_CMA_ALIGNMENT)
+		align = CONFIG_CMA_ALIGNMENT;
+
+	return cma_alloc(dev_get_cma_area(dev), count, align, gfp_mask);
+}
+
+/**
+ * dma_release_from_contiguous() - release allocated pages
+ * @dev:   Pointer to device for which the pages were allocated.
+ * @pages: Allocated pages.
+ * @count: Number of allocated pages.
+ *
+ * This function releases memory allocated by dma_alloc_from_contiguous().
+ * It returns false when provided pages do not belong to contiguous area and
+ * true otherwise.
+ */
+bool dma_release_from_contiguous(struct device *dev, struct page *pages,
+				 int count)
+{
+	return cma_release(dev_get_cma_area(dev), pages, count);
+}
+
+/*
+ * Support for reserved memory regions defined in device tree
+ */
+#ifdef CONFIG_OF_RESERVED_MEM
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) fmt
+
+static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
+{
+	dev_set_cma_area(dev, rmem->priv);
+	return 0;
+}
+
+static void rmem_cma_device_release(struct reserved_mem *rmem,
+				    struct device *dev)
+{
+	dev_set_cma_area(dev, NULL);
+}
+
+static const struct reserved_mem_ops rmem_cma_ops = {
+	.device_init	= rmem_cma_device_init,
+	.device_release = rmem_cma_device_release,
+};
+
+static int __init rmem_cma_setup(struct reserved_mem *rmem)
+{
+	phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
+	phys_addr_t mask = align - 1;
+	unsigned long node = rmem->fdt_node;
+	struct cma *cma;
+	int err;
+
+	if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
+	    of_get_flat_dt_prop(node, "no-map", NULL))
+		return -EINVAL;
+
+	if ((rmem->base & mask) || (rmem->size & mask)) {
+		pr_err("Reserved memory: incorrect alignment of CMA region\n");
+		return -EINVAL;
+	}
+
+	err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);
+	if (err) {
+		pr_err("Reserved memory: unable to setup CMA region\n");
+		return err;
+	}
+	/* Architecture specific contiguous memory fixup. */
+	dma_contiguous_early_fixup(rmem->base, rmem->size);
+
+	if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
+		dma_contiguous_set_default(cma);
+
+	rmem->ops = &rmem_cma_ops;
+	rmem->priv = cma;
+
+	pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",
+		&rmem->base, (unsigned long)rmem->size / SZ_1M);
+
+	return 0;
+}
+RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
+#endif
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
new file mode 100644
index 000000000000..c007d25bee09
--- /dev/null
+++ b/kernel/dma/debug.c
@@ -0,0 +1,1773 @@
+/*
+ * Copyright (C) 2008 Advanced Micro Devices, Inc.
+ *
+ * Author: Joerg Roedel <joerg.roedel@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/sched/task_stack.h>
+#include <linux/scatterlist.h>
+#include <linux/dma-mapping.h>
+#include <linux/sched/task.h>
+#include <linux/stacktrace.h>
+#include <linux/dma-debug.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/export.h>
+#include <linux/device.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/ctype.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include <asm/sections.h>
+
+#define HASH_SIZE       1024ULL
+#define HASH_FN_SHIFT   13
+#define HASH_FN_MASK    (HASH_SIZE - 1)
+
+/* allow architectures to override this if absolutely required */
+#ifndef PREALLOC_DMA_DEBUG_ENTRIES
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
+#endif
+
+enum {
+	dma_debug_single,
+	dma_debug_page,
+	dma_debug_sg,
+	dma_debug_coherent,
+	dma_debug_resource,
+};
+
+enum map_err_types {
+	MAP_ERR_CHECK_NOT_APPLICABLE,
+	MAP_ERR_NOT_CHECKED,
+	MAP_ERR_CHECKED,
+};
+
+#define DMA_DEBUG_STACKTRACE_ENTRIES 5
+
+/**
+ * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
+ * @list: node on pre-allocated free_entries list
+ * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
+ * @type: single, page, sg, coherent
+ * @pfn: page frame of the start address
+ * @offset: offset of mapping relative to pfn
+ * @size: length of the mapping
+ * @direction: enum dma_data_direction
+ * @sg_call_ents: 'nents' from dma_map_sg
+ * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
+ * @map_err_type: track whether dma_mapping_error() was checked
+ * @stacktrace: support backtraces when a violation is detected
+ */
+struct dma_debug_entry {
+	struct list_head list;
+	struct device    *dev;
+	int              type;
+	unsigned long	 pfn;
+	size_t		 offset;
+	u64              dev_addr;
+	u64              size;
+	int              direction;
+	int		 sg_call_ents;
+	int		 sg_mapped_ents;
+	enum map_err_types  map_err_type;
+#ifdef CONFIG_STACKTRACE
+	struct		 stack_trace stacktrace;
+	unsigned long	 st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
+#endif
+};
+
+typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
+
+struct hash_bucket {
+	struct list_head list;
+	spinlock_t lock;
+} ____cacheline_aligned_in_smp;
+
+/* Hash list to save the allocated dma addresses */
+static struct hash_bucket dma_entry_hash[HASH_SIZE];
+/* List of pre-allocated dma_debug_entry's */
+static LIST_HEAD(free_entries);
+/* Lock for the list above */
+static DEFINE_SPINLOCK(free_entries_lock);
+
+/* Global disable flag - will be set in case of an error */
+static bool global_disable __read_mostly;
+
+/* Early initialization disable flag, set at the end of dma_debug_init */
+static bool dma_debug_initialized __read_mostly;
+
+static inline bool dma_debug_disabled(void)
+{
+	return global_disable || !dma_debug_initialized;
+}
+
+/* Global error count */
+static u32 error_count;
+
+/* Global error show enable*/
+static u32 show_all_errors __read_mostly;
+/* Number of errors to show */
+static u32 show_num_errors = 1;
+
+static u32 num_free_entries;
+static u32 min_free_entries;
+static u32 nr_total_entries;
+
+/* number of preallocated entries requested by kernel cmdline */
+static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
+
+/* debugfs dentry's for the stuff above */
+static struct dentry *dma_debug_dent        __read_mostly;
+static struct dentry *global_disable_dent   __read_mostly;
+static struct dentry *error_count_dent      __read_mostly;
+static struct dentry *show_all_errors_dent  __read_mostly;
+static struct dentry *show_num_errors_dent  __read_mostly;
+static struct dentry *num_free_entries_dent __read_mostly;
+static struct dentry *min_free_entries_dent __read_mostly;
+static struct dentry *filter_dent           __read_mostly;
+
+/* per-driver filter related state */
+
+#define NAME_MAX_LEN	64
+
+static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
+static struct device_driver *current_driver                    __read_mostly;
+
+static DEFINE_RWLOCK(driver_name_lock);
+
+static const char *const maperr2str[] = {
+	[MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
+	[MAP_ERR_NOT_CHECKED] = "dma map error not checked",
+	[MAP_ERR_CHECKED] = "dma map error checked",
+};
+
+static const char *type2name[5] = { "single", "page",
+				    "scather-gather", "coherent",
+				    "resource" };
+
+static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
+				   "DMA_FROM_DEVICE", "DMA_NONE" };
+
+/*
+ * The access to some variables in this macro is racy. We can't use atomic_t
+ * here because all these variables are exported to debugfs. Some of them even
+ * writeable. This is also the reason why a lock won't help much. But anyway,
+ * the races are no big deal. Here is why:
+ *
+ *   error_count: the addition is racy, but the worst thing that can happen is
+ *                that we don't count some errors
+ *   show_num_errors: the subtraction is racy. Also no big deal because in
+ *                    worst case this will result in one warning more in the
+ *                    system log than the user configured. This variable is
+ *                    writeable via debugfs.
+ */
+static inline void dump_entry_trace(struct dma_debug_entry *entry)
+{
+#ifdef CONFIG_STACKTRACE
+	if (entry) {
+		pr_warning("Mapped at:\n");
+		print_stack_trace(&entry->stacktrace, 0);
+	}
+#endif
+}
+
+static bool driver_filter(struct device *dev)
+{
+	struct device_driver *drv;
+	unsigned long flags;
+	bool ret;
+
+	/* driver filter off */
+	if (likely(!current_driver_name[0]))
+		return true;
+
+	/* driver filter on and initialized */
+	if (current_driver && dev && dev->driver == current_driver)
+		return true;
+
+	/* driver filter on, but we can't filter on a NULL device... */
+	if (!dev)
+		return false;
+
+	if (current_driver || !current_driver_name[0])
+		return false;
+
+	/* driver filter on but not yet initialized */
+	drv = dev->driver;
+	if (!drv)
+		return false;
+
+	/* lock to protect against change of current_driver_name */
+	read_lock_irqsave(&driver_name_lock, flags);
+
+	ret = false;
+	if (drv->name &&
+	    strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
+		current_driver = drv;
+		ret = true;
+	}
+
+	read_unlock_irqrestore(&driver_name_lock, flags);
+
+	return ret;
+}
+
+#define err_printk(dev, entry, format, arg...) do {			\
+		error_count += 1;					\
+		if (driver_filter(dev) &&				\
+		    (show_all_errors || show_num_errors > 0)) {		\
+			WARN(1, "%s %s: " format,			\
+			     dev ? dev_driver_string(dev) : "NULL",	\
+			     dev ? dev_name(dev) : "NULL", ## arg);	\
+			dump_entry_trace(entry);			\
+		}							\
+		if (!show_all_errors && show_num_errors > 0)		\
+			show_num_errors -= 1;				\
+	} while (0);
+
+/*
+ * Hash related functions
+ *
+ * Every DMA-API request is saved into a struct dma_debug_entry. To
+ * have quick access to these structs they are stored into a hash.
+ */
+static int hash_fn(struct dma_debug_entry *entry)
+{
+	/*
+	 * Hash function is based on the dma address.
+	 * We use bits 20-27 here as the index into the hash
+	 */
+	return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
+}
+
+/*
+ * Request exclusive access to a hash bucket for a given dma_debug_entry.
+ */
+static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
+					   unsigned long *flags)
+	__acquires(&dma_entry_hash[idx].lock)
+{
+	int idx = hash_fn(entry);
+	unsigned long __flags;
+
+	spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
+	*flags = __flags;
+	return &dma_entry_hash[idx];
+}
+
+/*
+ * Give up exclusive access to the hash bucket
+ */
+static void put_hash_bucket(struct hash_bucket *bucket,
+			    unsigned long *flags)
+	__releases(&bucket->lock)
+{
+	unsigned long __flags = *flags;
+
+	spin_unlock_irqrestore(&bucket->lock, __flags);
+}
+
+static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
+{
+	return ((a->dev_addr == b->dev_addr) &&
+		(a->dev == b->dev)) ? true : false;
+}
+
+static bool containing_match(struct dma_debug_entry *a,
+			     struct dma_debug_entry *b)
+{
+	if (a->dev != b->dev)
+		return false;
+
+	if ((b->dev_addr <= a->dev_addr) &&
+	    ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
+		return true;
+
+	return false;
+}
+
+/*
+ * Search a given entry in the hash bucket list
+ */
+static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
+						  struct dma_debug_entry *ref,
+						  match_fn match)
+{
+	struct dma_debug_entry *entry, *ret = NULL;
+	int matches = 0, match_lvl, last_lvl = -1;
+
+	list_for_each_entry(entry, &bucket->list, list) {
+		if (!match(ref, entry))
+			continue;
+
+		/*
+		 * Some drivers map the same physical address multiple
+		 * times. Without a hardware IOMMU this results in the
+		 * same device addresses being put into the dma-debug
+		 * hash multiple times too. This can result in false
+		 * positives being reported. Therefore we implement a
+		 * best-fit algorithm here which returns the entry from
+		 * the hash which fits best to the reference value
+		 * instead of the first-fit.
+		 */
+		matches += 1;
+		match_lvl = 0;
+		entry->size         == ref->size         ? ++match_lvl : 0;
+		entry->type         == ref->type         ? ++match_lvl : 0;
+		entry->direction    == ref->direction    ? ++match_lvl : 0;
+		entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
+
+		if (match_lvl == 4) {
+			/* perfect-fit - return the result */
+			return entry;
+		} else if (match_lvl > last_lvl) {
+			/*
+			 * We found an entry that fits better then the
+			 * previous one or it is the 1st match.
+			 */
+			last_lvl = match_lvl;
+			ret      = entry;
+		}
+	}
+
+	/*
+	 * If we have multiple matches but no perfect-fit, just return
+	 * NULL.
