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SubjectRe: [PATCH] dma-mapping: move the remap helpers to a separate file
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On 10/14/2018 11:16 AM, Christoph Hellwig wrote:
> The dma remap code only really makes sense for not cache coherent
> architectures, and currently is only used by arm, arm64 and xtensa.
> Split it out into a separate file with a separate Kconfig symbol.
>
> [Laura: you wrote this code back then, do you have a sensible
> copyright statement to add, given that the mapping.c statement
> obviously does not match your code that was written much later]
>

Hmmmmm, that was written and committed via my codeaurora.org e-mail
address. Probably best to use "Copyright (c) 2014, The Linux Foundation"
since that was the standard. If you want,

Acked-by: Laura Abbott <labbott@redhat.com>

Thanks,
Laura

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/arm/Kconfig | 1 +
> arch/arm64/Kconfig | 1 +
> arch/xtensa/Kconfig | 1 +
> kernel/dma/Kconfig | 4 +++
> kernel/dma/Makefile | 2 +-
> kernel/dma/mapping.c | 84 -------------------------------------------
> kernel/dma/remap.c | 85 ++++++++++++++++++++++++++++++++++++++++++++
> 7 files changed, 93 insertions(+), 85 deletions(-)
> create mode 100644 kernel/dma/remap.c
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index e8cd55a5b04c..cf54e572dafd 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -30,6 +30,7 @@ config ARM
> select CPU_PM if (SUSPEND || CPU_IDLE)
> select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
> select DMA_DIRECT_OPS if !MMU
> + select DMA_REMAP if MMU
> select EDAC_SUPPORT
> select EDAC_ATOMIC_SCRUB
> select GENERIC_ALLOCATOR
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1b1a0e95c751..179994b67d11 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -77,6 +77,7 @@ config ARM64
> select CPU_PM if (SUSPEND || CPU_IDLE)
> select DCACHE_WORD_ACCESS
> select DMA_DIRECT_OPS
> + select DMA_REMAP
> select EDAC_SUPPORT
> select FRAME_POINTER
> select GENERIC_ALLOCATOR
> diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
> index 9a7c654a7654..d57abe4cad0f 100644
> --- a/arch/xtensa/Kconfig
> +++ b/arch/xtensa/Kconfig
> @@ -10,6 +10,7 @@ config XTENSA
> select CLONE_BACKWARDS
> select COMMON_CLK
> select DMA_DIRECT_OPS
> + select DMA_REMAP if MMU
> select GENERIC_ATOMIC64
> select GENERIC_CLOCKEVENTS
> select GENERIC_IRQ_SHOW
> diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
> index 645c7a2ecde8..c92e08173ed8 100644
> --- a/kernel/dma/Kconfig
> +++ b/kernel/dma/Kconfig
> @@ -51,3 +51,7 @@ config SWIOTLB
> bool
> select DMA_DIRECT_OPS
> select NEED_DMA_MAP_STATE
> +
> +config DMA_REMAP
> + depends on MMU
> + bool
> diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
> index 7d581e4eea4a..f4feeceb8020 100644
> --- a/kernel/dma/Makefile
> +++ b/kernel/dma/Makefile
> @@ -7,4 +7,4 @@ obj-$(CONFIG_DMA_DIRECT_OPS) += direct.o
> obj-$(CONFIG_DMA_VIRT_OPS) += virt.o
> obj-$(CONFIG_DMA_API_DEBUG) += debug.o
> obj-$(CONFIG_SWIOTLB) += swiotlb.o
> -
> +obj-$(CONFIG_DMA_REMAP) += remap.o
> diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
> index 58dec7a92b7b..dfbc3deb95cd 100644
> --- a/kernel/dma/mapping.c
> +++ b/kernel/dma/mapping.c
> @@ -262,87 +262,3 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> #endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
> }
> EXPORT_SYMBOL(dma_common_mmap);
> -
> -#ifdef CONFIG_MMU
> -static struct vm_struct *__dma_common_pages_remap(struct page **pages,
> - size_t size, unsigned long vm_flags, pgprot_t prot,
> - const void *caller)
> -{
> - struct vm_struct *area;
> -
> - area = get_vm_area_caller(size, vm_flags, caller);
> - if (!area)
> - return NULL;
> -
> - if (map_vm_area(area, prot, pages)) {
> - vunmap(area->addr);
> - return NULL;
> - }
> -
> - return area;
> -}
