[PATCH v2 2/2] arm/dma-mapping: Respect NO_KERNEL_MAPPING when we don't have an IOMMU
Carlo Caione
carlo at caione.org
Wed Feb 4 01:23:20 PST 2015
From: "Jasper St. Pierre" <jstpierre at mecheye.net>
Even without an iommu, NO_KERNEL_MAPPING is still convenient to save on
kernel address space in places where we don't need a kernel mapping.
Implement support for it in the two places where we're creating an
expensive mapping.
__alloc_from_pool uses an internal pool from which we already have
virtual addresses, so it's not relevant, and __alloc_simple_buffer uses
alloc_pages, which will always return a lowmem page, which is already
mapped into kernel space, so we can't prevent a mapping for it in that
case.
Signed-off-by: Jasper St. Pierre <jstpierre at mecheye.net>
Signed-off-by: Carlo Caione <carlo at caione.org>
Reviewed-by: Rob Clark <robdclark at gmail.com>
Reviewed-by: Daniel Drake <dsd at endlessm.com>
---
arch/arm/mm/dma-mapping.c | 67 +++++++++++++++++++++++++++++------------------
1 file changed, 41 insertions(+), 26 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index a673c7f..d767bba 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -289,11 +289,11 @@ static void __dma_free_buffer(struct page *page, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
- const void *caller);
+ const void *caller, bool want_vaddr);
static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
pgprot_t prot, struct page **ret_page,
- const void *caller);
+ const void *caller, bool want_vaddr);
static void *
__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot,
@@ -357,10 +357,10 @@ static int __init atomic_pool_init(void)
if (dev_get_cma_area(NULL))
ptr = __alloc_from_contiguous(NULL, atomic_pool_size, prot,
- &page, atomic_pool_init);
+ &page, atomic_pool_init, true);
else
ptr = __alloc_remap_buffer(NULL, atomic_pool_size, gfp, prot,
- &page, atomic_pool_init);
+ &page, atomic_pool_init, true);
if (ptr) {
int ret;
@@ -467,13 +467,15 @@ static void __dma_remap(struct page *page, size_t size, pgprot_t prot)
static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
pgprot_t prot, struct page **ret_page,
- const void *caller)
+ const void *caller, bool want_vaddr)
{
struct page *page;
- void *ptr;
+ void *ptr = NULL;
page = __dma_alloc_buffer(dev, size, gfp);
if (!page)
return NULL;
+ if (!want_vaddr)
+ goto out;
ptr = __dma_alloc_remap(page, size, gfp, prot, caller);
if (!ptr) {
@@ -481,6 +483,7 @@ static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
return NULL;
}
+ out:
*ret_page = page;
return ptr;
}
@@ -523,12 +526,12 @@ static int __free_from_pool(void *start, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
- const void *caller)
+ const void *caller, bool want_vaddr)
{
unsigned long order = get_order(size);
size_t count = size >> PAGE_SHIFT;
struct page *page;
- void *ptr;
+ void *ptr = NULL;
page = dma_alloc_from_contiguous(dev, count, order);
if (!page)
@@ -536,6 +539,9 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
__dma_clear_buffer(page, size);
+ if (!want_vaddr)
+ goto out;
+
if (PageHighMem(page)) {
ptr = __dma_alloc_remap(page, size, GFP_KERNEL, prot, caller);
if (!ptr) {
@@ -546,17 +552,21 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
__dma_remap(page, size, prot);
ptr = page_address(page);
}
+
+ out:
*ret_page = page;
return ptr;
}
static void __free_from_contiguous(struct device *dev, struct page *page,
- void *cpu_addr, size_t size)
+ void *cpu_addr, size_t size, bool want_vaddr)
{
- if (PageHighMem(page))
- __dma_free_remap(cpu_addr, size);
- else
- __dma_remap(page, size, PAGE_KERNEL);
+ if (want_vaddr) {
