Merge branch 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping

Pull DMA-mapping updates from Marek Szyprowski:
 "Those patches are continuation of my earlier work.

  They contains extensions to DMA-mapping framework to remove limitation
  of the current ARM implementation (like limited total size of DMA
  coherent/write combine buffers), improve performance of buffer sharing
  between devices (attributes to skip cpu cache operations or creation
  of additional kernel mapping for some specific use cases) as well as
  some unification of the common code for dma_mmap_attrs() and
  dma_mmap_coherent() functions.  All extensions have been implemented
  and tested for ARM architecture."

* 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  ARM: dma-mapping: add support for DMA_ATTR_SKIP_CPU_SYNC attribute
  common: DMA-mapping: add DMA_ATTR_SKIP_CPU_SYNC attribute
  ARM: dma-mapping: add support for dma_get_sgtable()
  common: dma-mapping: introduce dma_get_sgtable() function
  ARM: dma-mapping: add support for DMA_ATTR_NO_KERNEL_MAPPING attribute
  common: DMA-mapping: add DMA_ATTR_NO_KERNEL_MAPPING attribute
  common: dma-mapping: add support for generic dma_mmap_* calls
  ARM: dma-mapping: fix error path for memory allocation failure
  ARM: dma-mapping: add more sanity checks in arm_dma_mmap()
  ARM: dma-mapping: remove custom consistent dma region
  mm: vmalloc: use const void * for caller argument
  scatterlist: add sg_alloc_table_from_pages function

Documentation/DMA-attributes.txt

@@ -49,3 +49,45 @@ DMA_ATTR_NON_CONSISTENT lets the platform to choose to return either
 consistent or non-consistent memory as it sees fit.  By using this API,
 you are guaranteeing to the platform that you have all the correct and
 necessary sync points for this memory in the driver.
+
+DMA_ATTR_NO_KERNEL_MAPPING
+--------------------------
+
+DMA_ATTR_NO_KERNEL_MAPPING lets the platform to avoid creating a kernel
+virtual mapping for the allocated buffer. On some architectures creating
+such mapping is non-trivial task and consumes very limited resources
+(like kernel virtual address space or dma consistent address space).
+Buffers allocated with this attribute can be only passed to user space
+by calling dma_mmap_attrs(). By using this API, you are guaranteeing
+that you won't dereference the pointer returned by dma_alloc_attr(). You
+can threat it as a cookie that must be passed to dma_mmap_attrs() and
+dma_free_attrs(). Make sure that both of these also get this attribute
+set on each call.
+
+Since it is optional for platforms to implement
+DMA_ATTR_NO_KERNEL_MAPPING, those that do not will simply ignore the
+attribute and exhibit default behavior.
+
+DMA_ATTR_SKIP_CPU_SYNC
+----------------------
+
+By default dma_map_{single,page,sg} functions family transfer a given
+buffer from CPU domain to device domain. Some advanced use cases might
+require sharing a buffer between more than one device. This requires
+having a mapping created separately for each device and is usually
+performed by calling dma_map_{single,page,sg} function more than once
+for the given buffer with device pointer to each device taking part in
+the buffer sharing. The first call transfers a buffer from 'CPU' domain
+to 'device' domain, what synchronizes CPU caches for the given region
+(usually it means that the cache has been flushed or invalidated
+depending on the dma direction). However, next calls to
+dma_map_{single,page,sg}() for other devices will perform exactly the
+same sychronization operation on the CPU cache. CPU cache sychronization
+might be a time consuming operation, especially if the buffers are
+large, so it is highly recommended to avoid it if possible.
+DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of
+the CPU cache for the given buffer assuming that it has been already
+transferred to 'device' domain. This attribute can be also used for
+dma_unmap_{single,page,sg} functions family to force buffer to stay in
+device domain after releasing a mapping for it. Use this attribute with
+care!