+	 */
+	ret = (matches == 1) ? ret : NULL;
+
+	return ret;
+}
+
+static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
+						 struct dma_debug_entry *ref)
+{
+	return __hash_bucket_find(bucket, ref, exact_match);
+}
+
+static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
+						   struct dma_debug_entry *ref,
+						   unsigned long *flags)
+{
+
+	unsigned int max_range = dma_get_max_seg_size(ref->dev);
+	struct dma_debug_entry *entry, index = *ref;
+	unsigned int range = 0;
+
+	while (range <= max_range) {
+		entry = __hash_bucket_find(*bucket, ref, containing_match);
+
+		if (entry)
+			return entry;
+
+		/*
+		 * Nothing found, go back a hash bucket
+		 */
+		put_hash_bucket(*bucket, flags);
+		range          += (1 << HASH_FN_SHIFT);
+		index.dev_addr -= (1 << HASH_FN_SHIFT);
+		*bucket = get_hash_bucket(&index, flags);
+	}
+
+	return NULL;
+}
+
+/*
+ * Add an entry to a hash bucket
+ */
+static void hash_bucket_add(struct hash_bucket *bucket,
+			    struct dma_debug_entry *entry)
+{
+	list_add_tail(&entry->list, &bucket->list);
+}
+
+/*
+ * Remove entry from a hash bucket list
+ */
+static void hash_bucket_del(struct dma_debug_entry *entry)
+{
+	list_del(&entry->list);
+}
+
+static unsigned long long phys_addr(struct dma_debug_entry *entry)
+{
+	if (entry->type == dma_debug_resource)
+		return __pfn_to_phys(entry->pfn) + entry->offset;
+
+	return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
+}
+
+/*
+ * Dump mapping entries for debugging purposes
+ */
+void debug_dma_dump_mappings(struct device *dev)
+{
+	int idx;
+
+	for (idx = 0; idx < HASH_SIZE; idx++) {
+		struct hash_bucket *bucket = &dma_entry_hash[idx];
+		struct dma_debug_entry *entry;
+		unsigned long flags;
+
+		spin_lock_irqsave(&bucket->lock, flags);
+
+		list_for_each_entry(entry, &bucket->list, list) {
+			if (!dev || dev == entry->dev) {
+				dev_info(entry->dev,
+					 "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n",
+					 type2name[entry->type], idx,
+					 phys_addr(entry), entry->pfn,
+					 entry->dev_addr, entry->size,
+					 dir2name[entry->direction],
+					 maperr2str[entry->map_err_type]);
+			}
+		}
+
+		spin_unlock_irqrestore(&bucket->lock, flags);
+	}
+}
+
+/*
+ * For each mapping (initial cacheline in the case of
+ * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
+ * scatterlist, or the cacheline specified in dma_map_single) insert
+ * into this tree using the cacheline as the key. At
+ * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry.  If
+ * the entry already exists at insertion time add a tag as a reference
+ * count for the overlapping mappings.  For now, the overlap tracking
+ * just ensures that 'unmaps' balance 'maps' before marking the
+ * cacheline idle, but we should also be flagging overlaps as an API
+ * violation.
+ *
+ * Memory usage is mostly constrained by the maximum number of available
+ * dma-debug entries in that we need a free dma_debug_entry before
+ * inserting into the tree.  In the case of dma_map_page and
+ * dma_alloc_coherent there is only one dma_debug_entry and one
+ * dma_active_cacheline entry to track per event.  dma_map_sg(), on the
+ * other hand, consumes a single dma_debug_entry, but inserts 'nents'
+ * entries into the tree.
+ *
+ * At any time debug_dma_assert_idle() can be called to trigger a
+ * warning if any cachelines in the given page are in the active set.
+ */
+static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
+static DEFINE_SPINLOCK(radix_lock);
+#define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
+#define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
+#define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
+
+static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
+{
+	return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
+		(entry->offset >> L1_CACHE_SHIFT);
+}
+
+static int active_cacheline_read_overlap(phys_addr_t cln)
+{
+	int overlap = 0, i;
+
+	for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
+		if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
+			overlap |= 1 << i;
+	return overlap;
+}
+
+static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
+{
+	int i;
+
+	if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
+		return overlap;
+
+	for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
+		if (overlap & 1 << i)
+			radix_tree_tag_set(&dma_active_cacheline, cln, i);
+		else
+			radix_tree_tag_clear(&dma_active_cacheline, cln, i);
+
+	return overlap;
+}
+
+static void active_cacheline_inc_overlap(phys_addr_t cln)
+{
+	int overlap = active_cacheline_read_overlap(cln);
+
+	overlap = active_cacheline_set_overlap(cln, ++overlap);
+
+	/* If we overflowed the overlap counter then we're potentially
+	 * leaking dma-mappings.  Otherwise, if maps and unmaps are
+	 * balanced then this overflow may cause false negatives in
+	 * debug_dma_assert_idle() as the cacheline may be marked idle
+	 * prematurely.
+	 */
+	WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
+		  "DMA-API: exceeded %d overlapping mappings of cacheline %pa\n",
+		  ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
+}
+
+static int active_cacheline_dec_overlap(phys_addr_t cln)
+{
+	int overlap = active_cacheline_read_overlap(cln);
+
+	return active_cacheline_set_overlap(cln, --overlap);
+}
+
+static int active_cacheline_insert(struct dma_debug_entry *entry)
+{
+	phys_addr_t cln = to_cacheline_number(entry);
+	unsigned long flags;
+	int rc;
+
+	/* If the device is not writing memory then we don't have any
+	 * concerns about the cpu consuming stale data.  This mitigates
+	 * legitimate usages of overlapping mappings.
+	 */
+	if (entry->direction == DMA_TO_DEVICE)
+		return 0;
+
+	spin_lock_irqsave(&radix_lock, flags);
+	rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
+	if (rc == -EEXIST)
+		active_cacheline_inc_overlap(cln);
+	spin_unlock_irqrestore(&radix_lock, flags);
+
+	return rc;
+}
+
+static void active_cacheline_remove(struct dma_debug_entry *entry)
+{
+	phys_addr_t cln = to_cacheline_number(entry);
+	unsigned long flags;
+
+	/* ...mirror the insert case */
+	if (entry->direction == DMA_TO_DEVICE)
+		return;
+
+	spin_lock_irqsave(&radix_lock, flags);
+	/* since we are counting overlaps the final put of the
+	 * cacheline will occur when the overlap count is 0.
+	 * active_cacheline_dec_overlap() returns -1 in that case
+	 */
+	if (active_cacheline_dec_overlap(cln) < 0)
+		radix_tree_delete(&dma_active_cacheline, cln);
+	spin_unlock_irqrestore(&radix_lock, flags);
+}
+
+/**
+ * debug_dma_assert_idle() - assert that a page is not undergoing dma
+ * @page: page to lookup in the dma_active_cacheline tree
+ *
+ * Place a call to this routine in cases where the cpu touching the page
+ * before the dma completes (page is dma_unmapped) will lead to data
+ * corruption.
+ */
+void debug_dma_assert_idle(struct page *page)
+{
+	static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
+	struct dma_debug_entry *entry = NULL;
+	void **results = (void **) &ents;
+	unsigned int nents, i;
+	unsigned long flags;
+	phys_addr_t cln;
+
+	if (dma_debug_disabled())
+		return;
+
+	if (!page)
+		return;
+
+	cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
+	spin_lock_irqsave(&radix_lock, flags);
+	nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
+				       CACHELINES_PER_PAGE);
+	for (i = 0; i < nents; i++) {
+		phys_addr_t ent_cln = to_cacheline_number(ents[i]);
+
+		if (ent_cln == cln) {
+			entry = ents[i];
+			break;
+		} else if (ent_cln >= cln + CACHELINES_PER_PAGE)
+			break;
+	}
+	spin_unlock_irqrestore(&radix_lock, flags);
+
+	if (!entry)
+		return;
+
+	cln = to_cacheline_number(entry);
+	err_printk(entry->dev, entry,
+		   "DMA-API: cpu touching an active dma mapped cacheline [cln=%pa]\n",
+		   &cln);
+}
+
+/*
+ * Wrapper function for adding an entry to the hash.
+ * This function takes care of locking itself.
+ */
+static void add_dma_entry(struct dma_debug_entry *entry)
+{
+	struct hash_bucket *bucket;
+	unsigned long flags;
+	int rc;
+
+	bucket = get_hash_bucket(entry, &flags);
+	hash_bucket_add(bucket, entry);
+	put_hash_bucket(bucket, &flags);
+
+	rc = active_cacheline_insert(entry);
+	if (rc == -ENOMEM) {
+		pr_err("DMA-API: cacheline tracking ENOMEM, dma-debug disabled\n");
+		global_disable = true;
+	}
+
+	/* TODO: report -EEXIST errors here as overlapping mappings are
+	 * not supported by the DMA API
+	 */
+}
+
+static struct dma_debug_entry *__dma_entry_alloc(void)
+{
+	struct dma_debug_entry *entry;
+
+	entry = list_entry(free_entries.next, struct dma_debug_entry, list);
+	list_del(&entry->list);
+	memset(entry, 0, sizeof(*entry));
+
+	num_free_entries -= 1;
+	if (num_free_entries < min_free_entries)
+		min_free_entries = num_free_entries;
+
+	return entry;
+}
+
+/* struct dma_entry allocator
+ *
+ * The next two functions implement the allocator for
+ * struct dma_debug_entries.
+ */
+static struct dma_debug_entry *dma_entry_alloc(void)
+{
+	struct dma_debug_entry *entry;
+	unsigned long flags;
+
+	spin_lock_irqsave(&free_entries_lock, flags);
+
+	if (list_empty(&free_entries)) {
+		global_disable = true;
+		spin_unlock_irqrestore(&free_entries_lock, flags);
+		pr_err("DMA-API: debugging out of memory - disabling\n");
+		return NULL;
+	}
+
+	entry = __dma_entry_alloc();
+
+	spin_unlock_irqrestore(&free_entries_lock, flags);
+
+#ifdef CONFIG_STACKTRACE
+	entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
+	entry->stacktrace.entries = entry->st_entries;
+	entry->stacktrace.skip = 2;
+	save_stack_trace(&entry->stacktrace);
+#endif
+
+	return entry;
+}
+
+static void dma_entry_free(struct dma_debug_entry *entry)
+{
+	unsigned long flags;
+
+	active_cacheline_remove(entry);
+
+	/*
+	 * add to beginning of the list - this way the entries are
+	 * more likely cache hot when they are reallocated.
+	 */
+	spin_lock_irqsave(&free_entries_lock, flags);
+	list_add(&entry->list, &free_entries);
+	num_free_entries += 1;
+	spin_unlock_irqrestore(&free_entries_lock, flags);
+}
+
+int dma_debug_resize_entries(u32 num_entries)
+{
+	int i, delta, ret = 0;
+	unsigned long flags;
+	struct dma_debug_entry *entry;
+	LIST_HEAD(tmp);
+
+	spin_lock_irqsave(&free_entries_lock, flags);
+
+	if (nr_total_entries < num_entries) {
+		delta = num_entries - nr_total_entries;
+
+		spin_unlock_irqrestore(&free_entries_lock, flags);
+
+		for (i = 0; i < delta; i++) {
+			entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+			if (!entry)
+				break;
+
+			list_add_tail(&entry->list, &tmp);
+		}
+
+		spin_lock_irqsave(&free_entries_lock, flags);
+
+		list_splice(&tmp, &free_entries);
+		nr_total_entries += i;
+		num_free_entries += i;
+	} else {
+		delta = nr_total_entries - num_entries;
+
+		for (i = 0; i < delta && !list_empty(&free_entries); i++) {
+			entry = __dma_entry_alloc();
+			kfree(entry);
+		}
+
+		nr_total_entries -= i;
+	}
+
+	if (nr_total_entries != num_entries)
+		ret = 1;
+
+	spin_unlock_irqrestore(&free_entries_lock, flags);
+
+	return ret;
+}
+
+/*
+ * DMA-API debugging init code
+ *
+ * The init code does two things:
+ *   1. Initialize core data structures
+ *   2. Preallocate a given number of dma_debug_entry structs
+ */
+
+static int prealloc_memory(u32 num_entries)
+{
+	struct dma_debug_entry *entry, *next_entry;
+	int i;
+
+	for (i = 0; i < num_entries; ++i) {
+		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+		if (!entry)
+			goto out_err;
+
+		list_add_tail(&entry->list, &free_entries);
+	}
+
+	num_free_entries = num_entries;
+	min_free_entries = num_entries;
+
+	pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
+
+	return 0;
+
+out_err:
+
+	list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
+		list_del(&entry->list);
+		kfree(entry);
+	}
+
+	return -ENOMEM;
+}
+
+static ssize_t filter_read(struct file *file, char __user *user_buf,
+			   size_t count, loff_t *ppos)
+{
+	char buf[NAME_MAX_LEN + 1];
+	unsigned long flags;
+	int len;
+
+	if (!current_driver_name[0])
+		return 0;
+
+	/*
+	 * We can't copy to userspace directly because current_driver_name can
+	 * only be read under the driver_name_lock with irqs disabled. So
+	 * create a temporary copy first.
+	 */
+	read_lock_irqsave(&driver_name_lock, flags);
+	len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
+	read_unlock_irqrestore(&driver_name_lock, flags);
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t filter_write(struct file *file, const char __user *userbuf,
+			    size_t count, loff_t *ppos)
+{
+	char buf[NAME_MAX_LEN];
+	unsigned long flags;
+	size_t len;
+	int i;
+
+	/*
+	 * We can't copy from userspace directly. Access to
+	 * current_driver_name is protected with a write_lock with irqs
+	 * disabled. Since copy_from_user can fault and may sleep we
+	 * need to copy to temporary buffer first
+	 */
+	len = min(count, (size_t)(NAME_MAX_LEN - 1));
+	if (copy_from_user(buf, userbuf, len))
+		return -EFAULT;
+
+	buf[len] = 0;
+
+	write_lock_irqsave(&driver_name_lock, flags);
+
+	/*
+	 * Now handle the string we got from userspace very carefully.
