[PATCHv3 0/3] ARM: replace custom consistent dma region with vmalloc

[PATCHv3 0/3] ARM: replace custom consistent dma region with vmalloc

[Marek Szyprowski]

Hello!

This patchset replaces custom consistent dma regions usage in
dma-mapping framework in favour of generic vmalloc areas created on
demand for each allocation. The main purpose for this patchset is to
remove 2MiB limit of dma coherent/writecombine allocations.

Atomic allocations are served from special pool preallocated on boot,
becasue vmalloc areas cannot be reliably created in atomic context.

Linux v3.5-rc1 introduced a lot of changes to ARM dma-mapping subsystem
(CMA and dmamap_ops based implementation has been finally merged), so
the previous version of these patches is not applicable anymore. This
version provides an update required for applying them on v3.5-rc2 kernel
as well as some changes requested by Minchan Kim in his review.

This patch is based on vanilla v3.5-rc2 release.

Atomic allocations have been tested with s3c-sdhci driver on Samsung
UniversalC210 board with dmabounce code enabled to force
dma_alloc_coherent() use on each dma_map_* call (some of them are made
from interrupts).

Best regards
Marek Szyprowski
Samsung Poland R&D Center

Changelog:

v3:
- rebased onto v3.4-rc2: added support for IOMMU-aware implementation 
  of dma-mapping calls, unified with CMA coherent dma pool
- implemented changes requested by Minchan Kim: added more checks for
  vmarea->flags & VM_DMA, renamed some variables, removed obsole locks,
  squashed find_vm_area() exporting patch into the main redesign patch 

v2: http://thread.gmane.org/gmane.linux.kernel.mm/78563
- added support for atomic allocations (served from preallocated pool)
- minor cleanup here and there
- rebased onto v3.4-rc7

v1: http://thread.gmane.org/gmane.linux.kernel.mm/76703
- initial version

Patch summary:

Marek Szyprowski (3):
  mm: vmalloc: use const void * for caller argument
  mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping
    framework
  ARM: dma-mapping: remove custom consistent dma region

 Documentation/kernel-parameters.txt |    2 +-
 arch/arm/include/asm/dma-mapping.h  |    2 +-
 arch/arm/mm/dma-mapping.c           |  503 ++++++++++++-----------------------
 include/linux/vmalloc.h             |   10 +-
 mm/vmalloc.c                        |   31 ++-
 5 files changed, 206 insertions(+), 342 deletions(-)

-- 
1.7.1.569.g6f426

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[PATCHv3 1/3] mm: vmalloc: use const void * for caller argument

[Marek Szyprowski]

'const void *' is a safer type for caller function type. This patch
updates all references to caller function type.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/vmalloc.h |    8 ++++----
 mm/vmalloc.c            |   18 +++++++++---------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index dcdfc2b..2e28f4d 100644
--- a/include/linux/vmalloc.h
+++ b/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,
@@ -85,13 +85,13 @@ 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 int map_vm_area(struct vm_struct *area, pgprot_t prot,
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2aad499..11308f0 100644
--- a/mm/vmalloc.c
+++ b/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);
@@ -1397,7 +1397,7 @@ 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);
@@ -1568,9 +1568,9 @@ 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 +1643,7 @@ fail:
  */
 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 +1699,7 @@ fail:
  */
 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);
-- 
1.7.1.569.g6f426

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[PATCHv3 2/3] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework

[Marek Szyprowski]

Add new type of vm_area intented to be used for mappings created by
dma-mapping framework.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 include/linux/vmalloc.h |    1 +
 mm/vmalloc.c            |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 2e28f4d..e725b7b 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -14,6 +14,7 @@ struct vm_area_struct;		/* vma defining user mapping in mm_types.h */
 #define VM_USERMAP	0x00000008	/* suitable for remap_vmalloc_range */
 #define VM_VPAGES	0x00000010	/* buffer for pages was vmalloc'ed */
 #define VM_UNLIST	0x00000020	/* vm_struct is not listed in vmlist */
+#define VM_DMA		0x00000040	/* used by dma-mapping framework */
 /* bits [20..32] reserved for arch specific ioremap internals */
 