Documentation/kernel-parameters.txt

@@ -526,7 +526,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
 	coherent_pool=nn[KMG]	[ARM,KNL]
 			Sets the size of memory pool for coherent, atomic dma
-			allocations if Contiguous Memory Allocator (CMA) is used.
+			allocations, by default set to 256K.
 
 	code_bytes	[X86] How many bytes of object code to print
 			in an oops report.

arch/arm/common/dmabounce.c

@@ -452,6 +452,7 @@ static struct dma_map_ops dmabounce_ops = {
 	.alloc			= arm_dma_alloc,
 	.free			= arm_dma_free,
 	.mmap			= arm_dma_mmap,
+	.get_sgtable		= arm_dma_get_sgtable,
 	.map_page		= dmabounce_map_page,
 	.unmap_page		= dmabounce_unmap_page,
 	.sync_single_for_cpu	= dmabounce_sync_for_cpu,

arch/arm/include/asm/dma-mapping.h

@@ -186,17 +186,6 @@ extern int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 			void *cpu_addr, dma_addr_t dma_addr, size_t size,
 			struct dma_attrs *attrs);
 
-#define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)
-
-static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
-				  void *cpu_addr, dma_addr_t dma_addr,
-				  size_t size, struct dma_attrs *attrs)
-{
-	struct dma_map_ops *ops = get_dma_ops(dev);
-	BUG_ON(!ops);
-	return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
-}
-
 static inline void *dma_alloc_writecombine(struct device *dev, size_t size,
 				       dma_addr_t *dma_handle, gfp_t flag)
 {
@@ -213,20 +202,12 @@ static inline void dma_free_writecombine(struct device *dev, size_t size,
 	return dma_free_attrs(dev, size, cpu_addr, dma_handle, &attrs);
 }
 
-static inline int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
-		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
-{
-	DEFINE_DMA_ATTRS(attrs);
-	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
-	return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size, &attrs);
-}
-
 /*
  * This can be called during boot to increase the size of the consistent
  * DMA region above it's default value of 2MB. It must be called before the
  * memory allocator is initialised, i.e. before any core_initcall.
  */
-extern void __init init_consistent_dma_size(unsigned long size);
+static inline void init_consistent_dma_size(unsigned long size) { }
 
 /*
  * For SA-1111, IXP425, and ADI systems  the dma-mapping functions are "magic"
@@ -280,6 +261,9 @@ extern void arm_dma_sync_sg_for_cpu(struct device *, struct scatterlist *, int,
 		enum dma_data_direction);
 extern void arm_dma_sync_sg_for_device(struct device *, struct scatterlist *, int,
 		enum dma_data_direction);
+extern int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
+		void *cpu_addr, dma_addr_t dma_addr, size_t size,
+		struct dma_attrs *attrs);
 
 #endif /* __KERNEL__ */
 #endif

arch/arm/mm/mm.h

@@ -59,6 +59,9 @@ extern void __flush_dcache_page(struct address_space *mapping, struct page *page
 #define VM_ARM_MTYPE(mt)		((mt) << 20)
 #define VM_ARM_MTYPE_MASK	(0x1f << 20)
 
+/* consistent regions used by dma_alloc_attrs() */
+#define VM_ARM_DMA_CONSISTENT	0x20000000
+
 #endif
 
 #ifdef CONFIG_ZONE_DMA

arch/powerpc/include/asm/dma-mapping.h

@@ -27,7 +27,10 @@ extern void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 extern void dma_direct_free_coherent(struct device *dev, size_t size,
 				     void *vaddr, dma_addr_t dma_handle,
 				     struct dma_attrs *attrs);
-
+extern int dma_direct_mmap_coherent(struct device *dev,
+				    struct vm_area_struct *vma,
+				    void *cpu_addr, dma_addr_t handle,
+				    size_t size, struct dma_attrs *attrs);
 
 #ifdef CONFIG_NOT_COHERENT_CACHE
 /*
@@ -207,11 +210,8 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
 #define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)
 
-extern int dma_mmap_coherent(struct device *, struct vm_area_struct *,
-			     void *, dma_addr_t, size_t);
 #define ARCH_HAS_DMA_MMAP_COHERENT
 