+	 * The rules are:
+	 *         - only use the first token we got
+	 *         - token delimiter is everything looking like a space
+	 *           character (' ', '\n', '\t' ...)
+	 *
+	 */
+	if (!isalnum(buf[0])) {
+		/*
+		 * If the first character userspace gave us is not
+		 * alphanumerical then assume the filter should be
+		 * switched off.
+		 */
+		if (current_driver_name[0])
+			pr_info("DMA-API: switching off dma-debug driver filter\n");
+		current_driver_name[0] = 0;
+		current_driver = NULL;
+		goto out_unlock;
+	}
+
+	/*
+	 * Now parse out the first token and use it as the name for the
+	 * driver to filter for.
+	 */
+	for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
+		current_driver_name[i] = buf[i];
+		if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
+			break;
+	}
+	current_driver_name[i] = 0;
+	current_driver = NULL;
+
+	pr_info("DMA-API: enable driver filter for driver [%s]\n",
+		current_driver_name);
+
+out_unlock:
+	write_unlock_irqrestore(&driver_name_lock, flags);
+
+	return count;
+}
+
+static const struct file_operations filter_fops = {
+	.read  = filter_read,
+	.write = filter_write,
+	.llseek = default_llseek,
+};
+
+static int dma_debug_fs_init(void)
+{
+	dma_debug_dent = debugfs_create_dir("dma-api", NULL);
+	if (!dma_debug_dent) {
+		pr_err("DMA-API: can not create debugfs directory\n");
+		return -ENOMEM;
+	}
+
+	global_disable_dent = debugfs_create_bool("disabled", 0444,
+			dma_debug_dent,
+			&global_disable);
+	if (!global_disable_dent)
+		goto out_err;
+
+	error_count_dent = debugfs_create_u32("error_count", 0444,
+			dma_debug_dent, &error_count);
+	if (!error_count_dent)
+		goto out_err;
+
+	show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
+			dma_debug_dent,
+			&show_all_errors);
+	if (!show_all_errors_dent)
+		goto out_err;
+
+	show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
+			dma_debug_dent,
+			&show_num_errors);
+	if (!show_num_errors_dent)
+		goto out_err;
+
+	num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
+			dma_debug_dent,
+			&num_free_entries);
+	if (!num_free_entries_dent)
+		goto out_err;
+
+	min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
+			dma_debug_dent,
+			&min_free_entries);
+	if (!min_free_entries_dent)
+		goto out_err;
+
+	filter_dent = debugfs_create_file("driver_filter", 0644,
+					  dma_debug_dent, NULL, &filter_fops);
+	if (!filter_dent)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	debugfs_remove_recursive(dma_debug_dent);
+
+	return -ENOMEM;
+}
+
+static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
+{
+	struct dma_debug_entry *entry;
+	unsigned long flags;
+	int count = 0, i;
+
+	for (i = 0; i < HASH_SIZE; ++i) {
+		spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
+		list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
+			if (entry->dev == dev) {
+				count += 1;
+				*out_entry = entry;
+			}
+		}
+		spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
+	}
+
+	return count;
+}
+
+static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
+{
+	struct device *dev = data;
+	struct dma_debug_entry *uninitialized_var(entry);
+	int count;
+
+	if (dma_debug_disabled())
+		return 0;
+
+	switch (action) {
+	case BUS_NOTIFY_UNBOUND_DRIVER:
+		count = device_dma_allocations(dev, &entry);
+		if (count == 0)
+			break;
+		err_printk(dev, entry, "DMA-API: device driver has pending "
+				"DMA allocations while released from device "
+				"[count=%d]\n"
+				"One of leaked entries details: "
+				"[device address=0x%016llx] [size=%llu bytes] "
+				"[mapped with %s] [mapped as %s]\n",
+			count, entry->dev_addr, entry->size,
+			dir2name[entry->direction], type2name[entry->type]);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+void dma_debug_add_bus(struct bus_type *bus)
+{
+	struct notifier_block *nb;
+
+	if (dma_debug_disabled())
+		return;
+
+	nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
+	if (nb == NULL) {
+		pr_err("dma_debug_add_bus: out of memory\n");
+		return;
+	}
+
+	nb->notifier_call = dma_debug_device_change;
+
+	bus_register_notifier(bus, nb);
+}
+
+static int dma_debug_init(void)
+{
+	int i;
+
+	/* Do not use dma_debug_initialized here, since we really want to be
+	 * called to set dma_debug_initialized
+	 */
+	if (global_disable)
+		return 0;
+
+	for (i = 0; i < HASH_SIZE; ++i) {
+		INIT_LIST_HEAD(&dma_entry_hash[i].list);
+		spin_lock_init(&dma_entry_hash[i].lock);
+	}
+
+	if (dma_debug_fs_init() != 0) {
+		pr_err("DMA-API: error creating debugfs entries - disabling\n");
+		global_disable = true;
+
+		return 0;
+	}
+
+	if (prealloc_memory(nr_prealloc_entries) != 0) {
+		pr_err("DMA-API: debugging out of memory error - disabled\n");
+		global_disable = true;
+
+		return 0;
+	}
+
+	nr_total_entries = num_free_entries;
+
+	dma_debug_initialized = true;
+
+	pr_info("DMA-API: debugging enabled by kernel config\n");
+	return 0;
+}
+core_initcall(dma_debug_init);
+
+static __init int dma_debug_cmdline(char *str)
+{
+	if (!str)
+		return -EINVAL;
+
+	if (strncmp(str, "off", 3) == 0) {
+		pr_info("DMA-API: debugging disabled on kernel command line\n");
+		global_disable = true;
+	}
+
+	return 0;
+}
+
+static __init int dma_debug_entries_cmdline(char *str)
+{
+	if (!str)
+		return -EINVAL;
+	if (!get_option(&str, &nr_prealloc_entries))
+		nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
+	return 0;
+}
+
+__setup("dma_debug=", dma_debug_cmdline);
+__setup("dma_debug_entries=", dma_debug_entries_cmdline);
+
+static void check_unmap(struct dma_debug_entry *ref)
+{
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+
+	bucket = get_hash_bucket(ref, &flags);
+	entry = bucket_find_exact(bucket, ref);
+
+	if (!entry) {
+		/* must drop lock before calling dma_mapping_error */
+		put_hash_bucket(bucket, &flags);
+
+		if (dma_mapping_error(ref->dev, ref->dev_addr)) {
+			err_printk(ref->dev, NULL,
+				   "DMA-API: device driver tries to free an "
+				   "invalid DMA memory address\n");
+		} else {
+			err_printk(ref->dev, NULL,
+				   "DMA-API: device driver tries to free DMA "
+				   "memory it has not allocated [device "
+				   "address=0x%016llx] [size=%llu bytes]\n",
+				   ref->dev_addr, ref->size);
+		}
+		return;
+	}
+
+	if (ref->size != entry->size) {
+		err_printk(ref->dev, entry, "DMA-API: device driver frees "
+			   "DMA memory with different size "
+			   "[device address=0x%016llx] [map size=%llu bytes] "
+			   "[unmap size=%llu bytes]\n",
+			   ref->dev_addr, entry->size, ref->size);
+	}
+
+	if (ref->type != entry->type) {
+		err_printk(ref->dev, entry, "DMA-API: device driver frees "
+			   "DMA memory with wrong function "
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[mapped as %s] [unmapped as %s]\n",
+			   ref->dev_addr, ref->size,
+			   type2name[entry->type], type2name[ref->type]);
+	} else if ((entry->type == dma_debug_coherent) &&
+		   (phys_addr(ref) != phys_addr(entry))) {
+		err_printk(ref->dev, entry, "DMA-API: device driver frees "
+			   "DMA memory with different CPU address "
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[cpu alloc address=0x%016llx] "
+			   "[cpu free address=0x%016llx]",
+			   ref->dev_addr, ref->size,
+			   phys_addr(entry),
+			   phys_addr(ref));
+	}
+
+	if (ref->sg_call_ents && ref->type == dma_debug_sg &&
+	    ref->sg_call_ents != entry->sg_call_ents) {
+		err_printk(ref->dev, entry, "DMA-API: device driver frees "
+			   "DMA sg list with different entry count "
+			   "[map count=%d] [unmap count=%d]\n",
+			   entry->sg_call_ents, ref->sg_call_ents);
+	}
+
+	/*
+	 * This may be no bug in reality - but most implementations of the
+	 * DMA API don't handle this properly, so check for it here
+	 */
+	if (ref->direction != entry->direction) {
+		err_printk(ref->dev, entry, "DMA-API: device driver frees "
+			   "DMA memory with different direction "
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[mapped with %s] [unmapped with %s]\n",
+			   ref->dev_addr, ref->size,
+			   dir2name[entry->direction],
+			   dir2name[ref->direction]);
+	}
+
+	/*
+	 * Drivers should use dma_mapping_error() to check the returned
+	 * addresses of dma_map_single() and dma_map_page().
+	 * If not, print this warning message. See Documentation/DMA-API.txt.
+	 */
+	if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+		err_printk(ref->dev, entry,
+			   "DMA-API: device driver failed to check map error"
+			   "[device address=0x%016llx] [size=%llu bytes] "
+			   "[mapped as %s]",
+			   ref->dev_addr, ref->size,
+			   type2name[entry->type]);
+	}
+
+	hash_bucket_del(entry);
+	dma_entry_free(entry);
+
+	put_hash_bucket(bucket, &flags);
+}
+
+static void check_for_stack(struct device *dev,
+			    struct page *page, size_t offset)
+{
+	void *addr;
+	struct vm_struct *stack_vm_area = task_stack_vm_area(current);
+
+	if (!stack_vm_area) {
+		/* Stack is direct-mapped. */
+		if (PageHighMem(page))
+			return;
+		addr = page_address(page) + offset;
+		if (object_is_on_stack(addr))
+			err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
+	} else {
+		/* Stack is vmalloced. */
+		int i;
+
+		for (i = 0; i < stack_vm_area->nr_pages; i++) {
+			if (page != stack_vm_area->pages[i])
+				continue;
+
+			addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
+			err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
+			break;
+		}
+	}
+}
+
+static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
+{
+	unsigned long a1 = (unsigned long)addr;
+	unsigned long b1 = a1 + len;
+	unsigned long a2 = (unsigned long)start;
+	unsigned long b2 = (unsigned long)end;
+
+	return !(b1 <= a2 || a1 >= b2);
+}
+
+static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
+{
+	if (overlap(addr, len, _stext, _etext) ||
+	    overlap(addr, len, __start_rodata, __end_rodata))
+		err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
+}
+
+static void check_sync(struct device *dev,
+		       struct dma_debug_entry *ref,
+		       bool to_cpu)
+{
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+
+	bucket = get_hash_bucket(ref, &flags);
+
+	entry = bucket_find_contain(&bucket, ref, &flags);
+
+	if (!entry) {
+		err_printk(dev, NULL, "DMA-API: device driver tries "
+				"to sync DMA memory it has not allocated "
+				"[device address=0x%016llx] [size=%llu bytes]\n",
+				(unsigned long long)ref->dev_addr, ref->size);
+		goto out;
+	}
+
+	if (ref->size > entry->size) {
+		err_printk(dev, entry, "DMA-API: device driver syncs"
+				" DMA memory outside allocated range "
+				"[device address=0x%016llx] "
+				"[allocation size=%llu bytes] "
+				"[sync offset+size=%llu]\n",
+				entry->dev_addr, entry->size,
+				ref->size);
+	}
+
+	if (entry->direction == DMA_BIDIRECTIONAL)
+		goto out;
+
+	if (ref->direction != entry->direction) {
+		err_printk(dev, entry, "DMA-API: device driver syncs "
+				"DMA memory with different direction "
+				"[device address=0x%016llx] [size=%llu bytes] "
+				"[mapped with %s] [synced with %s]\n",
+				(unsigned long long)ref->dev_addr, entry->size,
+				dir2name[entry->direction],
+				dir2name[ref->direction]);
+	}
+
+	if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
+		      !(ref->direction == DMA_TO_DEVICE))
+		err_printk(dev, entry, "DMA-API: device driver syncs "
+				"device read-only DMA memory for cpu "
+				"[device address=0x%016llx] [size=%llu bytes] "
+				"[mapped with %s] [synced with %s]\n",
+				(unsigned long long)ref->dev_addr, entry->size,
+				dir2name[entry->direction],
+				dir2name[ref->direction]);
+
+	if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
+		       !(ref->direction == DMA_FROM_DEVICE))
+		err_printk(dev, entry, "DMA-API: device driver syncs "
+				"device write-only DMA memory to device "
+				"[device address=0x%016llx] [size=%llu bytes] "
+				"[mapped with %s] [synced with %s]\n",
+				(unsigned long long)ref->dev_addr, entry->size,
+				dir2name[entry->direction],
+				dir2name[ref->direction]);
+
+	if (ref->sg_call_ents && ref->type == dma_debug_sg &&
+	    ref->sg_call_ents != entry->sg_call_ents) {
+		err_printk(ref->dev, entry, "DMA-API: device driver syncs "
+			   "DMA sg list with different entry count "
+			   "[map count=%d] [sync count=%d]\n",
+			   entry->sg_call_ents, ref->sg_call_ents);
+	}
+
+out:
+	put_hash_bucket(bucket, &flags);
+}
+
+static void check_sg_segment(struct device *dev, struct scatterlist *sg)
+{
+#ifdef CONFIG_DMA_API_DEBUG_SG
+	unsigned int max_seg = dma_get_max_seg_size(dev);
+	u64 start, end, boundary = dma_get_seg_boundary(dev);
+
+	/*
+	 * Either the driver forgot to set dma_parms appropriately, or
+	 * whoever generated the list forgot to check them.
