Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code
> > +int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
> > +{
> > + unsigned int pool_size_order = get_order(atomic_pool_size);
> > + unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
> > + struct page *page;
> > + void *addr;
> > + int ret;
> > +
> > + if (dev_get_cma_area(NULL))
> > + page = dma_alloc_from_contiguous(NULL, nr_pages,
> > +pool_size_order, false);
> > + else
> > + page = alloc_pages(gfp, pool_size_order);
> > + if (!page)
> > + goto out;
> > +
> > + memset(page_address(page), 0, atomic_pool_size);
>
> Note that this won't work if 'page' is a highmem page - should there
> be a check for that, or a check for the gfp flags?
>
> Also, is this memset() actually useful, or a waste of cycles - when we
> allocate from this pool (see dma_alloc_from_pool()), we always memset()
> the buffer.
Currently there is no user that supports highmem, but yes, the memset
should probably simply be removed.
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Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code
On Mon, Nov 05, 2018 at 01:19:26PM +0100, Christoph Hellwig wrote:
> The arm64 codebase to implement coherent dma allocation for architectures
> with non-coherent DMA is a good start for a generic implementation, given
> that is uses the generic remap helpers, provides the atomic pool for
> allocations that can't sleep and still is realtively simple and well
> tested. Move it to kernel/dma and allow architectures to opt into it
> using a config symbol. Architectures just need to provide a new
> arch_dma_prep_coherent helper to writeback an invalidate the caches
> for any memory that gets remapped for uncached access.
>
> Signed-off-by: Christoph Hellwig
> ---
> arch/arm64/Kconfig | 2 +-
> arch/arm64/mm/dma-mapping.c | 184 ++--
> include/linux/dma-mapping.h | 5 +
> include/linux/dma-noncoherent.h | 2 +
> kernel/dma/Kconfig | 6 ++
> kernel/dma/remap.c | 158 ++-
> 6 files changed, 181 insertions(+), 176 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 5d065acb6d10..2e645ea693ea 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -82,7 +82,7 @@ config ARM64
> select CRC32
> select DCACHE_WORD_ACCESS
> select DMA_DIRECT_OPS
> - select DMA_REMAP
> + select DMA_DIRECT_REMAP
> select EDAC_SUPPORT
> select FRAME_POINTER
> select GENERIC_ALLOCATOR
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index a3ac26284845..e2e7e5d0f94e 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -33,113 +33,6 @@
>
> #include
>
> -static struct gen_pool *atomic_pool __ro_after_init;
> -
> -#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K
> -static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
> -
> -static int __init early_coherent_pool(char *p)
> -{
> - atomic_pool_size = memparse(p, &p);
> - return 0;
> -}
> -early_param("coherent_pool", early_coherent_pool);
> -
> -static void *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t
> flags)
> -{
> - unsigned long val;
> - void *ptr = NULL;
> -
> - if (!atomic_pool) {
> - WARN(1, "coherent pool not initialised!\n");
> - return NULL;
> - }
> -
> - val = gen_pool_alloc(atomic_pool, size);
> - if (val) {
> - phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
> -
> - *ret_page = phys_to_page(phys);
> - ptr = (void *)val;
> - memset(ptr, 0, size);
> - }
> -
> - return ptr;
> -}
> -
> -static bool __in_atomic_pool(void *start, size_t size)
> -{
> - return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
> -}
> -
> -static int __free_from_pool(void *start, size_t size)
> -{
> - if (!__in_atomic_pool(start, size))
> - return 0;
> -
> - gen_pool_free(atomic_pool, (unsigned long)start, size);
> -
> - return 1;
> -}
> -
> -void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
> - gfp_t flags, unsigned long attrs)
> -{
> - struct page *page;
> - void *ptr, *coherent_ptr;
> - pgprot_t prot = pgprot_writecombine(PAGE_KERNEL);