-
 static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		enum dma_data_direction direction)
 {

arch/powerpc/kernel/dma-iommu.c

@@ -109,6 +109,7 @@ static u64 dma_iommu_get_required_mask(struct device *dev)
 struct dma_map_ops dma_iommu_ops = {
 	.alloc			= dma_iommu_alloc_coherent,
 	.free			= dma_iommu_free_coherent,
+	.mmap			= dma_direct_mmap_coherent,
 	.map_sg			= dma_iommu_map_sg,
 	.unmap_sg		= dma_iommu_unmap_sg,
 	.dma_supported		= dma_iommu_dma_supported,

arch/powerpc/kernel/dma-swiotlb.c

@@ -49,6 +49,7 @@ static u64 swiotlb_powerpc_get_required(struct device *dev)
 struct dma_map_ops swiotlb_dma_ops = {
 	.alloc = dma_direct_alloc_coherent,
 	.free = dma_direct_free_coherent,
+	.mmap = dma_direct_mmap_coherent,
 	.map_sg = swiotlb_map_sg_attrs,
 	.unmap_sg = swiotlb_unmap_sg_attrs,
 	.dma_supported = swiotlb_dma_supported,

arch/powerpc/kernel/dma.c

@@ -67,6 +67,24 @@ void dma_direct_free_coherent(struct device *dev, size_t size,
 #endif
 }
 
+int dma_direct_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
+			     void *cpu_addr, dma_addr_t handle, size_t size,
+			     struct dma_attrs *attrs)
+{
+	unsigned long pfn;
+
+#ifdef CONFIG_NOT_COHERENT_CACHE
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	pfn = __dma_get_coherent_pfn((unsigned long)cpu_addr);
+#else
+	pfn = page_to_pfn(virt_to_page(cpu_addr));
+#endif
+	return remap_pfn_range(vma, vma->vm_start,
+			       pfn + vma->vm_pgoff,
+			       vma->vm_end - vma->vm_start,
+			       vma->vm_page_prot);
+}
+
 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
 			     int nents, enum dma_data_direction direction,
 			     struct dma_attrs *attrs)
@@ -156,6 +174,7 @@ static inline void dma_direct_sync_single(struct device *dev,
 struct dma_map_ops dma_direct_ops = {
 	.alloc				= dma_direct_alloc_coherent,
 	.free				= dma_direct_free_coherent,
+	.mmap				= dma_direct_mmap_coherent,
 	.map_sg				= dma_direct_map_sg,
 	.unmap_sg			= dma_direct_unmap_sg,
 	.dma_supported			= dma_direct_dma_supported,
@@ -219,20 +238,3 @@ static int __init dma_init(void)
 }
 fs_initcall(dma_init);
 
-int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
-		      void *cpu_addr, dma_addr_t handle, size_t size)
-{
-	unsigned long pfn;
-
-#ifdef CONFIG_NOT_COHERENT_CACHE
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-	pfn = __dma_get_coherent_pfn((unsigned long)cpu_addr);
-#else
-	pfn = page_to_pfn(virt_to_page(cpu_addr));
-#endif
-	return remap_pfn_range(vma, vma->vm_start,
-			       pfn + vma->vm_pgoff,
-			       vma->vm_end - vma->vm_start,
-			       vma->vm_page_prot);
-}
-EXPORT_SYMBOL_GPL(dma_mmap_coherent);

arch/powerpc/kernel/vio.c

@@ -611,6 +611,7 @@ static u64 vio_dma_get_required_mask(struct device *dev)
 struct dma_map_ops vio_dma_mapping_ops = {
 	.alloc             = vio_dma_iommu_alloc_coherent,
 	.free              = vio_dma_iommu_free_coherent,
+	.mmap		   = dma_direct_mmap_coherent,
 	.map_sg            = vio_dma_iommu_map_sg,
 	.unmap_sg          = vio_dma_iommu_unmap_sg,
 	.map_page          = vio_dma_iommu_map_page,

drivers/base/dma-mapping.c

@@ -10,6 +10,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/export.h>
 #include <linux/gfp.h>
+#include <asm-generic/dma-coherent.h>
 
