summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/pci-dma.c
diff options
context:
space:
mode:
authorAkinobu Mita <akinobu.mita@gmail.com>2014-06-04 16:06:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:53:57 -0700
commitd92ef66c4f8fdf7a24736b1ab6c48d32de9bfc07 (patch)
treebde652bc3ad56f3496fc3fe980c6b9dc6600efb5 /arch/x86/kernel/pci-dma.c
parent6b4ebc3a9078c5b7b8c4cf495a0b1d2d0e0bfe7a (diff)
x86: make dma_alloc_coherent() return zeroed memory if CMA is enabled
This patchset enhances the DMA Contiguous Memory Allocator on x86. Currently the DMA CMA is only supported with pci-nommu dma_map_ops and furthermore it can't be enabled on x86_64. But I would like to allocate big contiguous memory with dma_alloc_coherent() and tell it to the device that requires it, regardless of which dma mapping implementation is actually used in the system. So this makes it work with swiotlb and intel-iommu dma_map_ops, too. And this also extends "cma=" kernel parameter to specify placement constraint by the physical address range of memory allocations. For example, CMA allocates memory below 4GB by "cma=64M@0-4G", it is required for the devices only supporting 32-bit addressing on 64-bit systems without iommu. This patch (of 5): Calling dma_alloc_coherent() with __GFP_ZERO must return zeroed memory. But when the contiguous memory allocator (CMA) is enabled on x86 and the memory region is allocated by dma_alloc_from_contiguous(), it doesn't return zeroed memory. Because dma_generic_alloc_coherent() forgot to fill the memory region with zero if it was allocated by dma_alloc_from_contiguous() Most implementations of dma_alloc_coherent() return zeroed memory regardless of whether __GFP_ZERO is specified. So this fixes it by unconditionally zeroing the allocated memory region. Alternatively, we could fix dma_alloc_from_contiguous() to return zeroed out memory and remove memset() from all caller of it. But we can't simply remove the memset on arm because __dma_clear_buffer() is used there for ensuring cache flushing and it is used in many places. Of course we can do redundant memset in dma_alloc_from_contiguous(), but I think this patch is less impact for fixing this problem. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Don Dutile <ddutile@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/kernel/pci-dma.c')
-rw-r--r--arch/x86/kernel/pci-dma.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index f7d0672481fd..e5f4e9629e61 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -97,7 +97,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
dma_mask = dma_alloc_coherent_mask(dev, flag);
- flag |= __GFP_ZERO;
+ flag &= ~__GFP_ZERO;
again:
page = NULL;
/* CMA can be used only in the context which permits sleeping */
@@ -120,7 +120,7 @@ again:
return NULL;
}
-
+ memset(page_address(page), 0, size);
*dma_addr = addr;
return page_address(page);
}