> -
> -/*
> - * remaps an array of PAGE_SIZE pages into another vm_area
> - * Cannot be used in non-sleeping contexts
> - */
> -void *dma_common_pages_remap(struct page **pages, size_t size,
> - unsigned long vm_flags, pgprot_t prot,
> - const void *caller)
> -{
> - struct vm_struct *area;
> -
> - area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> - if (!area)
> - return NULL;
> -
> - area->pages = pages;
> -
> - return area->addr;
> -}
> -
> -/*
> - * remaps an allocated contiguous region into another vm_area.
> - * Cannot be used in non-sleeping contexts
> - */
> -
> -void *dma_common_contiguous_remap(struct page *page, size_t size,
> - unsigned long vm_flags,
> - pgprot_t prot, const void *caller)
> -{
> - int i;
> - struct page **pages;
> - struct vm_struct *area;
> -
> - pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
> - if (!pages)
> - return NULL;
> -
> - for (i = 0; i < (size >> PAGE_SHIFT); i++)
> - pages[i] = nth_page(page, i);
> -
> - area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> -
> - kfree(pages);
> -
> - if (!area)
> - return NULL;
> - return area->addr;
> -}
> -
> -/*
> - * unmaps a range previously mapped by dma_common_*_remap
> - */
> -void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
> -{
> - struct vm_struct *area = find_vm_area(cpu_addr);
> -
> - if (!area || (area->flags & vm_flags) != vm_flags) {
> - WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
> - return;
> - }
> -
> - unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
> - vunmap(cpu_addr);
> -}
> -#endif
> diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
> new file mode 100644
> index 000000000000..33dff4096d46
> --- /dev/null
> +++ b/kernel/dma/remap.c
> @@ -0,0 +1,85 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/dma-mapping.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +
> +static struct vm_struct *__dma_common_pages_remap(struct page **pages,
> + size_t size, unsigned long vm_flags, pgprot_t prot,
> + const void *caller)
> +{
> + struct vm_struct *area;
> +
> + area = get_vm_area_caller(size, vm_flags, caller);
> + if (!area)
> + return NULL;
> +
> + if (map_vm_area(area, prot, pages)) {
> + vunmap(area->addr);
> + return NULL;
> + }
> +
> + return area;
> +}
> +
> +/*
> + * remaps an array of PAGE_SIZE pages into another vm_area
> + * Cannot be used in non-sleeping contexts
> + */
> +void *dma_common_pages_remap(struct page **pages, size_t size,
> + unsigned long vm_flags, pgprot_t prot,
> + const void *caller)
> +{
> + struct vm_struct *area;
> +
> + area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> + if (!area)
> + return NULL;
> +
> + area->pages = pages;
> +
> + return area->addr;
> +}
> +
> +/*
> + * Remaps an allocated contiguous region into another vm_area.
> + * Cannot be used in non-sleeping contexts
> + */
> +void *dma_common_contiguous_remap(struct page *page, size_t size,
> + unsigned long vm_flags,
> + pgprot_t prot, const void *caller)
> +{
> + int i;
> + struct page **pages;
> + struct vm_struct *area;
> +
> + pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
> + if (!pages)
> + return NULL;
> +
> + for (i = 0; i < (size >> PAGE_SHIFT); i++)
> + pages[i] = nth_page(page, i);
> +
> + area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> +
> + kfree(pages);
> +
> + if (!area)
> + return NULL;
> + return area->addr;
> +}
> +
> +/*
> + * Unmaps a range previously mapped by dma_common_*_remap
> + */
> +void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
> +{
> + struct vm_struct *area = find_vm_area(cpu_addr);
> +
> + if (!area || (area->flags & vm_flags) != vm_flags) {
> + WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
> + return;
> + }
> +
> + unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
> + vunmap(cpu_addr);
> +}

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