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Subject[PATCH 3/4] dma-mapping: introduce a dma_common_find_pages helper
Date
A helper to find the backing page array based on a virtual address.
This also ensures we do the same vm_flags check everywhere instead
of slightly different or missing ones in a few places.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/arm/mm/dma-mapping.c | 7 +------
drivers/iommu/dma-iommu.c | 15 +++------------
include/linux/dma-mapping.h | 1 +
kernel/dma/remap.c | 13 +++++++++++--
4 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 054a66f725b3..d07e5c865557 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1447,18 +1447,13 @@ static struct page **__atomic_get_pages(void *addr)

static struct page **__iommu_get_pages(void *cpu_addr, unsigned long attrs)
{
- struct vm_struct *area;
-
if (__in_atomic_pool(cpu_addr, PAGE_SIZE))
return __atomic_get_pages(cpu_addr);

if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
return cpu_addr;

- area = find_vm_area(cpu_addr);
- if (area && (area->flags & VM_DMA_COHERENT))
- return area->pages;
- return NULL;
+ return dma_common_find_pages(cpu_addr);
}

static void *__iommu_alloc_simple(struct device *dev, size_t size, gfp_t gfp,
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 013416f5ad38..eafc378da448 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -541,15 +541,6 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev,
return pages;
}

-static struct page **__iommu_dma_get_pages(void *cpu_addr)
-{
- struct vm_struct *area = find_vm_area(cpu_addr);
-
- if (!area || !area->pages)
- return NULL;
- return area->pages;
-}
-
/**
* iommu_dma_alloc_remap - Allocate and map a buffer contiguous in IOVA space
* @dev: Device to allocate memory for. Must be a real device
@@ -938,7 +929,7 @@ static void __iommu_dma_free(struct device *dev, size_t size, void *cpu_addr)
* If it the address is remapped, then it's either non-coherent
* or highmem CMA, or an iommu_dma_alloc_remap() construction.
*/
- pages = __iommu_dma_get_pages(cpu_addr);
+ pages = dma_common_find_pages(cpu_addr);
if (!pages)
page = vmalloc_to_page(cpu_addr);
dma_common_free_remap(cpu_addr, alloc_size);
@@ -1045,7 +1036,7 @@ static int iommu_dma_mmap(struct device *dev, struct vm_area_struct *vma,
return -ENXIO;

if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
- struct page **pages = __iommu_dma_get_pages(cpu_addr);
+ struct page **pages = dma_common_find_pages(cpu_addr);

if (pages)
return __iommu_dma_mmap(pages, size, vma);
@@ -1067,7 +1058,7 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
int ret;

if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
- struct page **pages = __iommu_dma_get_pages(cpu_addr);
+ struct page **pages = dma_common_find_pages(cpu_addr);

if (pages) {
return sg_alloc_table_from_pages(sgt, pages,
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index c9725390fbbc..e4840f40ae69 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -615,6 +615,7 @@ extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs);

+struct page **dma_common_find_pages(void *cpu_addr);
void *dma_common_contiguous_remap(struct page *page, size_t size,
pgprot_t prot, const void *caller);

diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
index 01d4ef5685a4..3482fc585c59 100644
--- a/kernel/dma/remap.c
+++ b/kernel/dma/remap.c
@@ -11,6 +11,15 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>

+struct page **dma_common_find_pages(void *cpu_addr)
+{
+ struct vm_struct *area = find_vm_area(cpu_addr);
+
+ if (!area || area->flags != VM_DMA_COHERENT)
+ return NULL;
+ return area->pages;
+}
+
static struct vm_struct *__dma_common_pages_remap(struct page **pages,
size_t size, pgprot_t prot, const void *caller)
{
@@ -78,9 +87,9 @@ void *dma_common_contiguous_remap(struct page *page, size_t size,
*/
void dma_common_free_remap(void *cpu_addr, size_t size)
{
- struct vm_struct *area = find_vm_area(cpu_addr);
+ struct page **pages = dma_common_find_pages(cpu_addr);

- if (!area || area->flags != VM_DMA_COHERENT) {
+ if (!pages) {
WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
return;
}
--
2.20.1
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