+ if (PageHighMem(page))
+ __dma_free_remap(cpu_addr, size);
+ else
+ __dma_remap(page, size, PAGE_KERNEL);
+ }
dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
}
@@ -574,12 +584,12 @@ static inline pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot)
#define nommu() 1
-#define __get_dma_pgprot(attrs, prot) __pgprot(0)
-#define __alloc_remap_buffer(dev, size, gfp, prot, ret, c) NULL
+#define __get_dma_pgprot(attrs, prot) __pgprot(0)
+#define __alloc_remap_buffer(dev, size, gfp, prot, ret, c, wv) NULL
#define __alloc_from_pool(size, ret_page) NULL
-#define __alloc_from_contiguous(dev, size, prot, ret, c) NULL
+#define __alloc_from_contiguous(dev, size, prot, ret, c, wv) NULL
#define __free_from_pool(cpu_addr, size) 0
-#define __free_from_contiguous(dev, page, cpu_addr, size) do { } while (0)
+#define __free_from_contiguous(dev, page, cpu_addr, size, wv) do { } while (0)
#define __dma_free_remap(cpu_addr, size) do { } while (0)
#endif /* CONFIG_MMU */
@@ -599,11 +609,13 @@ static void *__alloc_simple_buffer(struct device *dev, size_t size, gfp_t gfp,
static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
- gfp_t gfp, pgprot_t prot, bool is_coherent, const void *caller)
+ gfp_t gfp, pgprot_t prot, bool is_coherent,
+ struct dma_attrs *attrs, const void *caller)
{
u64 mask = get_coherent_dma_mask(dev);
struct page *page = NULL;
void *addr;
+ bool want_vaddr;
#ifdef CONFIG_DMA_API_DEBUG
u64 limit = (mask + 1) & ~mask;
@@ -631,20 +643,21 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
*handle = DMA_ERROR_CODE;
size = PAGE_ALIGN(size);
+ want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs);
if (is_coherent || nommu())
addr = __alloc_simple_buffer(dev, size, gfp, &page);
else if (!(gfp & __GFP_WAIT))
addr = __alloc_from_pool(size, &page);
else if (!dev_get_cma_area(dev))
- addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
+ addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller, want_vaddr);
else
- addr = __alloc_from_contiguous(dev, size, prot, &page, caller);
+ addr = __alloc_from_contiguous(dev, size, prot, &page, caller, want_vaddr);
- if (addr)
+ if (page)
*handle = pfn_to_dma(dev, page_to_pfn(page));
- return addr;
+ return want_vaddr ? addr : page;
}
/*
@@ -661,7 +674,7 @@ void *arm_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
return memory;
return __dma_alloc(dev, size, handle, gfp, prot, false,
- __builtin_return_address(0));
+ attrs, __builtin_return_address(0));
}
static void *arm_coherent_dma_alloc(struct device *dev, size_t size,
@@ -674,7 +687,7 @@ static void *arm_coherent_dma_alloc(struct device *dev, size_t size,
return memory;
return __dma_alloc(dev, size, handle, gfp, prot, true,
- __builtin_return_address(0));
+ attrs, __builtin_return_address(0));
}
/*
@@ -715,6 +728,7 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
bool is_coherent)
{
struct page *page = pfn_to_page(dma_to_pfn(dev, handle));
+ bool want_vaddr = !dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs);
if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
return;
@@ -726,14 +740,15 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
} else if (__free_from_pool(cpu_addr, size)) {
return;
} else if (!dev_get_cma_area(dev)) {
- __dma_free_remap(cpu_addr, size);
+ if (want_vaddr)
+ __dma_free_remap(cpu_addr, size);
__dma_free_buffer(page, size);
} else {
/*
* Non-atomic allocations cannot be freed with IRQs disabled
*/
WARN_ON(irqs_disabled());
- __free_from_contiguous(dev, page, cpu_addr, size);
+ __free_from_contiguous(dev, page, cpu_addr, size, want_vaddr);
}
}
--
2.2.2
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