+	 */
+	if (sg->length > max_seg)
+		err_printk(dev, NULL, "DMA-API: mapping sg segment longer than device claims to support [len=%u] [max=%u]\n",
+			   sg->length, max_seg);
+	/*
+	 * In some cases this could potentially be the DMA API
+	 * implementation's fault, but it would usually imply that
+	 * the scatterlist was built inappropriately to begin with.
+	 */
+	start = sg_dma_address(sg);
+	end = start + sg_dma_len(sg) - 1;
+	if ((start ^ end) & ~boundary)
+		err_printk(dev, NULL, "DMA-API: mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n",
+			   start, end, boundary);
+#endif
+}
+
+void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
+			size_t size, int direction, dma_addr_t dma_addr,
+			bool map_single)
+{
+	struct dma_debug_entry *entry;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	if (dma_mapping_error(dev, dma_addr))
+		return;
+
+	entry = dma_entry_alloc();
+	if (!entry)
+		return;
+
+	entry->dev       = dev;
+	entry->type      = dma_debug_page;
+	entry->pfn	 = page_to_pfn(page);
+	entry->offset	 = offset,
+	entry->dev_addr  = dma_addr;
+	entry->size      = size;
+	entry->direction = direction;
+	entry->map_err_type = MAP_ERR_NOT_CHECKED;
+
+	if (map_single)
+		entry->type = dma_debug_single;
+
+	check_for_stack(dev, page, offset);
+
+	if (!PageHighMem(page)) {
+		void *addr = page_address(page) + offset;
+
+		check_for_illegal_area(dev, addr, size);
+	}
+
+	add_dma_entry(entry);
+}
+EXPORT_SYMBOL(debug_dma_map_page);
+
+void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	struct dma_debug_entry ref;
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	ref.dev = dev;
+	ref.dev_addr = dma_addr;
+	bucket = get_hash_bucket(&ref, &flags);
+
+	list_for_each_entry(entry, &bucket->list, list) {
+		if (!exact_match(&ref, entry))
+			continue;
+
+		/*
+		 * The same physical address can be mapped multiple
+		 * times. Without a hardware IOMMU this results in the
+		 * same device addresses being put into the dma-debug
+		 * hash multiple times too. This can result in false
+		 * positives being reported. Therefore we implement a
+		 * best-fit algorithm here which updates the first entry
+		 * from the hash which fits the reference value and is
+		 * not currently listed as being checked.
+		 */
+		if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+			entry->map_err_type = MAP_ERR_CHECKED;
+			break;
+		}
+	}
+
+	put_hash_bucket(bucket, &flags);
+}
+EXPORT_SYMBOL(debug_dma_mapping_error);
+
+void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
+			  size_t size, int direction, bool map_single)
+{
+	struct dma_debug_entry ref = {
+		.type           = dma_debug_page,
+		.dev            = dev,
+		.dev_addr       = addr,
+		.size           = size,
+		.direction      = direction,
+	};
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	if (map_single)
+		ref.type = dma_debug_single;
+
+	check_unmap(&ref);
+}
+EXPORT_SYMBOL(debug_dma_unmap_page);
+
+void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
+		      int nents, int mapped_ents, int direction)
+{
+	struct dma_debug_entry *entry;
+	struct scatterlist *s;
+	int i;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	for_each_sg(sg, s, mapped_ents, i) {
+		entry = dma_entry_alloc();
+		if (!entry)
+			return;
+
+		entry->type           = dma_debug_sg;
+		entry->dev            = dev;
+		entry->pfn	      = page_to_pfn(sg_page(s));
+		entry->offset	      = s->offset,
+		entry->size           = sg_dma_len(s);
+		entry->dev_addr       = sg_dma_address(s);
+		entry->direction      = direction;
+		entry->sg_call_ents   = nents;
+		entry->sg_mapped_ents = mapped_ents;
+
+		check_for_stack(dev, sg_page(s), s->offset);
+
+		if (!PageHighMem(sg_page(s))) {
+			check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
+		}
+
+		check_sg_segment(dev, s);
+
+		add_dma_entry(entry);
+	}
+}
+EXPORT_SYMBOL(debug_dma_map_sg);
+
+static int get_nr_mapped_entries(struct device *dev,
+				 struct dma_debug_entry *ref)
+{
+	struct dma_debug_entry *entry;
+	struct hash_bucket *bucket;
+	unsigned long flags;
+	int mapped_ents;
+
+	bucket       = get_hash_bucket(ref, &flags);
+	entry        = bucket_find_exact(bucket, ref);
+	mapped_ents  = 0;
+
+	if (entry)
+		mapped_ents = entry->sg_mapped_ents;
+	put_hash_bucket(bucket, &flags);
+
+	return mapped_ents;
+}
+
+void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
+			int nelems, int dir)
+{
+	struct scatterlist *s;
+	int mapped_ents = 0, i;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	for_each_sg(sglist, s, nelems, i) {
+
+		struct dma_debug_entry ref = {
+			.type           = dma_debug_sg,
+			.dev            = dev,
+			.pfn		= page_to_pfn(sg_page(s)),
+			.offset		= s->offset,
+			.dev_addr       = sg_dma_address(s),
+			.size           = sg_dma_len(s),
+			.direction      = dir,
+			.sg_call_ents   = nelems,
+		};
+
+		if (mapped_ents && i >= mapped_ents)
+			break;
+
+		if (!i)
+			mapped_ents = get_nr_mapped_entries(dev, &ref);
+
+		check_unmap(&ref);
+	}
+}
+EXPORT_SYMBOL(debug_dma_unmap_sg);
+
+void debug_dma_alloc_coherent(struct device *dev, size_t size,
+			      dma_addr_t dma_addr, void *virt)
+{
+	struct dma_debug_entry *entry;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	if (unlikely(virt == NULL))
+		return;
+
+	/* handle vmalloc and linear addresses */
+	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
+		return;
+
+	entry = dma_entry_alloc();
+	if (!entry)
+		return;
+
+	entry->type      = dma_debug_coherent;
+	entry->dev       = dev;
+	entry->offset	 = offset_in_page(virt);
+	entry->size      = size;
+	entry->dev_addr  = dma_addr;
+	entry->direction = DMA_BIDIRECTIONAL;
+
+	if (is_vmalloc_addr(virt))
+		entry->pfn = vmalloc_to_pfn(virt);
+	else
+		entry->pfn = page_to_pfn(virt_to_page(virt));
+
+	add_dma_entry(entry);
+}
+EXPORT_SYMBOL(debug_dma_alloc_coherent);
+
+void debug_dma_free_coherent(struct device *dev, size_t size,
+			 void *virt, dma_addr_t addr)
+{
+	struct dma_debug_entry ref = {
+		.type           = dma_debug_coherent,
+		.dev            = dev,
+		.offset		= offset_in_page(virt),
+		.dev_addr       = addr,
+		.size           = size,
+		.direction      = DMA_BIDIRECTIONAL,
+	};
+
+	/* handle vmalloc and linear addresses */
+	if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
+		return;
+
+	if (is_vmalloc_addr(virt))
+		ref.pfn = vmalloc_to_pfn(virt);
+	else
+		ref.pfn = page_to_pfn(virt_to_page(virt));
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	check_unmap(&ref);
+}
+EXPORT_SYMBOL(debug_dma_free_coherent);
+
+void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
+			    int direction, dma_addr_t dma_addr)
+{
+	struct dma_debug_entry *entry;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	entry = dma_entry_alloc();
+	if (!entry)
+		return;
+
+	entry->type		= dma_debug_resource;
+	entry->dev		= dev;
+	entry->pfn		= PHYS_PFN(addr);
+	entry->offset		= offset_in_page(addr);
+	entry->size		= size;
+	entry->dev_addr		= dma_addr;
+	entry->direction	= direction;
+	entry->map_err_type	= MAP_ERR_NOT_CHECKED;
+
+	add_dma_entry(entry);
+}
+EXPORT_SYMBOL(debug_dma_map_resource);
+
+void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
+			      size_t size, int direction)
+{
+	struct dma_debug_entry ref = {
+		.type           = dma_debug_resource,
+		.dev            = dev,
+		.dev_addr       = dma_addr,
+		.size           = size,
+		.direction      = direction,
+	};
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	check_unmap(&ref);
+}
+EXPORT_SYMBOL(debug_dma_unmap_resource);
+
+void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
+				   size_t size, int direction)
+{
+	struct dma_debug_entry ref;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	ref.type         = dma_debug_single;
+	ref.dev          = dev;
+	ref.dev_addr     = dma_handle;
+	ref.size         = size;
+	ref.direction    = direction;
+	ref.sg_call_ents = 0;
+
+	check_sync(dev, &ref, true);
+}
+EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
+
+void debug_dma_sync_single_for_device(struct device *dev,
+				      dma_addr_t dma_handle, size_t size,
+				      int direction)
+{
+	struct dma_debug_entry ref;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	ref.type         = dma_debug_single;
+	ref.dev          = dev;
+	ref.dev_addr     = dma_handle;
+	ref.size         = size;
+	ref.direction    = direction;
+	ref.sg_call_ents = 0;
+
+	check_sync(dev, &ref, false);
+}
+EXPORT_SYMBOL(debug_dma_sync_single_for_device);
+
+void debug_dma_sync_single_range_for_cpu(struct device *dev,
+					 dma_addr_t dma_handle,
+					 unsigned long offset, size_t size,
+					 int direction)
+{
+	struct dma_debug_entry ref;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	ref.type         = dma_debug_single;
+	ref.dev          = dev;
+	ref.dev_addr     = dma_handle;
+	ref.size         = offset + size;
+	ref.direction    = direction;
+	ref.sg_call_ents = 0;
+
+	check_sync(dev, &ref, true);
+}
+EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
+
+void debug_dma_sync_single_range_for_device(struct device *dev,
+					    dma_addr_t dma_handle,
+					    unsigned long offset,
+					    size_t size, int direction)
+{
+	struct dma_debug_entry ref;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	ref.type         = dma_debug_single;
+	ref.dev          = dev;
+	ref.dev_addr     = dma_handle;
+	ref.size         = offset + size;
+	ref.direction    = direction;
+	ref.sg_call_ents = 0;
+
+	check_sync(dev, &ref, false);
+}
+EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
+
+void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
+			       int nelems, int direction)
+{
+	struct scatterlist *s;
+	int mapped_ents = 0, i;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	for_each_sg(sg, s, nelems, i) {
+
+		struct dma_debug_entry ref = {
+			.type           = dma_debug_sg,
+			.dev            = dev,
+			.pfn		= page_to_pfn(sg_page(s)),
+			.offset		= s->offset,
+			.dev_addr       = sg_dma_address(s),
+			.size           = sg_dma_len(s),
+			.direction      = direction,
+			.sg_call_ents   = nelems,
+		};
+
+		if (!i)
+			mapped_ents = get_nr_mapped_entries(dev, &ref);
+
+		if (i >= mapped_ents)
+			break;
+
+		check_sync(dev, &ref, true);
+	}
+}
+EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
+
+void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
+				  int nelems, int direction)
+{
+	struct scatterlist *s;
+	int mapped_ents = 0, i;
+
+	if (unlikely(dma_debug_disabled()))
+		return;
+
+	for_each_sg(sg, s, nelems, i) {
+
+		struct dma_debug_entry ref = {
+			.type           = dma_debug_sg,
+			.dev            = dev,
+			.pfn		= page_to_pfn(sg_page(s)),
+			.offset		= s->offset,
+			.dev_addr       = sg_dma_address(s),
+			.size           = sg_dma_len(s),
+			.direction      = direction,
+			.sg_call_ents   = nelems,
+		};
+		if (!i)
+			mapped_ents = get_nr_mapped_entries(dev, &ref);
+
+		if (i >= mapped_ents)
+			break;
+
+		check_sync(dev, &ref, false);
+	}
+}
+EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
+
+static int __init dma_debug_driver_setup(char *str)
+{
+	int i;
+
+	for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
+		current_driver_name[i] = *str;
+		if (*str == 0)
+			break;
+	}
+
+	if (current_driver_name[0])
+		pr_info("DMA-API: enable driver filter for driver [%s]\n",
+			current_driver_name);
+
+
+	return 1;
+}
+__setup("dma_debug_driver=", dma_debug_driver_setup);
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
new file mode 100644
index 000000000000..8be8106270c2
--- /dev/null
+++ b/kernel/dma/direct.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DMA operations that map physical memory directly without using an IOMMU or
+ * flushing caches.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-direct.h>
+#include <linux/scatterlist.h>
+#include <linux/dma-contiguous.h>
+#include <linux/pfn.h>
+#include <linux/set_memory.h>
+
+#define DIRECT_MAPPING_ERROR		0
+
+/*
+ * Most architectures use ZONE_DMA for the first 16 Megabytes, but
+ * some use it for entirely different regions:
+ */
+#ifndef ARCH_ZONE_DMA_BITS
+#define ARCH_ZONE_DMA_BITS 24
+#endif
+
+/*
+ * For AMD SEV all DMA must be to unencrypted addresses.