 /*
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 11308f0..e04d59b 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2575,6 +2575,9 @@ static int s_show(struct seq_file *m, void *p)
 	if (v->flags & VM_IOREMAP)
 		seq_printf(m, " ioremap");
 
+	if (v->flags & VM_DMA)
+		seq_printf(m, " dma");
+
 	if (v->flags & VM_ALLOC)
 		seq_printf(m, " vmalloc");
 
-- 
1.7.1.569.g6f426

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[PATCHv3 3/3] ARM: dma-mapping: remove custom consistent dma region

[Marek Szyprowski]

This patch changes dma-mapping subsystem to use generic vmalloc areas
for all consistent dma allocations. This increases the total size limit
of the consistent allocations and removes platform hacks and a lot of
duplicated code.

Atomic allocations are served from special pool preallocated on boot,
becasue vmalloc areas cannot be reliably created in atomic context.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 Documentation/kernel-parameters.txt |    2 +-
 arch/arm/include/asm/dma-mapping.h  |    2 +-
 arch/arm/mm/dma-mapping.c           |  503 ++++++++++++-----------------------
 include/linux/vmalloc.h             |    1 +
 mm/vmalloc.c                        |   10 +-
 5 files changed, 189 insertions(+), 329 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a92c5eb..da07f6c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/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.
 
 	code_bytes	[X86] How many bytes of object code to print
 			in an oops report.
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index bbef15d..80777d87 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -226,7 +226,7 @@ static inline int dma_mmap_writecombine(struct device *dev, struct vm_area_struc
  * 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"
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 106c4c0..b3ffcf9 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -22,6 +22,7 @@
 #include <linux/memblock.h>
 #include <linux/slab.h>
 #include <linux/iommu.h>
+#include <linux/io.h>
 #include <linux/vmalloc.h>
 
 #include <asm/memory.h>
@@ -217,115 +218,66 @@ static void __dma_free_buffer(struct page *page, size_t size)
 }
 
 #ifdef CONFIG_MMU
-
-#define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - consistent_base) >> PAGE_SHIFT)
-#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - consistent_base) >> PMD_SHIFT)
-
-/*
- * These are the page tables (2MB each) covering uncached, DMA consistent allocations
- */
-static pte_t **consistent_pte;
-
-#define DEFAULT_CONSISTENT_DMA_SIZE SZ_2M
-
-unsigned long consistent_base = CONSISTENT_END - DEFAULT_CONSISTENT_DMA_SIZE;
-
-void __init init_consistent_dma_size(unsigned long size)
-{
-	unsigned long base = CONSISTENT_END - ALIGN(size, SZ_2M);
-
-	BUG_ON(consistent_pte); /* Check we're called before DMA region init */
-	BUG_ON(base < VMALLOC_END);
-
-	/* Grow region to accommodate specified size  */
-	if (base < consistent_base)
-		consistent_base = base;
-}
-
-#include "vmregion.h"
-
-static struct arm_vmregion_head consistent_head = {
-	.vm_lock	= __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
-	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
-	.vm_end		= CONSISTENT_END,
-};
-
 #ifdef CONFIG_HUGETLB_PAGE
 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 #endif
 