 /*
  * Managed DMA API
@@ -217,4 +218,52 @@ void dmam_release_declared_memory(struct device *dev)
 }
 EXPORT_SYMBOL(dmam_release_declared_memory);
 
+/*
+ * 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);
+
 #endif
+
+/*
+ * 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;
+#ifdef CONFIG_MMU
+	unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
+	unsigned long off = vma->vm_pgoff;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
+		return ret;
+
+	if (off < count && user_count <= (count - off)) {
+		ret = remap_pfn_range(vma, vma->vm_start,
+				      pfn + off,
+				      user_count << PAGE_SHIFT,
+				      vma->vm_page_prot);
+	}
+#endif	/* CONFIG_MMU */
+
+	return ret;
+}
+EXPORT_SYMBOL(dma_common_mmap);

include/asm-generic/dma-coherent.h

@@ -29,6 +29,7 @@ dma_mark_declared_memory_occupied(struct device *dev,
 #else
 #define dma_alloc_from_coherent(dev, size, handle, ret) (0)
 #define dma_release_from_coherent(dev, order, vaddr) (0)
+#define dma_mmap_from_coherent(dev, vma, vaddr, order, ret) (0)
 #endif
 
 #endif

include/asm-generic/dma-mapping-common.h

@@ -176,4 +176,59 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, NULL)
 #define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, NULL)
 
+extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
+			   void *cpu_addr, dma_addr_t dma_addr, size_t size);
+
+/**
+ * dma_mmap_attrs - map a coherent DMA allocation into user space
+ * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
+ * @vma: vm_area_struct describing requested user mapping
+ * @cpu_addr: kernel CPU-view address returned from dma_alloc_attrs
+ * @handle: device-view address returned from dma_alloc_attrs
+ * @size: size of memory originally requested in dma_alloc_attrs
+ * @attrs: attributes of mapping properties requested in dma_alloc_attrs
+ *
+ * Map a coherent DMA buffer previously allocated by dma_alloc_attrs
+ * into user space.  The coherent DMA buffer must not be freed by the
+ * driver until the user space mapping has been released.
+ */
+static inline int
+dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, void *cpu_addr,
+	       dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
+{
+	struct dma_map_ops *ops = get_dma_ops(dev);
+	BUG_ON(!ops);
+	if (ops->mmap)
+		return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
+	return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
+}
+
+#define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)
+
+static inline int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
+		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
+{
+	DEFINE_DMA_ATTRS(attrs);
+	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
+	return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size, &attrs);
+}
+
+int
+dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
+		       void *cpu_addr, dma_addr_t dma_addr, size_t size);
+
+static inline int
+dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr,
+		      dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
+{
+	struct dma_map_ops *ops = get_dma_ops(dev);
+	BUG_ON(!ops);
+	if (ops->get_sgtable)
+		return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size,
+					attrs);
+	return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr, size);
+}
+
+#define dma_get_sgtable(d, t, v, h, s) dma_get_sgtable_attrs(d, t, v, h, s, NULL)
+
 #endif

include/linux/dma-attrs.h

@@ -15,6 +15,8 @@ enum dma_attr {
 	DMA_ATTR_WEAK_ORDERING,
 	DMA_ATTR_WRITE_COMBINE,
 	DMA_ATTR_NON_CONSISTENT,
+	DMA_ATTR_NO_KERNEL_MAPPING,
+	DMA_ATTR_SKIP_CPU_SYNC,
 	DMA_ATTR_MAX,
 };
 

include/linux/dma-mapping.h

@@ -18,6 +18,9 @@ struct dma_map_ops {
 	int (*mmap)(struct device *, struct vm_area_struct *,
 			  void *, dma_addr_t, size_t, struct dma_attrs *attrs);
 
