Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
On 8/7/19 8:04 AM, Christoph Hellwig wrote: Actually it is typical modern Linux style to just provide a prototype and then use "if (IS_ENABLED(CONFIG_FOO))" to guard the call(s) to it. I see. Also, like Will mentioned earlier, the function name isn't entirely accurate anymore. I second the suggestion of using something like arch_dma_noncoherent_pgprot(). As mentioned I plan to remove arch_dma_mmap_pgprot for 5.4, so I'd rather avoid churn for the short period of time. Yeah, fair enough. As for your idea of defining pgprot_dmacoherent for all architectures as #ifndef pgprot_dmacoherent #define pgprot_dmacoherent pgprot_noncached #endif I think that the name here is kind of misleading too, since this definition will only be used when there is no support for proper DMA coherency. Do you have a suggestion for a better name? I'm pretty bad at naming, so just reusing the arm name seemed like a good way to avoid having to make naming decisions myself. Good question. Perhaps something like `pgprot_dmacoherent_fallback` would better convey that this is only used for devices that don't support DMA coherency? Or maybe `pgprot_dma_noncoherent`? ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
All the way back to introducing dma_common_mmap we've defaulted to mark
the pages as uncached. But this is wrong for DMA coherent devices.
Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that
flag is only treated special on the alloc side for non-coherent devices.
Introduce a new dma_pgprot helper that deals with the check for coherent
devices so that only the remapping cases ever reach arch_dma_mmap_pgprot
and we thus ensure no aliasing of page attributes happens, which makes
the powerpc version of arch_dma_mmap_pgprot obsolete and simplifies the
remaining ones.
Note that this means arch_dma_mmap_pgprot is a bit misnamed now, but
we'll phase it out soon.
Fixes: 64ccc9c033c6 ("common: dma-mapping: add support for generic dma_mmap_*
calls")
Reported-by: Shawn Anastasio
Reported-by: Gavin Li
Signed-off-by: Christoph Hellwig
Acked-by: Catalin Marinas # arm64
---
arch/arm/mm/dma-mapping.c| 4 +---
arch/arm64/mm/dma-mapping.c | 4 +---
arch/powerpc/Kconfig | 1 -
arch/powerpc/kernel/dma-common.c | 17 -
drivers/iommu/dma-iommu.c| 6 +++---
include/linux/dma-noncoherent.h | 13 +
kernel/dma/mapping.c | 17 -
kernel/dma/remap.c | 2 +-
8 files changed, 31 insertions(+), 33 deletions(-)
delete mode 100644 arch/powerpc/kernel/dma-common.c
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 6774b03aa405..d42557ee69c2 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2405,9 +2405,7 @@ long arch_dma_coherent_to_pfn(struct device *dev, void
*cpu_addr,
pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
unsigned long attrs)
{
- if (!dev_is_dma_coherent(dev))
- return __get_dma_pgprot(attrs, prot);
- return prot;
+ return __get_dma_pgprot(attrs, prot);
}
void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 1d3f0b5a9940..bd2b039f43a6 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -14,9 +14,7 @@
pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
unsigned long attrs)
{
- if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE))
- return pgprot_writecombine(prot);
- return prot;
+ return pgprot_writecombine(prot);
}
void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 77f6ebf97113..d8dcd8820369 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -121,7 +121,6 @@ config PPC
select ARCH_32BIT_OFF_T if PPC32
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEVMEM_IS_ALLOWED
- select ARCH_HAS_DMA_MMAP_PGPROT
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/powerpc/kernel/dma-common.c b/arch/powerpc/kernel/dma-common.c
deleted file mode 100644
index dc7ef6b17b69..
--- a/arch/powerpc/kernel/dma-common.c
+++ /dev/null
@@ -1,17 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Contains common dma routines for all powerpc platforms.
- *
- * Copyright (C) 2019 Shawn Anastasio.