-/*
- * Initialise the consistent memory allocation.
- */
-static int __init consistent_init(void)
-{
-	int ret = 0;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-	int i = 0;
-	unsigned long base = consistent_base;
-	unsigned long num_ptes = (CONSISTENT_END - base) >> PMD_SHIFT;
-
-	if (IS_ENABLED(CONFIG_CMA) && !IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU))
-		return 0;
-
-	consistent_pte = kmalloc(num_ptes * sizeof(pte_t), GFP_KERNEL);
-	if (!consistent_pte) {
-		pr_err("%s: no memory\n", __func__);
-		return -ENOMEM;
-	}
-
-	pr_debug("DMA memory: 0x%08lx - 0x%08lx:\n", base, CONSISTENT_END);
-	consistent_head.vm_start = base;
-
-	do {
-		pgd = pgd_offset(&init_mm, base);
-
-		pud = pud_alloc(&init_mm, pgd, base);
-		if (!pud) {
-			pr_err("%s: no pud tables\n", __func__);
-			ret = -ENOMEM;
-			break;
-		}
-
-		pmd = pmd_alloc(&init_mm, pud, base);
-		if (!pmd) {
-			pr_err("%s: no pmd tables\n", __func__);
-			ret = -ENOMEM;
-			break;
-		}
-		WARN_ON(!pmd_none(*pmd));
-
-		pte = pte_alloc_kernel(pmd, base);
-		if (!pte) {
-			pr_err("%s: no pte tables\n", __func__);
-			ret = -ENOMEM;
-			break;
-		}
-
-		consistent_pte[i++] = pte;
-		base += PMD_SIZE;
-	} while (base < CONSISTENT_END);
-
-	return ret;
-}
-core_initcall(consistent_init);
-
 static void *__alloc_from_contiguous(struct device *dev, size_t size,
 				     pgprot_t prot, struct page **ret_page);
 
-static struct arm_vmregion_head coherent_head = {
-	.vm_lock	= __SPIN_LOCK_UNLOCKED(&coherent_head.vm_lock),
-	.vm_list	= LIST_HEAD_INIT(coherent_head.vm_list),
+static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
+				 pgprot_t prot, struct page **ret_page,
+				 const void *caller);
+
+static void *
+__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
+	const void *caller)
+{
+	struct vm_struct *area;
+	unsigned long addr;
+
+	area = get_vm_area_caller(size, VM_DMA | VM_USERMAP, caller);
+	if (!area)
+		return NULL;
+	addr = (unsigned long)area->addr;
+	area->phys_addr = __pfn_to_phys(page_to_pfn(page));
+
+	if (ioremap_page_range(addr, addr + size, area->phys_addr, prot)) {
+		vunmap((void *)addr);
+		return NULL;
+	}
+	return (void *)addr;
+}
+
+static void __dma_free_remap(void *cpu_addr, size_t size)
+{
+	struct vm_struct *area = find_vm_area(cpu_addr);
+	if (!area || !(area->flags & VM_DMA)) {
+		pr_err("%s: trying to free invalid coherent area: %p\n",
+		       __func__, cpu_addr);
+		dump_stack();
+		return;
+	}
+	unmap_kernel_range((unsigned long)cpu_addr, size);
+	vunmap(cpu_addr);
+}
+
+struct dma_pool {
+	size_t size;
+	spinlock_t lock;
+	unsigned long *bitmap;
+	unsigned long nr_pages;
+	void *vaddr;
+	struct page *page;
 };
 
-size_t coherent_pool_size = DEFAULT_CONSISTENT_DMA_SIZE / 8;
+static struct dma_pool atomic_pool = {
+	.size = SZ_256K,
+};
 
 static int __init early_coherent_pool(char *p)
 {
-	coherent_pool_size = memparse(p, &p);
+	atomic_pool.size = memparse(p, &p);
 	return 0;
 }
 early_param("coherent_pool", early_coherent_pool);
@@ -333,32 +285,45 @@ early_param("coherent_pool", early_coherent_pool);
 /*
  * Initialise the coherent pool for atomic allocations.
  */
-static int __init coherent_init(void)
+static int __init atomic_pool_init(void)
 {
+	struct dma_pool *pool = &atomic_pool;
 	pgprot_t prot = pgprot_dmacoherent(pgprot_kernel);
-	size_t size = coherent_pool_size;
+	unsigned long nr_pages = pool->size >> PAGE_SHIFT;
+	unsigned long *bitmap;
 	struct page *page;
 	void *ptr;
+	int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long);
 
-	if (!IS_ENABLED(CONFIG_CMA))
-		return 0;
+	bitmap = kzalloc(bitmap_size, GFP_KERNEL);
+	if (!bitmap)
+		goto no_bitmap;
 