+ */
+static inline bool force_dma_unencrypted(void)
+{
+	return sev_active();
+}
+
+static bool
+check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
+		const char *caller)
+{
+	if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
+		if (!dev->dma_mask) {
+			dev_err(dev,
+				"%s: call on device without dma_mask\n",
+				caller);
+			return false;
+		}
+
+		if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
+			dev_err(dev,
+				"%s: overflow %pad+%zu of device mask %llx\n",
+				caller, &dma_addr, size, *dev->dma_mask);
+		}
+		return false;
+	}
+	return true;
+}
+
+static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
+{
+	dma_addr_t addr = force_dma_unencrypted() ?
+		__phys_to_dma(dev, phys) : phys_to_dma(dev, phys);
+	return addr + size - 1 <= dev->coherent_dma_mask;
+}
+
+void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		gfp_t gfp, unsigned long attrs)
+{
+	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	int page_order = get_order(size);
+	struct page *page = NULL;
+	void *ret;
+
+	/* we always manually zero the memory once we are done: */
+	gfp &= ~__GFP_ZERO;
+
+	/* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
+	if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+		gfp |= GFP_DMA;
+	if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
+		gfp |= GFP_DMA32;
+
+again:
+	/* CMA can be used only in the context which permits sleeping */
+	if (gfpflags_allow_blocking(gfp)) {
+		page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
+		if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
+			dma_release_from_contiguous(dev, page, count);
+			page = NULL;
+		}
+	}
+	if (!page)
+		page = alloc_pages_node(dev_to_node(dev), gfp, page_order);
+
+	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
+		__free_pages(page, page_order);
+		page = NULL;
+
+		if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
+		    dev->coherent_dma_mask < DMA_BIT_MASK(64) &&
+		    !(gfp & (GFP_DMA32 | GFP_DMA))) {
+			gfp |= GFP_DMA32;
+			goto again;
+		}
+
+		if (IS_ENABLED(CONFIG_ZONE_DMA) &&
+		    dev->coherent_dma_mask < DMA_BIT_MASK(32) &&
+		    !(gfp & GFP_DMA)) {
+			gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
+			goto again;
+		}
+	}
+
+	if (!page)
+		return NULL;
+	ret = page_address(page);
+	if (force_dma_unencrypted()) {
+		set_memory_decrypted((unsigned long)ret, 1 << page_order);
+		*dma_handle = __phys_to_dma(dev, page_to_phys(page));
+	} else {
+		*dma_handle = phys_to_dma(dev, page_to_phys(page));
+	}
+	memset(ret, 0, size);
+	return ret;
+}
+
+/*
+ * NOTE: this function must never look at the dma_addr argument, because we want
+ * to be able to use it as a helper for iommu implementations as well.
+ */
+void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
+		dma_addr_t dma_addr, unsigned long attrs)
+{
+	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	unsigned int page_order = get_order(size);
+
+	if (force_dma_unencrypted())
+		set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
+	if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
+		free_pages((unsigned long)cpu_addr, page_order);
+}
+
+dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
+		unsigned long offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	dma_addr_t dma_addr = phys_to_dma(dev, page_to_phys(page)) + offset;
+
+	if (!check_addr(dev, dma_addr, size, __func__))
+		return DIRECT_MAPPING_ERROR;
+	return dma_addr;
+}
+
+int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	int i;
+	struct scatterlist *sg;
+
+	for_each_sg(sgl, sg, nents, i) {
+		BUG_ON(!sg_page(sg));
+
+		sg_dma_address(sg) = phys_to_dma(dev, sg_phys(sg));
+		if (!check_addr(dev, sg_dma_address(sg), sg->length, __func__))
+			return 0;
+		sg_dma_len(sg) = sg->length;
+	}
+
+	return nents;
+}
+
+int dma_direct_supported(struct device *dev, u64 mask)
+{
+#ifdef CONFIG_ZONE_DMA
+	if (mask < DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+		return 0;
+#else
+	/*
+	 * Because 32-bit DMA masks are so common we expect every architecture
+	 * to be able to satisfy them - either by not supporting more physical
+	 * memory, or by providing a ZONE_DMA32.  If neither is the case, the
+	 * architecture needs to use an IOMMU instead of the direct mapping.
+	 */
+	if (mask < DMA_BIT_MASK(32))
+		return 0;
+#endif
+	/*
+	 * Various PCI/PCIe bridges have broken support for > 32bit DMA even
+	 * if the device itself might support it.
+	 */
+	if (dev->dma_32bit_limit && mask > DMA_BIT_MASK(32))
+		return 0;
+	return 1;
+}
+
+int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	return dma_addr == DIRECT_MAPPING_ERROR;
+}
+
+const struct dma_map_ops dma_direct_ops = {
+	.alloc			= dma_direct_alloc,
+	.free			= dma_direct_free,
+	.map_page		= dma_direct_map_page,
+	.map_sg			= dma_direct_map_sg,
+	.dma_supported		= dma_direct_supported,
+	.mapping_error		= dma_direct_mapping_error,
+};
+EXPORT_SYMBOL(dma_direct_ops);
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
new file mode 100644
index 000000000000..d2a92ddaac4d
--- /dev/null
+++ b/kernel/dma/mapping.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch-independent dma-mapping routines
+ *
+ * Copyright (c) 2006  SUSE Linux Products GmbH
+ * Copyright (c) 2006  Tejun Heo <teheo@suse.de>
+ */
+
+#include <linux/acpi.h>
+#include <linux/dma-mapping.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+/*
+ * Managed DMA API
+ */
+struct dma_devres {
+	size_t		size;
+	void		*vaddr;
+	dma_addr_t	dma_handle;
+	unsigned long	attrs;
+};
+
+static void dmam_release(struct device *dev, void *res)
+{
+	struct dma_devres *this = res;
+
+	dma_free_attrs(dev, this->size, this->vaddr, this->dma_handle,
+			this->attrs);
+}
+
+static int dmam_match(struct device *dev, void *res, void *match_data)
+{
+	struct dma_devres *this = res, *match = match_data;
+
+	if (this->vaddr == match->vaddr) {
+		WARN_ON(this->size != match->size ||
+			this->dma_handle != match->dma_handle);
+		return 1;
+	}
+	return 0;
+}
+
+/**
+ * dmam_alloc_coherent - Managed dma_alloc_coherent()
+ * @dev: Device to allocate coherent memory for
+ * @size: Size of allocation
+ * @dma_handle: Out argument for allocated DMA handle
+ * @gfp: Allocation flags
+ *
+ * Managed dma_alloc_coherent().  Memory allocated using this function
+ * will be automatically released on driver detach.
+ *
+ * RETURNS:
+ * Pointer to allocated memory on success, NULL on failure.
+ */
+void *dmam_alloc_coherent(struct device *dev, size_t size,
+			   dma_addr_t *dma_handle, gfp_t gfp)
+{
+	struct dma_devres *dr;
+	void *vaddr;
+
+	dr = devres_alloc(dmam_release, sizeof(*dr), gfp);
+	if (!dr)
+		return NULL;
+
+	vaddr = dma_alloc_coherent(dev, size, dma_handle, gfp);
+	if (!vaddr) {
+		devres_free(dr);
+		return NULL;
+	}
+
+	dr->vaddr = vaddr;
+	dr->dma_handle = *dma_handle;
+	dr->size = size;
+
+	devres_add(dev, dr);
+
+	return vaddr;
+}
+EXPORT_SYMBOL(dmam_alloc_coherent);
+
+/**
+ * dmam_free_coherent - Managed dma_free_coherent()
+ * @dev: Device to free coherent memory for
+ * @size: Size of allocation
+ * @vaddr: Virtual address of the memory to free
+ * @dma_handle: DMA handle of the memory to free
+ *
+ * Managed dma_free_coherent().
+ */
+void dmam_free_coherent(struct device *dev, size_t size, void *vaddr,
+			dma_addr_t dma_handle)
+{
+	struct dma_devres match_data = { size, vaddr, dma_handle };
+
+	dma_free_coherent(dev, size, vaddr, dma_handle);
+	WARN_ON(devres_destroy(dev, dmam_release, dmam_match, &match_data));
+}
+EXPORT_SYMBOL(dmam_free_coherent);
+
+/**
+ * dmam_alloc_attrs - Managed dma_alloc_attrs()
+ * @dev: Device to allocate non_coherent memory for
+ * @size: Size of allocation
+ * @dma_handle: Out argument for allocated DMA handle
+ * @gfp: Allocation flags
+ * @attrs: Flags in the DMA_ATTR_* namespace.
+ *
+ * Managed dma_alloc_attrs().  Memory allocated using this function will be
+ * automatically released on driver detach.
+ *
+ * RETURNS:
+ * Pointer to allocated memory on success, NULL on failure.
+ */
+void *dmam_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		gfp_t gfp, unsigned long attrs)
+{
+	struct dma_devres *dr;
+	void *vaddr;
+
+	dr = devres_alloc(dmam_release, sizeof(*dr), gfp);
+	if (!dr)
+		return NULL;
+
+	vaddr = dma_alloc_attrs(dev, size, dma_handle, gfp, attrs);
+	if (!vaddr) {
+		devres_free(dr);
+		return NULL;
+	}
+
+	dr->vaddr = vaddr;
+	dr->dma_handle = *dma_handle;
+	dr->size = size;
+	dr->attrs = attrs;
+
+	devres_add(dev, dr);
+
+	return vaddr;
+}
+EXPORT_SYMBOL(dmam_alloc_attrs);
+
+#ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
+
+static void dmam_coherent_decl_release(struct device *dev, void *res)
+{
+	dma_release_declared_memory(dev);
+}
+
+/**
+ * dmam_declare_coherent_memory - Managed dma_declare_coherent_memory()
+ * @dev: Device to declare coherent memory for
+ * @phys_addr: Physical address of coherent memory to be declared
+ * @device_addr: Device address of coherent memory to be declared
+ * @size: Size of coherent memory to be declared
+ * @flags: Flags
+ *
+ * Managed dma_declare_coherent_memory().
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int dmam_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
+				 dma_addr_t device_addr, size_t size, int flags)
+{
+	void *res;
+	int rc;
+
+	res = devres_alloc(dmam_coherent_decl_release, 0, GFP_KERNEL);
+	if (!res)
+		return -ENOMEM;
+
+	rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size,
+					 flags);
+	if (!rc)
+		devres_add(dev, res);
+	else
+		devres_free(res);
+
+	return rc;
+}
+EXPORT_SYMBOL(dmam_declare_coherent_memory);
+
+/**
+ * dmam_release_declared_memory - Managed dma_release_declared_memory().
+ * @dev: Device to release declared coherent memory for
+ *
+ * Managed dmam_release_declared_memory().
+ */
+void dmam_release_declared_memory(struct device *dev)
+{
+	WARN_ON(devres_destroy(dev, dmam_coherent_decl_release, NULL, NULL));
+}
+EXPORT_SYMBOL(dmam_release_declared_memory);
+
+#endif
+
+/*
+ * Create scatter-list for the already allocated DMA buffer.
+ */
+int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
+		 void *cpu_addr, dma_addr_t handle, size_t size)
+{
+	struct page *page = virt_to_page(cpu_addr);
+	int ret;
+
+	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+	if (unlikely(ret))
+		return ret;
+
+	sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+	return 0;
+}
+EXPORT_SYMBOL(dma_common_get_sgtable);
+
+/*
+ * Create userspace mapping for the DMA-coherent memory.
+ */
+int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
+		    void *cpu_addr, dma_addr_t dma_addr, size_t size)
+{
+	int ret = -ENXIO;
+#ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP
+	unsigned long user_count = vma_pages(vma);
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	unsigned long off = vma->vm_pgoff;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
+		return ret;
+
+	if (off < count && user_count <= (count - off))
+		ret = remap_pfn_range(vma, vma->vm_start,
+				      page_to_pfn(virt_to_page(cpu_addr)) + off,
+				      user_count << PAGE_SHIFT,
+				      vma->vm_page_prot);
+#endif	/* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
+
+	return ret;
+}
+EXPORT_SYMBOL(dma_common_mmap);
+
+#ifdef CONFIG_MMU
+static struct vm_struct *__dma_common_pages_remap(struct page **pages,
+			size_t size, unsigned long vm_flags, pgprot_t prot,
+			const void *caller)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area_caller(size, vm_flags, caller);
+	if (!area)
+		return NULL;
+
+	if (map_vm_area(area, prot, pages)) {
+		vunmap(area->addr);
+		return NULL;
+	}
+
+	return area;
+}
+
+/*
+ * remaps an array of PAGE_SIZE pages into another vm_area
+ * Cannot be used in non-sleeping contexts
+ */
+void *dma_common_pages_remap(struct page **pages, size_t size,
+			unsigned long vm_flags, pgprot_t prot,
+			const void *caller)
+{
+	struct vm_struct *area;
+
+	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+	if (!area)
+		return NULL;
+
+	area->pages = pages;
+
+	return area->addr;
+}
+
+/*
+ * remaps an allocated contiguous region into another vm_area.