+	int (*get_sgtable)(struct device *dev, struct sg_table *sgt, void *,
+			   dma_addr_t, size_t, struct dma_attrs *attrs);
+
 	dma_addr_t (*map_page)(struct device *dev, struct page *page,
 			       unsigned long offset, size_t size,
 			       enum dma_data_direction dir,

include/linux/scatterlist.h

@@ -214,6 +214,10 @@ void sg_free_table(struct sg_table *);
 int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t,
 		     sg_alloc_fn *);
 int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
+int sg_alloc_table_from_pages(struct sg_table *sgt,
+	struct page **pages, unsigned int n_pages,
+	unsigned long offset, unsigned long size,
+	gfp_t gfp_mask);
 
 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
 			   void *buf, size_t buflen);

include/linux/vmalloc.h

@@ -32,7 +32,7 @@ struct vm_struct {
 	struct page		**pages;
 	unsigned int		nr_pages;
 	phys_addr_t		phys_addr;
-	void			*caller;
+	const void		*caller;
 };
 
 /*
@@ -62,7 +62,7 @@ extern void *vmalloc_32_user(unsigned long size);
 extern void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot);
 extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
 			unsigned long start, unsigned long end, gfp_t gfp_mask,
-			pgprot_t prot, int node, void *caller);
+			pgprot_t prot, int node, const void *caller);
 extern void vfree(const void *addr);
 
 extern void *vmap(struct page **pages, unsigned int count,
@@ -85,14 +85,15 @@ static inline size_t get_vm_area_size(const struct vm_struct *area)
 
 extern struct vm_struct *get_vm_area(unsigned long size, unsigned long flags);
 extern struct vm_struct *get_vm_area_caller(unsigned long size,
-					unsigned long flags, void *caller);
+					unsigned long flags, const void *caller);
 extern struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
 					unsigned long start, unsigned long end);
 extern struct vm_struct *__get_vm_area_caller(unsigned long size,
 					unsigned long flags,
 					unsigned long start, unsigned long end,
-					void *caller);
+					const void *caller);
 extern struct vm_struct *remove_vm_area(const void *addr);
+extern struct vm_struct *find_vm_area(const void *addr);
 
 extern int map_vm_area(struct vm_struct *area, pgprot_t prot,
 			struct page ***pages);

lib/scatterlist.c

@@ -318,6 +318,70 @@ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(sg_alloc_table);
 
+/**
+ * sg_alloc_table_from_pages - Allocate and initialize an sg table from
+ *			       an array of pages
+ * @sgt:	The sg table header to use
+ * @pages:	Pointer to an array of page pointers
+ * @n_pages:	Number of pages in the pages array
+ * @offset:     Offset from start of the first page to the start of a buffer
+ * @size:       Number of valid bytes in the buffer (after offset)
+ * @gfp_mask:	GFP allocation mask
+ *
+ *  Description:
+ *    Allocate and initialize an sg table from a list of pages. Contiguous
+ *    ranges of the pages are squashed into a single scatterlist node. A user
+ *    may provide an offset at a start and a size of valid data in a buffer
+ *    specified by the page array. The returned sg table is released by
+ *    sg_free_table.
+ *
+ * Returns:
+ *   0 on success, negative error on failure
+ */
+int sg_alloc_table_from_pages(struct sg_table *sgt,
+	struct page **pages, unsigned int n_pages,
+	unsigned long offset, unsigned long size,
+	gfp_t gfp_mask)
+{
+	unsigned int chunks;
+	unsigned int i;
+	unsigned int cur_page;
+	int ret;
+	struct scatterlist *s;
+
+	/* compute number of contiguous chunks */
+	chunks = 1;
+	for (i = 1; i < n_pages; ++i)
+		if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
+			++chunks;
+
+	ret = sg_alloc_table(sgt, chunks, gfp_mask);
+	if (unlikely(ret))
+		return ret;
+
+	/* merging chunks and putting them into the scatterlist */
+	cur_page = 0;
+	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
+		unsigned long chunk_size;
+		unsigned int j;
+
+		/* look for the end of the current chunk */
+		for (j = cur_page + 1; j < n_pages; ++j)
+			if (page_to_pfn(pages[j]) !=
+			    page_to_pfn(pages[j - 1]) + 1)
+				break;
+
+		chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
+		sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
+		size -= chunk_size;
+		offset = 0;
+		cur_page = j;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(sg_alloc_table_from_pages);
+
 /**
  * sg_miter_start - start mapping iteration over a sg list
  * @miter: sg mapping iter to be started