-	ptr = __alloc_from_contiguous(NULL, size, prot, &page);
+	if (IS_ENABLED(CONFIG_CMA))
+		ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page);
+	else
+		ptr = __alloc_remap_buffer(NULL, pool->size, GFP_KERNEL, prot,
+					   &page, NULL);
 	if (ptr) {
-		coherent_head.vm_start = (unsigned long) ptr;
-		coherent_head.vm_end = (unsigned long) ptr + size;
-		printk(KERN_INFO "DMA: preallocated %u KiB pool for atomic coherent allocations\n",
-		       (unsigned)size / 1024);
+		spin_lock_init(&pool->lock);
+		pool->vaddr = ptr;
+		pool->page = page;
+		pool->bitmap = bitmap;
+		pool->nr_pages = nr_pages;
+		pr_info("DMA: preallocated %u KiB pool for atomic coherent allocations\n",
+		       (unsigned)pool->size / 1024);
 		return 0;
 	}
-	printk(KERN_ERR "DMA: failed to allocate %u KiB pool for atomic coherent allocation\n",
-	       (unsigned)size / 1024);
+	kfree(bitmap);
+no_bitmap:
+	pr_err("DMA: failed to allocate %u KiB pool for atomic coherent allocation\n",
+	       (unsigned)pool->size / 1024);
 	return -ENOMEM;
 }
 /*
  * CMA is activated by core_initcall, so we must be called after it.
  */
-postcore_initcall(coherent_init);
+postcore_initcall(atomic_pool_init);
 
 struct dma_contig_early_reserve {
 	phys_addr_t base;
@@ -406,112 +371,6 @@ void __init dma_contiguous_remap(void)
 	}
 }
 
-static void *
-__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
-	const void *caller)
-{
-	struct arm_vmregion *c;
-	size_t align;
-	int bit;
-
-	if (!consistent_pte) {
-		pr_err("%s: not initialised\n", __func__);
-		dump_stack();
-		return NULL;
-	}
-
-	/*
-	 * Align the virtual region allocation - maximum alignment is
-	 * a section size, minimum is a page size.  This helps reduce
-	 * fragmentation of the DMA space, and also prevents allocations
-	 * smaller than a section from crossing a section boundary.
-	 */
-	bit = fls(size - 1);
-	if (bit > SECTION_SHIFT)
-		bit = SECTION_SHIFT;
-	align = 1 << bit;
-
-	/*
-	 * Allocate a virtual address in the consistent mapping region.
-	 */
-	c = arm_vmregion_alloc(&consistent_head, align, size,
-			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM), caller);
-	if (c) {
-		pte_t *pte;
-		int idx = CONSISTENT_PTE_INDEX(c->vm_start);
-		u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
-
-		pte = consistent_pte[idx] + off;
-		c->priv = page;
-
-		do {
-			BUG_ON(!pte_none(*pte));
-
-			set_pte_ext(pte, mk_pte(page, prot), 0);
-			page++;
-			pte++;
-			off++;
-			if (off >= PTRS_PER_PTE) {
-				off = 0;
-				pte = consistent_pte[++idx];
-			}
-		} while (size -= PAGE_SIZE);
-
-		dsb();
-
-		return (void *)c->vm_start;
-	}
-	return NULL;
-}
-
-static void __dma_free_remap(void *cpu_addr, size_t size)
-{
-	struct arm_vmregion *c;
-	unsigned long addr;
-	pte_t *ptep;
-	int idx;
-	u32 off;
-
-	c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
-	if (!c) {
-		pr_err("%s: trying to free invalid coherent area: %p\n",
-		       __func__, cpu_addr);
-		dump_stack();
-		return;
-	}
-
-	if ((c->vm_end - c->vm_start) != size) {
-		pr_err("%s: freeing wrong coherent size (%ld != %d)\n",
-		       __func__, c->vm_end - c->vm_start, size);
-		dump_stack();
-		size = c->vm_end - c->vm_start;
-	}
-
-	idx = CONSISTENT_PTE_INDEX(c->vm_start);
-	off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
-	ptep = consistent_pte[idx] + off;
-	addr = c->vm_start;
-	do {
-		pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
-
-		ptep++;
-		addr += PAGE_SIZE;
-		off++;
-		if (off >= PTRS_PER_PTE) {
-			off = 0;
-			ptep = consistent_pte[++idx];
-		}
-
-		if (pte_none(pte) || !pte_present(pte))
-			pr_crit("%s: bad page in kernel page table\n",
-				__func__);
-	} while (size -= PAGE_SIZE);
-
-	flush_tlb_kernel_range(c->vm_start, c->vm_end);
-
-	arm_vmregion_free(&consistent_head, c);
-}
-
 static int __dma_update_pte(pte_t *pte, pgtable_t token, unsigned long addr,
 			    void *data)
 {
@@ -552,15 +411,17 @@ static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
 	return ptr;
 }
 