> -
> - size = PAGE_ALIGN(size);
> -
> - if (!gfpflags_allow_blocking(flags)) {
> - struct page *page = NULL;
> - void *addr = __alloc_from_pool(size, &page, flags);
> -
> - if (addr)
> - *dma_handle = phys_to_dma(dev, page_to_phys(page));
> -
> - return addr;
> - }
> -
> - ptr = dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs);
> - if (!ptr)
> - goto no_mem;
> -
> - /* remove any dirty cache lines on the kernel alias */
> - __dma_flush_area(ptr, size);
> -
> - /* create a coherent mapping */
> - page = virt_to_page(ptr);
> - coherent_ptr = dma_common_contiguous_remap(page, size, VM_USERMAP,
> -prot,
> __builtin_return_address(0));
> - if (!coherent_ptr)
> - goto no_map;
> -
> - return coherent_ptr;
> -
> -no_map:
> - dma_direct_free_pages(dev, size, ptr, *dma_handle, attrs);
> -no_mem:
> - return NULL;
> -}
> -
> -void arch_dma_free(struct device *dev, size_t size, void *vaddr,
> - dma_addr_t dma_handle, unsigned long attrs)
> -{
> - if (!__free_from_pool(vaddr, PAGE_ALIGN(size))) {
> - void *kaddr = phys_to_virt(dma_to_phys(dev, dma_handle));
> -
> - vunmap(vaddr);
> - dma_direct_free_pages(dev, size, kaddr, dma_handle, attrs);
> - }
> -}
> -
> -long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
> - dma_addr_t dma_addr)
> -{
> - return __phys_to_pfn(dma_to_phys(dev, dma_addr));
> -}
> -
> pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
> unsigned long att
Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code
On Fri, Nov 30, 2018 at 07:05:23PM +, Robin Murphy wrote:
> It's a bit yuck that we now end up with arch_* hooks being a mix of arch
> code and not-actually-arch-code, but I guess there's some hope of coming
> back and streamlining things in future once all the big moves are done.
Yes, I hope we can use some form of common code here for most
architectures eventually. But that will some time.
> I can't really be bothered to nitpick the typos above and the slight
> inconsistencies in some of the cosmetic code changes, but one worthwhile
> thing stands out...
I'm usually fine picking up nitpicks. For now I'll apply the series
with the pointed out fixups, but if you want to send the fixups
I'd be glad.
>> +val = gen_pool_alloc(atomic_pool, size);
>> +if (val) {
>> +phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
>> +
>> +*ret_page = phys_to_page(phys);
>
> Looks like phys_to_page() isn't particularly portable, so we probably want
> an explicit pfn_to_page(__phys_to_pfn(phys)) here. Otherwise, the
> fundamental refactoring looks OK.
Ok, I'll updated it.
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Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code
On 05/11/2018 12:19, Christoph Hellwig wrote:
The arm64 codebase to implement coherent dma allocation for architectures
with non-coherent DMA is a good start for a generic implementation, given
that is uses the generic remap helpers, provides the atomic pool for
allocations that can't sleep and still is realtively simple and well
tested. Move it to kernel/dma and allow architectures to opt into it
using a config symbol. Architectures just need to provide a new
arch_dma_prep_coherent helper to writeback an invalidate the caches
for any memory that gets remapped for uncached access.
It's a bit yuck that we now end up with arch_* hooks being a mix of arch
code and not-actually-arch-code, but I guess there's some hope of coming
back and streamlining things in future once all the big moves are done.
I can't really be bothered to nitpick the typos above and the slight
inconsistencies in some of the cosmetic code changes, but one worthwhile
thing stands out...
Signed-off-by: Christoph Hellwig
---
arch/arm64/Kconfig | 2 +-
arch/arm64/mm/dma-mapping.c | 184 ++--
include/linux/dma-mapping.h | 5 +
include/linux/dma-noncoherent.h | 2 +
kernel/dma/Kconfig | 6 ++
kernel/dma/remap.c | 158 ++-
6 files changed, 181 insertions(+), 176 deletions(-)
[...]