+ * Cannot be used in non-sleeping contexts
+ */
+
+void *dma_common_contiguous_remap(struct page *page, size_t size,
+			unsigned long vm_flags,
+			pgprot_t prot, const void *caller)
+{
+	int i;
+	struct page **pages;
+	struct vm_struct *area;
+
+	pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
+	if (!pages)
+		return NULL;
+
+	for (i = 0; i < (size >> PAGE_SHIFT); i++)
+		pages[i] = nth_page(page, i);
+
+	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
+
+	kfree(pages);
+
+	if (!area)
+		return NULL;
+	return area->addr;
+}
+
+/*
+ * unmaps a range previously mapped by dma_common_*_remap
+ */
+void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
+{
+	struct vm_struct *area = find_vm_area(cpu_addr);
+
+	if (!area || (area->flags & vm_flags) != vm_flags) {
+		WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
+		return;
+	}
+
+	unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
+	vunmap(cpu_addr);
+}
+#endif
+
+/*
+ * enables DMA API use for a device
+ */
+int dma_configure(struct device *dev)
+{
+	if (dev->bus->dma_configure)
+		return dev->bus->dma_configure(dev);
+	return 0;
+}
+
+void dma_deconfigure(struct device *dev)
+{
+	of_dma_deconfigure(dev);
+	acpi_dma_deconfigure(dev);
+}
diff --git a/kernel/dma/noncoherent.c b/kernel/dma/noncoherent.c
new file mode 100644
index 000000000000..79e9a757387f
--- /dev/null
+++ b/kernel/dma/noncoherent.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Christoph Hellwig.
+ *
+ * DMA operations that map physical memory directly without providing cache
+ * coherence.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
+#include <linux/scatterlist.h>
+
+static void dma_noncoherent_sync_single_for_device(struct device *dev,
+		dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+	arch_sync_dma_for_device(dev, dma_to_phys(dev, addr), size, dir);
+}
+
+static void dma_noncoherent_sync_sg_for_device(struct device *dev,
+		struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgl, sg, nents, i)
+		arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, dir);
+}
+
+static dma_addr_t dma_noncoherent_map_page(struct device *dev, struct page *page,
+		unsigned long offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	dma_addr_t addr;
+
+	addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
+	if (!dma_mapping_error(dev, addr) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		arch_sync_dma_for_device(dev, page_to_phys(page) + offset,
+				size, dir);
+	return addr;
+}
+
+static int dma_noncoherent_map_sg(struct device *dev, struct scatterlist *sgl,
+		int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+	nents = dma_direct_map_sg(dev, sgl, nents, dir, attrs);
+	if (nents > 0 && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		dma_noncoherent_sync_sg_for_device(dev, sgl, nents, dir);
+	return nents;
+}
+
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
+static void dma_noncoherent_sync_single_for_cpu(struct device *dev,
+		dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+	arch_sync_dma_for_cpu(dev, dma_to_phys(dev, addr), size, dir);
+}
+
+static void dma_noncoherent_sync_sg_for_cpu(struct device *dev,
+		struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgl, sg, nents, i)
+		arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
+}
+
+static void dma_noncoherent_unmap_page(struct device *dev, dma_addr_t addr,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		dma_noncoherent_sync_single_for_cpu(dev, addr, size, dir);
+}
+
+static void dma_noncoherent_unmap_sg(struct device *dev, struct scatterlist *sgl,
+		int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		dma_noncoherent_sync_sg_for_cpu(dev, sgl, nents, dir);
+}
+#endif
+
+const struct dma_map_ops dma_noncoherent_ops = {
+	.alloc			= arch_dma_alloc,
+	.free			= arch_dma_free,
+	.mmap			= arch_dma_mmap,
+	.sync_single_for_device	= dma_noncoherent_sync_single_for_device,
+	.sync_sg_for_device	= dma_noncoherent_sync_sg_for_device,
+	.map_page		= dma_noncoherent_map_page,
+	.map_sg			= dma_noncoherent_map_sg,
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
+	.sync_single_for_cpu	= dma_noncoherent_sync_single_for_cpu,
+	.sync_sg_for_cpu	= dma_noncoherent_sync_sg_for_cpu,
+	.unmap_page		= dma_noncoherent_unmap_page,
+	.unmap_sg		= dma_noncoherent_unmap_sg,
+#endif
+	.dma_supported		= dma_direct_supported,
+	.mapping_error		= dma_direct_mapping_error,
+	.cache_sync		= arch_dma_cache_sync,
+};
+EXPORT_SYMBOL(dma_noncoherent_ops);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
new file mode 100644
index 000000000000..04b68d9dffac
--- /dev/null
+++ b/kernel/dma/swiotlb.c
@@ -0,0 +1,1087 @@
+/*
+ * Dynamic DMA mapping support.
+ *
+ * This implementation is a fallback for platforms that do not support
+ * I/O TLBs (aka DMA address translation hardware).
+ * Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
+ * Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
+ * Copyright (C) 2000, 2003 Hewlett-Packard Co
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * 03/05/07 davidm	Switch from PCI-DMA to generic device DMA API.
+ * 00/12/13 davidm	Rename to swiotlb.c and add mark_clean() to avoid
+ *			unnecessary i-cache flushing.
+ * 04/07/.. ak		Better overflow handling. Assorted fixes.
+ * 05/09/10 linville	Add support for syncing ranges, support syncing for
+ *			DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
+ * 08/12/11 beckyb	Add highmem support
+ */
+
+#include <linux/cache.h>
+#include <linux/dma-direct.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/swiotlb.h>
+#include <linux/pfn.h>
+#include <linux/types.h>
+#include <linux/ctype.h>
+#include <linux/highmem.h>
+#include <linux/gfp.h>
+#include <linux/scatterlist.h>
+#include <linux/mem_encrypt.h>
+#include <linux/set_memory.h>
+
+#include <asm/io.h>
+#include <asm/dma.h>
+
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/iommu-helper.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/swiotlb.h>
+
+#define OFFSET(val,align) ((unsigned long)	\
+	                   ( (val) & ( (align) - 1)))
+
+#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
+
+/*
+ * Minimum IO TLB size to bother booting with.  Systems with mainly
+ * 64bit capable cards will only lightly use the swiotlb.  If we can't
+ * allocate a contiguous 1MB, we're probably in trouble anyway.
+ */
+#define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
+
+enum swiotlb_force swiotlb_force;
+
+/*
+ * Used to do a quick range check in swiotlb_tbl_unmap_single and
+ * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
+ * API.
+ */
+static phys_addr_t io_tlb_start, io_tlb_end;
+
+/*
+ * The number of IO TLB blocks (in groups of 64) between io_tlb_start and
+ * io_tlb_end.  This is command line adjustable via setup_io_tlb_npages.
+ */
+static unsigned long io_tlb_nslabs;
+
+/*
+ * When the IOMMU overflows we return a fallback buffer. This sets the size.
+ */
+static unsigned long io_tlb_overflow = 32*1024;
+
+static phys_addr_t io_tlb_overflow_buffer;
+
+/*
+ * This is a free list describing the number of free entries available from
+ * each index
+ */
+static unsigned int *io_tlb_list;
+static unsigned int io_tlb_index;
+
+/*
+ * Max segment that we can provide which (if pages are contingous) will
+ * not be bounced (unless SWIOTLB_FORCE is set).
+ */
+unsigned int max_segment;
+
+/*
+ * We need to save away the original address corresponding to a mapped entry
+ * for the sync operations.
+ */
+#define INVALID_PHYS_ADDR (~(phys_addr_t)0)
+static phys_addr_t *io_tlb_orig_addr;
+
+/*
+ * Protect the above data structures in the map and unmap calls
+ */
+static DEFINE_SPINLOCK(io_tlb_lock);
+
+static int late_alloc;
+
+static int __init
+setup_io_tlb_npages(char *str)
+{
+	if (isdigit(*str)) {
+		io_tlb_nslabs = simple_strtoul(str, &str, 0);
+		/* avoid tail segment of size < IO_TLB_SEGSIZE */
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+	}
+	if (*str == ',')
+		++str;
+	if (!strcmp(str, "force")) {
+		swiotlb_force = SWIOTLB_FORCE;
+	} else if (!strcmp(str, "noforce")) {
+		swiotlb_force = SWIOTLB_NO_FORCE;
+		io_tlb_nslabs = 1;
+	}
+
+	return 0;
+}
+early_param("swiotlb", setup_io_tlb_npages);
+/* make io_tlb_overflow tunable too? */
+
+unsigned long swiotlb_nr_tbl(void)
+{
+	return io_tlb_nslabs;
+}
+EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
+
+unsigned int swiotlb_max_segment(void)
+{
+	return max_segment;
+}
+EXPORT_SYMBOL_GPL(swiotlb_max_segment);
+
+void swiotlb_set_max_segment(unsigned int val)
+{
+	if (swiotlb_force == SWIOTLB_FORCE)
+		max_segment = 1;
+	else
+		max_segment = rounddown(val, PAGE_SIZE);
+}
+
+/* default to 64MB */
+#define IO_TLB_DEFAULT_SIZE (64UL<<20)
+unsigned long swiotlb_size_or_default(void)
+{
+	unsigned long size;
+
+	size = io_tlb_nslabs << IO_TLB_SHIFT;
+
+	return size ? size : (IO_TLB_DEFAULT_SIZE);
+}
+
+static bool no_iotlb_memory;
+
+void swiotlb_print_info(void)
+{
+	unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
+	unsigned char *vstart, *vend;
+
+	if (no_iotlb_memory) {
+		pr_warn("software IO TLB: No low mem\n");
+		return;
+	}
+
+	vstart = phys_to_virt(io_tlb_start);
+	vend = phys_to_virt(io_tlb_end);
+
+	printk(KERN_INFO "software IO TLB [mem %#010llx-%#010llx] (%luMB) mapped at [%p-%p]\n",
+	       (unsigned long long)io_tlb_start,
+	       (unsigned long long)io_tlb_end,
+	       bytes >> 20, vstart, vend - 1);
+}
+
+/*
+ * Early SWIOTLB allocation may be too early to allow an architecture to
+ * perform the desired operations.  This function allows the architecture to
+ * call SWIOTLB when the operations are possible.  It needs to be called
+ * before the SWIOTLB memory is used.
+ */
+void __init swiotlb_update_mem_attributes(void)
+{
+	void *vaddr;
+	unsigned long bytes;
+
+	if (no_iotlb_memory || late_alloc)
+		return;
+
+	vaddr = phys_to_virt(io_tlb_start);
+	bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT);
+	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
+	memset(vaddr, 0, bytes);
+
+	vaddr = phys_to_virt(io_tlb_overflow_buffer);
+	bytes = PAGE_ALIGN(io_tlb_overflow);
+	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
+	memset(vaddr, 0, bytes);
+}
+
+int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
+{
+	void *v_overflow_buffer;
+	unsigned long i, bytes;
+
+	bytes = nslabs << IO_TLB_SHIFT;
+
+	io_tlb_nslabs = nslabs;
+	io_tlb_start = __pa(tlb);
+	io_tlb_end = io_tlb_start + bytes;
+
+	/*
+	 * Get the overflow emergency buffer
+	 */
+	v_overflow_buffer = memblock_virt_alloc_low_nopanic(
+						PAGE_ALIGN(io_tlb_overflow),
+						PAGE_SIZE);
+	if (!v_overflow_buffer)
+		return -ENOMEM;
+
+	io_tlb_overflow_buffer = __pa(v_overflow_buffer);
+
+	/*
+	 * Allocate and initialize the free list array.  This array is used
+	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
+	 * between io_tlb_start and io_tlb_end.
+	 */
+	io_tlb_list = memblock_virt_alloc(
+				PAGE_ALIGN(io_tlb_nslabs * sizeof(int)),
+				PAGE_SIZE);
+	io_tlb_orig_addr = memblock_virt_alloc(
+				PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)),
+				PAGE_SIZE);
+	for (i = 0; i < io_tlb_nslabs; i++) {
+		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
+	}
+	io_tlb_index = 0;
+
+	if (verbose)
+		swiotlb_print_info();
+
+	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
+	return 0;
+}
+
+/*
+ * Statically reserve bounce buffer space and initialize bounce buffer data
+ * structures for the software IO TLB used to implement the DMA API.
+ */
+void  __init
+swiotlb_init(int verbose)
+{
+	size_t default_size = IO_TLB_DEFAULT_SIZE;
+	unsigned char *vstart;
+	unsigned long bytes;
+
+	if (!io_tlb_nslabs) {
+		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+	}
+
+	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
+
+	/* Get IO TLB memory from the low pages */
+	vstart = memblock_virt_alloc_low_nopanic(PAGE_ALIGN(bytes), PAGE_SIZE);
+	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
+		return;
+
+	if (io_tlb_start)
+		memblock_free_early(io_tlb_start,
+				    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+	pr_warn("Cannot allocate SWIOTLB buffer");
+	no_iotlb_memory = true;
+}
+
+/*
+ * Systems with larger DMA zones (those that don't support ISA) can
+ * initialize the swiotlb later using the slab allocator if needed.
+ * This should be just like above, but with some error catching.