-static void *__alloc_from_pool(struct device *dev, size_t size,
-			       struct page **ret_page, const void *caller)
+static void *__alloc_from_pool(size_t size, struct page **ret_page)
 {
-	struct arm_vmregion *c;
+	struct dma_pool *pool = &atomic_pool;
+	unsigned int count = size >> PAGE_SHIFT;
+	unsigned int pageno;
+	unsigned long flags;
+	void *ptr = NULL;
 	size_t align;
 
-	if (!coherent_head.vm_start) {
-		printk(KERN_ERR "%s: coherent pool not initialised!\n",
-		       __func__);
+	if (!pool->vaddr) {
+		pr_err("%s: coherent pool not initialised!\n", __func__);
 		dump_stack();
 		return NULL;
 	}
@@ -571,35 +432,42 @@ static void *__alloc_from_pool(struct device *dev, size_t size,
 	 * size. This helps reduce fragmentation of the DMA space.
 	 */
 	align = PAGE_SIZE << get_order(size);
-	c = arm_vmregion_alloc(&coherent_head, align, size, 0, caller);
-	if (c) {
-		void *ptr = (void *)c->vm_start;
-		struct page *page = virt_to_page(ptr);
-		*ret_page = page;
-		return ptr;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	pageno = bitmap_find_next_zero_area(pool->bitmap, pool->nr_pages,
+					    0, count, (1 << align) - 1);
+	if (pageno < pool->nr_pages) {
+		bitmap_set(pool->bitmap, pageno, count);
+		ptr = pool->vaddr + PAGE_SIZE * pageno;
+		*ret_page = pool->page + pageno;
 	}
-	return NULL;
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	return ptr;
 }
 
-static int __free_from_pool(void *cpu_addr, size_t size)
+static int __free_from_pool(void *start, size_t size)
 {
-	unsigned long start = (unsigned long)cpu_addr;
-	unsigned long end = start + size;
-	struct arm_vmregion *c;
+	struct dma_pool *pool = &atomic_pool;
+	unsigned long pageno, count;
+	unsigned long flags;
 
-	if (start < coherent_head.vm_start || end > coherent_head.vm_end)
+	if (start < pool->vaddr || start > pool->vaddr + pool->size)
 		return 0;
 
-	c = arm_vmregion_find_remove(&coherent_head, (unsigned long)start);
-
-	if ((c->vm_end - c->vm_start) != size) {
-		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
-		       __func__, c->vm_end - c->vm_start, size);
+	if (start + size > pool->vaddr + pool->size) {
+		pr_err("%s: freeing wrong coherent size from pool\n", __func__);
 		dump_stack();
-		size = c->vm_end - c->vm_start;
+		return 0;
 	}
 
-	arm_vmregion_free(&coherent_head, c);
+	pageno = (start - pool->vaddr) >> PAGE_SHIFT;
+	count = size >> PAGE_SHIFT;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	bitmap_clear(pool->bitmap, pageno, count);
+	spin_unlock_irqrestore(&pool->lock, flags);
+
 	return 1;
 }
 