+void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
+{
+ unsigned long val;
+ void *ptr = NULL;
+
+ if (!atomic_pool) {
+ WARN(1, "coherent pool not initialised!\n");
+ return NULL;
+ }
+
+ val = gen_pool_alloc(atomic_pool, size);
+ if (val) {
+ phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
+
+ *ret_page = phys_to_page(phys);
Looks like phys_to_page() isn't particularly portable, so we probably
want an explicit pfn_to_page(__phys_to_pfn(phys)) here. Otherwise, the
fundamental refactoring looks OK.
Reviewed-by: Robin Murphy
[ In fact, looking at phys_to_page(), microblaze, riscv, unicore and
csky (by the end of this series if it's fixed here) don't need to define
it at all; s390 defines it for the sake of a single call in a single
driver; it's used in two other places in arm-related drivers but at
least one of those is clearly wrong. All in all it's quite the sorry mess. ]
+ ptr = (void *)val;
+ memset(ptr, 0, size);
+ }
+
+ return ptr;
+}
+
+bool dma_free_from_pool(void *start, size_t size)
+{
+ if (!dma_in_atomic_pool(start, size))
+ return false;
+ gen_pool_free(atomic_pool, (unsigned long)start, size);
+ return true;
+}
+
+void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+ gfp_t flags, unsigned long attrs)
+{
+ struct page *page = NULL;
+ void *ret, *kaddr;
+
+ size = PAGE_ALIGN(size);
+
+ if (!gfpflags_allow_blocking(flags)) {
+ ret = dma_alloc_from_pool(size, &page, flags);
+ if (!ret)
+ return NULL;
+ *dma_handle = phys_to_dma(dev, page_to_phys(page));
+ return ret;
+ }
+
+ kaddr = dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs);
+ if (!kaddr)
+ return NULL;
+ page = virt_to_page(kaddr);
+
+ /* remove any dirty cache lines on the kernel alias */
+ arch_dma_prep_coherent(page, size);
+
+ /* create a coherent mapping */
+ ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
+ arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
+ __builtin_return_address(0));
+ if (!ret)
+ dma_direct_free_pages(dev, size, kaddr, *dma_handle, attrs);
+ return ret;
+}
+
+void arch_dma_free(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_handle, unsigned long attrs)
+{
+ if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) {
+ void *kaddr = phys_to_virt(dma_to_phys(dev, dma_handle));
+
+ vunmap(vaddr);
+ dma_direct_free_pages(dev, size, kaddr, dma_handle, attrs);
+ }
+}
+
+long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
+ dma_addr_t dma_addr)
+{
+ return __phys_to_pfn(dma_to_phys(dev, dma_addr));
+}
+#endif /* CONFIG_DMA_DIRECT_REMAP */
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Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code
Hi Christoph, Minor nit: typo in the subject "ncoherent". On Mon, Nov 05, 2018 at 01:19:26PM +0100, Christoph Hellwig wrote: > The arm64 codebase to implement coherent dma allocation for architectures > with non-coherent DMA is a good start for a generic implementation, given > that is uses the generic remap helpers, provides the atomic pool for > allocations that can't sleep and still is realtively simple and well > tested. Move it to kernel/dma and allow architectures to opt into it > using a config symbol. Architectures just need to provide a new > arch_dma_prep_coherent helper to writeback an invalidate the caches > for any memory that gets remapped for uncached access. > > Signed-off-by: Christoph Hellwig > --- > arch/arm64/Kconfig | 2 +- > arch/arm64/mm/dma-mapping.c | 184 ++-- > include/linux/dma-mapping.h | 5 + > include/linux/dma-noncoherent.h | 2 + > kernel/dma/Kconfig | 6 ++ > kernel/dma/remap.c | 158 ++- > 6 files changed, 181 insertions(+), 176 deletions(-) I'm currently at LPC, so I've not been able to test this, but I've been through the changes this morning and they look fine to me, so: Reviewed-by: Will Deacon Hopefully we'll get the fallout from the previous changes addressed next week. Cheers, Will ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