mm/vmalloc.c

@@ -1280,7 +1280,7 @@ DEFINE_RWLOCK(vmlist_lock);
 struct vm_struct *vmlist;
 
 static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
-			      unsigned long flags, void *caller)
+			      unsigned long flags, const void *caller)
 {
 	vm->flags = flags;
 	vm->addr = (void *)va->va_start;
@@ -1306,7 +1306,7 @@ static void insert_vmalloc_vmlist(struct vm_struct *vm)
 }
 
 static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
-			      unsigned long flags, void *caller)
+			      unsigned long flags, const void *caller)
 {
 	setup_vmalloc_vm(vm, va, flags, caller);
 	insert_vmalloc_vmlist(vm);
@@ -1314,7 +1314,7 @@ static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
 
 static struct vm_struct *__get_vm_area_node(unsigned long size,
 		unsigned long align, unsigned long flags, unsigned long start,
-		unsigned long end, int node, gfp_t gfp_mask, void *caller)
+		unsigned long end, int node, gfp_t gfp_mask, const void *caller)
 {
 	struct vmap_area *va;
 	struct vm_struct *area;
@@ -1375,7 +1375,7 @@ EXPORT_SYMBOL_GPL(__get_vm_area);
 
 struct vm_struct *__get_vm_area_caller(unsigned long size, unsigned long flags,
 				       unsigned long start, unsigned long end,
-				       void *caller)
+				       const void *caller)
 {
 	return __get_vm_area_node(size, 1, flags, start, end, -1, GFP_KERNEL,
 				  caller);
@@ -1397,13 +1397,21 @@ struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
 }
 
 struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
-				void *caller)
+				const void *caller)
 {
 	return __get_vm_area_node(size, 1, flags, VMALLOC_START, VMALLOC_END,
 						-1, GFP_KERNEL, caller);
 }
 
-static struct vm_struct *find_vm_area(const void *addr)
+/**
+ *	find_vm_area  -  find a continuous kernel virtual area
+ *	@addr:		base address
+ *
+ *	Search for the kernel VM area starting at @addr, and return it.
+ *	It is up to the caller to do all required locking to keep the returned
+ *	pointer valid.
+ */
+struct vm_struct *find_vm_area(const void *addr)
 {
 	struct vmap_area *va;
 
@@ -1568,9 +1576,9 @@ EXPORT_SYMBOL(vmap);
 
 static void *__vmalloc_node(unsigned long size, unsigned long align,
 			    gfp_t gfp_mask, pgprot_t prot,
-			    int node, void *caller);
+			    int node, const void *caller);
 static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
-				 pgprot_t prot, int node, void *caller)
+				 pgprot_t prot, int node, const void *caller)
 {
 	const int order = 0;
 	struct page **pages;
@@ -1643,7 +1651,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
  */
 void *__vmalloc_node_range(unsigned long size, unsigned long align,
 			unsigned long start, unsigned long end, gfp_t gfp_mask,
-			pgprot_t prot, int node, void *caller)
+			pgprot_t prot, int node, const void *caller)
 {
 	struct vm_struct *area;
 	void *addr;
@@ -1699,7 +1707,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
  */
 static void *__vmalloc_node(unsigned long size, unsigned long align,
 			    gfp_t gfp_mask, pgprot_t prot,
-			    int node, void *caller)
+			    int node, const void *caller)
 {
 	return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
 				gfp_mask, prot, node, caller);