+ */
+int
+swiotlb_late_init_with_default_size(size_t default_size)
+{
+	unsigned long bytes, req_nslabs = io_tlb_nslabs;
+	unsigned char *vstart = NULL;
+	unsigned int order;
+	int rc = 0;
+
+	if (!io_tlb_nslabs) {
+		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
+		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+	}
+
+	/*
+	 * Get IO TLB memory from the low pages
+	 */
+	order = get_order(io_tlb_nslabs << IO_TLB_SHIFT);
+	io_tlb_nslabs = SLABS_PER_PAGE << order;
+	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
+
+	while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
+		vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
+						  order);
+		if (vstart)
+			break;
+		order--;
+	}
+
+	if (!vstart) {
+		io_tlb_nslabs = req_nslabs;
+		return -ENOMEM;
+	}
+	if (order != get_order(bytes)) {
+		printk(KERN_WARNING "Warning: only able to allocate %ld MB "
+		       "for software IO TLB\n", (PAGE_SIZE << order) >> 20);
+		io_tlb_nslabs = SLABS_PER_PAGE << order;
+	}
+	rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
+	if (rc)
+		free_pages((unsigned long)vstart, order);
+
+	return rc;
+}
+
+int
+swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
+{
+	unsigned long i, bytes;
+	unsigned char *v_overflow_buffer;
+
+	bytes = nslabs << IO_TLB_SHIFT;
+
+	io_tlb_nslabs = nslabs;
+	io_tlb_start = virt_to_phys(tlb);
+	io_tlb_end = io_tlb_start + bytes;
+
+	set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
+	memset(tlb, 0, bytes);
+
+	/*
+	 * Get the overflow emergency buffer
+	 */
+	v_overflow_buffer = (void *)__get_free_pages(GFP_DMA,
+						     get_order(io_tlb_overflow));
+	if (!v_overflow_buffer)
+		goto cleanup2;
+
+	set_memory_decrypted((unsigned long)v_overflow_buffer,
+			io_tlb_overflow >> PAGE_SHIFT);
+	memset(v_overflow_buffer, 0, io_tlb_overflow);
+	io_tlb_overflow_buffer = virt_to_phys(v_overflow_buffer);
+
+	/*
+	 * Allocate and initialize the free list array.  This array is used
+	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
+	 * between io_tlb_start and io_tlb_end.
+	 */
+	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
+	                              get_order(io_tlb_nslabs * sizeof(int)));
+	if (!io_tlb_list)
+		goto cleanup3;
+
+	io_tlb_orig_addr = (phys_addr_t *)
+		__get_free_pages(GFP_KERNEL,
+				 get_order(io_tlb_nslabs *
+					   sizeof(phys_addr_t)));
+	if (!io_tlb_orig_addr)
+		goto cleanup4;
+
+	for (i = 0; i < io_tlb_nslabs; i++) {
+		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
+	}
+	io_tlb_index = 0;
+
+	swiotlb_print_info();
+
+	late_alloc = 1;
+
+	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
+
+	return 0;
+
+cleanup4:
+	free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
+	                                                 sizeof(int)));
+	io_tlb_list = NULL;
+cleanup3:
+	free_pages((unsigned long)v_overflow_buffer,
+		   get_order(io_tlb_overflow));
+	io_tlb_overflow_buffer = 0;
+cleanup2:
+	io_tlb_end = 0;
+	io_tlb_start = 0;
+	io_tlb_nslabs = 0;
+	max_segment = 0;
+	return -ENOMEM;
+}
+
+void __init swiotlb_exit(void)
+{
+	if (!io_tlb_orig_addr)
+		return;
+
+	if (late_alloc) {
+		free_pages((unsigned long)phys_to_virt(io_tlb_overflow_buffer),
+			   get_order(io_tlb_overflow));
+		free_pages((unsigned long)io_tlb_orig_addr,
+			   get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
+		free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
+								 sizeof(int)));
+		free_pages((unsigned long)phys_to_virt(io_tlb_start),
+			   get_order(io_tlb_nslabs << IO_TLB_SHIFT));
+	} else {
+		memblock_free_late(io_tlb_overflow_buffer,
+				   PAGE_ALIGN(io_tlb_overflow));
+		memblock_free_late(__pa(io_tlb_orig_addr),
+				   PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
+		memblock_free_late(__pa(io_tlb_list),
+				   PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
+		memblock_free_late(io_tlb_start,
+				   PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+	}
+	io_tlb_nslabs = 0;
+	max_segment = 0;
+}
+
+int is_swiotlb_buffer(phys_addr_t paddr)
+{
+	return paddr >= io_tlb_start && paddr < io_tlb_end;
+}
+
+/*
+ * Bounce: copy the swiotlb buffer back to the original dma location
+ */
+static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
+			   size_t size, enum dma_data_direction dir)
+{
+	unsigned long pfn = PFN_DOWN(orig_addr);
+	unsigned char *vaddr = phys_to_virt(tlb_addr);
+
+	if (PageHighMem(pfn_to_page(pfn))) {
+		/* The buffer does not have a mapping.  Map it in and copy */
+		unsigned int offset = orig_addr & ~PAGE_MASK;
+		char *buffer;
+		unsigned int sz = 0;
+		unsigned long flags;
+
+		while (size) {
+			sz = min_t(size_t, PAGE_SIZE - offset, size);
+
+			local_irq_save(flags);
+			buffer = kmap_atomic(pfn_to_page(pfn));
+			if (dir == DMA_TO_DEVICE)
+				memcpy(vaddr, buffer + offset, sz);
+			else
+				memcpy(buffer + offset, vaddr, sz);
+			kunmap_atomic(buffer);
+			local_irq_restore(flags);
+
+			size -= sz;
+			pfn++;
+			vaddr += sz;
+			offset = 0;
+		}
+	} else if (dir == DMA_TO_DEVICE) {
+		memcpy(vaddr, phys_to_virt(orig_addr), size);
+	} else {
+		memcpy(phys_to_virt(orig_addr), vaddr, size);
+	}
+}
+
+phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
+				   dma_addr_t tbl_dma_addr,
+				   phys_addr_t orig_addr, size_t size,
+				   enum dma_data_direction dir,
+				   unsigned long attrs)
+{
+	unsigned long flags;
+	phys_addr_t tlb_addr;
+	unsigned int nslots, stride, index, wrap;
+	int i;
+	unsigned long mask;
+	unsigned long offset_slots;
+	unsigned long max_slots;
+
+	if (no_iotlb_memory)
+		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
+
+	if (mem_encrypt_active())
+		pr_warn_once("%s is active and system is using DMA bounce buffers\n",
+			     sme_active() ? "SME" : "SEV");
+
+	mask = dma_get_seg_boundary(hwdev);
+
+	tbl_dma_addr &= mask;
+
+	offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+
+	/*
+ 	 * Carefully handle integer overflow which can occur when mask == ~0UL.
+ 	 */
+	max_slots = mask + 1
+		    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
+		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);
+
+	/*
+	 * For mappings greater than or equal to a page, we limit the stride
+	 * (and hence alignment) to a page size.
+	 */
+	nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	if (size >= PAGE_SIZE)
+		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
+	else
+		stride = 1;
+
+	BUG_ON(!nslots);
+
+	/*
+	 * Find suitable number of IO TLB entries size that will fit this
+	 * request and allocate a buffer from that IO TLB pool.
+	 */
+	spin_lock_irqsave(&io_tlb_lock, flags);
+	index = ALIGN(io_tlb_index, stride);
+	if (index >= io_tlb_nslabs)
+		index = 0;
+	wrap = index;
+
+	do {
+		while (iommu_is_span_boundary(index, nslots, offset_slots,
+					      max_slots)) {
+			index += stride;
+			if (index >= io_tlb_nslabs)
+				index = 0;
+			if (index == wrap)
+				goto not_found;
+		}
+
+		/*
+		 * If we find a slot that indicates we have 'nslots' number of
+		 * contiguous buffers, we allocate the buffers from that slot
+		 * and mark the entries as '0' indicating unavailable.
+		 */
+		if (io_tlb_list[index] >= nslots) {
+			int count = 0;
+
+			for (i = index; i < (int) (index + nslots); i++)
+				io_tlb_list[i] = 0;
+			for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--)
+				io_tlb_list[i] = ++count;
+			tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT);
+
+			/*
+			 * Update the indices to avoid searching in the next
+			 * round.
+			 */
+			io_tlb_index = ((index + nslots) < io_tlb_nslabs
+					? (index + nslots) : 0);
+
+			goto found;
+		}
+		index += stride;
+		if (index >= io_tlb_nslabs)
+			index = 0;
+	} while (index != wrap);
+
+not_found:
+	spin_unlock_irqrestore(&io_tlb_lock, flags);
+	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
+		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size);
+	return SWIOTLB_MAP_ERROR;
+found:
+	spin_unlock_irqrestore(&io_tlb_lock, flags);
+
+	/*
+	 * Save away the mapping from the original address to the DMA address.
+	 * This is needed when we sync the memory.  Then we sync the buffer if
+	 * needed.
+	 */
+	for (i = 0; i < nslots; i++)
+		io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT);
+	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+		swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE);
+
+	return tlb_addr;
+}
+
+/*
+ * Allocates bounce buffer and returns its physical address.
+ */
+static phys_addr_t
+map_single(struct device *hwdev, phys_addr_t phys, size_t size,
+	   enum dma_data_direction dir, unsigned long attrs)
+{
+	dma_addr_t start_dma_addr;
+
+	if (swiotlb_force == SWIOTLB_NO_FORCE) {
+		dev_warn_ratelimited(hwdev, "Cannot do DMA to address %pa\n",
+				     &phys);
+		return SWIOTLB_MAP_ERROR;
+	}
+
+	start_dma_addr = __phys_to_dma(hwdev, io_tlb_start);
+	return swiotlb_tbl_map_single(hwdev, start_dma_addr, phys, size,
+				      dir, attrs);
+}
+
+/*
+ * tlb_addr is the physical address of the bounce buffer to unmap.
+ */
+void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
+			      size_t size, enum dma_data_direction dir,
+			      unsigned long attrs)
+{
+	unsigned long flags;
+	int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
+	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
+	phys_addr_t orig_addr = io_tlb_orig_addr[index];
+
+	/*
+	 * First, sync the memory before unmapping the entry
+	 */
+	if (orig_addr != INVALID_PHYS_ADDR &&
+	    !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
+	    ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+		swiotlb_bounce(orig_addr, tlb_addr, size, DMA_FROM_DEVICE);
+
+	/*
+	 * Return the buffer to the free list by setting the corresponding
+	 * entries to indicate the number of contiguous entries available.
+	 * While returning the entries to the free list, we merge the entries
+	 * with slots below and above the pool being returned.
+	 */
+	spin_lock_irqsave(&io_tlb_lock, flags);
+	{
+		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
+			 io_tlb_list[index + nslots] : 0);
+		/*
+		 * Step 1: return the slots to the free list, merging the
+		 * slots with superceeding slots
+		 */
+		for (i = index + nslots - 1; i >= index; i--) {
+			io_tlb_list[i] = ++count;
+			io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
+		}
+		/*
+		 * Step 2: merge the returned slots with the preceding slots,
+		 * if available (non zero)
+		 */
+		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
+			io_tlb_list[i] = ++count;
+	}
+	spin_unlock_irqrestore(&io_tlb_lock, flags);
+}
+
+void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
+			     size_t size, enum dma_data_direction dir,
+			     enum dma_sync_target target)
+{
+	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
+	phys_addr_t orig_addr = io_tlb_orig_addr[index];
+
+	if (orig_addr == INVALID_PHYS_ADDR)
+		return;
+	orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
+
+	switch (target) {
+	case SYNC_FOR_CPU:
+		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
+			swiotlb_bounce(orig_addr, tlb_addr,
+				       size, DMA_FROM_DEVICE);
+		else
+			BUG_ON(dir != DMA_TO_DEVICE);
+		break;
+	case SYNC_FOR_DEVICE:
+		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+			swiotlb_bounce(orig_addr, tlb_addr,
+				       size, DMA_TO_DEVICE);
+		else
+			BUG_ON(dir != DMA_FROM_DEVICE);
+		break;
+	default:
+		BUG();
+	}
+}
+
+static inline bool dma_coherent_ok(struct device *dev, dma_addr_t addr,
+		size_t size)
+{
+	u64 mask = DMA_BIT_MASK(32);
+
+	if (dev && dev->coherent_dma_mask)
+		mask = dev->coherent_dma_mask;
+	return addr + size - 1 <= mask;
+}
+
+static void *
+swiotlb_alloc_buffer(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		unsigned long attrs)
+{
+	phys_addr_t phys_addr;
+
+	if (swiotlb_force == SWIOTLB_NO_FORCE)
+		goto out_warn;
+
+	phys_addr = swiotlb_tbl_map_single(dev,
+			__phys_to_dma(dev, io_tlb_start),
+			0, size, DMA_FROM_DEVICE, attrs);
+	if (phys_addr == SWIOTLB_MAP_ERROR)
+		goto out_warn;
+
+	*dma_handle = __phys_to_dma(dev, phys_addr);
+	if (!dma_coherent_ok(dev, *dma_handle, size))
+		goto out_unmap;
+
+	memset(phys_to_virt(phys_addr), 0, size);
+	return phys_to_virt(phys_addr);
+
+out_unmap:
+	dev_warn(dev, "hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016Lx\n",
+		(unsigned long long)dev->coherent_dma_mask,
+		(unsigned long long)*dma_handle);
+
+	/*
+	 * DMA_TO_DEVICE to avoid memcpy in unmap_single.
+	 * DMA_ATTR_SKIP_CPU_SYNC is optional.