@@ -702,10 +570,10 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 
 	if (arch_is_coherent() || nommu())
 		addr = __alloc_simple_buffer(dev, size, gfp, &page);
+	else if (gfp & GFP_ATOMIC)
+		addr = __alloc_from_pool(size, &page);
 	else if (!IS_ENABLED(CONFIG_CMA))
 		addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
-	else if (gfp & GFP_ATOMIC)
-		addr = __alloc_from_pool(dev, size, &page, caller);
 	else
 		addr = __alloc_from_contiguous(dev, size, prot, &page);
 
@@ -741,16 +609,22 @@ int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 {
 	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 = dma_to_pfn(dev, dma_addr);
+	unsigned long off = vma->vm_pgoff;
+
 	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
 
 	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
 		return ret;
 
-	ret = remap_pfn_range(vma, vma->vm_start,
-			      pfn + vma->vm_pgoff,
-			      vma->vm_end - vma->vm_start,
-			      vma->vm_page_prot);
+	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;
@@ -998,9 +872,6 @@ static int arm_dma_set_mask(struct device *dev, u64 dma_mask)
 
 static int __init dma_debug_do_init(void)
 {
-#ifdef CONFIG_MMU
-	arm_vmregion_create_proc("dma-mappings", &consistent_head);
-#endif
 	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 	return 0;
 }
@@ -1117,61 +988,31 @@ static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t s
  * Create a CPU mapping for a specified pages
  */
 static void *
-__iommu_alloc_remap(struct page **pages, size_t size, gfp_t gfp, pgprot_t prot)
+__iommu_alloc_remap(struct page **pages, size_t size, gfp_t gfp, pgprot_t prot,
+		    const void *caller)
 {
-	struct arm_vmregion *c;
-	size_t align;
-	size_t count = size >> PAGE_SHIFT;
-	int bit;
+	unsigned int i, nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	struct vm_struct *area;
+	unsigned long p;
 
-	if (!consistent_pte[0]) {
-		pr_err("%s: not initialised\n", __func__);
-		dump_stack();
+	area = get_vm_area_caller(size, VM_DMA | VM_USERMAP, caller);
+	if (!area)
 		return NULL;
-	}
-
-	/*
-	 * Align the virtual region allocation - maximum alignment is
-	 * a section size, minimum is a page size.  This helps reduce
-	 * fragmentation of the DMA space, and also prevents allocations
-	 * smaller than a section from crossing a section boundary.
-	 */
-	bit = fls(size - 1);
-	if (bit > SECTION_SHIFT)
-		bit = SECTION_SHIFT;
-	align = 1 << bit;
-
-	/*
-	 * Allocate a virtual address in the consistent mapping region.
-	 */
-	c = arm_vmregion_alloc(&consistent_head, align, size,
-			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM), NULL);
-	if (c) {
-		pte_t *pte;
-		int idx = CONSISTENT_PTE_INDEX(c->vm_start);
-		int i = 0;
-		u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
-
-		pte = consistent_pte[idx] + off;
-		c->priv = pages;
-
-		do {
-			BUG_ON(!pte_none(*pte));
-
-			set_pte_ext(pte, mk_pte(pages[i], prot), 0);
-			pte++;
-			off++;
-			i++;
-			if (off >= PTRS_PER_PTE) {
-				off = 0;
-				pte = consistent_pte[++idx];
-			}
-		} while (i < count);
 
-		dsb();
+	area->pages = pages;
+	area->nr_pages = nr_pages;
+	p = (unsigned long)area->addr;
 
-		return (void *)c->vm_start;
+	for (i = 0; i < nr_pages; i++) {
+		phys_addr_t phys = __pfn_to_phys(page_to_pfn(pages[i]));
+		if (ioremap_page_range(p, p + PAGE_SIZE, phys, prot))
+			goto err;
+		p += PAGE_SIZE;
 	}
+	return area->addr;
+err:
+	unmap_kernel_range((unsigned long)area->addr, size);
+	vunmap(area->addr);
 	return NULL;
 }
 