- */
-
-#include
-#include
-
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
- unsigned long attrs)
-{
- if (!dev_is_dma_coherent(dev))
- return pgprot_noncached(prot);
- return prot;
-}
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index a7f9c3edbcb2..0015fe610b23 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -574,7 +574,7 @@ static void *iommu_dma_alloc_remap(struct device *dev,
size_t size,
struct iova_domain *iovad = >iovad;
bool coherent = dev_is_dma_coherent(dev);
int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
- pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
+ pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
struct page **pages;
struct sg_table sgt;
@@ -975,7 +975,7 @@ static void *iommu_dma_alloc_pages(struct device *dev,
size_t size,
return NULL;
if (IS_ENABLED(CONFIG_DMA_REMAP) && (!coherent || PageHighMem(page))) {
- pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
+ pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
cpu_addr = dma_common_contiguous_remap(page, alloc_size,
VM_USERMAP, prot, __builtin_return_address(0));
@@ -1035,7 +1035,7 @@ static int iommu_dma_mmap(struct device *dev, struct
vm_area_struct *vma,
unsigned long pfn, off = vma->vm_pgoff;
int ret;
-
Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
On Tue, Aug 06, 2019 at 09:39:06PM +0200, Shawn Anastasio wrote: >> -#ifdef CONFIG_ARCH_HAS_DMA_MMAP_PGPROT >> pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, >> unsigned long attrs); >> -#else >> -# define arch_dma_mmap_pgprot(dev, prot, attrs) pgprot_noncached(prot) >> -#endif > > Nit, but maybe the prototype should still be ifdef'd here? It at least > could prevent a reader from incorrectly thinking that the function is > always present. Actually it is typical modern Linux style to just provide a prototype and then use "if (IS_ENABLED(CONFIG_FOO))" to guard the call(s) to it. > > Also, like Will mentioned earlier, the function name isn't entirely > accurate anymore. I second the suggestion of using something like > arch_dma_noncoherent_pgprot(). As mentioned I plan to remove arch_dma_mmap_pgprot for 5.4, so I'd rather avoid churn for the short period of time. > As for your idea of defining > pgprot_dmacoherent for all architectures as > > #ifndef pgprot_dmacoherent > #define pgprot_dmacoherent pgprot_noncached > #endif > > I think that the name here is kind of misleading too, since this > definition will only be used when there is no support for proper > DMA coherency. Do you have a suggestion for a better name? I'm pretty bad at naming, so just reusing the arm name seemed like a good way to avoid having to make naming decisions myself.
Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
On 8/5/19 10:01 AM, Christoph Hellwig wrote: diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h index 3813211a9aad..9ae5cee543c4 100644 --- a/include/linux/dma-noncoherent.h +++ b/include/linux/dma-noncoherent.h @@ -42,13 +42,8 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs); long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, dma_addr_t dma_addr); - -#ifdef CONFIG_ARCH_HAS_DMA_MMAP_PGPROT pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs); -#else -# define arch_dma_mmap_pgprot(dev, prot, attrs)pgprot_noncached(prot) -#endif Nit, but maybe the prototype should still be ifdef'd here? It at least could prevent a reader from incorrectly thinking that the function is always present. Also, like Will mentioned earlier, the function name isn't entirely accurate anymore. I second the suggestion of using something like arch_dma_noncoherent_pgprot(). As for your idea of defining pgprot_dmacoherent for all architectures as #ifndef pgprot_dmacoherent #define pgprot_dmacoherent pgprot_noncached #endif I think that the name here is kind of misleading too, since this definition will only be used when there is no support for proper DMA coherency. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
On Mon, Aug 05, 2019 at 11:01:44AM +0300, Christoph Hellwig wrote:
> All the way back to introducing dma_common_mmap we've defaulyed to mark
s/defaultyed/defaulted/
> the pages as uncached. But this is wrong for DMA coherent devices.
> Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that
> flag is only treated special on the alloc side for non-coherent devices.
>
> Introduce a new dma_pgprot helper that deals with the check for coherent
> devices so that only the remapping cases even reach arch_dma_mmap_pgprot
s/even/ever/
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 1d3f0b5a9940..bd2b039f43a6 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -14,9 +14,7 @@
> pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
> unsigned long attrs)
> {
> - if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE))
> - return pgprot_writecombine(prot);
> - return prot;
> + return pgprot_writecombine(prot);
> }
For arm64:
Acked-by: Catalin Marinas
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
All the way back to introducing dma_common_mmap we've defaulyed to mark
the pages as uncached. But this is wrong for DMA coherent devices.
Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that
flag is only treated special on the alloc side for non-coherent devices.
Introduce a new dma_pgprot helper that deals with the check for coherent
devices so that only the remapping cases even reach arch_dma_mmap_pgprot
and we thus ensure no aliasing of page attributes happens, which makes
the powerpc version of arch_dma_mmap_pgprot obsolete and simplifies the
remaining ones.
Note that this means arch_dma_mmap_pgprot is a bit misnamed now, but
we'll phase it out soon.
Fixes: 64ccc9c033c6 ("common: dma-mapping: add support for generic dma_mmap_*
calls")
Reported-by: Shawn Anastasio
Reported-by: Gavin Li
Signed-off-by: Christoph Hellwig
---
arch/arm/mm/dma-mapping.c| 4 +---
arch/arm64/mm/dma-mapping.c | 4 +---
arch/powerpc/Kconfig | 1 -
arch/powerpc/kernel/dma-common.c | 17 -
drivers/iommu/dma-iommu.c| 6 +++---
include/linux/dma-mapping.h | 1 +
include/linux/dma-noncoherent.h | 5 -
kernel/dma/mapping.c | 17 -
kernel/dma/remap.c | 2 +-
9 files changed, 23 insertions(+), 34 deletions(-)
delete mode 100644 arch/powerpc/kernel/dma-common.c
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 6774b03aa405..d42557ee69c2 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2405,9 +2405,7 @@ long arch_dma_coherent_to_pfn(struct device *dev, void
*cpu_addr,
pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
unsigned long attrs)
{
- if (!dev_is_dma_coherent(dev))
- return __get_dma_pgprot(attrs, prot);
- return prot;
+ return __get_dma_pgprot(attrs, prot);
}
void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 1d3f0b5a9940..bd2b039f43a6 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -14,9 +14,7 @@
pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
unsigned long attrs)
{
- if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE))
- return pgprot_writecombine(prot);
- return prot;
+ return pgprot_writecombine(prot);
}
void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 77f6ebf97113..d8dcd8820369 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -121,7 +121,6 @@ config PPC
select ARCH_32BIT_OFF_T if PPC32
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEVMEM_IS_ALLOWED
- select ARCH_HAS_DMA_MMAP_PGPROT
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/powerpc/kernel/dma-common.c b/arch/powerpc/kernel/dma-common.c
deleted file mode 100644
index dc7ef6b17b69..
--- a/arch/powerpc/kernel/dma-common.c
+++ /dev/null
@@ -1,17 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Contains common dma routines for all powerpc platforms.
- *
- * Copyright (C) 2019 Shawn Anastasio.
- */
-
-#include
-#include
-
-pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
- unsigned long attrs)
-{
- if (!dev_is_dma_coherent(dev))
- return pgprot_noncached(prot);
- return prot;
-}
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index a7f9c3edbcb2..0015fe610b23 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -574,7 +574,7 @@ static void *iommu_dma_alloc_remap(struct device *dev,
size_t size,
struct iova_domain *iovad = >iovad;
bool coherent = dev_is_dma_coherent(dev);
int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
- pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
+ pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
struct page **pages;
struct sg_table sgt;
@@ -975,7 +975,7 @@ static void *iommu_dma_alloc_pages(struct device *dev,
size_t size,
return NULL;
if (IS_ENABLED(CONFIG_DMA_REMAP) && (!coherent || PageHighMem(page))) {
- pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
+ pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
cpu_addr = dma_common_contiguous_remap(page, alloc_size,
VM_USERMAP, prot, __builtin_return_address(0));
@@ -1035,7 +1035,7 @@ static int iommu_dma_mmap(struct device *dev, struct
vm_area_struct *vma,
unsigned long pfn, off = vma->vm_pgoff;
int ret;
-