+	 */
+	swiotlb_tbl_unmap_single(dev, phys_addr, size, DMA_TO_DEVICE,
+			DMA_ATTR_SKIP_CPU_SYNC);
+out_warn:
+	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit()) {
+		dev_warn(dev,
+			"swiotlb: coherent allocation failed, size=%zu\n",
+			size);
+		dump_stack();
+	}
+	return NULL;
+}
+
+static bool swiotlb_free_buffer(struct device *dev, size_t size,
+		dma_addr_t dma_addr)
+{
+	phys_addr_t phys_addr = dma_to_phys(dev, dma_addr);
+
+	WARN_ON_ONCE(irqs_disabled());
+
+	if (!is_swiotlb_buffer(phys_addr))
+		return false;
+
+	/*
+	 * DMA_TO_DEVICE to avoid memcpy in swiotlb_tbl_unmap_single.
+	 * DMA_ATTR_SKIP_CPU_SYNC is optional.
+	 */
+	swiotlb_tbl_unmap_single(dev, phys_addr, size, DMA_TO_DEVICE,
+				 DMA_ATTR_SKIP_CPU_SYNC);
+	return true;
+}
+
+static void
+swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
+	     int do_panic)
+{
+	if (swiotlb_force == SWIOTLB_NO_FORCE)
+		return;
+
+	/*
+	 * Ran out of IOMMU space for this operation. This is very bad.
+	 * Unfortunately the drivers cannot handle this operation properly.
+	 * unless they check for dma_mapping_error (most don't)
+	 * When the mapping is small enough return a static buffer to limit
+	 * the damage, or panic when the transfer is too big.
+	 */
+	dev_err_ratelimited(dev, "DMA: Out of SW-IOMMU space for %zu bytes\n",
+			    size);
+
+	if (size <= io_tlb_overflow || !do_panic)
+		return;
+
+	if (dir == DMA_BIDIRECTIONAL)
+		panic("DMA: Random memory could be DMA accessed\n");
+	if (dir == DMA_FROM_DEVICE)
+		panic("DMA: Random memory could be DMA written\n");
+	if (dir == DMA_TO_DEVICE)
+		panic("DMA: Random memory could be DMA read\n");
+}
+
+/*
+ * Map a single buffer of the indicated size for DMA in streaming mode.  The
+ * physical address to use is returned.
+ *
+ * Once the device is given the dma address, the device owns this memory until
+ * either swiotlb_unmap_page or swiotlb_dma_sync_single is performed.
+ */
+dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
+			    unsigned long offset, size_t size,
+			    enum dma_data_direction dir,
+			    unsigned long attrs)
+{
+	phys_addr_t map, phys = page_to_phys(page) + offset;
+	dma_addr_t dev_addr = phys_to_dma(dev, phys);
+
+	BUG_ON(dir == DMA_NONE);
+	/*
+	 * If the address happens to be in the device's DMA window,
+	 * we can safely return the device addr and not worry about bounce
+	 * buffering it.
+	 */
+	if (dma_capable(dev, dev_addr, size) && swiotlb_force != SWIOTLB_FORCE)
+		return dev_addr;
+
+	trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
+
+	/* Oh well, have to allocate and map a bounce buffer. */
+	map = map_single(dev, phys, size, dir, attrs);
+	if (map == SWIOTLB_MAP_ERROR) {
+		swiotlb_full(dev, size, dir, 1);
+		return __phys_to_dma(dev, io_tlb_overflow_buffer);
+	}
+
+	dev_addr = __phys_to_dma(dev, map);
+
+	/* Ensure that the address returned is DMA'ble */
+	if (dma_capable(dev, dev_addr, size))
+		return dev_addr;
+
+	attrs |= DMA_ATTR_SKIP_CPU_SYNC;
+	swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
+
+	return __phys_to_dma(dev, io_tlb_overflow_buffer);
+}
+
+/*
+ * Unmap a single streaming mode DMA translation.  The dma_addr and size must
+ * match what was provided for in a previous swiotlb_map_page call.  All
+ * other usages are undefined.
+ *
+ * After this call, reads by the cpu to the buffer are guaranteed to see
+ * whatever the device wrote there.
+ */
+static void unmap_single(struct device *hwdev, dma_addr_t dev_addr,
+			 size_t size, enum dma_data_direction dir,
+			 unsigned long attrs)
+{
+	phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
+
+	BUG_ON(dir == DMA_NONE);
+
+	if (is_swiotlb_buffer(paddr)) {
+		swiotlb_tbl_unmap_single(hwdev, paddr, size, dir, attrs);
+		return;
+	}
+
+	if (dir != DMA_FROM_DEVICE)
+		return;
+
+	/*
+	 * phys_to_virt doesn't work with hihgmem page but we could
+	 * call dma_mark_clean() with hihgmem page here. However, we
+	 * are fine since dma_mark_clean() is null on POWERPC. We can
+	 * make dma_mark_clean() take a physical address if necessary.
+	 */
+	dma_mark_clean(phys_to_virt(paddr), size);
+}
+
+void swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
+			size_t size, enum dma_data_direction dir,
+			unsigned long attrs)
+{
+	unmap_single(hwdev, dev_addr, size, dir, attrs);
+}
+
+/*
+ * Make physical memory consistent for a single streaming mode DMA translation
+ * after a transfer.
+ *
+ * If you perform a swiotlb_map_page() but wish to interrogate the buffer
+ * using the cpu, yet do not wish to teardown the dma mapping, you must
+ * call this function before doing so.  At the next point you give the dma
+ * address back to the card, you must first perform a
+ * swiotlb_dma_sync_for_device, and then the device again owns the buffer
+ */
+static void
+swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
+		    size_t size, enum dma_data_direction dir,
+		    enum dma_sync_target target)
+{
+	phys_addr_t paddr = dma_to_phys(hwdev, dev_addr);
+
+	BUG_ON(dir == DMA_NONE);
+
+	if (is_swiotlb_buffer(paddr)) {
+		swiotlb_tbl_sync_single(hwdev, paddr, size, dir, target);
+		return;
+	}
+
+	if (dir != DMA_FROM_DEVICE)
+		return;
+
+	dma_mark_clean(phys_to_virt(paddr), size);
+}
+
+void
+swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
+			    size_t size, enum dma_data_direction dir)
+{
+	swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
+}
+
+void
+swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
+			       size_t size, enum dma_data_direction dir)
+{
+	swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
+}
+
+/*
+ * Map a set of buffers described by scatterlist in streaming mode for DMA.
+ * This is the scatter-gather version of the above swiotlb_map_page
+ * interface.  Here the scatter gather list elements are each tagged with the
+ * appropriate dma address and length.  They are obtained via
+ * sg_dma_{address,length}(SG).
+ *
+ * NOTE: An implementation may be able to use a smaller number of
+ *       DMA address/length pairs than there are SG table elements.
+ *       (for example via virtual mapping capabilities)
+ *       The routine returns the number of addr/length pairs actually
+ *       used, at most nents.
+ *
+ * Device ownership issues as mentioned above for swiotlb_map_page are the
+ * same here.
+ */
+int
+swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
+		     enum dma_data_direction dir, unsigned long attrs)
+{
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(dir == DMA_NONE);
+
+	for_each_sg(sgl, sg, nelems, i) {
+		phys_addr_t paddr = sg_phys(sg);
+		dma_addr_t dev_addr = phys_to_dma(hwdev, paddr);
+
+		if (swiotlb_force == SWIOTLB_FORCE ||
+		    !dma_capable(hwdev, dev_addr, sg->length)) {
+			phys_addr_t map = map_single(hwdev, sg_phys(sg),
+						     sg->length, dir, attrs);
+			if (map == SWIOTLB_MAP_ERROR) {
+				/* Don't panic here, we expect map_sg users
+				   to do proper error handling. */
+				swiotlb_full(hwdev, sg->length, dir, 0);
+				attrs |= DMA_ATTR_SKIP_CPU_SYNC;
+				swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
+						       attrs);
+				sg_dma_len(sgl) = 0;
+				return 0;
+			}
+			sg->dma_address = __phys_to_dma(hwdev, map);
+		} else
+			sg->dma_address = dev_addr;
+		sg_dma_len(sg) = sg->length;
+	}
+	return nelems;
+}
+
+/*
+ * Unmap a set of streaming mode DMA translations.  Again, cpu read rules
+ * concerning calls here are the same as for swiotlb_unmap_page() above.
+ */
+void
+swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
+		       int nelems, enum dma_data_direction dir,
+		       unsigned long attrs)
+{
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(dir == DMA_NONE);
+
+	for_each_sg(sgl, sg, nelems, i)
+		unmap_single(hwdev, sg->dma_address, sg_dma_len(sg), dir,
+			     attrs);
+}
+
+/*
+ * Make physical memory consistent for a set of streaming mode DMA translations
+ * after a transfer.
+ *
+ * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
+ * and usage.
+ */
+static void
+swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
+		int nelems, enum dma_data_direction dir,
+		enum dma_sync_target target)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgl, sg, nelems, i)
+		swiotlb_sync_single(hwdev, sg->dma_address,
+				    sg_dma_len(sg), dir, target);
+}
+
+void
+swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
+			int nelems, enum dma_data_direction dir)
+{
+	swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
+}
+
+void
+swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
+			   int nelems, enum dma_data_direction dir)
+{
+	swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
+}
+
+int
+swiotlb_dma_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
+{
+	return (dma_addr == __phys_to_dma(hwdev, io_tlb_overflow_buffer));
+}
+
+/*
+ * Return whether the given device DMA address mask can be supported
+ * properly.  For example, if your device can only drive the low 24-bits
+ * during bus mastering, then you would pass 0x00ffffff as the mask to
+ * this function.
+ */
+int
+swiotlb_dma_supported(struct device *hwdev, u64 mask)
+{
+	return __phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
+}
+
+void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		gfp_t gfp, unsigned long attrs)
+{
+	void *vaddr;
+
+	/* temporary workaround: */
+	if (gfp & __GFP_NOWARN)
+		attrs |= DMA_ATTR_NO_WARN;
+
+	/*
+	 * Don't print a warning when the first allocation attempt fails.
+	 * swiotlb_alloc_coherent() will print a warning when the DMA memory
+	 * allocation ultimately failed.
+	 */
+	gfp |= __GFP_NOWARN;
+
+	vaddr = dma_direct_alloc(dev, size, dma_handle, gfp, attrs);
+	if (!vaddr)
+		vaddr = swiotlb_alloc_buffer(dev, size, dma_handle, attrs);
+	return vaddr;
+}
+
+void swiotlb_free(struct device *dev, size_t size, void *vaddr,
+		dma_addr_t dma_addr, unsigned long attrs)
+{
+	if (!swiotlb_free_buffer(dev, size, dma_addr))
+		dma_direct_free(dev, size, vaddr, dma_addr, attrs);
+}
+
+const struct dma_map_ops swiotlb_dma_ops = {
+	.mapping_error		= swiotlb_dma_mapping_error,
+	.alloc			= swiotlb_alloc,
+	.free			= swiotlb_free,
+	.sync_single_for_cpu	= swiotlb_sync_single_for_cpu,
+	.sync_single_for_device	= swiotlb_sync_single_for_device,
+	.sync_sg_for_cpu	= swiotlb_sync_sg_for_cpu,
+	.sync_sg_for_device	= swiotlb_sync_sg_for_device,
+	.map_sg			= swiotlb_map_sg_attrs,
+	.unmap_sg		= swiotlb_unmap_sg_attrs,
+	.map_page		= swiotlb_map_page,
+	.unmap_page		= swiotlb_unmap_page,
+	.dma_supported		= dma_direct_supported,
+};
diff --git a/kernel/dma/virt.c b/kernel/dma/virt.c
new file mode 100644
index 000000000000..631ddec4b60a
--- /dev/null
+++ b/kernel/dma/virt.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DMA operations that map to virtual addresses without flushing memory.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+
+static void *dma_virt_alloc(struct device *dev, size_t size,
+			    dma_addr_t *dma_handle, gfp_t gfp,
+			    unsigned long attrs)
+{
+	void *ret;
+
+	ret = (void *)__get_free_pages(gfp, get_order(size));
+	if (ret)
+		*dma_handle = (uintptr_t)ret;
+	return ret;
+}
+
+static void dma_virt_free(struct device *dev, size_t size,
+			  void *cpu_addr, dma_addr_t dma_addr,
+			  unsigned long attrs)
+{
+	free_pages((unsigned long)cpu_addr, get_order(size));
+}
+
+static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
+				    unsigned long offset, size_t size,
+				    enum dma_data_direction dir,
+				    unsigned long attrs)
+{
+	return (uintptr_t)(page_address(page) + offset);
+}
+
+static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
+			   int nents, enum dma_data_direction dir,
+			   unsigned long attrs)
+{
+	int i;
+	struct scatterlist *sg;
+
+	for_each_sg(sgl, sg, nents, i) {
+		BUG_ON(!sg_page(sg));
+		sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
+		sg_dma_len(sg) = sg->length;
+	}
+
+	return nents;
+}
+
+const struct dma_map_ops dma_virt_ops = {
+	.alloc			= dma_virt_alloc,
+	.free			= dma_virt_free,
+	.map_page		= dma_virt_map_page,
+	.map_sg			= dma_virt_map_sg,
+};
+EXPORT_SYMBOL(dma_virt_ops);