@@ -1230,6 +1071,16 @@ static int __iommu_remove_mapping(struct device *dev, dma_addr_t iova, size_t si
 	return 0;
 }
 
+static struct page **__iommu_get_pages(void *cpu_addr)
+{
+	struct vm_struct *area;
+
+	area = find_vm_area(cpu_addr);
+	if (area && (area->flags & VM_DMA))
+		return area->pages;
+	return NULL;
+}
+
 static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
 	    dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs)
 {
@@ -1248,7 +1099,8 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
 	if (*handle == DMA_ERROR_CODE)
 		goto err_buffer;
 
-	addr = __iommu_alloc_remap(pages, size, gfp, prot);
+	addr = __iommu_alloc_remap(pages, size, gfp, prot,
+				   __builtin_return_address(0));
 	if (!addr)
 		goto err_mapping;
 
@@ -1265,31 +1117,25 @@ static int arm_iommu_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 arm_vmregion *c;
+	unsigned long uaddr = vma->vm_start;
+	unsigned long usize = vma->vm_end - vma->vm_start;
+	struct page **pages = __iommu_get_pages(cpu_addr);
 
 	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot);
-	c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
 
-	if (c) {
-		struct page **pages = c->priv;
+	if (!pages)
+		return -ENXIO;
 
-		unsigned long uaddr = vma->vm_start;
-		unsigned long usize = vma->vm_end - vma->vm_start;
-		int i = 0;
+	do {
+		int ret = vm_insert_page(vma, uaddr, *pages++);
+		if (ret) {
+			pr_err("Remapping memory failed: %d\n", ret);
+			return ret;
+		}
+		uaddr += PAGE_SIZE;
+		usize -= PAGE_SIZE;
+	} while (usize > 0);
 
-		do {
-			int ret;
-
-			ret = vm_insert_page(vma, uaddr, pages[i++]);
-			if (ret) {
-				pr_err("Remapping memory, error: %d\n", ret);
-				return ret;
-			}
-
-			uaddr += PAGE_SIZE;
-			usize -= PAGE_SIZE;
-		} while (usize > 0);
-	}
 	return 0;
 }
 
@@ -1300,16 +1146,21 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 void arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 			  dma_addr_t handle, struct dma_attrs *attrs)
 {
-	struct arm_vmregion *c;
+	struct page **pages = __iommu_get_pages(cpu_addr);
 	size = PAGE_ALIGN(size);
 
-	c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
-	if (c) {
-		struct page **pages = c->priv;
-		__dma_free_remap(cpu_addr, size);
-		__iommu_remove_mapping(dev, handle, size);
-		__iommu_free_buffer(dev, pages, size);
+	if (!pages) {
+		pr_err("%s: trying to free invalid coherent area: %p\n",
+		       __func__, cpu_addr);
+		dump_stack();
+		return;
 	}
+
+	unmap_kernel_range((unsigned long)cpu_addr, size);
+	vunmap(cpu_addr);
+
+	__iommu_remove_mapping(dev, handle, size);
+	__iommu_free_buffer(dev, pages, size);
 }
 
 /*
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index e725b7b..8a9555a 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -94,6 +94,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size,
 					unsigned long start, unsigned long end,
 					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);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e04d59b..4ab106c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1403,7 +1403,15 @@ struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
 						-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;
 
-- 
1.7.1.569.g6f426

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Re: [PATCHv3 2/3] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework

[Minchan Kim]

Hi Marek,

On 06/13/2012 08:01 PM, Marek Szyprowski wrote:

> Add new type of vm_area intented to be used for mappings created by
> dma-mapping framework.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  include/linux/vmalloc.h |    1 +
>  mm/vmalloc.c            |    3 +++
>  2 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 2e28f4d..e725b7b 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -14,6 +14,7 @@ struct vm_area_struct;		/* vma defining user mapping in mm_types.h */
>  #define VM_USERMAP	0x00000008	/* suitable for remap_vmalloc_range */
>  #define VM_VPAGES	0x00000010	/* buffer for pages was vmalloc'ed */
>  #define VM_UNLIST	0x00000020	/* vm_struct is not listed in vmlist */
> +#define VM_DMA		0x00000040	/* used by dma-mapping framework */
>  /* bits [20..32] reserved for arch specific ioremap internals */
>  
>  /*
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 11308f0..e04d59b 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2575,6 +2575,9 @@ static int s_show(struct seq_file *m, void *p)
>  	if (v->flags & VM_IOREMAP)
>  		seq_printf(m, " ioremap");
>  
> +	if (v->flags & VM_DMA)
> +		seq_printf(m, " dma");
> +
>  	if (v->flags & VM_ALLOC)
>  		seq_printf(m, " vmalloc");
>  


I still don't make sure that we should add new type for only ARM arch.
I remember you said "It would be used for other architectures once we add" and 
Paul said he has a plan for SH. So at least, you should add such comment in changelog
for persuading grumpy maintainers. :)

Frankly speaking, I could add my Reviewed-by but I think it wouldn't carry much weight
because code is very tiny so you need Acked-by rather than Reviewed-by.
IMHO, This problem is the thing only maintainer should decide.
So I will toss the decision to akpm. Ccing akpm.(Ccing KOSAKI because he had a concern about this).

If anyone have a question to me, I'm Acked-by iff other architecture will use it.
-- 
Kind regards,
Minchan Kim

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RE: [PATCHv3 2/3] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework

[Marek Szyprowski]

Hi,

On Thursday, June 21, 2012 10:36 AM Minchan Kim wrote:

> On 06/13/2012 08:01 PM, Marek Szyprowski wrote:
> 
> > Add new type of vm_area intented to be used for mappings created by
> > dma-mapping framework.
> >
> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
> > ---
> >  include/linux/vmalloc.h |    1 +
> >  mm/vmalloc.c            |    3 +++
> >  2 files changed, 4 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> > index 2e28f4d..e725b7b 100644
> > --- a/include/linux/vmalloc.h
> > +++ b/include/linux/vmalloc.h
> > @@ -14,6 +14,7 @@ struct vm_area_struct;		/* vma defining user mapping in
> mm_types.h */
> >  #define VM_USERMAP	0x00000008	/* suitable for remap_vmalloc_range */
> >  #define VM_VPAGES	0x00000010	/* buffer for pages was vmalloc'ed */
> >  #define VM_UNLIST	0x00000020	/* vm_struct is not listed in vmlist */
> > +#define VM_DMA		0x00000040	/* used by dma-mapping framework */
> >  /* bits [20..32] reserved for arch specific ioremap internals */
> >
> >  /*
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 11308f0..e04d59b 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -2575,6 +2575,9 @@ static int s_show(struct seq_file *m, void *p)
> >  	if (v->flags & VM_IOREMAP)
> >  		seq_printf(m, " ioremap");
> >
> > +	if (v->flags & VM_DMA)
> > +		seq_printf(m, " dma");
> > +
> >  	if (v->flags & VM_ALLOC)
> >  		seq_printf(m, " vmalloc");
> >
> 
> 
> I still don't make sure that we should add new type for only ARM arch.
> I remember you said "It would be used for other architectures once we add" and
> Paul said he has a plan for SH. So at least, you should add such comment in changelog
> for persuading grumpy maintainers. :)
> 
> Frankly speaking, I could add my Reviewed-by but I think it wouldn't carry much weight
> because code is very tiny so you need Acked-by rather than Reviewed-by.
> IMHO, This problem is the thing only maintainer should decide.
> So I will toss the decision to akpm. Ccing akpm.(Ccing KOSAKI because he had a concern about
> this).
> 
> If anyone have a question to me, I'm Acked-by iff other architecture will use it.

Ok, if this flag is so controversial, I can change it to arch specific VM flag and utilize
'bits [20..32] reserved for arch specific ioremap internals'. Later, when other architectures 
start using similar flag, one can unify them and add such generic flag.

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center


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